WO2024137988A2 - Respiratory support control using respiratory rate - Google Patents

Respiratory support control using respiratory rate

Info

Publication number
WO2024137988A2
WO2024137988A2 PCT/US2023/085431 US2023085431W WO2024137988A2 WO 2024137988 A2 WO2024137988 A2 WO 2024137988A2 US 2023085431 W US2023085431 W US 2023085431W WO 2024137988 A2 WO2024137988 A2 WO 2024137988A2
Authority
WO
WIPO (PCT)
Prior art keywords
patient
flow rate
operating
respiratory
rate
Prior art date
Application number
PCT/US2023/085431
Other languages
French (fr)
Inventor
Benjamin Wilson Casse
Brett John Huddart
Anton Kim GULLEY
Julie Jackson
Original Assignee
Fisher & Paykel Healthcare Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fisher & Paykel Healthcare Limited filed Critical Fisher & Paykel Healthcare Limited
Publication of WO2024137988A2 publication Critical patent/WO2024137988A2/en

Links

Abstract

A method for controlling the flow rate of gas delivered to a patient, comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.

Description

RESPIRATORY SUPPORT CONTROL USING RESPIRATORY RATE
FIELD OF THE DISCLOSURE
The present disclosure relates to methods and systems for providing a respiratory flow therapy to a patient. In particular, the present disclosure relates to controlling operating parameters during use of an unsealed respiratory apparatus (i.e. open respiratory apparatus) by a patient, based on the patient's measured respiratory rate.
BACKGROUND
Breathing assistance apparatuses are used in various environments such as hospital, medical facility, residential care, or home environments to deliver a flow of gases to users or patients. A breathing assistance or respiratory therapy apparatus (collectively, "respiratory apparatus" or "respiratory devices") may be used to deliver supplementary oxygen or other gases with a flow of gases, and/or a humidification apparatus to deliver heated and humidified gases. A respiratory apparatus may allow adjustment and control over characteristics of the gases flow, including flow rate and gases concentration.
SUMMARY
In a first aspect, the present disclosure broadly comprises a method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to a patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate. In a configuration, the method further comprises delivering a gas flow to a patient via a patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more patient characteristics.
In a configuration, the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
In a configuration, the one or more sensors comprise one or more sensors configured to be attached to or located near to a patient to measure a patient parameter indicative of the patient's respiratory rate.
In a configuration, the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
In a configuration, wherein the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time-averaged respiratory rate.
In a configuration, wherein the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
In a configuration, the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
In a configuration, the status of the patient's respiratory rate indicates that a patient's respiratory rate is increasing, or is decreasing, or is substantially stable, based on said comparison. In a configuration, the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate further comprises comparing the status of the patient's respiratory rate to one or more thresholds.
In a configuration, the step of adjusting the operating flow rate by an increment comprises increasing the operating flow rate by an increment based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
In a configuration, the increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
In a configuration, the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
In a configuration, the method is performed continually over a therapy session.
In a configuration, the gas is delivered to a patient at conditions suitable for the provision of high flow therapy.
In a configuration, the method further comprises delivering a gas flow to a patient via a patient interface at an operating oxygen concentration level. In a configuration, the method further comprises, at said intervals, performing the steps of: determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In a second aspect, the present disclosure broadly comprises a method for controlling operating parameters of gas delivered to a patient, said method comprising: delivering a gas flow to a patient via a patient interface at an operating flow rate and an operating oxygen concentration level; at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate and the operating oxygen concentration level based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In a third aspect, the present disclosure broadly comprises a method for controlling operating parameters of gas delivered to a patient, said method comprising: delivering a gas flow to a patient via a patient interface at an operating flow rate and an operating oxygen concentration level; at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate and determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, wherein based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
The method of the second aspect or the third aspect may further have any one or more of the following aspects or features defined in the following paragraphs.
In a configuration, wherein the method further comprises delivering a gas flow to a patient via a patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more patient characteristics.
In a configuration, the method further comprises delivering a gas flow to a patient via a patient interface at an initial operating oxygen concentration level, wherein the initial operating oxygen concentration level is determined based on one or more patient characteristics.
In a configuration, the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
In a configuration, the one or more sensors comprise one or more sensors configured to be attached to or located near to a patient to measure a patient parameter indicative of the patient's respiratory rate. In a configuration, the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
In a configuration, the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time-averaged respiratory rate.
In a configuration, the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
In a configuration, the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
In a configuration, the status of the patient's respiratory rate indicates that a patient's respiratory rate is increasing, or is decreasing, or is substantially stable, based on said comparison.
In a configuration, the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
In a configuration, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate and/or the operating oxygen concentration level further comprises comparing the status of the patient's respiratory rate to one or more thresholds. In a configuration, the step of adjusting the operating flow rate by an increment comprises increasing the operating flow rate by an increment based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
In a configuration, the increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
In a configuration, the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
In a configuration, the method is performed continually over a therapy session.
In a configuration, wherein the gas is delivered to a patient at conditions suitable for the provision of high flow therapy.
In a fourth aspect, the present disclosure broadly comprises a method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to a patient via a patient interface at an operating flow rate; at intervals, progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors, and determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals; based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable, maintaining the operating flow rate, and performing the iterative process of continuing to receive or determine said patient parameter and determine said status of the patient's respiratory rate at further intervals, wherein based on the status of the patient's respiratory rate indicating the patient's respiratory rate is no longer stable, adjusting the operating flow rate at said further intervals until the status of the patient's respiratory rate indicates that the patient's respiratory rate is stable. In a configuration, the step of receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors occurs at a predetermined time period after adjusting the operating flow rate.
In a configuration, the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable comprises determining that said status of the patient's respiratory rate is within a range or threshold.
In a configuration, the status of the patient's respiratory rate indicating that the patient's respiratory rate is no longer stable comprises determining that said status of the patient's respiratory rate is outside a range or threshold.
In a configuration, the method further comprises delivering a gas flow to a patient via a patient interface at an initial operating flow rate, wherein the initial flow rate is determined based on one or more patient characteristics.
In a configuration, the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
In a configuration, the one or more sensors comprise one or more sensors configured to be attached to or located near to a patient to measure a patient parameter indicative of the patient's respiratory rate.
In a configuration, wherein the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
In a configuration, the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time-averaged respiratory rate. In a configuration, the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
In a configuration, the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
In a configuration, the status of the patient's respiratory rate indicates that a patient's respiratory rate is increasing, or is decreasing, or is stable, based on said comparison.
In a configuration, the step of determining whether the patient's respiratory rate is unstable comprises the status of the patient's respiratory rate indicating that the patient's respiratory rate is increasing or decreasing.
In a configuration, the step of progressively applying a plurality of flow rate values as the operating flow rate comprises increasing the operating flow rate by an increment at each interval.
In a configuration, said increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
In a configuration, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
In a configuration, the method is performed continually over a therapy session.
In a configuration, the gas is delivered to a patient at conditions suitable for the provision of high flow therapy. In a configuration, the method further comprises delivering a gas flow to a patient via a patient interface at an operating oxygen concentration level.
In a configuration, the method further comprises, at said intervals, performing the steps of: determining whether to adjust or maintain the operating oxygen concentration level based on at least the patient parameter indicative of the patient's respiratory rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In a fifth aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to a patient; a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
In a sixth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
In a seventh aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to a patient; a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate and the operating oxygen concentration level based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In an eighth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate and the operating oxygen concentration level based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In a ninth aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to a patient; a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate and determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, wherein based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In a tenth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate and determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, wherein based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In an eleventh aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to a patient; a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors, and determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals; based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable, maintaining the operating flow rate, and performing the iterative process of continuing to receive or determine said patient parameter and determine said status of the patient's respiratory rate at further intervals, wherein based on the status of the patient's respiratory rate indicating the patient's respiratory rate is no longer stable, adjusting the operating flow rate at said further intervals until the status of the patient's respiratory rate indicates that the patient's respiratory rate is stable.
In a twelfth aspect, the present disclosure broadly comprises a respiratory apparatus configured to provide a flow of gases to a user for respiratory therapy, comprising a flow generator configured to generate the flow of gases for the user at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors, and determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals; based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable, maintaining the operating flow rate, and performing the iterative process of continuing to receive or determine said patient parameter and determine said status of the patient's respiratory rate at further intervals, wherein based on the status of the patient's respiratory rate indicating the patient's respiratory rate is no longer stable, adjusting the operating flow rate at said further intervals until the status of the patient's respiratory rate indicates that the patient's respiratory rate is stable.
The respiratory therapy system of any of the fifth aspect, seventh aspect, ninth aspect, or eleventh aspect, or the respiratory apparatus of the sixth aspect, eighth aspect, tenth aspect, or twelfth aspect, may further have any one or more of the following aspects or features defined in the following paragraphs. In a configuration, wherein the flow generator is further configured to delivering a gas flow to a patient via a patient interface at an initial operating flow rate, and wherein the initial operating flow rate is determined based on one or more patient characteristics.
In a configuration, the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
In a configuration, the one or more sensors comprise one or more sensors configured to be attached to or located near to a patient to measure a patient parameter indicative of the patient's respiratory rate.
In a configuration, the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
In a configuration, the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time-averaged respiratory rate.
In a configuration, the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
In a configuration, wherein the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
In a configuration, the status of the patient's respiratory rate indicates that a patient's respiratory rate is increasing, or is decreasing, or is substantially stable, based on said comparison. In a configuration, the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate further comprises comparing the status of the patient's respiratory rate to one or more thresholds.
In a configuration, the step of adjusting the operating flow rate by an increment comprises increasing the operating flow rate by an increment based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
In a configuration, the increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
In a configuration, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
In a configuration, the steps are performed at said intervals continually over a therapy session.
In a configuration, the gas is delivered to a patient at conditions suitable for the provision of high flow therapy.
In a configuration, the controller is further configured to deliver a gas flow to a patient via a patient interface at an operating oxygen concentration level. In a configuration, the controller is further configured to deliver a gas flow to a patient via a patient interface at an initial operating oxygen concentration level, wherein the initial operating oxygen concentration level is determined based on one or more patient characteristics.
In a configuration, the controller is further configured to, at said intervals, perform the steps of: determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
In a configuration, the system or apparatus further comprises a humidifier configured to humidify the flow of gases.
In a thirteenth aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a user for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to a patient; a flow generator configured to generate the flow of gases for the user at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to: receive or determine a patient parameter indicative of the patient's respiratory rate based on data received from the one or more sensors, and control the operating flow rate of the flow generator based on the received or determined patient parameter indicative of the patient's respiratory rate.
The respiratory therapy system of the thirteenth aspect, may have any one or more of the aspects or features defined in relation to the fifth aspect, the seventh aspect, the ninth aspect, or the eleventh aspect.
In a fourteenth aspect, the present disclosure broadly comprises a method for controlling the flow rate of gas delivered to a patient, said method comprising delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more non-patient contacting sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
The method of the fourteenth aspect, may have any one or more of the aspects or features defined in relation to the first aspect, the second aspect, the third aspect, or the fourth aspect.
In a fifteenth aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient at an operating flow rate; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more non-patient contacting sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from the one or more non-patient contacting sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
The respiratory therapy system of the fifteenth aspect, may have any one or more of the aspects or features defined in relation to the fifth aspect, the seventh aspect, the ninth aspect, the eleventh aspect, or the thirteenth aspect.
In a sixteenth aspect, the present disclosure broadly comprises a method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
The method of the sixteenth aspect, may have any one or more of the aspects or features defined in relation to the first aspect, the second aspect, the third aspect, the fourth aspect, or the fourteenth aspect.
In a configuration, the method further comprises receiving or determining a patient parameter indicative of the patient's SpO2 based on data from one or more sensors.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate is based further on comparing the patient parameter indicative of the patient's SpO2 to one or more thresholds.
In a configuration, wherein the method further comprises receiving or determining a therapy parameter indicative of the FiO2 being provided or to be provided to the patient.
In a configuration, the therapy parameter indicative of the FiO2 being provided or to be provided to the patient is based at least in part on the patient parameter indicative of the patient's SpO2.
In a configuration, the step of determining whether to adjust or maintain the operating flow rate is based further on comparing the patient therapy indicative of the FiO2 being provided or to be provided to the patient to one or more thresholds.
In a configuration, the one or more thresholds comprise one or more parameter thresholds, each of the one or more parameter thresholds relating to a patient or therapy parameter. In a configuration, the or each parameter threshold is set by a user. In a configuration, the parameter threshold relates to a maximum acceptable respiratory rate.
In a configuration, the one or more thresholds further comprise a time based threshold. In a configuration, the time based threshold is set by a user. In a configuration, the time based threshold relates to a minimum amount of time the patient parameter is above the patient parameter threshold.
In a configuration, the increment for the operating flow rate to be adjusted by is an increase in the operating flow rate. In a configuration, the increment is an absolute or fixed amount. In a configuration, the increment is a percentage or fraction of the operational flow rate. In a configuration, wherein the increment for the operating flow rate is set by a user.
In a configuration, adjusting the operating flow rate by an increment comprises changing the operating flow rate by a step change. In a configuration, adjusting the operating flow rate by an increment comprises ramping the operating flow rate.
In a configuration, when the operating flow rate is adjusted by the increment, the method further comprises displaying a prompt or alert to the user indicating the operating flow rate has been adjusted.
In a configuration, the method further comprises presenting an audible alarm to the user indicating the operating flow rate has been adjusted.
In a configuration, once the operating flow rate has been adjusted by the increment, the method no longer comprises determining whether to adjust or maintain the operating flow rate.
In a seventeenth aspect, the present disclosure broadly comprises a respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
The respiratory therapy system of the seventeenth aspect, may have any one or more of the aspects or features defined in relation to the sixteenth aspect, the fifth aspect, the seventh aspect, the ninth aspect, the eleventh aspect, or the thirteenth aspect.
In another aspect, the present disclosure relates to an electronically-implemented method comprising software code or coded instructions that are executable or implemented by a computer, processor, or controller to carry out any one or more of the methods or aspects described above.
In another aspect, the present disclosure broadly comprises a non-transitory computer- readable medium having stored thereon computer executable instructions that, when executed on a processing device or devices, cause the processing device or devices to perform or execute any one or more of the methods or aspects described above.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure.
Figure 1 shows schematically a respiratory system configured to provide a respiratory therapy to a patient. Figure 2 is a front view of an example respiratory device with a humidification chamber in position and a raised handle/lever.
Figure 3 is a top view corresponding to Figure 2.
Figure 4 is a right side view corresponding to Figure 2.
Figure 5 is a left side view corresponding to Figure 2.
Figure 6 is a rear view corresponding to Figure 2.
Figure 7 is a front left perspective view corresponding to Figure 2.
Figure 8 is a front right perspective view corresponding to Figure 2.
Figure 9 is a bottom view corresponding to Figure 2.
Figure 10 shows an example configuration of an air and oxygen inlet arrangement of a respiratory device.
Figure 11 shows another example configuration of an air and oxygen inlet arrangement of the respiratory device.
Figure 12 is a transverse sectional view showing further detail of the air and oxygen inlet arrangement of Figure 11.
Figure 13 is another transverse sectional view showing further detail of the air and oxygen inlet arrangement of Figure 11.
Figure 14 is a longitudinal sectional view showing further detail of the air and oxygen inlet arrangement of Figure 11.
Figure 15 is an exploded view of upper and lower chassis components of a main housing of the respiratory device.
Figure 16 is a front left side perspective view of the lower chassis of the main housing showing a housing for receipt of a motor/sensor module sub-assembly.
Figure 17 is a first underside perspective view of the main housing of the respiratory device showing a recess inside the housing for the motor/sensor module sub-assembly.
Figure 18 is a second underside perspective view of the main housing of the respiratory device showing the recess for the motor/sensor module sub-assembly.
Figure 19A illustrates a block diagram of a control system interacting with and/or providing control and direction to components of a respiratory system.
Figure 19B illustrates a block diagram of an example controller.
Figure 20 illustrates a block diagram of a motor and sensor module.
Figure 21 illustrates a sensing chamber of an example motor and sensor module. Figure 22 shows schematically a respiratory system configured to provide a respiratory therapy to a patient.
Figure 23 illustrates a block diagram of a control system interacting with and/or providing control and direction to components of a respiratory system.
Figure 24 shows a flow diagram of an embodiment of an operating flow rate determination process.
Figure 25 shows a flow diagram of an embodiment of an operating flow rate and operating oxygen concentration level determination process.
Figure 26 shows a graphical representation of an example respiratory rate versus flow rate relationship.
Figure 27 show a graphical representation of an example respiratory rate versus flow rate relationship.
Figure 28 show a graphical representation of an example respiratory rate versus flow rate relationship.
Figure 29 show a graphical representation of an example respiratory rate versus flow rate relationship.
Figure 30 shows a flow diagram of an embodiment of an operating oxygen concentration level determination process.
DETAILED DESCRIPTION
Although certain examples are described below, those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed examples and/or uses and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the disclosure herein disclosed should not be limited by any particular examples described below.
A respiratory assistance system including a humidification apparatus may be used to deliver heated and humidified respiratory gases to a patient through a conduit and a patient interface. The respiratory assistance system can provide a number of therapies for patients requiring respiratory support. One of the therapies includes providing a high flow therapy. In high flow therapy, the respiratory support system delivers relatively high flows of gases through a nasal interface, which may be unsealed. The flow of gases can be in the range of 5L/min to 120L/min. In some examples, the flow of gases can be in the range of 10L/min to 120L/min. In some examples, the flow of gases can be in the range of 20L/min to 120L/min. In some examples, the flow of gases is in the range of 30L/Min to 50L/min. In some examples, the flow rate of gases can be as high as 60 L/min. In some examples, the flow rate is greater than 60 L/min, but less than 120 L/min. In other examples, the flow rate is 120 L/min or higher. The respiration assistance system can adjust the flow rate of gases during the treatment through a control system. A discussion of high flow therapy and how the flow rate can be changed in a respiratory assistance system can be found in PCT Pub. No. WO 2015/033288, titled "Improvements to Flow Therapy", which is hereby incorporated by reference in its entirety.
The flow rate in the high flow therapies may be a function of patient condition and can vary during the treatment. A clinician or patient may not be able to determine the value of the flow rate for the respiratory assistance system to provide the optimal therapy and comfort. Care providers often do not know proper flow rates for particular patients and tend to set flow rates too low or too high to be clinically optimal. Care providers also often do not know how to gauge the effectiveness of the therapy or how long they should wait to determine effectiveness.
Accordingly, the present disclosure provides methods and systems for controlling operating parameters of the device, specifically flow rate and/or oxygen concentration level, for a given patient. The methods can be performed by a control system of the device. The respiratory assistance device and system discussed below include a control system implemented using a controller for controlling the operating parameters of the device. The control system can control the operating flow rate and/or oxygen concentration level of gas delivered to a patient automatically over the time of therapy and based on changes in patient conditions. Thus, the control system may advantageously improve the efficacy of the high flow therapy and reduce the probability of the patient requiring more invasive treatment such as invasive mechanical ventilation. A flow rate and/or oxygen concentration level control method for high flow respiratory therapy may help in a patient spending less time with a flow rate set too high or too low for their immediate breathing support requirements over the course of the therapy. Flow rate is likely to affect a number of physiological and clinical parameters including work of breathing, end tidal CO2, respiration rate, thoraco-abdominal phase, and other parameters of clinical relevance. The control system and method described can automatically control an operating high flow respiratory therapy flow rate based at least on a patient parameter indicative of the patient's respiratory rate.
Physiological parameters such as respiratory rate may provide information on whether a patient's condition is worsening or improving. Physiological parameters such as respiratory rate may also provide information on when a patient has stabilised after being placed on high flow therapy. Using respiratory rate can thus aid in controlling operating parameters relating to the provision of high flow respiratory therapy. Respiratory rate can provide a means to identify optimal or otherwise acceptable operating parameters or therapy settings when a patient is receiving high flow therapy.
Controlling operating parameters based on physiological parameters typically involves monitoring how a physiological parameters such as respiratory rate changes or reacts in order to determine optimal operating parameters for high flow therapy. If the operating parameters are changed manually by a clinician or other person in response to measured physiological parameters, it can be a very time-consuming process to reach optimal operating parameters. It is unlikely that the operating parameters are set at optimal or otherwise acceptable conditions due to this requirement of a long titration duration, as clinicians will not have the time needed to do so.
Some physiological parameters used can also take an impractically long time to change in response to therapy changes or to a worsening patient condition. One example of this is SpO2, which is widely used as a physiological parameter. Generally, when a patient's condition worsens, the body initially keeps SpO2 levels stable by increasing minute ventilation and providing more oxygen to the lungs. As such, SpO2 levels may only be affected after a significant delay and/or once the patient's condition has greatly deteriorated. In such cases, it is impractical to use these physiological parameters for therapy parameter control, which requires minimised response delay. There is thus a need for a control system and method that can automatically control operating parameters of a respiratory therapy device based on a measured patient condition. Such a system should be able to titrate the parameters to optimal or otherwise acceptable values when a patient is using the therapy. The patient condition should be measured using a physiological parameter that provides early-indication of changes in patient condition, and that is accurately and continuously measured.
The control system's automatic control of the operating parameters of the respiratory therapy device can help to deliver optimal respiratory therapy to the patient, and can help to reduce their respiratory rate, which allows the patient to be more relaxed and reduces their work of breathing, or in other terms the physical load of breathing hard. The control system can also assist in faster identification of therapy success or failure. For example, it may be advantageous to know that high flow therapy is not working on a particular patient earlier rather than later. The control system may compare the physiological parameters of the patient as a function of flow rate to expected predetermined parameters for determining effectiveness of the therapy.
Delivery of optimal respiratory therapy by controlling the operating parameters of a respiratory therapy device can help to reduce a patient's respiratory distress and to reduce their work of breathing i.e. the effort it takes them to breathe. As will be discussed, the respiratory rate of the patient can provide an indication of their work of breathing. In particular, a higher respiratory rate may be indicative of higher work of breathing. The present disclosure relates to controlling a respiratory apparatus based on respiratory rate to reduce work of breathing.
The control system discussed may generate an indication of the operating parameters such as flow rate or oxygen concentration level for display to a physician. The control system may warn the clinician if the therapy is not efficacious for the particular patient based on the sensitivity or insensitivity of clinical and physiological parameters (such as a measured respiratory rate) to the operating parameters. The present disclosure may detect if the respiratory therapy is not efficacious and indicate this to a clinician. The clinician can then make a decision to escalate the patient to a different therapy e.g. Bi-Level pressure therapy or invasive ventilation.
1. Overview of Respiratory Assistance System
The methods and processes of controlling the flow rate of gas delivered to a patient, will be described in the context of an example respiratory apparatus 10 that is configured or operable to provide nasal high flow therapy via a unsealed patient interface. This is intended as a non-limiting example. It will be appreciated that the methods and processes may be applied to other respiratory apparatus and/or to other modes of operation and/or modes of therapy delivered by such apparatus.
A schematic representation of the example respiratory apparatus 10 is provided in Figure 1.
The respiratory apparatus 10 (or 'respiratory system') comprises a flow source 50 for providing a high flow gas 31 such as air, oxygen, air blended with oxygen, or a mix of air and/or oxygen and one or more other gases. Alternatively, the breathing assistance apparatus can have a connection for coupling to a flow source. As such, the flow source might be considered to form part of the apparatus or be separate to it, depending on context, or even part of the flow source forms part of the apparatus, and part of the flow source falls outside of the apparatus. In short, depending on the configuration (some components may be optional), the system can include a combination of components selected from the following:
• a flow source
• humidifier for humidifying the gas-flow,
• conduit (e.g. dry line or heated breathing tube),
• patient interface,
• non-return valve,
• filter.
The apparatus or system will be described in more detail. The flow source could be an in-wall supply of oxygen, a tank of oxygen 50A, a tank of other gas and/or a high flow apparatus with a flow generator 50B. Figure 1 shows a flow source 50 with a flow generator 50B, with an optional air inlet 50C and optional connection to an 02 source (such as tank or 02 generator) 50A via a shut off valve and/or regulator and/or other gas flow control 50D, but this is just one option. The flow generator 50B can control flows delivered to the patient 56 using one or more valve, or optionally the flow generator 50B can comprise a blower. The flow source could be one or a combination of a flow generator 50B, 02 source 50A, air source 50C as described. The flow source 50 is shown as part of the apparatus 10, although in the case of an external oxygen tank or in-wall source, it may be considered a separate component, in which case the apparatus has a connection port to connect to such flow source. The flow source provides a (preferably high) flow of gas that can be delivered to a patient via a delivery conduit 16, and patient interface 51.
The patient interface 51 may be an unsealed (non-sealing) interface (for example when used in high flow therapy) such as a non-sealing nasal cannula, or non-sealing tracheostomy interface. In some embodiments, the patient interface 51 is a non-sealing patient interface which would for example help to prevent barotrauma (e.g. tissue damage to the lungs or other organs of the respiratory system due to difference in pressure relative to the atmosphere. The patient interface may be a non-sealing nasal cannula with a manifold and nasal prongs, and/or a tracheostomy interface, or any other suitable type of patient interface. The flow source could provide a base gas flow rate of between, e.g. 0.5 litres/min and 120 litres/min, or any range within that range, or even ranges with higher or lower limits. Details of the ranges and nature of flow rates will be described later.
A humidifier 52 can optionally be provided between the flow source 50 and the patient to provide humidification of the delivered gas. One or more sensors 53A, 53B, 53C, 53D such as flow, oxygen fraction, pressure, humidity, temperature or other sensors can be placed throughout the system and/or at, on or near the patient 56.
In some configurations, the respiratory system 10 can include a sensor 14 for measuring the oxygen fraction of air the patient inspires. In some examples, the sensor 14 can be placed on the patient interface 51 , to measure or otherwise determine the fraction of oxygen proximate (at/near/close to) the patient's mouth and/or nose. In some configurations, the output from the sensor 14 is sent to a controller 19 to assist control of the respiratory system 10 alter operation accordingly. The controller 1 is coupled to the flow source 50, humidifier 52 and sensor 14. In some configurations, the controller 19 controls these and other aspects of the respiratory system 10 as described herein. In some examples, the controller can operate the flow source 50 to provide the delivered flow of gas at a desired flow rate high enough to meet or exceed a user's (i.e. patient's) inspiratory demand. The flow rate is provided is sufficient that ambient gases are not entrained as the user (i.e. patient) inspires. In some configurations, the sensor 14 can convey measurements of oxygen fraction at the patient mouth and/or nose to a user, who can input the information to the respiratory system 10/controller 19.
An optional non-return valve 23 may be provided in the breathing conduit 16. A filter or filters may be provided at the air inlet 50C and/or inlets to the flow generator 50B to filter the incoming gases before they are pressurized into a high flow gas 31 by to the flow generator 50B.
The breathing assistance apparatus 10 could be an integrated or a separate componentbased arrangement, generally shown in the dotted box 100 in Figure 1. In some configurations, the apparatus or system could be a modular arrangement of components. Furthermore, the apparatus or system may just comprise some of the components shown, not necessarily all are essential. Also, the conduit and patient interface do not have to be part of the system, and could be considered separate. Hereinafter it will be referred to as a breathing assistance apparatus or respiratory system, but this should not be considered limiting. Breathing assistance apparatus and respiratory system will be broadly considered herein to comprise anything that provides a flow rate of gas to a patient. Some such apparatus and systems include a detection system that can be used to determine if the flow rate of gas meets inspiratory demand.
The respiratory apparatus 10 can include a main device housing 100. The main device housing 100 can contain the flow generator 50B that can be in the form of a motor/impeller arrangement, an optional humidifier or humidification chamber 52, a controller 19, and an input/output I/O user interface 54. The user interface 54 can include a display and input device(s) such as button(s), a touch screen (e.g. an LCD screen), a combination of a touch screen and button(s), or the like. The controller 19 can include one or more hardware and/or software processors and can be configured or programmed to control the components of the system, including but not limited to operating the flow generator 50B to create a flow of gases for delivery to a patient, operating the humidifier or humidification chamber 52 (if present) to humidify and/or heat the gases flow, receiving user input from the user interface 54 for reconfiguration and/or user-defined operation of the respiratory apparatus 10, and outputting information (for example on the display) to the user. The user can be a patient, healthcare professional, or others.
With continued reference to Figure 1, a patient breathing conduit 16 can be coupled to a gases flow outlet (gases outlet or patient outlet port) 21 in the main device housing 100 of the respiratory apparatus 10, and be coupled to a patient interface 17, such as a non-sealing interface like a nasal cannula with a manifold and nasal prongs. The patient breathing conduit 16 can also be a tracheostomy interface, or other unsealed interfaces.
The gases flow can be generated by the flow generator 50B, and may be humidified, before being delivered to the patient via the patient breathing conduit 16 through the patient interface 51. The controller 19 can control the flow generator 50B to generate a gases flow of a desired flow rate, and/or one or more valves to control mixing of air and oxygen or other breathable gas. The controller 19 can control a heating element in or associated with the humidification chamber 52, if present, to heat the gases to a desired temperature that achieves a desired level of temperature and/or humidity for delivery to the patient. The patient breathing conduit 16 can have a heating element, such as a heater wire, to heat gases flow passing through to the patient. The heating element can also be under the control of the controller 19.
The humidifier 52 of the apparatus is configured to combine or introduce humidity with or into the gases flow. Various humidifier 52 configurations may be employed. In one configuration, the humidifier 52 can comprise a humidification chamber that is removable. For example, the humidification chamber may be partially or entirely removed or disconnected from the flow path and/or apparatus. By way of example, the humidification chamber may be removed for refilling, cleaning, replacement and/or repair for example. In one configuration, the humidification chamber may be received and retained by or within a humidification compartment or bay of the apparatus, or may otherwise couple onto or within the housing of the apparatus.
The humidification chamber of the humidifier 52 may comprise a gases inlet and a gases outlet to enable connection into the gases flow path of the apparatus. For example, the flow of gases from the flow generator 50B is received into the humidification chamber via its gases inlet and exits the chamber via its gases outlet, after being heated and/or humidified.
The humidification chamber contains a volume of liquid, typically water or similar. In operation, the liquid in the humidification chamber is controllably heated by one or more heaters or heating elements associated with the chamber to generate water vapour or steam to increase the humidity of the gases flowing through the chamber.
In one configuration, the humidifier is a passover humidifier. In another configuration, the humidifier may be a non-passover humidifier.
In one configuration, the humidifier may comprise a heater plate, for example associated or within a humidification bay that the chamber sits on for heating. The chamber may be provided with a heat transfer surface, e.g a metal insert, plate or similar, in the base or other surface of the chamber that interfaces or engages with the heater plate of the humidifier.
In another configuration, the humidification chamber may comprise an internal heater or heater elements inside or within the chamber. The internal heater or heater elements may be integrally mounted or provided inside the chamber, or may be removable from the chamber.
The humidification chamber may be any suitable shape and/or size. The location, number, size, and/or shape of the gases inlet and gases outlet of the chamber may be varied as required. In one configuration, the humidification chamber may have a base surface, one or more side walls extending up from the base surface, and an upper or top surface. In one configuration, the gases inlet and gases outlet may be position on the same side of the chamber. In another configuration, the gases inlet and gases outlet may be on different surfaces of the chamber, such as on opposite sides or locations, or other different locations.
In some configurations, the gases inlet and gases outlet may have parallel flow axes. In some configurations, the gases inlet and gases outlet may be positioned at the same height on the chamber.
The apparatus 10 can use ultrasonic transducer(s), flow sensor(s) such as a thermistor flow sensor, pressure sensor(s), temperature sensor(s), humidity sensor(s), or other sensors, in communication with the controller 19, to monitor characteristics of the gases flow and/or operate the system 10 in a manner that provides suitable therapy. The gases flow characteristics can include gases concentration, flow rate, pressure, temperature, humidity, or others. The sensors 53A, 53B, 53C, 53D, 14, such as pressure, temperature, humidity, and/or flow sensors, can be placed in various locations in the main device housing 100, the patient conduit 16, and/or the patient interface 51. The controller 19 can receive output from the sensors to assist it in operating the respiratory apparatus 10 in a manner that provides suitable therapy, such as to determine a suitable target temperature, flow rate, and/or pressure of the gases flow. Providing suitable therapy can include meeting or exceeding a patient's inspiratory demand. In the illustrated embodiment sensors 53A, 53B, and 53C are positioned in the housing of the apparatus, sensor 53D in the patient conduit 16, and sensor 14 in the patient interface 51.
The apparatus 10 can include one or more communication modules to enable data communication or connection with one or more external devices or servers over a data or communication link or data network, whether wired, wireless or a combination thereof. In one configuration for example, the apparatus 10 can include a wireless data transmitter and/or receiver, or a transceiver 15 to enable the controller 19 to receive data signals in a wireless manner from the operation sensors and/or to control the various components of the system 10. The transceiver 15 or data transmitter and/or receiver module may have an antenna 15a as shown. In one example, the transceiver may comprise a Wi-Fi modem. Additionally, or alternatively, the data transmitter and/or receiver 15 can deliver data to a remote patient management system (i.e. remote server) or enable remote control of the system 10. The system 10 can include a wired connection, for example, using cables or wires, to enable the controller 19 to receive data signals from the operation sensors and/or to control the various components of the apparatus 10. The apparatus 10 may comprise one or more wireless communication modules. For example, the apparatus may comprise a cellular communication module such as for example a 3G, 4G or 5G module. The module 15 may be or may comprise a modem that enables the apparatus to communicate with a remote patient management system (not illustrated in the figures) using an appropriate communication network. The remote management system may comprise a single server or multiple servers or multiple computing devices implemented in a cloud computing network. The communication may be two-way communication between the apparatus and a patient management system (e.g. a server) or other remote system. The apparatus 10 may also comprise other wireless communication modules such as for example a Bluetooth module and/or a Wi-Fi module. The Bluetooth and/or WiFi module allow the apparatus to wirelessly send information to another device such as for example a smartphone or tablet or operate over a LAN (local area network) or Wireless LAN (WLAN). The apparatus may additionally, or alternatively, comprise a Near Field Communication (NFC) module to allow for data transfer and/or data communication.
For example, measured patient and/or device data (e.g., respiratory rate, usage time) may be communicated to a remote patient management system (i.e. a remote server). The remote patient management system may be a single server or a network of servers or a cloud computing system or other suitable architecture for operating a remote patient management system. The remote patient management system (i.e. remote server) further includes memory for storing received data and various software applications or services that are executed to perform multiple functions. Then, for example, the remote patient management system (i.e. remote server) may communicate information or instructions to the system 10 at least in part dependent on the data received. For example, the nature of the data received may trigger the remote server (or a software application running on the remote server) to communicate an alert, alarm, or notification to the system 10. The remote patient management system may further store the received data for access by an authorized party such as a clinician or the patient or another authorized party. The remote patient management system may further be configured to generate reports in response to a request from an authorized party, and the measured patient and/or device data may be included into the generated reports. The reports may further comprise other patient breathing parameters e.g. respiratory rate or SpO2 and/or device parameters e.g. flow rate, humidity level.
The respiratory apparatus 10 may comprise a high flow therapy apparatus. High flow therapy as discussed herein is intended to be given its typical ordinary meaning, as understood by a person of skill in the art, which generally refers to a respiratory system delivering a targeted flow of humidified respiratory gases via an intentionally unsealed patient interface with flow rates generally intended to meet or exceed inspiratory flow of a user. Typical patient interfaces include, but are not limited to, a nasal or tracheal patient interface. Typical flow rates for adults often range from, but are not limited to, about fifteen litres per minute to about sixty litres per minute or greater. Typical flow rates for pediatric users (such as neonates, infants and children) often range from, but are not limited to, about one litre per minute per kilogram of user weight to about three litres per minute per kilogram of user weight or greater.
High flow therapy can also optionally include gas mixture compositions including supplemental oxygen and/or administration of therapeutic medicaments.
High flow therapy is often referred to as nasal high flow (NHF), humidified high flow nasal cannula (HHFNC), high flow nasal oxygen (HFNO), high flow therapy (HFT), or tracheal high flow (THF), among other common names. For example, in some configurations, for an adult patient 'high flow therapy' may refer to the delivery of gases to a patient at a flow rate of greater than or equal to about 10 litres per minute (10 LPM), such as between about 10 LPM and about 100 LPM, or between about 15 LPM and about 95 LPM, or between about 20 LPM and about 90 LPM, or between about 25 LPM and about 85 LPM, or between about 30 LPM and about 80 LPM, or between about 35 LPM and about 75 LPM, or between about 40 LPM and about 70 LPM, or between about 45 LPM and about 65 LPM, or between about 50 LPM and about 60 LPM. In some configurations, for a neonatal, infant, or child patient 'high flow therapy' may refer to the delivery of gases to a patient at a flow rate of greater than 1 LPM, such as between about 1 LPM and about 25 LPM, or between about 2 LPM and about 25 LPM, or between about 2 LPM and about 5 LPM, or between about 5 LPM and about 25 LPM, or between about 5 LPM and about 10 LPM, or between about 10 LPM and about 25 LPM, or between about 10 LPM and about 20 LPM, or between about 10 LPM and 15 LPM, or between about 20 LPM and 25 LPM. A high flow therapy apparatus with an adult patient, a neonatal, infant, or child patient, may deliver gases to the patient at a flow rate of between about 1 LPM and about 100 LPM, or at a flow rate in any of the sub-ranges outlined above.
High flow therapy can be effective in meeting or exceeding the patient's inspiratory demand, increasing oxygenation of the patient and/or reducing the work of breathing. Additionally, high flow therapy may generate a flushing effect in the nasopharynx such that the anatomical dead space of the upper airways is flushed by the high incoming gases flow. The flushing effect can create a reservoir of fresh gas available of each and every breath, while minimizing re-breathing of carbon dioxide, nitrogen, etc. High flow therapy can also increase expiratory time of the patient due to pressure during expiration. This in turn reduces the respiratory rate of the patient.
The patient interface for use in a high flow therapy can be a non-sealing interface to prevent barotrauma, which can include tissue damage to the lungs or other organs of the patient's respiratory system due to difference in pressure relative to the atmosphere. The patient interface can be a nasal cannula with a manifold and nasal prongs, and/or an unsealed tracheostomy interface, or any other suitable type of patient interface.
Figures 2 to 18 show an example respiratory device of the respiratory apparatus 10 having a main housing 100. The main housing 100 has a main housing upper chassis 102 and a main housing lower chassis 202. The main housing upper chassis 102 has a peripheral wall arrangement 106 (see Figure 15). The peripheral wall arrangement defines a humidifier or humidification chamber bay 108 for receipt of a removable humidification chamber 300. The removable humidification chamber 300 contains a suitable liquid such as water for humidifying gases that can be delivered to a patient.
In the form shown, the peripheral wall arrangement 106 of the main housing upper chassis 102 can include a substantially vertical left side outer wall 110 that is oriented in a front-to- rear direction of the main housing 100, a substantially vertical left side inner wall 112 that is oriented in a front-to-rear direction of the main housing 100, and an interconnecting wall 114 that extends between and interconnects the upper ends of the left side inner and outer walls 1 10, 1 12. The main housing upper chassis 102 can further include a substantially vertical right side outer wall 116 that is oriented in a front-to-rear direction of the main housing 100, a substantially vertical right side inner wall 1 18 that is oriented in a front-to-rear direction of the main housing 100, and an interconnecting wall 120 that extends between and interconnects the upper ends of the right side inner and outer walls 1 16, 118. The interconnecting walls 1 14, 120 are angled towards respective outer edges of the main housing 100, but can alternatively be substantially horizontal or inwardly angled.
The main housing upper chassis 102 can further include a substantially vertical rear outer wall 122. An upper part of the main housing upper chassis 102 can include a forwardly angled surface 124. The surface 124 can have a recess 126 for receipt of a display and user interface module 54. The display can be configured to display characteristics of sensed gas(es) in real time. The system can display the patient detection status of the patient interface. If the patient is not detected, the controller may not output or can stop outputting the respiratory rate value(s) and/or other parameters for display. The controller can also optionally output a message for display that no patient is detected at block 2708. An example of the message can be a icon. An interconnecting wall 128 can extend between and interconnect the upper end of the rear outer wall 122 and the rear edge of the surface 124.
A substantially vertical wall portion 130 can extend downwardly from a front end of the surface 124. A substantially horizontal wall portion 132 can extend forwardly from a lower end of the wall portion 130 to form a ledge. A substantially vertical wall portion 134 can extend downwardly from a front end of the wall portion 132 and terminate at a substantially horizontal floor portion 136 of the humidification chamber bay 108. The left side inner wall 1 12, right side inner wall 1 18, wall portion 134, and floor portion 136 together can define the humidification chamber bay 108. The floor portion 136 of the humidification chamber bay 108 can have a recess 138 to receive a heater arrangement such as a heater plate 140 or other suitable heating element(s) for heating liquid in the humidification chamber 300 for use during a humidification process. The main housing lower chassis 202 can be attachable to the upper chassis 102, either by suitable fasteners or integrated attachment features such as clips for example. The main housing lower chassis 202 can include a substantially vertical left side outer wall 210 that is oriented in a front-to-rear direction of the main housing 100 and is contiguous with the left side outer wall 110 of the upper chassis 102, and a substantially vertical right side outer wall 216 that is oriented in a front-to-rear direction of the main housing 100 and is contiguous with the right side outer wall 1 16 of the upper chassis 102. The main housing lower chassis 202 can further include a substantially vertical rear outer wall 222 that is contiguous with the rear outer wall 122 of the upper chassis 102.
The lower housing chassis 202 can have a lip 242 that is contiguous with the lip 142 of the upper housing chassis 102, and also forms part of the recess for receiving the handle portion 506 of the lever 500. The lower lip 242 can include a forwardly directed protrusion 243 that acts as a retainer for the handle portion 506 of the lever 500. Instead of the lever 500, the system can have a spring-loaded guard to retain the humidification chamber 300 in the humidification chamber bay 108.
An underside of the lower housing chassis 202 can include a bottom wall 230. Respective interconnecting walls 214, 220, 228 can extend between and interconnect the substantially vertical walls 210, 216, 222 and the bottom wall 230. The bottom wall 230 can include a grill 232 comprising a plurality of apertures to enable drainage of liquid in case of leakage from the humidification chamber 300 (e.g. from spills). The bottom wall 230 additionally can include elongated forward -rearward oriented slots 234. The slots 234 can additionally enable drainage of liquid in case of leakage from the humidification chamber 300, without the liquid entering the electronics housing. In the illustrated configuration, the slots 234 can be wide and elongate relative to the apertures of the grill 232 to maximize the drainage of liquid.
As shown in Figure 17 to 18, the lower chassis 202 can have a motor recess 250 for receipt of a motor and sensor module. The motor and sensor module may be non-removable from the main housing 100. The motor and sensor module can be removable from the main housing 100, as illustrated in Figures 17-18. A recess opening 251 can be provided in the bottom wall 230 adjacent a rear edge thereof, for receipt of a motor/sensor module. A continuous, gas impermeable, unbroken peripheral wall 252 can be integrally formed with the bottom wall 230 of the lower chassis 202 and extend upwardly from the periphery of the opening 251. A rearward portion 254 of the peripheral wall 252 has a first height, and a forward portion 256 of the peripheral wall 252 has a second height that is greater than the first height. The rearward portion 254 of the peripheral wall 252 terminates at a substantially horizontal step 258, which in turn terminates at an upper auxiliary rearward portion 260 of the peripheral wall 252. The forward portion 256 and upper auxiliary rearward portion 260 of the peripheral wall 252 terminate at a ceiling 262. All of the walls and the ceiling 262 can be continuous, gas impermeable, and unbroken other than the gases flow passage. Therefore, the entire motor recess 250 can be gas impermeable and unbroken, other than the gases flow passage.
The motor and sensor module can be insertable into the recess 250 and attachable to the lower chassis 202. Upon insertion of the motor and sensor module into the lower chassis 202, the gases flow passage tube 264 can extend through the downward extension tube 133 and be sealed by the soft seal.
The humidification chamber 300 can be fluidly coupled to the apparatus 10 in a linear slide- on motion in a rearward direction of the humidification chamber 300 into the chamber bay 108, from a position at the front of the housing 100 in a direction toward the rear of the housing 100. A gases outlet port 322 can be in fluid communication with the motor.
A gases inlet port 340 (humidified gases return) as shown in Figure 8 can include a removable L-shaped elbow. The removable elbow can further include a patient outlet port 344 for coupling to the patient conduit 16 to deliver gases to the patient interface. The gases outlet port 322, gases inlet port 340, and patient outlet port 344 each can have soft seals such as Coring seals or T-seals to provide a sealed gases passageway between the apparatus 10, the humidification chamber 300, and the patient conduit 16.
The humidification chamber gases inlet port 306 can be complementary with the gases outlet port 322, and the humidification chamber gases outlet port 308 can be complementary with the gases inlet port 340. The axes of those ports can be parallel to each other to enable the humidification chamber 300 to be inserted into the chamber bay 108 in a linear movement.
The respiratory device can have air and oxygen (or alternative auxiliary gas) inlets in fluid communication with the motor to enable the motor to deliver air, oxygen (or alternative auxiliary gas), or a mixture thereof to the humidification chamber 300 and thereby to the patient. As shown in Figure 10, the device can have a combined air/oxygen (or alternative auxiliary gas) inlet arrangement 350. This arrangement can include a combined air/oxygen port 352 into the housing 100, a filter 354, and a cover 356 with a hinge 358. A gases tube can also optionally extend laterally or in another appropriate direction and be in fluid communication with an oxygen (or alternative auxiliary gas) source. The port 352 can be fluidly coupled with the motor 402. For example, the port 352 may be coupled with the motor/sensor module 400 via a gases flow passage between the port 352 and an inlet aperture or port in the motor and sensor module 400, which in turn would lead to the motor.
The device can have the arrangement shown in Figures 11 to 14 to enable the blower to deliver air, oxygen (or alternative auxiliary gas), or a suitable mixture thereof to the humidification chamber 300 and thereby to the patient. This arrangement can include an air inlet 356' in the rear wall 222 of the lower chassis 202 of the housing 100. The air inlet 356' comprises a rigid plate with a suitable grill arrangement of apertures and/or slots. Sound dampening foam may be provided adjacent the plate on the interior side of the plate. An air filter box 354' can be positioned adjacent the air inlet 356' internally in the main housing 100, and include an air outlet port 360 to deliver filtered air to the motor via an air inlet port 404 in the motor/sensor module 400. The air filter box 354' may include a filter configured to remove particulates (e.g. dust) and/or pathogens (e.g. viruses or bacteria) from the gases flow. A soft seal such as an O-ring seal can be provided between the air outlet port 360 and air inlet port 404 to seal between the components. The device can include a separate oxygen inlet port 358' positioned adjacent one side of the housing 100 at a rear end thereof, the oxygen port 358' for receipt of oxygen from an oxygen source such as a tank or source of piped oxygen. The oxygen inlet port 358' is in fluid communication with a valve 362. The valve 362 can suitably be a solenoid valve that enables the control of the amount of oxygen that is added to the gases flow that is delivered to the humidification chamber 300. The oxygen port 358' and valve 362 may be used with other auxiliary gases to control the addition of other auxiliary gases to the gases flow. The other auxiliary gases can include any one or more of a number of gases useful for gas therapy, including but not limited to heliox and nitric oxide.
As shown in Figures 13 to 16, the lower housing chassis 202 can include suitable electronics boards, such as sensing circuit boards. The electronics boards can be positioned adjacent respective outer side walls 210, 216 of the lower housing chassis 202. The electronics boards can contain, or can be in electrical communication with, suitable electrical or electronics components, such as but not limited to microprocessors, capacitors, resistors, diodes, operational amplifiers, comparators, and switches. Sensors can be used with the electronic boards. Components of the electronics boards (such as but not limited to one or more microprocessors) can act as the controller 19 of the apparatus.
One or more of the electronics boards can be in electrical communication with the electrical components of the apparatus 10, including the display unit and user interface 54, motor, valve 362, and the heater plate 140 to operate the motor to provide the desired flow rate of gases, operate the humidification chamber 300 to humidify and heat the gases flow to an appropriate level, and supply appropriate quantities of oxygen (or quantities of an alternative auxiliary gas) to the gases flow.
The electronics boards can be in electrical communication with a connector arrangement 274 projecting from the rear wall 122 of the upper housing chassis 102. The connector arrangement 274 may be coupled to an alarm, pulse oximetry port, and/or other suitable accessories. The electronics boards can also be in electrical communication with an electrical connector 276 that can also be provided in the rear wall 122 of the upper housing chassis 102 to provide mains or battery power to the components of the device.
As mentioned above, operation sensors, such as flow, temperature, humidity, and/or pressure sensors can be placed in various locations in the respiratory device, the patient breathing conduit 16, and/or cannula 51 such as shown in Figure 1. The electronics boards can be in electrical communication with those sensors. Output from the sensors can be received by the controller 19, to assist the controller 19 to operate the respiratory apparatus 10 in a manner that provides optimal therapy, for example controlling to a set flow rate. The set flow rate may be selected such that it provides flushing of the patient's upper airways and/or meets or exceeds a patient's inspiratory demand and/or provides other advantages of high flow therapy described herein. In the illustrated embodiment the sensors are positioned on electronic boards that are positioned within the housing. The sensors are encapsulated within the housing.
As outlined above, the electronics boards and other electrical and electronic components can be pneumatically isolated from the gases flow path to improve safety. The sealing also prevents water ingress.
1.1 Control System
Figure 19A illustrates a block diagram 900 of an example control system 920 (which can be the controller 19 in Figure 1) that can detect patient conditions and control operation of the respiratory system including the gases source. The control system 920 can manage a flow rate of the gases flowing through the respiratory system as is the gases are delivered to a patient. For example, the control system 920 can increase or decrease the flow rate by controlling an output of a motor speed of the blower (hereinafter also referred to as a "blower motor") 930 or an output of a valve 932 in a blender. The control system 920 can automatically determine a set value or a personalized value of the flow rate for a particular patient as discussed below. The flow rate can be optimized by the control system 920 to improve patient comfort and therapy.
The control system 920 can also generate audio and/or display/visual outputs 938, 939. For example, the flow therapy apparatus can include a display and/or a speaker. The display can indicate to the physicians any warnings or alarms generated by the control system 920. The display can also indicate control parameters that can be adjusted by the physicians. For example, the control system 920 can automatically recommend a flow rate for a particular patient. The control system 920 can also determine a respiratory state of the patient, including but not limited to generating a respiratory rate of the patient, and send it to the display, which will be described in greater detail below. The control system 920 can change heater control outputs to control one or more of the heating elements (for example, to maintain a temperature set point of the gases delivered to the patient). The control system 920 can also change the operation or duty cycle of the heating elements. The heater control outputs can include heater plate control output(s) 934 and heated breathing tube control output(s) 936.
The control system 920 can determine the outputs 930-939 based on one or more received inputs 901 -916. The inputs 901 -916 can correspond to sensor measurements received automatically by the controller 600 (shown in Figure 19B). The control system 920 can receive sensor inputs including but not limited to temperature sensor(s) inputs 901, flow rate sensor(s) inputs 902, motor speed inputs 903, pressure sensor(s) inputs 904, gas(s) fraction sensor(s) inputs 905, humidity sensor(s) inputs 906, pulse oximeter (for example, SpO2) sensor(s) inputs 907, stored or user parameter(s) 908, duty cycle or pulse width modulation (PWM) inputs 909, voltage(s) inputs 910, current(s) inputs 911 , acoustic sensor(s) inputs 912, power(s) inputs 913, resistance(s) inputs 914, CO2 sensor(s) inputs 915, and/or spirometer inputs 916. The control system 920 can receive inputs from the user or stored parameter values in a memory 624 (shown in Figure 19B). The control system 920 can dynamically adjust flow rate for a patient over the time of their therapy. The control system 920 can continuously detect system parameters and patient parameters. A person of ordinary skill in the art will appreciate based on the disclosure herein that any other suitable inputs and/or outputs can be used with the control system 920.
1.2 Controller
Figure 19B illustrates a block diagram of an embodiment of a controller 600 (which can be the controller 19 in Figure 1). The controller 600 can include programming instructions for detection of input conditions and control of output conditions. The programming instructions can be stored in the memory 624 of the controller 600. The programming instructions can correspond to the methods, processes and functions described herein. The programming instructions can be executed by one or more hardware processors 622 of the controller 600. The programming instructions can be implemented in C, C+ +, JAVA, or any other suitable programming languages. Some or all of the portions of the programming instructions can be implemented in application specific circuitry 628 such as ASICs and FPGAs. The controller 600 can also include circuits 628 for receiving sensor signals. The controller 600 can further include a display 630 for transmitting status of the patient and the respiratory assistance system. The display 630 can also show warnings and/or other alerts. The display 630 can be configured to display characteristics of sensed gas(es) in real time or otherwise. The controller 600 can also receive user inputs via the user interface such as display 630. The user interface can include button(s) and/or dial(s). The user interface can comprise a touch screen.
1.3 Motor and Sensor module
Any of the features of the respiratory system described herein, including but not limited to the humidification chamber, the flow generator, the user interface, the controller, and the patient breathing conduit configured to couple the gases flow outlet of the respiratory system to the patient interface, can be combined with any of the sensor modules described herein.
Figure 20 illustrates a block diagram of the motor and sensor module 2000, which can be received by the recess 250 in the respiratory device (shown in Figures 17 and 18). The motor and sensor module can include a blower 2001, which entrains room air to deliver to a patient. The blower 2001 can be a centrifugal blower.
One or more sensors (for example, Hall-effect sensors) may be used to measure a motor speed of the blower motor. The blower motor may comprise a brushless DC motor, from which motor speed can be measured without the use of separate sensors. For example, during operation of a brushless DC motor, back-EMF can be measured from the nonenergized windings of the motor, from which a motor position can be determined, which can in turn be used to calculate a motor speed. In addition, a motor driver may be used to measure motor current, which can be used with the measured motor speed to calculate a motor torque. The blower motor may comprise a low inertia motor.
Room air can enter a room air inlet 2002, which enters the blower 2001 through an inlet port 2003. The inlet port 2003 can include a valve 2004 through which a pressurized gas may enter the blower 2001. The valve 2004 can control a flow of oxygen into the blower 2001. The valve 2004 can be any type of valve, including a proportional valve or a binary valve. In some embodiments, the inlet port does not include a valve.
The blower 2001 can operate at a motor speed of greater than 1,000 RPM and less than 30,000 RPM, greater than 2,000 RPM and less than 21 ,000 RPM, or between any of the foregoing values. Operation of the blower 2001 mixes the gases entering the blower 2001 through the inlet port 2003. Using the blower 2001 as the mixer can decrease the pressure drop that would otherwise occur in a system with a separate mixer, such as a static mixer comprising baffles, because mixing requires energy.
The mixed air can exit the blower 2001 through a conduit 2005 and enters the flow path 2006 in the sensor chamber 2007. A sensing circuit board with sensors 2008 can positioned in the sensor chamber 2007 such that the sensing circuit board is at least partially immersed in the gases flow. At least some of the sensors 2008 on the sensing circuit board can be positioned within the gases flow to measure gases properties within the flow. After passing through the flow path 2006 in the sensor chamber 2007, the gases can exit 2009 to the humidification chamber.
Positioning sensors 2008 downstream of the combined blower and mixer 2001 can increase accuracy of measurements, such as the measurement of gases fraction concentration, including oxygen concentration, over systems that position the sensors upstream of the blower and/or the mixer. Such a positioning can give a repeatable flow profile. Further, positioning the sensors downstream of the combined blower and mixer avoids the pressure drop that would otherwise occur, as where sensing occurs prior to the blower, a separate mixer, such as a static mixer with baffles, is required between the inlet and the sensing system. The mixer can introduce a pressure drop across the mixer. Positioning the sensing after the blower can allow the blower to be a mixer, and while a static mixer would lower pressure, in contrast, a blower increases pressure. Also, immersing at least part of the sensing circuit board and sensors 2008 in the flow path can increase the accuracy of measurements because the sensors being immersed in the flow means they are more likely to be subject to the same conditions, such as temperature and pressure, as the gases flow and therefore provide a better representation of the gases flow characteristics. Referring to Figure 21, the gases exiting the blower can enter a flow path 402 in a sensor chamber 400, which can be positioned within the motor and sensor module and can be the sensor chamber 2007 of Figure 20. The flow path 402 can have a curved shape. The flow path 402 can be configured to have a curved shape with no sharp turns. The flow path 402 can have curved ends with a straighter section between the curved ends. A curved flow path shape can reduce pressure drop in a gases flow without reducing the sensitivity of flow measurements by partially coinciding a measuring region with the flow path to form a measurement portion of the flow path.
A sensing circuit board 404 with sensors, such as acoustic transmitters and/or receivers, humidity sensor, temperature sensor, thermistor, and the like, can be positioned in the sensor chamber 400 such that the sensing circuit board 404 is at least partially immersed in the flow path 402. Immersing at least part of the sensing circuit board and sensors in the flow path can increase the accuracy of measurements because the sensors immersed in the flow are more likely to be subject to the same conditions, such as temperature and pressure, as the gases flow, and therefore provide a better representation of the characteristics of the gases flow. After passing through the flow path 402 in the sensor chamber 400, the gases can exit to the humidification chamber.
The gases flow rate may be measured using at least two different types of sensors. The first type of sensor can comprise a thermistor, which can determine a flow rate by monitoring heat transfer between the gases flow and the thermistor. The thermistor flow sensor can run the thermistor at a constant target temperature within the flow when the gases flow around and past the thermistor. The sensor can measure an amount of power required to maintain the thermistor at the target temperature. The target temperature can be configured to be higher than a temperature of the gases flow, such that more power is required to maintain the thermistor at the target temperature at a higher flow rate.
The thermistor flow rate sensor can also maintain a plurality of (for example, two, three, or more) constant temperatures on a thermistor to avoid the difference between the target temperature and the gases flow temperature from being too small or too large. The plurality of different target temperatures can allow the thermistor flow rate sensor to be accurate across a large temperature range of the gases. For example, the thermistor circuit can be configured to be able to switch between two different target temperatures, such that the temperature of the gases flow will always fall within a certain range relative to one of the two target temperatures (for example, not too close but not too far). The thermistor circuit can be configured to operate at a first target temperature of about 50°C to about 70°C, or about 66°C. The first target temperature can be associated with a desirable flow temperature range of between about 0°C to about 60°C, or about 0°C and about 40°C. The thermistor circuit can be configured to operate at a second target temperature of about 90°C to about 1 10°C, or about 100°C. The second target temperature can be associated with a desirable flow temperature range of between about 20°C to about 100°C, or about 30°C and about 70°C.
The controller can be configured to adjust the thermistor circuit to change between at least the first and second target temperature modes by connecting or bypassing a resistor within the thermistor circuit. The thermistor circuit can be arranged as a Wheatstone bridge configuration comprising a first voltage divider arm and a second voltage divider arm. The thermistor can be located on one of the voltage divider arms. More details of a thermistor flow rate sensor are described in PCT Application Publication No. WO2018/052320, filed 3 September 2017, which is incorporated by reference herein in its entirety.
The second type of sensor can comprise an acoustic sensor assembly. Acoustic sensors including acoustic transmitters and/or receivers can be used to measure a time of flight of acoustic signals to determine gases velocity and/or composition, which can be used in flow therapy apparatuses. In one ultrasonic sensing (including ultrasonic transmitters and/or receivers) topology, a driver causes a first sensor, such as an ultrasonic transducer, to produce an ultrasonic pulse in a first direction. A second sensor, such as a second ultrasonic transducer, receives this pulse and provides a measurement of the time of flight of the pulse between the first and second ultrasonic transducers. Using this time of flight measurement, the speed of sound of the gases flow between the ultrasonic transducers can be calculated by a processor or controller of the respiratory system. The second sensor can transmit and the first sensor can receive a pulse in a second direction opposite the first direction to provide a second measurement of the time of flight, allowing characteristics of the gases flow, such as a flow rate or velocity, to be determined. In another acoustic sensing topology, acoustic pulses transmitted by an acoustic transmitter, such as an ultrasonic transducer, can be received by acoustic receivers, such as microphones. More details of an acoustic flow rate sensor are described in PCT Application Publication No. WO2017/095241, filed 2 December 2016, which is incorporated by reference herein in its entirety.
The one or more flow rate sensors, or a sensor assembly comprising a flow rate sensor or sensors, may be located in various positions in the respiratory apparatus and/or along the gases flow path. In one configuration, a flow rate sensor or sensors, or a sensory assembly, may be located or arranged after the flow generator 50B, i.e. the sensor is configured or arranged to sense or measure the flow rate of the gases in the flow path after the flow generator 50B. In this configuration, the flow rate signal or flow rate data generated by the flow rate sensor or sensors may represent the flow generator output flow rate signal or data, i.e. the flow rate of the gases flow output from the flow generator 50B.
In one example configuration, a flow rate sensor or sensors, or sensor assembly, may be located in the main device housing 100 before or after the humidifier 52 (if present). For example, the flow rate sensor may be arranged or configured in the main device housing 100 to sense the flow rate of the gases in the flow path at a location between the flow generator 50B and humidifier 52, or a location in the flow path after the humidifier. In another example configuration, a flow rate sensor or sensors, or sensor assembly, may be located in or along the breathing conduit 16 and/or patient interface 51. In this configuration, the sensor or sensor assembly is configured to sense or measure the flow rate of the gases flow in the flow path comprising or formed by the breathing conduit 16 and/or patient interface 51, i.e. the flow path that follows the gases flow outlet 21 of the main device housing 100. In another example configuration, the apparatus may comprise any combination of the mentioned one or more flow rate sensor or sensor assembly configurations or locations. For example, the apparatus may comprise any combination of one or more flow rate sensors or sensor assemblies in any one or more locations along the gases flow path, whether in the main device housing 100, breathing conduit 16, and/or patient interface 51. In some configurations, readings from both the first and second types of sensors can be combined to determine a more accurate flow measurement. For example, a previously determined flow rate and one or more outputs from one of the types of sensor can be used to determine a predicted current flow rate. The predicted current flow rate can then be updated using one or more outputs from the other one of the first and second types of sensor, in order to calculate a final flow rate.
2. Examples of operating parameter control
Figure 22 shows a schematic of an example respiratory assistance system 2200, similar to the respiratory assistance system 10 shown in Figure 1. The respiratory assistance system 2200 includes a gases source 2202, a respiratory rate sensor 2215, and a patient interface 2216. The patient interface provides high flow therapy to the patient P. The patient interface may be referred to as a high flow therapy interface. The gases source 2202 may be referred to as a high flow therapy device. The respiratory assistance system 2200 shown in Figure 22 may comprise any of the elements of the respiratory assistance system 10 in Figure 1. The patient interface 2216 in this example is an unsealed nasal cannula. The respiratory rate sensor 2215 may comprise one or more sensors. The one or more respiratory rate sensors 2215 may be one or more sensors configured to be attached to or located near to the patient P. Each of the one or more sensors 2215 are configured to measure a patient parameter indicative of the patient's respiratory rate. In an example, one or more of the wearable sensors may be a body mounted respiratory rate sensor.
The gases source 2202 may include a flow generator or source 2224 that can create a flow of respiratory gases to be provided to the humidification apparatus 2224. In an example, the flow source 2224 is a blower. However, the flow source 2224 is not limited to a blower and can include a flow meter, a blender, flow mode from a ventilator, or any other flow generating device. Other flow sources known to those of skill in the art can also be used with any of the examples of the present disclosure as further discussed below.
The gases source 2202 may include a controller 2226 that can control the operation of the flow source 2224. For example, the controller 2226 can execute or implement a control system described more in detail below to control operations of the flow source and the associated operating parameters of the gases. The control system can, for example in some examples that use a blower as a flow source, determine an amount of power delivered to the blower. The fan or motor speed may depend on the amount of power.
In an example, the flow source 2224 can include a fan and a motor. As shown in Figure 22, the gases source may comprise a first inlet 2222 and a second inlet 2223. The first inlet 2222 may be configured to provide ambient air into the flow generator 2224, and the second inlet 2223 may be configured to be connected to a dry gas source, for example, a gas canister or tank, and to provide said gases into the flow generator 2224. The second inlet 2223 may draw or provide concentrated oxygen into the flow generator 2224. The amount of gases provided or drawn by the first inlet 2222 and/or the second inlet 2223 may be controlled by one or more valves (not shown). For example, the first inlet 2222 may be controlled by a first valve, and the second inlet 2223 may be controlled by a second valve. The one or more valves may be controlled by the controller 2226. The oxygen concentration level, which may also be referred to as the concentration of oxygen in the gases may be defined by the ratio of ambient air provided or drawn by the first inlet 2222 to the oxygen provided or drawn by the second inlet 2223. The oxygen concentration level may be controlled by controlling the first valve and/or the second valve. In an example, the oxygen concentration level may be controlled by controlling only the second valve.
2.1 Control System
Figure 23 illustrates a block diagram of an example of a control system 2320 that can detect patient conditions and control operation of the respiratory assistance system 10, 2200 including the gas source 124, 2202. In an example, the control system 2320 controls the operating flow rate 2332 of the gas flowing through the respiratory assistance system 10, 2200 as it is delivered to a patient.
The control system 2320 can increase or decrease the flow rate by controlling a motor speed of the blower and/or a valve in a blender. The control system 2320 can automatically control the operating flow rate for a particular patient based on a parameter indicative of the patient's respiratory rate, as discussed below. The flow rate can be optimized by the control system 2320 to improve patient comfort and therapy. Additionally, or alternatively, the control system 2320 can also increase or decrease the oxygen concentration level by controlling the first and second valves to provide gases from the first and second inlets respectively. The control system 2320 can automatically control the operating oxygen concentration level for a particular patient based on a parameter indicative of the patient's respiratory rate, as discussed below. The oxygen concentration level can be optimized by the control system 2320 to improve patient comfort and therapy.
The control system 2320 can also generate audio and/or visual outputs 2334. For example, the respiratory assistance system 100 can include a display which may further include a speaker. The display can indicate to the physicians any warnings or alarms generated by the control system 2320. The display can also indicate control parameters that can be adjusted by the physicians. For example, the control system 2320 can automatically display the operating a flow rate for a particular patient. The control system 2320 can also generate a recovery state of the patient and send it to the display.
In some examples, the control system 2320 can change a temperature set point 2330 of one of the heating elements, such as chamber heater, to control the output conditions of the gas delivered to the patient. The control system 2320 can also change the operation or duty cycle of the heaters described above.
As will be described, the control system 2320 can determine outputs 2330-2334 based on one or more received inputs 2302-2306. The inputs 2302, 2304 can correspond to sensor measurements received automatically by the controller 19, 600, or 2226.
The control system 2320 receives sensor inputs corresponding to patient sensor inputs 2302. Patient sensor inputs may be from one or more wearable sensors configured to be attached to patient to measure or provide an indication of a patient parameter. The patient parameter may be SpO2 or respiratory rate, as will be discussed.
The control system may also receive sensor inputs from device sensors 2304. For example, such device sensors may comprise one or more: pressure sensor(s), flow rate sensor(s), temperature sensor(s), oxygen concentration sensor(s), or ambient sensor(s) in the respiratory assistance system 10, 2200 described above.
The control system 2320 may also receive inputs from user 2306 or stored values in a memory. For example, the user may input one or more initial values for one or more of the operating parameters, and/or values defining a range for one or more of the operating parameters. In an example, the initial operating flow rate and/or initial operating oxygen concentration level may be manually set by a clinician. In an example, a range for the operating flow rate and/or the operating oxygen concentration level may also be manually set by a clinician. Alternatively, the initial and/or range for the operating flow rate and/or the operating oxygen concentration level could be pre-set or stored in a memory.
In a further example, the initial and/or range for the operating flow rate and/or the operating oxygen concentration level may be automatically determined based on one or more additional parameters. The one or more additional parameters may be inputted by the user and/or stored in memory. The one or more additional parameters may correspond to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, weight, sex, height, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the initial and/or range for the operating flow rate and/or the operating oxygen concentration level.
The control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy. The control system 2320 may also dynamically adjust the operating oxygen concentration level 2336 for a patient over the time of their therapy. The control system 2320 can continuously detect system parameters and patient parameters.
2.1.1 Controller
The control system 2320 can include programming instructions for detection of input conditions and control of output conditions. The programming instructions can be stored in a memory of the controller 19, 600, or 2226. In some examples, the programming instructions correspond to the methods, processes and functions described herein. The control system 2320 can be executed by one or more hardware processors of the controller 19, 600, or 2226. The programming instructions can be implemented in C, C+ +, JAVA, or any other suitable programming languages. In some examples, some or all of the portions of the control system 2320 can be implemented in application specific circuitry such as ASICs and FPGAs.
As illustrated in Figure 23, the control system 2320 can receive inputs from multiple components of the respiratory assistance system 100. Not all of the inputs 2302-206 shown in Figure 23 may be present. The inputs 2302 to 2306 and the outputs 2330 to 2336 may not necessarily be present in all examples. For example, the control system 2320 may only receive the patient sensor input(s) 2302 and generate a flow control output(s) 2332. Depending on the configuration, some of the components corresponding to the inputs may not be included in the respiratory assistance system 10, 2200. Lack of a certain input itself may be used by the control system 2320 to determine the input or system conditions.
2.2 Respiratory Rate
Respiratory rate can be an important indicator of patient condition. An abnormal respiratory rate has been shown to be a predictor of respiratory conditions and/or respiratory disease of a patient, and in some circumstances other serious events such as cardiac arrests and escalation to high levels of care. Respiratory rate can thus provide an indication of deterioration or improvement in patient condition. Respiratory rate may also be related to work of breathing.
Changes to the respiratory condition of a patient can quickly manifest into changes in respiratory rate. When a patient's condition worsens, their minute ventilation is likely to increase. For example, the efficiency of gas exchange in the lungs may decrease with a worsening condition, requiring a higher minute ventilation to maintain normal blood oxygen levels. This increase in minute ventilation is achieved through some combination of quicker breaths and larger tidal volumes. Furthermore, the body tends to favour taking quicker breaths over larger tidal volumes. In this way, respiratory rate responds relatively quickly to a change in the patient's condition when compared with other measurable patient parameters such as SpO2. Respiratory rate may be affected by other factors; for example, increased physical activity is likely to increase respiratory rate. However, patients receiving respiratory therapy, such as high flow therapy, are generally stationary and at rest, minimising other potential causes of respiratory rate changes.
2.2.1 Respiratory Rate Sensors
Respiratory rate is typically measured manually by counting breaths over a set period of time. This allows for a high possibility of errors as well as an inability to continuously monitor the patient. Manual measurement is thus not suited for the present use.
The present system and method for controlling the flow rate of gas delivered to a patient comprises receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors. The one or more sensors, such as sensors 2215 shown in Figure 22, may be one or more sensors configured to be attached to or located near to a patient to measure a patient parameter indicative of the patient's respiratory rate. In an example, one or more of the sensors may be a body mounted respiratory rate sensor. In these examples, the sensor may be attached to the clothing of the patient. In some examples, one or more of the sensors may be a wearable respiratory rate sensor configured to be worn by the patient, on their body and/or clothing, such as the wearable sensor is in contact with, or is in close proximity to the patient.
In one example, one or more body-contacting sensors may measure the movement of the diaphragm to determine respiratory rate. In one example, light transmittance-type and/or reflectance-type sensors are able to measure respiratory rate by measuring pulsations in venous and/or arterial blood. For example, pulse oximeters may be used to find respiratory rate. In one example, acoustic sensors may be placed on or near the patient to measure respiratory rate sonically or through vibrations in the trachea. In one example, a CO2 sensor located near the patient's mouth and/or nose (for example, attached to a cannula) can determine respiratory rate through the periodic increase of CO2 concentrations as the patient breathes out.
In some examples, one or more of the wearable respiratory rate sensors may be mechanical sensors. In some examples, the mechanical sensor(s) may be piezoelectric sensor(s). The piezoelectric sensor may comprise one or more piezoelectric elements. The piezo electric elements may mounted on the chest or near the diaphragm of the patient. The movement of the patient's chest during respiration causes the piezo electric elements to move and generate a voltage in light of the movement signal. In some examples, the voltage values may be transmitted to the respiratory therapy device for processing. The respiratory therapy device may determine the respiratory rate of the patient based on the voltage values. In other examples, the piezoelectric sensor(s) may comprise a processor that processes the voltage values and determines the respiratory rate. The determined respiratory rate can then be sent to the respiratory therapy device.
In one example, one or more of the sensors may not be wearable sensors. In these examples, one or more of the sensors may not contact the patient directly. Such sensors may be referred to as non-patient contacting sensors. In one such example, a piezoelectric sensor may be placed under the mattress of a patient that detects movement that occurs as the patient breathes to determine respiratory rate. In another example, an acoustic based sensor may be used, utilising one or more microphones to detect audio waves relating to the respiratory function of the patient. In other examples, a radar-based sensor configured to measure a patient's respiratory rate may be used. The radar-based sensor may measure or detect displacement patterns of the patient which can be used to characterise various cardiopulmonary functions including respiratory rate.
Other examples of measuring a parameter indicative of a patient's respiratory rate are also envisaged, such as via wearable sensors such as a smart watch.
Alternatively, or additionally to sensors attached to or located near to a patient to measure a patient parameter, analysis of flow and pressure delivered by the NHF therapy device can be used to determine respiratory rate. For example, the controller may use signals from one or more pressure sensors and/or one or more flow sensors of the device. The one or more pressure sensors and/or one or more flow sensors may be located in the flow path of the respiratory system. The patient's breathing during the provision of therapy may cause changes or fluctuations in the gases in the flow path of the respiratory system. These changes or fluctuations can be measured or determined based on the signals from one or more pressure sensors and/or one or more flow sensors of the device. The changes or fluctuations may then be evaluated (e.g. through Fourier transforms or other waveform analysis) to determine or estimate the respiratory rate of the patient.
Any one or more of the above-mentioned sensors and methods for measuring or determining respiratory rate may be utilised in the present system and method. These methods of measuring a patient's respiratory rate are generally non-invasive and unobtrusive, and thus may offer good patient compliance with the monitoring equipment. They can provide continuous and accurate measurement of respiratory rate.
In some examples, one or more of the sensors may be a dedicated, body-contacting respiratory rate sensor such as one that uses any of the methods describe above. A dedicated, body-contacting respiratory rate sensor may provide accurate and non-invasive measurements of the patient's respiratory rate. For example, some patients may be somewhat active during therapy, such as when they are moving around or sitting down. In these cases, a wearable sensor that attaches to the body or clothing of the patient would be more convenient.
In other examples, a patient may not be active, and a non-contact sensor may be utilised. For example, a patient may be reclined on a bed while receiving therapy, and as such does not move as much. In such examples, a non-contact stationary sensor such as under-mattress piezoelectric sensor could be used.
The one or more sensors may communicate directly with the controller of the high flow therapy device through a wireless transmitter on the sensor using any suitable wireless communication protocol (such as, for example, near field communication, Wi-Fi or Bluetooth ®). Alternatively, one or more of the sensors may communicate through a wired connection. One or more of the sensors may also connect to an intermediate connector, such as a cloud-based connector. The cloud-based connector may then connect with the controller of the high flow therapy device. Alternatively, the cloud-based connector may provide respiratory rate data to a clinician, who then performs the settings adjustment on the high flow therapy device. The one or more sensors may be configured to measure or provide data indicative of an instantaneous respiratory rate of the patient. The one or more sensors may be configured to measure or provide data indicative of an instantaneous respiratory rate at specific time intervals. The time intervals may be a fixed time interval. In some examples, the fixed time interval is a pre-set time interval. In such examples, the pre-set time interval may be between about 1 minute to about 8 hours. The pre-set time interval may be for example 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes, or 45 minutes, or 1 hour, or 1 hour and 30 minutes, or 2 hours, or 3 hours, or 4 hours, or 5 hours, or 6 hours. In another example, the time interval is a variable time interval. The variable time interval may be based on the respiratory rate of the patient, and/or the status of the respiratory rate of the patient, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session.
Alternatively, or additionally, the one or more sensors may be able to measure or provide data relating to a patient parameter indicative of a time-averaged measurement of the patient's respiratory rate. The time-averaged measurement may be used to achieve a steady state reading of respiratory rate. The steady state reading of respiratory rate may ignore any transient measurements. The time-averaged measurement may be calculated over a measurement period. In one example, the measurement period is a fixed measurement period. In some examples, the fixed measurement period is a pre-set measurement period. In such examples, the pre-set measurement period may be between about 5 seconds to about 30 minutes. The pre-set measurement period may be between about 10 seconds to about 15 minutes. The pre-set measurement period may be between about 30 seconds to about 5 minutes. The pre-set measurement period may be for example 30 seconds, or, or 1 minute, or 2 minutes, or 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes. In another example, the measurement period is a variable measurement period. The variable measurement period may be based on the respiratory rate of the patient, and/or the status of the respiratory rate of the patient, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session.
In some examples, one or more of the sensors may measure and store a plurality of instantaneous measurements indicative of the patient's respiratory rate over the measurement period. In such embodiments the sensor may calculate the time-averaged measurement based on the plurality of instantaneous measurements. The sensor may then then send the calculated time-averaged measurement to the controller of the respiratory therapy device, as discussed above.
Alternatively, the sensor may send instantaneous measurements to the controller of the respiratory therapy device during the measurement period. In such examples, the controller of the respiratory therapy device then calculates the time-averaged measurement. The controller of the respiratory therapy device may then use the time-averaged measurement to determine the status of the patient's respiratory rate, as will be discussed.
Alternatively, the sensor may send instantaneous measurements to an intermediate controller, such as a remote server, during the measurement period. In such embodiments, the intermediate controller may store the instantaneous measurements and calculate the time-averaged measurement. The intermediate controller may then use the time-averaged measurement to determine the status of the patient's respiratory rate, or may send the time- averaged measurement to the controller of the respiratory therapy device.
In some examples, the respiratory rate reading may comprise a rolling average, such that the current reading at any one point comprises the time-averaged respiratory rate across the most recent measurement period. This rolling average may be calculated by the sensor, the intermediate connector and/or the therapy controller.
In some examples, the one or more sensors may comprise a plurality of sensors. The plurality of sensors may be used simultaneously to provide respiratory rate readings. For example, the plurality of sensors may comprise a combination of two or more of: one or more wearable sensors, and/or an under-mattress sensor, and/or the flow and/or pressure sensors in the device. In such examples where a plurality of sensors are utilised, each sensor may send measurements to a controller in a form as described above. The controller may then determine an average respiratory rate across the plurality of sensors, based on the measurements received from two or more of the available sensors. In some examples, the controller uses the measurements from all of the plurality of sensors to provide a more accurate measurement of the patient's respiratory rate.
In some examples, the plurality of sensors may provide redundancy in case of failure. For example, if one of the sensors stops working or is unattached from the patient somehow, respiratory rate information may still be able to be gathered by the other one or more sensor. In some examples, the plurality of sensors may be used for single-fault tolerance. In such examples, the controller may use the measurements from the plurality of sensors to detect for faults in the sensors, such that a sensor which is providing outlying readings is not taken into account for determining the average respiratory rate of the patient.
2.2.2 Respiratory Rate vs Flow Rate
An example set of collected measurements is illustrated in a graph format in Figure 26. The control system 220 can control the operating flow rate of the gas flow delivered to the patient via the patient interface. The control of the operating flow rate in turn has an effect on the patient's measured respiratory rate, as shown by the graph 2600 of Figure 26 and discussed below.
When providing respiratory therapy to a patient using the respiratory therapy system 10, 2200, the patient's respiratory response can vary over different flow rates, as shown by the graph 2600 in Figure 26. High flow therapy may decrease the respiratory rate of the patient relative to unaided respiration. This may be due to an increased resistance to expiration that leads to longer expiration times, as well as improved dead-space clearance of expired gas and the reduction of rebreathing.
The current understanding in the art is that decreases in the respiratory rate of the patient, especially those which may occur more rapidly as the flow rate is increased, are caused by improved flushing of the airways, improving CO2 clearance and allowing more fresh gas (oxygen) reaching the lungs. This improves efficiency of gas exchange, and less breaths are required.
As flow rates continue to increase, there may be a decrease in the respiratory rate of the patient, as seen in Figure 28. As shown, this decrease may be shallow. As the flow rate (and thus the level of pressure) increases, there may be more expiratory resistance which causes the lungs to expand more, resulting in a higher surface area of the lungs (alveoli) and more efficient 02 and C02 exchange. Thus, the respiratory rate of the patient slowly decreases as the flow rate increases further.
When the respiratory therapy is not providing any flow of gases to the patient, the flow rate of gases delivered to the patient is 0 l/min. At said flow rate of 0 l/min, the patient will have a certain measured respiratory rate Ro, 2604. The patient's respiratory rate may be measured in breaths per minute (bpm). Testing has shown that over a range of flow rates, the flow rate vs respiratory rate curve 2602 substantially follows a shape similar to that shown in Figure 26.
The first portion of this curve 2602 follows a reverse s-shaped curve (or reversed sigmoid curve). After a certain point, shown by 2606, however, further increases in flow rates cease to further decrease respiratory rate. At substantially this point 2606, a minimum respiratory rate M is reached, at flow rate FM. At even higher flow rates, the respiratory rate may begin to rise. This may be due to the increased effort required to exhale against the high flow rate. In other patients, the patient's respiratory rate may remain substantially constant at higher flow rates (i.e. at the minimum). In other patients, the patient's respiratory rate may continue to decrease after reaching Rm, but may decrease below a threshold, as discussed later. In further patients, the patient's respiratory rate may increase and decrease after reaching Rm, as will be discussed below in relation to Figure 28 and Figure 29.
For some adult patients, the flow rate FM at which the respiratory rate reaches a minimum may be around 45 l/min. This may vary amongst different patients. It may also differ for the same patient at different times, such as when they are healthy compared to when suffering from respiratory distress. Thus, the minimising flow rate cannot be assumed to be the same for all patients.
An alternative example set of collected measurements is illustrated in a graph format in Figure 28 and Figure 29. As with Figure 26, the patient's respiratory response can vary over different flow rates, as shown by the graph 2800 in Figure 28 and Figure 29. Over a range of flow rates, the flow rate vs respiratory rate curve 2802 substantially follows a shape similar to that shown.
The alternative curve 2802 shown in Figure 28 and Figure 29 starts similarly to that shown in Figure 26 at lower flow rates, with a steeper negative gradient between about 25 and 30 l/min. Then, the curve 2802 shallows out to a 'minimum' point as shown by 2806. As shown in Figure 28, at substantially point 2806, a minimum respiratory rate RM is reached, at flow rate FM. AS shown, after the minimum point, shown by 2806, further increases in the flow rate may cause the patient's respiratory rate to rise and fall, such that it further decreases and/or increases.
In alternative examples, a set of measurements may show a curve that does not have a shallow gradient section at low flow rates like that shown in that of Figure 26 to Figure 29. In such alternative examples, the curve may have a steeper negative gradient at lower flow rates. This may indicate that the increasing flow rates are having an effect on reducing the patient's respiratory rate, even at lower flow rates.
As shown in Figure 29, at least a first respiratory rate R1 of the patient may be determined at a first flow rate F1. At least a second respiratory rate R2 of the patient may be determined at a second flow rate F2, The gradient, or rate of change of the patient's respiratory rate between these two flow rates may be calculated. In one example, a difference AR between at least the first respiratory rate R1 and the second respiratory rate R2 might be determined. As will be discussed, the minimum point 2806 may be established based on AR, or the negative gradient between two or more readings of respiratory rate at corresponding flow rates being above a certain threshold.
As shown, after the minimum point, shown by 2806, further increases in the flow rate may cause the patient's respiratory rate to rise and fall, such that it further decreases and/or increases, The further increases and decreases in the patient's respiratory rate after the minimum point shown by 2806 may be determined to have a gradient or difference AR which is below a certain threshold. The subsequent negative gradients proceeding the minimum 2806 may be below this threshold, and so do not define the minimum flow rate. This curve will vary between patients based on various parameters and conditions, but generally a minimum will occur after a steep initial decrease in respiratory rate. If a point after said first determined minimum, such as that shown by 2806, is determined to have a gradient or difference AR which is above said certain threshold, then a new minimum may be established.
2.2.3 Respiratory Rate Ranges
A respiratory rate that is within a desirable range may indicate a healthy and/or stable patient. In Figure 26, this range is shown between Ry+ and Ry- This range may be, in some examples, between about 12 - 20 breaths per minute (BPM), 12 - 18 BPM, or 12 - 16 BPM. This range is typically defined by a clinician or physician.
This range may be different based on the type of patient, the type of respiratory disease and other conditions. For example, the range may be different based on if the patient is receiving treatment in a hospital or at home. At home, it may be desirable to have an earlier warning that a patient's condition is worsening or cannot be stabilised by the high flow therapy. As such, the range used at home may be narrower than that used in the hospital.
A healthy patient is likely to have a resting respiratory rate within the desired range. However, a patient suffering from respiratory distress is likely to have a raised respiratory rate. In the example shown in Figure 26, the patient's respiratory rate Ro at a flow rate of 0 l/min is above the upper threshold Ry+. The desirable range is shown by the shaded area in Figure 26, between Ry+ and Ry.
2.3 Flow Control Method
Figure 24 illustrates a flow chart of an example of a method 2400 for controlling the flow rate of gas delivered to a patient based on a measured respiratory rate of a patient. The process or method 2400 can be implemented by any of the systems described herein. The process or method 2400 may for example be implemented by the control system 2220.
The process or method 2400 may be performed continually or continuously over a therapy session. In some examples, the therapy session may be a single therapy session defined from a commencement of therapy being provided at a certain flow rate until the end of the therapy being provided at or above a certain flow rate. In some examples, the flow rate defining the commencement and end of therapy may be any flow rate at or above 0 l/min. The control system 2320 can adjust the operating flow rate of the gases delivered or provided by the respiratory therapy device 2202. The control system 2320 follows the iterative process or method 2400 discussed below of titration to find a substantially optimal operating flow rate using feedback from one or more sensors. A substantially optimal operating flow rate may be a flow rate at which a patient's respiratory rate is at or close to a minimum. Additionally, in some examples, a substantially optimal operating flow rate may be a flow rate at which a patient's respiratory rate is within a range.
The control system 2320 can, for example, increase the motor speed of the blower when a blower is used as the flow source 2224 to increase the operating flow rate of gases through the respiratory assistance system 10, 2200. The control system 2320 can measure one or more patient conditions in response to changes to one or more system parameters. The control system 2320 can measure the patient's respiratory rate in response to changes to the operating flow rate. a. Initial operating flow rate
The process 2400 can begin at block 2402 with the respiratory therapy device 2202 commencing delivery of a gas flow. The gas flow is provided at at least an operating flow rate. In some examples, the operating flow rate is sufficient to provide high flow therapy to the patient in use, such as within the ranges of flow rates as previously discussed. The control system 2320 may set an initial operating flow rate. The control system may also set other operating parameters of the respiratory therapy device 2202. The operating parameters of the respiratory therapy device 2202 may control the characteristics of the flow of gases delivered or provided by the respiratory therapy device 2202.
As described previously, the initial operating flow rate may be manually set by a clinician. In an example, a range for the operating flow rate may also be manually set by a clinician. Alternatively, the initial and/or range for the operating flow rate may be pre-set or stored in a memory. The initial and/or range for the operating flow rate may alternatively be determined based on one or more additional parameters. Additional parameters may include patient characteristics, such as age, weight, height, sex, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like, and/or system parameters including time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the initial and/or range for the operating flow rate.
In some examples, once therapy has commenced, in an optional step (not shown), the operating flow rate may initially be increased by an increment. In such examples, once the operating flow rate has been increased by an increment in this step, the process 2400 then proceeds to start the iterative control loop comprising steps 2404 to 2414. b. Intervals
Once therapy has commenced, and gas flow is provided by the respiratory therapy device at on operating flow rate, the process 2400 then proceeds to start an iterative control loop comprising steps 2404 to 2414. The iterative control loop is performed at intervals, and comprises, at said intervals, performing the steps 2404 to 2414.
In some examples, an interval is defined by the control system 2320 waiting for a time interval before performing each of steps 2404 to 2410/2412. For example, the control system 220 can wait for a time interval before proceeding to perform the steps of 2404 to 2410/2412. This step is shown by block 2414 of the process 2400. The step 2414 of waiting for an interval may be performed before step 2404, and after step 2410 or 2412 has been performed, such that there is a delay between performing each iteration of the control loop 2400. It will be appreciated that steps 2404 to 2410/2412 may be performed substantially in the same time interval.
In some examples, the time interval may be a fixed time interval. The fixed time interval may be the same interval for each iteration of the control loop. In some examples, the fixed time interval is a pre-set time interval. For example, the pre-set time period can be less than 10 minutes or greater than or equal to 10 minutes. In such examples, the pre-set time interval may be between about 1 minute to about 8 hours. The pre-set time interval may be for example 5 minutes, or 10 minutes, or 15 minutes, or 30 minutes, or 45 minutes, or 1 hour, or 1 hour and 30 minutes, or 2 hours. In other examples, the time interval is a variable time interval. The variable time interval may be different or have the option of being different between each interval for each iteration of the control loop. The variable time interval may be based on a calculation or determination.
In some examples, the variable time interval may be based on the respiratory rate of the patient, and/or the status of the respiratory rate of the patient, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session. In some examples, the variable time period is calculated or determined by the control system 2320 at each interval.
In further examples, the time period is set to a first value when the status of the patient's respiratory rate is within a first range, and to at least a second value when the status of the patient's respiratory rate is within a second range. For example, if the control system 2320 determines that the patient's respiratory rate is decreasing at a certain rate above a threshold between intervals, the time period may be set to a first value. If the control system 2320 determines that the patient's respiratory rate is decreasing at a certain rate below a threshold between intervals, the time period may be set to a second value. The first value may be shorter than the second value. In other embodiments, the first value may be greater than the second value. Further thresholds and corresponding values are envisaged. c. Measuring or determining respiratory rate
At block 2404, the control system 2320 receives or determines a patient parameter indicative of the patient's respiratory rate. The patient parameter indicative of the patient's respiratory rate may be based on data from one or more sensors, as discussed above.
As discussed above, the control system 2320 can determine the patient's respiratory rate based on one or more received sensor measurements at block 2404. In an example, the sensor measurement is a plethysmographic signal. Other measurements for determining respiratory rate are discussed above. In some examples, the patient's respiratory rate may be inputted via a user interface and received by the control system 2320. The control system 2320 may store the received or determined respiratory rate in the memory. In some examples, the control system 2320 may assess the quality of the received data or determined respiratory rate. In such examples, the control system 2320 may determine that additional measurements of respiration rate are required based on the received data or determined respiratory rate being unsuitable. For example, the control system 2320 can determine if the last measured respiration rate is at or exceeded a boundary condition. If the control system 2320 determines that additional measurements are needed, then the control system 2320 can perform step 2404 again until a suitable reading is obtained. In the alternative, if the control system 2320 determines that additional measurements are not required, the control system 2320 can then proceed to determine a status of the patient's respiratory rate at block 2406, as will be discussed.
The control system 2320 may store the measured patient parameter indicative of the patient's respiratory rate for each interval or measurement period in the memory. The control system 2320 can also store additional parameters of patient and/or system in the memory and associate it with the measured patient parameter for each interval. Accordingly, the control system 2320 can store the state of the patient and the respiratory assistance system 10, 2200 in conjunction with the measured parameter. d. Determining status of respiratory rate
At block 2406, the control system 2320 determines a status of the patient's respiratory rate. The control system 2320 determines a status of the patient's respiratory rate based at least on said patient parameter received or determined at step 2404. The control system 2320 may also determine the status of the patient's respiratory rate based on one or more patient parameters received or determined at one or more previous intervals.
In some examples, the status of the patient's respiratory rate is determined based on comparing said received or determined patient parameter indicative of the patient's respiratory rate at the present interval, to at least the patient parameter indicative of the patient's respiratory rate received or determined at one or more previous intervals.
In some examples, the status of the patient's respiratory rate is based at least on comparing said received or determined patient parameter indicative of the patient's respiratory rate to the patient parameter indicative of the patient's respiratory rate received or determined at the most recent previous interval.
In examples such as the above, said comparison may indicate the change of the patient parameter indicative of the patient's respiratory rate between two or more intervals.
In some examples, the status of the patient's respiratory rate may be determined based on assessing a trend in the patient's respiratory rate over time. The trend may be based at least on said measured patient parameter indicative of the patient's respiratory rate taken at the present interval, and one or more patient parameters indicative of the patient's respiratory rate measured at one or more previous intervals. The trend may indicate the change of the patient parameter indicative of the patient's respiratory rate between two or more intervals.
In some examples, the step of determining the status of the patient's respiratory rate may include calculating by the control system 2320 the rate of the change of the patient's respiration rate over time. The status of the patient's respiratory rate may be determined based on assessing a rate of change of the patient parameter indicative of the patient's respiratory rate. The rate of change of the patient parameter indicative of the patient's respiratory rate may be determined based on a calculation which uses the patient parameter indicative of the patient's respiratory rate received or determined at the present interval, and one or more patient parameters indicative of the patient's respiratory rate received or determined at one or more previous intervals. The control system 2320 may determine a derivative of a function using the one or more patient parameters indicative of the patient's respiratory rate in the function.
In some examples, the status of the patient's respiratory rate may be a state of a patient's respiratory rate. The state of the patient's respiratory rate may be for example grouped into a category. In some examples, the category may be such as 'stable' or 'reducing' or 'increasing'. The state of the patient's respiratory rate may be for example grouped into a category based on the comparison of the patient parameter indicative of the patient's respiratory rate at different intervals, and/or the calculated rate of change of the patient's respiratory rate. For example, if based on the comparison or determination or calculation discussed above between said received or determined patient parameter indicative of the patient's respiratory rate at the present interval with at least the patient parameter indicative of the patient's respiratory rate received or determined at one or more previous intervals the control system determines that the patient's respiratory rate has decreased between intervals, the status of the patient's respiratory rate may be indicated as 'reducing'.
Additionally, if the comparison or determination or calculation indicates that the patient's respiratory rate has increased between intervals, the status of the patient's respiratory rate may be indicated as 'increasing'.
Additionally, if the comparison or determination or calculation indicates that the patient's respiratory rate has substantially stayed the same between intervals, the status of the patient's respiratory rate may be indicated as 'stable'. The control system 2320 may indicate that the status of the patient's respiratory rate is 'stable' if the comparison or determination or calculation indicates that the change in patient's respiratory rate is below a threshold.
In some examples, the threshold may be quantified as a percentage of difference, or change between said received or determined patient parameter indicative of the patient's respiratory rate at the present interval with at least the patient parameter indicative of the patient's respiratory rate received or determined at one or more previous intervals. In such examples, the threshold may be percentage of difference, or change of above 2.5%. In further examples, the threshold may be percentage of difference, or change of above 5%. In further examples, the threshold may be percentage of difference, or change of above 7.5%. In further examples, the threshold may be percentage of difference, or change of above 10%. In further examples, the threshold may be percentage of difference, or change of above 12.5%. In further examples, the threshold may be percentage of difference, or change of above 15%. In further examples, the threshold may be percentage of difference, or change of above 20%. In further examples, the threshold may be percentage of difference, or change of above 25%.
In some examples, the threshold may be quantified as an amount of difference, or change between said received or determined patient parameter indicative of the patient's respiratory rate at the present interval with at least the patient parameter indicative of the patient's respiratory rate received or determined at one or more previous intervals. In such examples, the threshold may be amount of difference, or change of above 0.1 breaths per minute (bpm). In further examples, the threshold may be amount of difference, or change of above 0.5 bpm. In further examples, the threshold may be amount of difference, or change of above
1 bpm. In further examples, the threshold may be amount of difference, or change of above 1 ,5bpm. In further examples, the threshold may be amount of difference, or change of above
2 bpm. In further examples, the threshold may be amount of difference, or change of above 2.5 bpm. In further examples, the threshold may be amount of difference, or change of above 4 bpm. In further examples, the threshold may be amount of difference, or change of above 5 bpm.
In some examples, the threshold may be automatically determined based on one or more parameters. The one or more parameters may be inputted by the user and/or stored in memory. The one or more parameters may correspond to the patient conditions and/or system conditions. Parameters may include patient characteristics, such as age, weight, sex, height, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system can use these parameters in determination of the threshold.
The control system 2320 can dynamically adjust the operating flow rate 2332 for a patient over the time of their therapy. The control system 2320 may also dynamically adjust the operating oxygen concentration level 2336 for a patient over the time of their therapy. The control system 2320 can continuously detect system parameters and patient parameters.
As shown in Figure 29, at at least a first interval, relating to flow rate F1, one or more patient parameters indicative of the patient's respiratory rate, shown by R1, are received or determined. At at least a second interval, occurring after said first interval, said second interval relating to flow rate F2, one or more patient parameters indicative of the patient's respiratory rate, shown by R2, are received or determined. The status of the patient's respiratory rate may be determined based on at least R1 and R2. In an example, the gradient, or rate of change of the patient's respiratory rate between at least these two flow rates, F1 and F2, may be calculated. In one example, a difference AR between at least the first respiratory rate R1 and the second respiratory rate R2 may be determined. As discussed, the status of the patient's respiratory rate may be based on AR, or the negative gradient between two or more readings of respiratory rate at corresponding flow rates, and intervals. Additionally, the status of the patient's respiratory rate may be based on AR in comparison to a threshold. The threshold may be such as discussed above.
In some examples, the control system may determine if the patient's respiratory rate has reached a minimum respiratory rate. For example, as shown in Figure 26 and Figure 28, the minimum respiratory rate RM of the patient can be reached at flow rate FM. In such examples, the status of the patient's respiratory rate may be categorised as 'stable' when it is determined that the patient's respiratory rate has reached a minimum respiratory rate, based on the methodology as discussed above.
Additionally, or alternatively, the status of the patient's respiratory rate may be categorised by a degree of change based on the comparison or determination or calculation performed between the data from different intervals. In such examples, the status of the patient's respiratory rate may indicate the degree or amount of change at each interval. For example, the status of the patient's respiratory rate may indicate the patient's respiratory rate is decreasing, and the degree or amount of change at the present interval is a certain amount (for example, as quantified in breaths per minute (bpm)) when compared to the previous interval. For example, this may be in relation to a threshold which may be quantified as an amount or a percentage of difference or change, as previously discussed.
The determination of the status of the patient's respiratory rate may take into account the determined status at one or more previous intervals. As such, the control system 2320 may track the status of the patient's respiratory rate across or between multiple intervals.
In some examples, the determination of the status of the patient's respiratory rate may take into account the determined status of the patient's respiratory rate since the provision of therapy began. For example this may be from the provision of therapy at the initial operating flow rate. The control system may determine that the operating flow rate be adjusted or increased until the control system determines that the status of the patient's respiratory rate indicates that the patient's respiratory rate is decreasing, before it then makes a determination to subsequently maintain the flow rate. In other words, the control system adjusts the operating flow rate from the initial operating flow rate until the patient's respiratory rate or the status of the patient's respiratory rate changes above or outside of a threshold. After that point, the control system continues to adjust the flow rate, until the control system determines that the patient's respiratory rate or the status of the patient's respiratory rate is below or within said threshold, or a different threshold. At that point, the control system maintains the operating flow rate.
For example, in relation to the graphs shown in Figure 26 to Figure 29, as shown by the curve, the patient's respiratory rate is relatively stable at lower flow rates, with a steeper negative gradient between about 25 and 30 l/min. Then, the curve shallows out to a 'minimum' point. A minimum respiratory rate RM is reached, at flow rate FM. In this example, the control system adjusts the operating flow rate from the initial operating flow rate throughout said lower flow rate values where the patient's respiratory rate is substantially stable, until the patient's respiratory rate or the status of the patient's respiratory rate changes above or outside of a threshold, which corresponds to the steeper negative gradient of the curve. After that point, the control system continues to adjust the flow rate, until the control system determines that the patient's respiratory rate or the status of the patient's respiratory rate is below or within said threshold, or a different threshold. This would be considered to be the point at which the curve shallows out to the 'minimum' point, indicated by the minimum respiratory rate RM, at flow rate F . At that point, the control system maintains the operating flow rate. The control system then continues to determine the status of the patient's respiratory rate, and will determine that the operating flow rate be adjusted should the status of the patient's respiratory rate indicate that it should be, for example, if the rate of change of the patient's respiratory rate is outside a threshold.
In some examples, steps 2404 and 2406 to determine the status of the patient's respiratory rate may comprise the controller, at each interval, determining or receiving a patient parameter indicative of the patient's respiratory rate at the present operating flow rate, at a flow rate an increment above the operating flow rate, and at a flow rate an increment below the operating flow rate. The controller may then use the patient parameter indicative of the patient's respiratory rate at the present operating flow rate (i.e. the present respiratory rate), the patient parameter indicative of the patient's respiratory rate at a flow rate an increment above the operating flow rate (i.e. the higher flow respiratory rate), and the patient parameter indicative of the patient's respiratory rate at a flow rate an increment below the operating flow rate (i.e. the lower flow respiratory rate) to determine the status of the patient's respiratory rate.
In these examples, step 2404 of method 2400 comprises the controller, in any order, determining or receiving a patient parameter indicative of the patient's respiratory rate at the present operating flow rate; increasing the operating flow rate by an increment above the present operating flow rate, and determining or receiving a patient parameter indicative of the patient's respiratory rate at the increased operating flow rate; decreasing the flow rate to be an increment below the present operating flow rate and determining or receiving a patient parameter indicative of the patient's respiratory rate at the decreased operating flow rate. In some examples, further patient parameters are determined or received at one or more additional increments above and/or below the operating flow rate.
In some examples, the determination or receiving of the patient parameter indicative of the patient's respiratory rate at one or each of the present, decreased, and/or increased operating flow rates comprise waiting for a time interval for the patient to respond to the change in flow rate before determining or receiving of the patient parameter. The time interval and flow increment may be as previously discussed.
In these examples, step 2406 of method 2400 comprises determining the status of the patient's respiratory rate based on assessment of the patient parameters indicative of the patient's respiratory rate taken at the present operating flow rate (i.e. the present respiratory rate), at the one or more increments above the operating flow rate (i.e. the higher flow respiratory rate(s)), and at the one or more increments below the operating flow rate (i.e. the lower flow respiratory rate(s)). The controller is configured to assess higher flow respiratory rate(s) and determine whether the higher flow respiratory rate(s) indicates the patient's respiratory rate is stable or increasing using the method(s) previously described in relation to step 2406. The controller similarly assesses the lower flow respiratory rate(s) and determines whether the lower flow respiratory rate(s) indicate the patient's respiratory rate is stable or increasing using the method(s) previously described in relation to step 2406.
As such, the controller may be configured to assess the status of the patient's respiratory rate at the operating flow rate, at one or more increments above the operating flow rate, and at one or more increments below the operating flow rate. Based on the assessment, the controller may determine the patient's respiratory rate at the operating flow rate is stable, is increasing, or is decreasing; and similarly at the one or more increments above the operating flow rate is stable, is increasing, or is decreasing; and at the one or more increments below the operating flow rate is stable, is increasing, or is decreasing.
The controller may determine, in situations where at the one or more increments above the operating flow rate is stable or is increasing, and also where at the one or more increments below the operating flow rate is increasing, that the present operating flow rate is the optimal operating flow rate, and no change to the operating flow rate at step 2408 is required.
The controller may determine, in situations where at the one or more increments above the operating flow rate is decreasing, and where at the one or more increments below the operating flow rate is increasing, that the operating flow rate is lower than the optimal operating flow rate. In these situations, the controller may determine at step 2408 that the operating flow rate should be increased by an increment.
The controller may determine, in situations where at both the one or more increments above the operating flow rate, and the one or more increments below the operating flow rate is stable, that the operating flow rate is higher than optimal. In these situations, the controller may determine that the operating flow rate should be decreased by an increment. If the status of the patient's respiratory rate at the one or more increments above the operating flow rate and the one or more increments below the operating flow rate do not provide a conclusive determination on if the operating flow rate is the optimal operating flow rate, the controller may perform a second calibration using a second increment. In some examples, the second increment may be greater than first increment. The second increment may provide larger changes in the patient's respiratory rate that can assist in determining where the optimal operating flow rate is. The method as previously described may be repeated using the second increment.
Further, if the status of the patient's respiratory rate at the one or more increments above the operating flow rate and the one or more increments below the operating flow rate do not provide a conclusive determination on whether the operating flow rate is the optimal operating flow rate, the controller may perform the whole method 2400 again, starting at the initial flow rate again to determine the optimal operating flow rate.
In some examples, step 2406 may comprise, at each defined time interval, determining a status of the patient's respiratory rate at the maintained operating flow rate. Step 2406 may further comprise determining, at a first flow rate higher than the maintained operating flow rate, a status of the patient's respiratory rate. Step 2406 may additionally comprise determining, at a second flow rate lower than the maintained operating flow rate, a status of the patient's respiratory rate.
In these examples, step 2408 may comprise adjusting or maintaining the operating flow rate depending on a comparison of: the status of the patient's respiratory rate at the maintained operating flow rate, the status of the patient's respiratory rate at the first flow rate, and the status of the patient's respiratory rate at the second flow rate. The status determined at the maintained operating flow rate, at the first flow rate, and at the second flow rate may be compared relative to each other.
In some further examples, step 2406 may comprise, at each defined time interval, determining a status of the patient's respiratory rate at a fourth flow rate lower than the maintained operating flow rate. The fourth flow rate may be lower than the second flow rate. Step 2406 may further comprise determining, at a third flow rate higher than the maintained operating flow rate, a status of the patient's respiratory rate. The third flow rate may be higher than the first flow rate.
In these further examples, step 2408 may comprise adjusting or maintaining the operating flow rate depending on a comparison of: the status of the patient's respiratory rate at the maintained operating flow rate, the status of the patient's respiratory rate at the third flow rate and the status of the patient's respiratory rate at the fourth flow rate. The status determined at the maintained operating flow rate, at the third flow rate, and at the fourth flow rate may be compared relative to each other. e. Determining whether to adjust or maintain operating flow rate
At block 2408, the control system 2320 can then determine whether to adjust or maintain the operating flow rate, based on the determined status of the patient's respiratory rate.
The control system 2320 may use the determined status of the patient's respiratory rate to determine whether to adjust or maintain the operating flow rate. If the status of the patient's respiratory rate indicates that the patient's respiratory rate is decreasing, then the control system 2320 at step 2408 may determine that the operating flow rate be increased. Similarly, if the status of the patient's respiratory rate indicates that the patient's respiratory rate is substantially stable, then the control system 2320 at step 2408 may determine that the operating flow rate be maintained.
In some examples, if the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, then the control system 2320 at step 2408 may determine that the operating flow rate be decreased.
In some examples, the control system 2320 at step 2408 uses the status of the patient's respiratory rate and one or more previous adjustments to the operating flow rate to determine whether to increase or decrease the operating flow rate. For example, if the operating flow rate was increased in the previous interval, and the status of the patient's respiratory rate of the present interval indicates that the patient's respiratory rate is decreasing, then the control system 2320 may determine that the operating flow rate be increased.
Conversely, if the operating flow rate was decreased in the previous interval, and the status of the patient's respiratory rate indicates that the patient's respiratory rate is decreasing, then the control system 2320 at step 2408 may determine that the operating flow rate be decreased. Furthermore, if the operating flow rate was decreased in the previous interval, and the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, then the control system 2320 at step 2408 may determine that the operating flow rate be increased.
In some examples, at block 2408, the control system 2320 may determine that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially the same between intervals. The intervals may be the present interval and one or more previous intervals, as discussed above. In such examples, control system 2320 may determine that the patient's respiratory rate is substantially the same between intervals based on the comparison at step 2406 indicating that the patient parameter indicative of the patient's respiratory rate at the present interval is within a defined range or threshold of the one or more previous intervals.
In some examples, at block 2408, the control system 2320 may determine that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable, or is otherwise categorised as being 'stable'. The status of the patient's respiratory rate being determined at step 2406.
In some examples, at block 2408, based on determining that said operating flow rate be maintained for a first time, the control system 2320 may maintain the operating flow rate by adjusting the operating flow rate back to the operating flow rate of the previous interval. In such examples, the operating flow rate may be set back by the increment to the rate it was at which the minimum respiratory rate of the patient was achieved. In this way, the minimum respiratory rate RM can be reached at flow rate FM, as shown in Figure 26. In some examples, the determining that said operating flow rate be maintained for a first time may be a first time in a therapy session. In other examples, it may be the first time across a plurality of therapy sessions.
In these examples, where the patient's respiratory rate remains substantially constant between intervals, at two operating flow rates, it may be preferable that the lower of the two flow rates is used. In other words, where there is a minimum respiratory rate across multiple flow rates (for example where the curve has a flat portion at the minimum), it is preferable to use the lowest operating flow rate that achieves that minimum respiratory rate.
In other examples, the operating flow rate may not be set back an increment, even when the final increase in operating flow rate causes a slight rise in the patient's respiratory rate. As the patient's respiratory rate increases at a slower rate with increasing flow rate than decreasing flow rate from the minimum, it may be preferable to have a flow rate set higher than the minimum for added stability.
Increments
If the control system 2320 determines that the operating flow rate be adjusted, it may proceed to step 2410 and adjust the operating flow rate by an increment. In some examples, the increment may be a fixed time increment. The fixed time increment may be the same increment for each iteration of the control loop. In some examples, the fixed time increment is a pre-set time increment.
In another example, the increment is a variable time increment. The variable increment may be based on the respiratory rate of the patient, and/or the status of the respiratory rate of the patient, and/or one or more device and/or patient sensor readings, and/or the amount of time in the therapy session. At step 2408 the control system may also determine the size of the variable increment for adjusting the operating flow rate.
In a further example, the increment, whether fixed or variable, may be automatically determined based on one or more additional parameters. The one or more additional parameters may be inputted by the user and/or stored in memory. The one or more additional parameters may correspond to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, weight, height, sex, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the increment.
The increment may be between about 0.1 l/min and about 20 L/min, optionally it may be between about 0.5 l/min and about 15 l/min, optionally it may be between about 1 l/min and about 10 l/min, optionally it may be between about 2 l/min and about 8 l/min, optionally it may be between about 3 l/min and about 6 l/min, preferably it may be about 5 l/min.
In some examples, the process 2400 may use larger flow rate increments at the beginning of a therapy session. This is because the minimum respiratory rate is unlikely to be achieved at low flow rates. For example, increments of 10 l/min may be used up the system reaches 30 l/min. Once 30 l/min is reached, 5 l/min increments may be used. Alternatively, a medical practitioner may set the initial operating flow rate at a higher flow rate such that the titration process is quicker. In the case where the first increment above the initial flow rate yields an increase in respiratory rate, the titration process should begin decreasing the flow rate in increments to find the minimum.
In another example, the increments may be proportional to the difference between the respiratory rate received or determined at the present interval and an upper threshold RT+, discussed below. For example, if the patient has a respiratory rate much higher than the upper threshold, then the increments used are larger such that the respiratory rate is brought closer to the desired range at a quicker rate. As this difference becomes smaller, so too do the increments in flow rate used.
Thresholds
In some examples, at block 2408, the control system 2320 can also compare the received or determined patient's respiratory rate and/or the status of the patient's respiratory rate to one or more thresholds. In one example, the one or more thresholds may be an upper threshold and a lower threshold. The one or more thresholds can be such that the patient's respiratory rate does not fall outside of a predetermined range. A respiratory rate that is within a desirable range may indicate a healthy and/or stable patient.
In Figure 26, this range is shown between RT+ and RT- In this example, the upper threshold is RT+ and the lower threshold is RT- This range may be, in some examples, between about 12 - 20 breaths per minute (BPM), 12 - 18 BPM, or 12 - 16 BPM. This range is typically defined by a clinician or physician. The range may be inputted to the respiratory therapy device and received by the control system 220. In some examples, the control system 220 may determine the range based on one or more patient and/or system conditions.
This range may be different based on the type of patient, the type of respiratory disease and other conditions. For example, the range may be different based on if the patient is receiving treatment in a hospital or at home. At home, it may be desirable to have an earlier warning that a patient's condition is worsening or cannot be stabilised by the high flow therapy. As such, the range used at home may be narrower than that used in the hospital.
In some embodiments, at block 2408, the control system 2320 can receive additional parameters corresponding to the patient conditions and/or system conditions. Additional parameters may include patient characteristics, such as age, sex, weight, height, sleep state (awake or asleep), respiratory symptoms (e.g. presence of coughing and/or sputum production), and the like. System parameters may include time of day, type of therapy selected, and the like. The control system 2320 can use these additional parameters in determination of the one or more thresholds.
In some examples, the patient's curve may be such that the minimum respiratory rate RM is below the lower threshold RT- In this case, once respiratory rate drops below RT., the control system may set the operating flow rate back an increment such that respiratory rate is at or above RT- This ensures that the patient's respiratory rate is not kept below the lower threshold RT- In some examples, the high flow therapy device may reach its maximum operating flow rate before the minimum respiratory rate is found. In other words, the patient's minimum respiratory rate occurs at a flow rate above the maximum operating flow rate achievable by the high flow device. For some devices, the maximum operating flow rate may be 70 - 80 l/min. If the operating flow rate reaches this maximum without achieving the minimum respiratory rate, an alarm may sound that advises the patient is given a different therapy, for example CPAP, non-invasive ventilation, or invasive ventilation. Alternatively, the high flow therapy device may be capable of delivering different kinds of therapies, such as nasal high flow, CPAP and NIV. In this case, the high flow device may switch to a different type of therapy when the maximum flow rate is reached on the high flow therapy setting.
In another example, the control system 2320 may not seek to achieve the minimum respiratory rate. Instead, the control system may achieve the lowest flow rate at which the respiratory rate is within the desired range. For example, with reference to Figure 26, the control system may incrementally increase the flow rate until FT+ is reached, which is the lowest flow rate that provides a respiratory rate within the thresholds. This respiratory rate is likely to be close to the upper threshold, RT+ At this point, the control system stops increasing the flow rate.
In another example, it may be desirable to keep the respiratory rate somewhere between the upper and lower thresholds. In this embodiment, the control system 2320 would titrate by performing the steps 2404 - 2410/2412 for patient's respiratory rates that are somewhere in the desired range. In these examples, the control system 2320 may perform steps 2404 to 2412 so long as the patient's respiratory rate is within the desired range, by comparing the patient's respiratory rate to the thresholds. In these examples, the control system 2320 may maintain the operating flow rate when the status of the patient's respiratory rate indicates that the patient's respiratory rate is 'stable' or at a minimum, such as RM , and the patient's respiratory rate is additionally within the upper threshold RT+ and the lower threshold RT-
Additionally, or alternatively, the control system 2320 may set boundary or threshold conditions for the operating flow rate and not select a flow rate below a minimum rate. The control system 2320 can also cap flow rate at a maximum rate that may be set by the clinician or stored in the controller. This limit may be based on a flow above which the patient may feel discomfort, for example 120 L/min for adults and 3 L/min/kg for neonatal patients and children. Higher flow rates can also increase noise and pressure. Accordingly, based on the data collected by the control system 2320, it can compare the operating flow rate at the present interval to the boundary or threshold conditions for the flow rate at block 2408. f. Adjusting operating flow rate
At block 2410, the control system 2320 may adjust the operating flow rate based on the control system determining at block 2408 that said operating flow rate be adjusted. The control system 2320 may adjust the operating flow rate by the increment determined at block 2408.
As discussed above, at step 2408, if the status of the patient's respiratory rate indicates that the patient's respiratory rate is decreasing, then the control system 2320 may determine that the operating flow rate be increased. At step 2410, the control system 2320 proceeds to increase the operating flow rate by the increment.
In some examples, if the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, then the control system 2320 at step 2408 may determine that the operating flow rate be decreased.
Increasing the operating flow rate may comprise adjusting the operating flow rate from a first value to a second, higher value. The difference between the first value and the second value is the increment.
The adjustment of the operating flow rate comprises adjusting the motor speed of the flow generator. For example, this may be achieved by outputting one or more flow control outputs 2332, as discussed above. In such examples, increasing the operating flow rate by an increment comprises adjusting the motor speed of the blower from a first value to a second, higher value. The adjustment of the motor speed may be proportional to the adjustment of the operating flow rate. In some examples, the control system 2320 may adjust the operating flow rate within a range. The range may be defined by a maximum allowable flow rate and/or a minimum allowable flow rate. The control system 2320 may be configured to cease further increases of the operating flow rate should it be determined that a determined increase to the operating flow rate would be above a maximum allowable flow rate. g. Maintaining operating flow rate
At block 2412, the control system 2320 may maintain the operating flow rate based on the control system determining at block 2408 that said operating flow rate be maintained. As discussed above, at step 2408, if the status of the patient's respiratory rate indicates that the patient's respiratory rate is substantially stable, or is otherwise at a minimum, then the control system 2320 may determine that the operating flow rate be maintained. At step 2412, the control system 2320 proceeds to maintain the operating flow rate, as discussed above. f. Waiting for interval
At block 2414, after the control system 2320 either adjusts the operating flow rate at step 2410, or maintains the operating flow rate at step 2412, the process 2400 then proceeds to wait for a time interval before performing each of steps 2404 to 2410/2412 again, as previously discussed.
For example, the control system 2320 can wait for a time interval before proceeding to perform the steps of 2404 to 2410/2412. This step is shown by block 2414 of the process 2400. As such that there is a delay between performing each iteration of the control loop 2400. It will be appreciated that steps 2404 to 2410/2412 may be performed substantially in the same time interval. g. Additional/alternative implementations
In some alternative examples, the control system may be configured to perform steps 2402 and 2404 initially. The control system may then be configured to display the patient parameter indicative of the patient's respiratory rate to the user via the display of the respiratory therapy apparatus, or a display of an external device in operative communication with the respiratory therapy apparatus and forming a part of the respiratory therapy system. In some examples, alongside the display of the patient parameter indicative of the patient's respiratory rate, an indication of the operative flow rate may also be shown.
Additionally, a user input may be able to be received by the control system. The display may be configured to allow a user interface such as by way of a touchscreen which provides for the user input. In some examples the user input may be provided by one or more buttons, knobs, or dials of the respiratory therapy apparatus. The user input is configured to allow the user to adjust the operating flow rate manually. The adjustment of the operating flow rate performed by the user based on the displayed indication of the patient's respiratory rate (or other patient parameter).
In some further examples, the method 2400 may further comprise prompting the user based on the decision at step 2408. In these examples, once step 2408 has determined that the operating flow rate be adjusted, the user is prompted that the operating flow rate is being adjusted via the display. The new operating flow rate, and in some examples the previous operating flow rate, may additionally be presented to the user via the display. As such, the user is informed of the changing of the adjustment to the operating flow rate.
In other examples, once step 2408 has determined that the operating flow rate be adjusted, the user is prompted that the controller has determined that the operating flow rate should be adjusted. In such examples, the user is prompted to confirm whether the adjustment to the operating flow rate should proceed. The user can provide input in response to the prompting, for example via the display. Once a confirmatory input has been received from the user, the controller proceeds to step 2410 to adjust the operating flow rate by an increment. If a confirmatory input is not received, or not received within a time period, then the controller may proceed to step 2412 to maintain the present operating flow rate.
In some examples, the determination that the operating flow rate be adjusted, and/or the proposed new operating flow rate determined by the controller may be presented as a suggestion to a user rather than being automatically implemented by the controller. The controller may be configured to present one or more prompts to the user in relation to the proposed new operating flow rate and allow for user input. The user input may similarly be configured to provide confirmation of the proposed operating flow rate, and/or allow for adjustment of the proposed operating flow rate before confirmation.
In some additional examples, the controller may be configured to store the operating flow rate at the end of a therapy session in memory. At the end of each therapy session, the controller may store the latest operating flow rate in memory. At the initiation of the next therapy session, at step 2402 the stored operating flow rate may be used as the initial operating flow rate for the therapy session.
2.4 Alternative example of flow control method
In an alternative example flow control method, step 2408 of method 2400 is modified from the examples previously described. In this alternative example, the step 2408 of determining whether to adjust or maintain the operating flow rate is based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, as will be described. In these examples, step 2406 may not be performed, and the method may proceed from step 2404 to step 2408 directly. The other steps of the method 2400 in this alternative example are as previously described.
In this example, the user may be prompted to set one or more thresholds. The one or more thresholds may be one or more parameter thresholds. Each of the one or more parameter thresholds relating to a patient or therapy parameter. The one or more thresholds may relate to the respiratory rate of the patient, and/or one or more additional patient parameters or therapy parameters. One or more of the thresholds may relate to a corresponding parameter. The one or more thresholds may comprise an upper threshold and/or a lower threshold for each parameter. For example, the respiratory rate threshold may comprise an upper respiratory rate and a lower respiratory rate. The respiratory rate threshold may be for example between a lower threshold of about 5 breaths per minute and an upper limit of about 35 breaths per minute, optionally it may be between about 8 breaths per minute and an upper limit of about 25 breaths per minute, optionally it may be between about 11 breaths per minute and an upper limit of about 21 breaths per minute, optionally it may be between about 12 breaths per minute and an upper limit of about 20 breaths per minute, optionally it may be between about 12 breaths per minute and an upper limit of about 18 breaths per minute, preferably it may be between a lower limit of about 12 breaths per minute and an upper limit of about 16 breaths per minute. This range is typically defined by a clinician or physician.
The one or more thresholds may further comprise one or more time-based thresholds. The time-based thresholds may relate to a minimum amount of time the parameter or parameters are above each corresponding parameter threshold or thresholds. The timebased threshold could be a period of time. For example, the time-based threshold may be between 5 minutes and 60 minutes, or more preferably between 10 minutes and 45 minutes, or more preferably 15 minutes.
Any of the one or more thresholds, including the one or more parameter thresholds, and/or the one or more time-based thresholds may be set by a user. The threshold may be set by the user using the user interface. Any one or more of the thresholds may be alternatively predefined or pre-configured and stored in a memory in operational connection with the controller.
In these examples, step 2408 comprises assessing the received or determined patient parameter from step 2404 against the one or more thresholds. The method may proceed to step 2410 to adjust the operating flow rate based on the parameter or parameters meeting or exceeding the one or more thresholds. If the parameter does not meet or exceed the one or more thresholds, the method proceeds to step 2412 to maintain the operating flow rate.
In some examples, once the user has set the parameter(s) they can confirm these and start the provision of therapy using the device. The method 2400 will be performed as previously described, skipping step 2406. At step 2408, when the parameter, such as the respiratory rate of the patient, is greater than the threshold, for example a respiratory rate threshold, in some examples for a time threshold, the method will proceed to step 2410 to adjust the operating flow rate by an increment.
In any described example relating to step 2410 of the present method 2400, the increment for adjusting the operating flow rate may be an absolute value (i.e., a value in litres per minute (L/min)). The absolute value may be set by a user, for example the user may set the increment to a value between about 0.1 l/min and about 30 L/min, optionally it may be between about 0.1 l/min and about 15 l/min, optionally it may be between about 0.1 l/min and about 10 l/min, optionally it may be between about 0.1 l/min and about 5 l/min, optionally it may be between about 1 l/min and about 10 l/min, optionally it may be between about 2 l/min and about 8 l/min, optionally it may be between about 3 l/min and about 6 l/min, preferably it may be about 5 l/min, optionally it may be between about 5 l/min and about 10 l/min, optionally it may be between about 10 l/min and about 15 l/min, optionally it may be between about 10 l/min and about 20 l/min, optionally it may be between about 20 l/min and about 30 l/min. Alternatively, the absolute value may be pre-configured upon manufacture of the respiratory device or upon initial set up of the case and stored in the memory of the apparatus.
Alternatively, the increment for adjusting the operating flow rate may be determined as a percentage or fraction of the operating flow rate, or of the initial operating flow rate. The percentage or fraction may be set by a user, for example the user may set the percentage or fraction between 0 and 30% of the operating flow rate. Alternatively, the percentage or fraction may be pre-configured upon manufacture of the respiratory device or upon initial set up of the case and stored in the memory of the apparatus.
In these examples, the increment for the operating flow rate to be adjusted by at step 2410 may be an increase in the operating flow rate. In some examples, the increment for the adjustment may be a decrease in the operating flow rate.
In some examples, the step 2410 of adjusting the operating flow rate by an increment comprises changing the operating flow rate by a step change to the incremented operating flow rate. In other examples, the step 2410 of adjusting the operating flow rate by an increment comprises ramping the operating flow rate to the incremented operating flow rate over a period of time.
In some examples, when the operating flow rate is adjusted by the increment, the method 2400 further comprises displaying a prompt or alert to the user indicating the operating flow rate has been adjusted. The prompt or alert indicating the operating flow rate has been adjusted may be presented via the display. The display may be configured to show a symbol or text to indicate to the user that the operating flow rate has been adjusted. Thus, the user will be alerted that the parameter e.g., patient parameter has crossed the one or more threshold and is being provided with an adjusted (e.g., increased) operating flow rate.
Additionally, or alternatively, the method may comprise presenting an audible alarm to the user indicating the operating flow rate has been adjusted. The audible alarm may be provided alongside the prompt or alert presented on the display. In these examples, the controller may be configured to wait for an interval (e.g., 5, 10, 15 minutes or other as previously described). If the parameter (e.g., respiratory rate) has not decreased below the threshold after the interval, the controller may be configured to present the alert and/or alarm.
In some examples, once the operating flow rate has been adjusted by the increment, the method no longer comprises determining whether to adjust or maintain the operating flow rate. The controller may cease performing steps 2404-2414 at this point. The apparatus may be 'locked' at the adjusted (e.g., increased) operating flow rate. To make further adjustments to the operating flow rate after it has been adjusted may require the user to make manual adjustments via the user interface. This is because in some examples, the adjustment of the operating flow rate based on the thresholds may be actioned by the controller only when a patient is exhibiting high respiratory rates. Thus, as this may be considered a clinically serious situation, user intervention may be required in order to make further adjustments to the operating flow rate, particularly to reduce it from the increased level. In other examples, the method may comprise performing steps 2404 to 2414 as previously described, without preventing further adjustments to the operating flow rate.
In some examples, the controller may receive or determine a patient parameter indicative of the patient's SpO2 based on data from one or more sensors. In these examples, the step 2408 of determining whether to adjust or maintain the operating flow rate is based further on comparing the patient parameter indicative of the patient's SpO2 to one or more thresholds. The one or more thresholds in this example may relate to a range or lower limit for the SpO2 of the patient. The controller may at step 2404 use the patient's SpO2 as measured by one or more external sensors to trigger an adjustment of the operating flow rate, based on comparing the SpO2 to one or more threshold. For example, if the measured SpO2 drops below a threshold for a period of time (e.g., five minutes), the method determines that an adjustment (i.e. an increase) in the operating flow rate is required. Using the SpO2 of the patient could be an alternative to the use of the respiratory rate of the patient, or it could be used in combination with the respiratory rate of the patient. When used in combination with the respiratory rate of the patient, the SpO2 may have one or more specific thresholds, and the respiratory rate may have one or more specific thresholds.
Additionally, the controller may receive or determine a therapy parameter indicative of the FiO2 being provided or to be provided to the patient. The therapy parameter indicative of the FiO2 being provided or to be provided to the patient may be based at least in part on the patient parameter indicative of the patient's SpO2. The indication of the FiO2 of the patient might be a useful indicator when FiO2 is being automatically adjusted by the therapy device based on signals relating to the SpO2 of the patient, as described below. In these examples, the step 2408 of determining whether to adjust or maintain the operating flow rate is based further on comparing the patient therapy indicative of the FiO2 being provided or to be provided to the patient to one or more thresholds. In this example, if the controller in this system increases the FiO2 to above a certain threshold (for a minimum period of time), this may be a surrogate indicator for low SpO2. As such, the controller may use an FiO2 increase as an indication that the operating flow rate be adjusted. Using the FiO2 readings could be an alternative to the use of the respiratory rate of the patient, or it could be used in combination with the respiratory rate of the patient. When used in combination with the respiratory rate of the patient, the FiO2 may have one or more specific thresholds, and the respiratory rate may have one or more specific thresholds.
2.5 Oxygen Concentration Level Control Method
In some examples, the control system can additionally to the flow control method described above, control the operating oxygen concentration level of gas delivered to a patient automatically over the time of therapy and based on changes in patient conditions. In such examples, the control system 2320 can increase or decrease the oxygen concentration level (i.e. FiO2) by controlling one or more of the first and second valves to provide gases from the first and second inlets respectively. The control system 2320 can automatically control the operating oxygen concentration level for a particular patient based on a parameter indicative of the patient's respiratory rate and/or of the patient's SpO2. The oxygen concentration level can be optimized by the control system 2320 to improve patient comfort and therapy.
Details of example methods for automatically controlling a level of 02 provided to the patient by adjusting the 02 fraction (FiO2) provided to the patient in order to maintain a measured SpO2 level of the patient within the target SpO2 range are described in PCT Application Publication No. W02019/070136A1, filed 05 October 2018, which is incorporated by reference herein in its entirety. a. Oxygen concentration level effect on Respiratory Rate v Flow Rate relationship
An example set of collected measurements is illustrated in a graph format in Figure 27. The control system 2320 can control the operating flow rate and the operating oxygen concentration level of the gas flow delivered to the patient via the patient interface. The control of the operating flow rate and operating oxygen concentration level in turn has an effect on the patient's measured respiratory rate, as shown by the graph 2700 of Figure 27 and discussed below.
In this example, when the respiratory therapy is not providing any flow of gases to the patient, the flow rate of gases delivered to the patient is 0 l/min. At said flow rate of 0 l/min, the patient will have a certain measured respiratory rate Ro, 2704. The patient's respiratory rate may be measured in breaths per minute (bpm). Testing has shown that over a range of flow rates, the flow rate vs respiratory rate curve 2702, 2710 substantially follows a shape similar to that shown in Figure 27.
The first portion of this curve 2702, 2710 follows a reverse s-shaped curve (or reversed sigmoid curve). After a certain point, shown by 2706, 2708, however, further increases in flow rates cease to further decrease respiratory rate. At substantially this point 2706, 2708, a minimum respiratory rate RM is reached, at flow rate FM. At even higher flow rates, the respiratory rate begins to rise. This may be due to the increased effort required to exhale against the high flow rate.
Curve 2702 shows an of a first flow rate vs respiratory rate curve. Curve 2710 shows an of a second flow rate vs respiratory rate curve. When the fraction of inspired oxygen (FiO2) in the gases flow provided to the patient is increased, more oxygen is available per breath. This results in a reduced minute ventilation, as the patient receives the same amount of oxygen from a lower volume of inhaled gas. As the body tends to favour taking slower breaths rather than shallower breaths, respiratory rate may decrease. As such, curve 2710 shows the curve 2702 after an operating oxygen concentration level has been increased.
As shown, increasing the operating oxygen concentration level, or FiO2 can have the effect of moving the Flow Rate vs Respiratory Rate curve downwards. This is shown by the difference of curve 2702 down to curve 2710. Curve 2710 may be referred to as an increased oxygen concentration curve 2710. This shift may be proportional to the increase in operating oxygen concentration level, or FiO2.
At lower operating flow rates, it may be difficult to achieve high percentages of operating oxygen concentration level, or FiO2, as the total flow delivered is a low proportion of inhaled gas. For this reason, the increased oxygen concentration curve 2710 is not drawn at low flow rates.
This movement of the curve by increasing the operating oxygen concentration level can be used in situations where respiratory rate cannot be lowered to being within the desired range using increasing of the operating flow rates alone. In such situations, the curve 2702 as shown may look like that shown in Figure 27. As shown, even after the full titration to reach FM, the patient's respiratory rate RM is still above Rmax.
In some cases, a patient may begin undergoing high flow therapy while already in a deteriorated condition, where SpO2 levels may be suboptimal. In such cases, it is important to restore SpO2 to optimal levels quickly. As such, the controller may use closed loop SpO2 control in conjunction with the closed loop respiratory rate control method previously described. b. Overview of SpO2 control
In some examples, at the beginning of high flow therapy, the controller may be configured to receive one or more SpO2 readings, for example from one or more sensors. The controller may be configured to compare the one or more received SpO2 readings to one or more thresholds. In these examples, if the SpO2 level is below a threshold, the concentration of oxygen (FiO2) provided to the patient may be adjusted in an attempt to restore SpO2 to a stable level, as described for example in PCT Application Publication No. WO2019/070136A1.
In such examples, the respiratory rate-based adjustment of the operating flow rate, as disclosed above (for example in relation to method 2400), may take place either subsequently to this SpO2 control, or simultaneously with this SpO2 control. In these examples, as the SpO2 controller or control loop adjusts the FiO2, and the respiratory rate controller or control loop adjusts the operating flow rate, the two closed loop control methods may be operated simultaneously and independently. In these examples however, the respiratory rate-based FiO2 control described herein would not be operated at the same time as the SpO2-based FiO2 of this example control method.
In one example, at the start of the provision of therapy, the SpO2-based control of FiO2 may operate until the SpO2 has reached a stable level. This may comprise comparing the SpO2 reading received from one or more sensors to one or more thresholds. For example, a stable SpO2 level may be defined as the SpO2 reading being above a threshold. Once SpO2 has been at a stable level for a minimum period of time, such as for a time threshold, e.g. 10 to 30 minutes, or more preferably 15 minutes, then the SpO2 control may be disabled by the controller and the respiratory rate based control of the operating flow rate as described in relation to Figure 24 above, and optionally the respiratory rate-based control of the FiO2 as described in relation to Figure 25 below, may be enabled.
In some examples, at the start of therapy, the SpO2-based control of the FiO2 and the respiratory rate-based control of the operating flow rate may operate simultaneously. Once the SpO2 has been at a stable level (for example above a threshold for a time threshold) such as previously described, the SpO2-based control of Fi02 may be disabled and respiratory rate-based control of Fi02 as described in relation to method 2500 below may be enabled. c. Oxygen concentration control method
Figure 25 illustrate a flow chart of examples of a method 2500 for controlling the flow rate and oxygen concentration level of gas delivered to a patient based on a measured respiratory rate of a patient. The process or method 2500 comprises the steps of process or method 2400 as shown and described in relation to Figure 24. As will be appreciated, blocks or steps 2502, 2504, 2506, 2508, 2510, 2512, and 2514 correspond to blocks or steps 2402, 2404, 2406, 2408, 2410, 2412, and 2414 respectively.
As shown, at each interval, the control system 2320 can additionally adjust or maintain the operating flow rate and oxygen concentration level of the gases delivered or provided by the respiratory therapy device 100, 2202. The control system 2320 follows the iterative process or method 2500 discussed below of titration to find a substantially optimal operating flow rate and oxygen concentration level using feedback from one or more sensors.
The process or method 2500 may be performed continually or continuously over or throughout a therapy session.
A substantially optimal operating flow rate and oxygen concentration level may be such as which a patient's respiratory rate is at or close to a minimum, and at which a patient's respiratory rate is within a range.
The control system 2320 can increase the motor speed of the blower when a blower is used as the flow source 50, 2224 to increase the operating flow rate of gases through the respiratory assistance system 10, 2200.
The control system 2320 can also increase the oxygen concentration level by controlling one or both of the first and second valves to provide gases from the first and second inlets 2222, 2223 respectively. The control system 2320 can automatically control the operating flow rate and/or the operating oxygen concentration level for a particular patient based on a parameter indicative of the patient's respiratory rate. The operating flow rate and operating oxygen concentration level can be optimized by the control system 2320 to improve patient comfort and therapy.
The control system 2320 can measure one or more patient conditions in response to changes to the operating flow rate and/or oxygen concentration level. The control system 2320 can measure the patient's respiratory rate in response to changes to the operating flow rate and/or oxygen concentration level.
After the respiratory rate determination blocks or steps 2504 and 2506, and the flow control blocks or steps 2508, and 2510/2512, the control system 2320 may then perform oxygen control steps 2516 and 2518/2520. In other examples, oxygen control steps 2516 and 2518/2520 may occur before flow control steps 2508 and 2510/2512.
As shown in Figure 25, if the control system 2320 determines at block 2508 that the operating flow rate be adjusted, and then adjusts the operating flow rate at block 2510, then the method proceeds to step 2514 to wait an increment, similarly to the method described in relation to Figure 24.
Alternatively, if the control system 2320 determines at block 2508 that the operating flow rate be maintained, it then proceeds to maintain the operating flow rate at block 2512, then the method proceeds to step 2516 to perform oxygen control steps 2516 and 2518/2520, before it then proceeds to step 2514 to wait an increment.
In these examples, control of the operating flow rate is performed iteratively until the operating flow rate is maintained. Once it is maintained, then oxygen concentration control may be used to keep the operating flow rate at a stable or minimum level and to increase the concentration of oxygen, or FiO2, until the respiratory rate of the patient is within a desired range. In these embodiments, control of the operating flow rate allows for the patient's respiratory rate to be reduced to a stable level, however it might still be outside a preferred range. Hence, the oxygen concentration can then be controlled such that the patient's respiratory rate may be reduced further to be within said preferred range. If the patient's respiratory rate can be minimised and brought to a stable level and within desired range using flow rate alone, then adjustment of the oxygen concentration may not be required.
In alternative examples, if the control system 2320 determines at block 2508 that the operating flow rate be adjusted, and then adjusts the operating flow rate at block 2510, then the method proceeds to step 2516 to perform oxygen control steps 2516 and 2518/2520, before it then proceeds to step 2514 to wait an increment. In such examples, the control system 2320 performs control of the operating oxygen concentration level and the operating flow rate in the same interval regardless of the state of the patient's respiratory rate.
The respiratory rate determination blocks or steps 2504 and 2506, the flow control blocks or steps 2508, and 2510/2512, and the oxygen control steps 2516 and 2518/2520 may all be performed in the same interval. In other examples, one or more of these blocks or steps may be performed in different intervals. For example, in one interval the control system 2320 may perform the respiratory rate determination blocks or steps 2504 and 2506, and the flow control blocks or steps 2508, and 2510/2512. In the next interval, the control system 2320 may perform the respiratory rate determination blocks or steps 2504 and 2506, and oxygen control steps 2516 and 2518/2520. This alternating may repeat for the proceeding intervals. Oxygen control steps 2516 and 2518/2520 will now be discussed. Block 2516 comprises determining whether to adjust or maintain the operating oxygen concentration level. This determination may be based on the measured patient parameter indicative of the patient's respiratory rate at the present interval. In some examples, the determination may be based on the status of the patient's respiratory rate determined at the present interval, as discussed above. In some examples, determining whether to adjust or maintain the operating oxygen concentration level may be further based on comparing the patient parameter indicative of the patient's respiratory rate received or determined at the present interval to one or more thresholds. In other examples, determining whether to adjust or maintain the operating oxygen concentration level may be further based on comparing the status of the patient's respiratory rate determined at the present interval to one or more thresholds. The control system 2320 then proceeds to either block 2518 or 2520 based on the determination at block 2516. Block 2518 then comprises adjusting the operating oxygen concentration level by an increment based on determining that said operating oxygen concentration level be adjusted. Block 2520 comprises maintaining the operating oxygen concentration level at the present operating oxygen concentration level, based on determining that said operating oxygen concentration level be maintained. d. Determining whether to adjust or maintain operating oxygen concentration level
At block 2516, the control system 2320 can determine whether to adjust or maintain the operating oxygen concentration level. This determination may be based on the measured patient parameter indicative of the patient's respiratory rate at the present interval. In such examples, this may comprise determining whether to adjust or maintain the operating oxygen concentration level may be further based on comparing the patient parameter indicative of the patient's respiratory rate received or determined at the present interval to one or more thresholds.
The control system 2320 may compare the received or determined patient parameter indicative of the patient's respiratory rate with one or more target respiratory rates. The target respiratory rate(s) may define a respiratory rate threshold. In examples, the target(s) may comprise an upper range threshold, and a lower range threshold. For example, as shown in Figure 27, the upper range threshold is shown by Rmax and a lower range threshold by Rmin. In some examples, the target(s) may further comprise a midway point in the range, or any other value in the range. The range defined in such examples between the upper range threshold and the lower range threshold.
If the received or determined patient parameter indicative of the patient's respiratory rate indicates that the patient's respiratory rate is greater than the upper range threshold, then the control system 2320 at step 2516 may determine that the operating oxygen concentration level be increased.
Similarly, if the received or determined patient parameter indicative of the patient's respiratory rate indicates that the patient's respiratory rate is below the lower range threshold and above the lower range threshold, then the control system 2320 at step 2516 may determine that the operating oxygen concentration level be maintained.
In some examples, if the received or determined patient parameter indicative of the patient's respiratory rate indicates that the patient's respiratory rate is below the lower range threshold, then the control system 2320 at step 2516 may determine that the operating oxygen concentration level be reduced.
Additionally, or alternatively, the control system 2320 may set boundary conditions for the operating oxygen concentration level and not select a concentration level above a maximum rate. The control system 2320 can also cap oxygen concentration level at a minimum level that may be set by the clinician or stored in the controller. Accordingly, based on the data collected by the control system 2320, it can compare the operating oxygen concentration level at the present interval to the boundary conditions at block 2516.
In examples, if the operating oxygen concentration level reaches a maximum acceptable concentration level and the patient's respiratory rate has still not met the target(s) or is within the upper and lower range thresholds, an alarm may sound. Additionally, the control system 2320 may prevent the oxygen concentration level from being adjusted, and it may instead be maintained.
In some examples, once the status of a patient's respiratory rate is deemed stable or at a minimum, for example at step 2506, the patient's respiratory rate may be in the desirable range or within the upper and lower thresholds, but still above a target rate, such as between Rmax and Rmin, and above RT as shown in Figure 27. In such examples, as the patient's respiratory rate is within the upper and lower thresholds, the control system 2320 may determine that the operating oxygen concentration level be maintained, as no supplemental oxygen would be required. The operating oxygen concentration, or FiO2, would not be required to be adjusted or increased.
If the control system 2320 determines that the operating oxygen concentration level be adjusted, it may proceed to step 2518 and adjust the operating oxygen concentration level by an increment. In some examples, the increment may be a fixed time increment. In another example, the increment is a variable time increment. It will be appreciated that the increments for adjusting the operating oxygen concentration level may be determined in the same manner as the increments for the operating flow rate at block or step 2408/2508.
The increment may be between about 0.1% and about 20 %, optionally it may be between about 0.5 % and about 15 %, optionally it may be between about 1 % and about 10 %, optionally it may be between about 2 % and about 8 %, optionally it may be between about 3 % and about 6 %, preferably it may be about 5 %. e. Adjusting operating oxygen concentration
At block 2518, the control system 2320 may adjust the operating oxygen concentration level based on the control system determining at block 2516 that said operating oxygen concentration level be adjusted. The control system 2320 may adjust the operating oxygen concentration level by the increment determined at block 2516.
Adjusting the operating oxygen concentration level may comprise adjusting the operating oxygen concentration level from a first value to a second, higher value. The difference between the first value and the second value is the increment.
The adjustment of the operating oxygen concentration level may comprise adjusting the first and/or second valves of the flow generator. For example, this may be achieved by outputting one or more oxygen control outputs 2336, as discussed above. In such examples, increasing the operating oxygen concentration level by an increment comprises adjusting the second valve to increase the amount of oxygen being drawn or provided to the blower. The adjustment of the valve may be proportional to the adjustment of the operating oxygen concentration level. f. Maintaining operating oxygen concentration
At block 2520, the control system 2320 may maintain the operating oxygen concentration level based on the control system determining at block 2516 that said operating oxygen concentration level be maintained. As discussed above, at step 2516, if the patient's respiratory rate within the upper and lower thresholds, then the control system 2320 may determine that the operating oxygen concentration level be maintained. At step 2520, the control system 2320 proceeds to maintain the operating oxygen concentration level, as discussed above.
At block 2514, after the control system 2320 either adjusts the operating oxygen concentration level at step 2518, or maintains the operating oxygen concentration level at step 2520, the process 2500 then proceeds to wait for a time interval before performing step 2504 and the remainder of the process 2500 again, as previously discussed.
While the processes 2400, and 2500, are described separately, the control system 2320 can perform one or both of these processes at the same time to control flow rate and/or oxygen concentration level. Accordingly, the control system 2320 can use a combination of the steps of the processes 2400 and 2500 to control flow rate and/or oxygen concentration level to provide optimal therapy to the patient.
2.6 Control of oxygen concentration
In some alternative examples, the operating flow rate may be set by a clinician and not controlled by the control system 2320. In such examples, the control system 2320 may control only the oxygen concentration level.
Figure 30 illustrates a flow chart of examples of a method 3000 for controlling the oxygen concentration level of gas delivered to a patient based on a measured respiratory rate of a patient. The process or method 3000 comprises many of the steps of process or method 2500 as shown and described in relation to Figure 25. As will be appreciated, blocks or steps 3002, 3004, 3006, 3016, 3018, 3020, and 3014 correspond to blocks or steps 2502, 2504, 2506, 2516, 2518, 2520, and 2514 respectively.
As shown, at each interval, the control system 2320 can additionally adjust or maintain the operating flow rate and oxygen concentration level of the gases delivered or provided by the respiratory therapy device 100, 2202. The control system 2320 follows the iterative process or method 3000 of titration to find a substantially optimal oxygen concentration level using feedback from one or more sensors. A substantially optimal oxygen concentration level may be such as which a patient's respiratory rate is at or close to a minimum, and/or at which a patient's respiratory rate is within a range.
The process or method 3000 may be performed continually or continuously over or throughout a therapy session.
In this example, the operating flow rate may be set by clinician or user and not controlled in an iterative manner by the control system 2320such as that previously described in relation to Figure 24 and Figure 25. The control system 2320 can control the motor speed of the blower when a blower is used as the flow source 50, 2224 to set the operating flow rate of gases through the respiratory assistance system 10, 2200. The clinician or user of the respiratory apparatus may manually change the operating flow rate during therapy, but it will not be automatically titrated.
The operating oxygen concentration level may be iteratively titrated as described in relation to steps or blocks 2502, 2504, 2506, 2516, 2518, 2520, and 2514 of Figure 25 to get the patient's respiratory rate within a desired range. The control system 2320 may increase the oxygen concentration level by controlling one or both of the first and second valves to provide gases from the first and second inlets 2222,2223 respectively.
2.7 Warnings
The control system 220 can also generate alarms or warnings based on the measured physiological patient parameters. For instance, if the respiration rate exceeds or drops below an acceptable limit, the control system 220 can generate an alarm for the display. Alternatively, the control system can generate alarms or warnings based on relative insensitivity of measured parameters to changes in flow. For example, if the patient parameter such as respiratory rate is insensitive to flow this may indicate that the therapy is less likely to be efficacious. In an embodiment, the control system 220 can change the flow rate and determine that the patient parameter such as respiratory rate is not affected significantly by the flow rate change. Based on the lack of correlation, the control system 220 can determine that the therapy may not be optimal for the patient. 2.8 Applications
The respiratory assistance system 100 with high flow therapy can be used to provide support to patients in emergency rooms, intensive care units (ICU), the operating room (OR), other hospital areas or in-home. In particular, the respiratory assistance system 100 can be used to support a patient under anaesthesia, during preoxygenation and post operation. Using high flow therapy can have advantages in some embodiments because the patient can still communicate, and the mouth is not covered by a mask. Any time a patient requires intubation or endoscopy, the mouth may be blocked and cannot be used for providing invasive air support. Accordingly, high flow therapy along with the nasal cannula configuration of the respiration assistance system 100 can be used in those situations to provide breathing support. The control system 220 can determine a patient's respiratory rate or other physiological parameters in these cases and automatically determine a set value for flow rate. When patients use the respiratory assistance system 100 in their homes, the control system 220 can be used to adjust the set value of flow rate at the initial stage. The patient can also measure their respiration rate and enter it using the controller.
Terminology and definitions
The phrases 'computer-readable medium' or 'machine-readable medium' as used in this specification and claims should be taken to include, unless the context suggests otherwise, a single medium or multiple media. Examples of multiple media include a centralised or distributed database and/or associated caches. These multiple media store the one or more sets of computer executable instructions. The phrases ’computer-readable medium’ or 'machine-readable medium' should also be taken to include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor of a computing device and that cause the processor to perform any one or more of the methods described herein. The computer-readable medium is also capable of storing, encoding or carrying data structures used by or associated with these sets of instructions. The phrases 'computer-readable medium' and 'machine readable medium' include, but are not limited to, portable to fixed storage devices, solid-state memories, optical media or optical storage devices, magnetic media, and/or various other mediums capable of storing, containing or carrying instruction(s) and/or data. The 'computer-readable medium' or 'machine-readable medium' may be non-transitory. The term 'comprising' as used in this specification and claims means 'consisting at least in part of' or 'including, but not limited to' such that it is to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense. When interpreting each statement in this specification and claims that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner.
It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range (for example, 1, 1.1 , 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9 and 10) and also any range of rational numbers within that range (for example, 2 to 8, 1 .5 to 5.5 and 3.1 to 4.7) and, therefore, all sub-ranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended and all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be expressly stated in this application in a similar manner.
The term 'and/or' means 'and' or 'or', or both.
The use of '(s)' following a noun means the plural and/or singular forms of the noun.
Conditional language, such as "can," "could," "might," or "may," unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.
Language of degree used herein, such as the terms "approximately," "about," "generally," and "substantially" as used herein represent a value, amount, or characteristic close to the stated value, amount, or characteristic that still performs a desired function or achieves a desired result. For example, the terms "approximately", "about", "generally," and "substantially" may refer to an amount that is within less than 10% of, within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of the stated amount.
In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally for the purpose of providing a context for discussing the features of the invention. Unless specifically stated otherwise, reference to such external documents is not to be construed as an admission that such documents, or such sources of information, in anyjurisdiction, are prior art, or form part of the common general knowledge in the art.
In the above description, specific details are given to provide a thorough understanding of the embodiments. However, it will be understood by one of ordinary skill in the art that the embodiments may be practiced without these specific details. For example, software modules, functions, circuits, etc., may be shown in block diagrams in order not to obscure the embodiments in unnecessary detail. In other instances, well-known modules, structures and techniques may not be shown in detail in order not to obscure the embodiments.
Also, it is noted that the embodiments may be described as a process that is depicted as a flowchart, a flow diagram, a structure diagram, or a block diagram. Although a flowchart may describe the operations as a sequential process, many of the operations can be performed in parallel or concurrently. In addition, the order of the operations may be rearranged. A process is terminated when its operations are completed. A process may correspond to a method, a function, a procedure, a subroutine, a subprogram, etc., in a computer program. When a process corresponds to a function, its termination corresponds to a return of the function to the calling function or a main function.
Aspects of the systems and methods described above may be operable on any type of general purpose computer system or computing device, including, but not limited to, a desktop, laptop, notebook, tablet, smart television, gaming console, or mobile device. The term "mobile device" includes, but is not limited to, a wireless device, a mobile phone, a smart phone, a mobile communication device, a user communication device, personal digital assistant, mobile hand-held computer, a laptop computer, wearable electronic devices such as smart watches and head-mounted devices, an electronic book reader and reading devices capable of reading electronic contents and/or other types of mobile devices typically carried by individuals and/or having some form of communication capabilities (e.g., wireless, infrared, short-range radio, cellular etc.).
Aspects of the systems and methods described above may be operable or implemented on any type of specific-purpose or special computer, or any machine or computer or server or electronic device with a microprocessor, processor, microcontroller, programmable controller, or the like, or a cloud-based platform or other network of processors and/or servers, whether local or remote, or any combination of such devices.
Furthermore, embodiments may be implemented by hardware, software, firmware, middleware, microcode, or any combination thereof. When implemented in software, firmware, middleware or microcode, the program code or code segments to perform the necessary tasks may be stored in a machine-readable medium such as a storage medium or other storage(s). A processor may perform the necessary tasks. A code segment may represent a procedure, a function, a subprogram, a program, a routine, a subroutine, a module, a software package, a class, or any combination of instructions, data structures, or program statements. A code segment may be coupled to another code segment or a hardware circuit by passing and/or receiving information, data, arguments, parameters, or memory contents. Information, arguments, parameters, data, etc. may be passed, forwarded, or transmitted via any suitable means including memory sharing, message passing, token passing, network transmission, etc.
In the above description, a storage medium may represent one or more devices for storing data, including read-only memory (ROM), random access memory (RAM), magnetic disk storage mediums, optical storage mediums, flash memory devices and/or other machine or computer readable mediums for storing information. The various illustrative logical blocks, modules, circuits, elements, and/or components described in connection with the examples disclosed herein may be implemented or performed with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic component, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, circuit, and/or state machine. A processor may also be implemented as a combination of computing components, e.g., a combination of a DSP and a microprocessor, a number of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
The methods or algorithms described in connection with the examples disclosed herein may be embodied directly in hardware, in a software module executable by a processor, or in a combination of both, in the form of processing unit, programming instructions, or other directions, and may be contained in a single device or distributed across multiple devices. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD- ROM, or any other form of storage medium known in the art. A storage medium may be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor.
One or more of the components and functions illustrated the figures may be rearranged and/or combined into a single component or embodied in several components without departing from the scope of the disclosure. Additional elements or components may also be added without departing from the scope of the disclosure. Additionally, the features described herein may be implemented in software, hardware, as a business method, and/or combination thereof.
In its various aspects, embodiments of the disclosure can be embodied in a computer- implemented process, a machine (such as an electronic device, or a general-purpose computer or other device that provides a platform on which computer programs can be executed), processes performed by these machines, or an article of manufacture. Such articles can include a computer program product or digital information product in which a computer readable storage medium containing computer program instructions or computer readable data stored thereon, and processes and machines that create and use these articles of manufacture.
Although this disclosure has been described in the context of certain embodiments and examples, it will be understood by those skilled in the art that the disclosure extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses and obvious modifications and equivalents thereof. In addition, while several variations of the embodiments of the disclosure have been shown and described in detail, other modifications, which are within the scope of this disclosure, will be readily apparent to those of skill in the art. It is also contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the disclosure. For example, features described above in connection with one embodiment can be used with a different embodiment described herein and the combination still fall within the scope of the disclosure. It should be understood that various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order to form varying modes of the embodiments of the disclosure. Thus, it is intended that the scope of the disclosure herein should not be limited by the particular embodiments described above. Accordingly, unless otherwise stated, or unless clearly incompatible, each embodiment of this disclosure may comprise, additional to its essential features described herein, one or more features as described herein from each other embodiment of the invention disclosed herein.
This disclosure may also be said broadly to consist in the parts, elements and features referred to or indicated in this disclosure, individually or collectively, and any or all combinations of any two or more said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this disclosure relates, such known equivalents are deemed to be incorporated herein as if individually set forth. Features, materials, characteristics, or groups described in conjunction with a particular aspect, embodiment, or example are to be understood to be applicable to any other aspect, embodiment or example described in this section or elsewhere in this specification unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The protection is not restricted to the details of any foregoing embodiments. The protection extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
Furthermore, certain features that are described in this disclosure in the context of separate implementations or examples can also be implemented in combination in a single implementation or example. Conversely, various features that are described in the context of a single implementation or example can also be implemented in multiple implementations or examples separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations, one or more features from a claimed combination can, in some cases, be excised from the combination, and the combination may be claimed as a sub-combination or variation of a sub-combination.
Moreover, while operations may be depicted in the drawings or described in the specification in a particular order, such operations need not be performed in the particular order shown or in sequential order, or that all operations be performed, to achieve desirable results. Other operations that are not depicted or described can be incorporated in the example methods and processes. For example, one or more additional operations can be performed before, after, simultaneously, or between any of the described operations. Further, the operations may be rearranged or reordered in other implementations. Those skilled in the art will appreciate that in some embodiments, the actual steps taken in the processes illustrated and/or disclosed may differ from those shown in the figures. Depending on the embodiment, certain of the steps described above may be removed, others may be added. Furthermore, the features and attributes of the specific embodiments disclosed above may be combined in different ways to form additional embodiments, all of which fall within the scope of the present disclosure. Also, the separation of various system components in the implementations described above should not be understood as requiring such separation in all implementations, and it should be understood that the described components and systems can generally be integrated together in a single product or packaged into multiple products.
For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. Not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein.
The scope of the present disclosure is not intended to be limited by the specific disclosures of embodiments in this section or elsewhere in this specification, and may be defined by claims as presented in this section or elsewhere in this specification or as presented in the future. The language of the claims is to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as nonexclusive.

Claims

1. A method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
2. The method according to claim 1, wherein the method further comprises delivering a gas flow to the patient via a patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more patient characteristics.
3. The method according to claims 1 or 2, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
4. The method according to any preceding claim, wherein the one or more sensors comprise one or more sensors configured to be attached to or located near to the patient to measure a patient parameter indicative of the patient's respiratory rate.
5. The method according to any preceding claim, wherein the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
6. The method according to claim 5, wherein the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time- averaged respiratory rate.
7. The method according to any preceding claim, wherein the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
8. The method according to claim 7, wherein the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
9. The method according to claim 8, wherein the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, or is decreasing, or is substantially stable, based on said comparison.
10. The method according to claim 9, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
11. The method according to claim 9 or claim 10, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable.
12. The method according to any preceding claim, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises comparing the status of the patient's respiratory rate to one or more thresholds.
13. The method according to claim 10, wherein the step of adjusting the operating flow rate by an increment comprises increasing the operating flow rate by an increment based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
14. The method according to claim 13, wherein the increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
15. The method according to claim 11, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
16. The method according to any preceding claim, wherein the method is performed continually over a therapy session.
17. The method according to any preceding claim, wherein the gas is delivered to the patient at conditions suitable for the provision of high flow therapy.
18. The method according to any preceding claim, wherein the method further comprises delivering a gas flow to the patient via a patient interface at an operating oxygen concentration level.
19. The method according to claim 18, wherein the method further comprises, at said intervals, performing the steps of: determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
20. A method for controlling operating parameters of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate and an operating oxygen concentration level; at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate and the operating oxygen concentration level based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
21. A method for controlling operating parameters of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate and an operating oxygen concentration level; at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate and determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, wherein based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
22. The method according to claim 20 or 21, wherein the method further comprises delivering a gas flow to the patient via a patient interface at an initial operating flow rate, wherein the initial operating flow rate is determined based on one or more patient characteristics.
23. The method according to any one of claims 20 to 22, wherein the method further comprises delivering a gas flow to the patient via a patient interface at an initial operating oxygen concentration level, wherein the initial operating oxygen concentration level is determined based on one or more patient characteristics.
24. The method according to any one of claims 20 to 23, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
25. The method according to any one of claims 20 to 24, wherein the one or more sensors comprise one or more sensors configured to be attached to or located near to the patient to measure a patient parameter indicative of the patient's respiratory rate.
26. The method according to any one of claims 20 to 25, wherein the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
27. The method according to claim 26, wherein the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time- averaged respiratory rate.
28. The method according to any one of claims 20 to 27, wherein the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
29. The method according to claim 28, wherein the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
30. The method according to claim 29, wherein the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, or is decreasing, or is substantially stable, based on said comparison.
31. The method according to claim 30, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
32. The method according to claim 30 or claim 31, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable.
33. The method according to any of claims 20 to 32, wherein the step of determining whether to adjust or maintain the operating flow rate and/or the operating oxygen concentration level further comprises comparing the status of the patient's respiratory rate to one or more thresholds.
34. The method according to claim 31, wherein the step of adjusting the operating flow rate by an increment comprises increasing the operating flow rate by an increment based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
35. The method according to claim 34, wherein the increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
36. The method according to claim 32, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
37. The method according to any of claims 20 to 36, wherein the method is performed continually over a therapy session.
38. The method according to any of claims 20 to 37, wherein the gas is delivered to the patient at conditions suitable for the provision of high flow therapy.
39. A method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; at intervals, progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors, and determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals; based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable, maintaining the operating flow rate, and performing the iterative process of continuing to receive or determine said patient parameter and determine said status of the patient's respiratory rate at further intervals, wherein based on the status of the patient's respiratory rate indicating the patient's respiratory rate is no longer stable, adjusting the operating flow rate at said further intervals until the status of the patient's respiratory rate indicates that the patient's respiratory rate is stable.
40. The method according to claim 39, wherein the step of receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors occurs at a predetermined time period after adjusting the operating flow rate.
41. The method according to claim 39 or claim 40, wherein the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable comprises determining that said status of the patient's respiratory rate is within a range or threshold.
42. The method according to any of claims 39 to 41, wherein the status of the patient's respiratory rate indicating that the patient's respiratory rate is no longer stable comprises determining that said status of the patient's respiratory rate is outside a range or threshold.
43. The method according to any of claims 39 to 42, wherein the method further comprises delivering a gas flow to the patient via a patient interface at an initial operating flow rate, wherein the initial flow rate is determined based on one or more patient characteristics.
44. The method according to any of claims 39 to 43, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
45. The method according to any of claims 39 to 44, wherein the one or more sensors comprise one or more sensors configured to be attached to or located near to the patient to measure a patient parameter indicative of the patient's respiratory rate.
46. The method according to any of claims 39 to 45, wherein the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
47. The method according to claim 46, wherein the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time- averaged respiratory rate.
48. The method according to any one of claims 39 to 47, wherein the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
49. The method according to claim 48, wherein the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
50. The method according to claim 49, wherein the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, or is decreasing, or is stable, based on said comparison.
51. The method according to claim 50, wherein the step of determining whether the patient's respiratory rate is unstable comprises the status of the patient's respiratory rate indicating that the patient's respiratory rate is increasing or decreasing.
52. The method according to any of claims 39 to 51, wherein the step of progressively applying a plurality of flow rate values as the operating flow rate comprises increasing the operating flow rate by an increment at each interval.
53. The method according to claim 52, wherein said increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
54. The method according to any of claims 39 to 53, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
55. The method according to any of claims 39 to 54, wherein the method is performed continually over a therapy session.
56. The method according to any of claims 39 to 55, wherein the gas is delivered to the patient at conditions suitable for the provision of high flow therapy.
57. The method according to any of claims 39 to 56, wherein the method further comprises delivering a gas flow to the patient via a patient interface at an operating oxygen concentration level.
58. The method according to claim 57, wherein the method further comprises, at said intervals, performing the steps of: determining whether to adjust or maintain the operating oxygen concentration level based on at least the patient parameter indicative of the patient's respiratory rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
59. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
60. A respiratory apparatus configured to provide a flow of gases to a patient for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the patient at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
61. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate and the operating oxygen concentration level based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted. adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
62. A respiratory apparatus configured to provide a flow of gases to a patient for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the patient at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate and the operating oxygen concentration level based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
63. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate and determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, wherein based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
64. A respiratory apparatus configured to provide a flow of gases to a patient for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the patient at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals, determining whether to adjust or maintain the operating flow rate based on the status of the patient's respiratory rate, based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate and determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, wherein based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
65. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors, and determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals; based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable, maintaining the operating flow rate, and performing the iterative process of continuing to receive or determine said patient parameter and determine said status of the patient's respiratory rate at further intervals, wherein based on the status of the patient's respiratory rate indicating the patient's respiratory rate is no longer stable, adjusting the operating flow rate at said further intervals until the status of the patient's respiratory rate indicates that the patient's respiratory rate is stable.
66. A respiratory apparatus configured to provide a flow of gases to a patient for respiratory therapy, comprising: a flow generator configured to generate the flow of gases for the patient at an operating flow rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: progressively applying a plurality of flow rate values as the operating flow rate; at each of the plurality of flow rate values, receiving or determining a patient parameter indicative of the patient's respiratory rate based on data received from one or more sensors, and determining a status of the patient's respiratory rate based at least on said patient parameter and the patient parameter received or determined at one or more previous intervals; based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is stable, maintaining the operating flow rate, and performing the iterative process of continuing to receive or determine said patient parameter and determine said status of the patient's respiratory rate at further intervals, wherein based on the status of the patient's respiratory rate indicating the patient's respiratory rate is no longer stable, adjusting the operating flow rate at said further intervals until the status of the patient's respiratory rate indicates that the patient's respiratory rate is stable.
67. The respiratory therapy system according to any of claims 59, 61, 63, or 65, or the respiratory apparatus according to any of claims 60, 62, 64, or 66, wherein the flow generator is further configured to delivering a gas flow to the patient via a patient interface at an initial operating flow rate, and wherein the initial operating flow rate is determined based on one or more patient characteristics.
68. The respiratory therapy system or apparatus according to any of claims 59 to 67, wherein the intervals are spaced at a variable time period from each other, the variable time period based on at least the status of the patient's respiratory rate.
69. The respiratory therapy system or apparatus according to any of claims 59 to 68, wherein the one or more sensors comprise one or more sensors configured to be attached to or located near to the patient to measure a patient parameter indicative of the patient's respiratory rate.
70. The respiratory therapy system or apparatus according to any of claims 59 to 69, wherein the step of receiving or determining a patient parameter indicative of the patient's respiratory rate comprises receiving data from the one or more sensors indicative of a time-averaged respiratory rate over a measurement period.
71. The respiratory therapy system or apparatus according to claim 70, wherein the at least one sensor stores a plurality of instantaneous measurements over the measurement period and calculates a time-averaged respiratory rate.
72. The respiratory therapy system or apparatus according to any of claims 59 to 71, wherein the step of determining the status of the patient's respiratory rate comprises comparing the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals.
73. The respiratory therapy system or apparatus according to claim 72, wherein the status of the patient's respiratory rate relates to a degree or amount of change between the patient parameter received or determined at the present interval to the patient parameter received or determined at one or more previous intervals, based on said comparison.
74. The respiratory therapy system or apparatus according to claim 73, wherein the status of the patient's respiratory rate indicates that the patient's respiratory rate is increasing, or is decreasing, or is substantially stable, based on said comparison.
75. The respiratory therapy system or apparatus according to claim 74, wherein the step of determining whether to adjust the operating flow rate comprises determining that the operating flow rate be adjusted based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
76. The respiratory therapy system or apparatus according to claim 74 or claim 75, wherein the step of determining whether to adjust or maintain the operating flow rate comprises determining that the operating flow rate be maintained based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is substantially stable.
77. The respiratory therapy system or apparatus according to any of claims 59 to 76, wherein the step of determining whether to adjust or maintain the operating flow rate further comprises comparing the status of the patient's respiratory rate to one or more thresholds.
78. The respiratory therapy system or apparatus according to claim 75, wherein the step of adjusting the operating flow rate by an increment comprises increasing the operating flow rate by an increment based on the status of the patient's respiratory rate indicating that the patient's respiratory rate is decreasing.
79. The respiratory therapy system or apparatus according to claim 78, wherein the increment is a variable increment, the variable increment based on at least the status of the patient's respiratory rate.
80. The respiratory therapy system or apparatus according to claim 76, wherein the step of maintaining the operating flow rate comprises maintaining the operating flow rate at the operating flow rate of the previous increment.
81. The respiratory therapy system or apparatus according to any of claims 59 to 80, wherein the steps are performed at said intervals continually over a therapy session.
82. The respiratory therapy system or apparatus according to any of claims 59 to 81, wherein the gas is delivered to the patient at conditions suitable for the provision of high flow therapy.
83. The respiratory therapy system or apparatus according to any of claims 59 to 82, wherein the controller is further configured to deliver a gas flow to the patient via a patient interface at an operating oxygen concentration level.
84. The respiratory therapy system or apparatus according to claim 83, wherein the controller is further configured to deliver a gas flow to the patient via a patient interface at an initial operating oxygen concentration level, wherein the initial operating oxygen concentration level is determined based on one or more patient characteristics.
85. The respiratory therapy system or apparatus according to any of claims 59 to 84, wherein the controller is further configured to, at said intervals, perform the steps of: determining whether to adjust or maintain the operating oxygen concentration level based on the status of the patient's respiratory rate, and based on determining that said operating oxygen concentration level be adjusted, adjusting the operating oxygen concentration level by an increment, and based on determining that said operating oxygen concentration level be maintained, maintaining the operating oxygen concentration level at the present operating oxygen concentration level.
86. The respiratory therapy system or apparatus according to any of claims 59 to 85, further comprising a humidifier configured to humidify the flow of gases.
87. The respiratory therapy system or apparatus according to any of claims 59 to 86, wherein the system or apparatus further comprises a non-transitory computer- readable medium that is accessible or in data communication with the controller, and preferably wherein the non-transitory computer-readable medium comprises a nonvolatile memory having stored thereon computer executable instructions that, when executed on the controller or a processing device or devices, cause the controller or processing device or devices to perform or execute any one or more of the steps or methods or aspects described in any one of claims 59 to 86.
88. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient at an operating flow rate; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to: receive or determine a patient parameter indicative of the patient's respiratory rate based on data received from the one or more sensors, and control the operating flow rate of the flow generator based on the received or determined patient parameter indicative of the patient's respiratory rate.
89. A method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more non-patient contacting sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
90. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient at an operating flow rate; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more non-patient contacting sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from the one or more non- patient contacting sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
91. A method for controlling the flow rate of gas delivered to a patient, said method comprising: delivering a gas flow to the patient via a patient interface at an operating flow rate; and at intervals, performing the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
92. The method of claim 91, wherein the method further comprises receiving or determining a patient parameter indicative of the patient's SpO2 based on data from one or more sensors.
93. The method of claim 92, wherein the step of determining whether to adjust or maintain the operating flow rate is based further on comparing the patient parameter indicative of the patient's SpO2 to one or more thresholds.
94. The method of claim 92 or claim 93, wherein the method further comprises receiving or determining a therapy parameter indicative of the FiO2 being provided or to be provided to the patient.
95. The method of claim 94, wherein the therapy parameter indicative of the Fi02 being provided or to be provided to the patient is based at least in part on the patient parameter indicative of the patient's SpO2.
96. The method of claim 95, wherein the step of determining whether to adjust or maintain the operating flow rate is based further on comparing the patient therapy indicative of the FiO2 being provided or to be provided to the patient to one or more thresholds.
97. The method of any one of claims 91 to 96, wherein the one or more thresholds comprise one or more parameter thresholds, each of the one or more parameter thresholds relating to a patient or therapy parameter.
98. The method of claim 97, wherein the or each parameter threshold is set by a user.
99. The method of claim 97, wherein the parameter threshold relates to a maximum acceptable respiratory rate.
100. The method of claims 97 to 99, wherein the one or more thresholds further comprise a time based threshold.
101. The method of claim 100, wherein the time based threshold is set by a user.
102. The method of claim 101, wherein the time based threshold relates to a minimum amount of time the patient parameter is above the patient parameter threshold.
103. The method of any one of claims 91 to 102, wherein the increment for the operating flow rate to be adjusted by is an increase in the operating flow rate.
104. The method of claim 103, wherein the increment is an absolute or fixed amount.
105. The method of claim 103, wherein the increment is a percentage or fraction of the operational flow rate.
106. The method of any one of claims 103 to 105, wherein the increment for the operating flow rate is set by a user.
107. The method of any one of claims 91 to 106, wherein adjusting the operating flow rate by an increment comprises changing the operating flow rate by a step change.
108. The method of any one of claims 91 to 106, wherein adjusting the operating flow rate by an increment comprises ramping the operating flow rate.
109. The method of any one of claims 91 to 108, wherein when the operating flow rate is adjusted by the increment, the method further comprises displaying a prompt or alert to the user indicating the operating flow rate has been adjusted.
110. The method of claim 109, wherein the method further comprises presenting an audible alarm to the user indicating the operating flow rate has been adjusted.
111. The method of any one of claims 91 to 110, wherein once the operating flow rate has been adjusted by the increment, the method no longer comprises determining whether to adjust or maintain the operating flow rate.
112. A respiratory therapy system configured to provide a flow of gases to a patient for respiratory therapy, comprising: a patient interface configured to deliver a gas flow to the patient; a flow generator configured to generate the flow of gases for the patient at an operating flow rate; one or more sensors configured to measure a patient parameter indicative of the patient's respiratory rate; and a controller, wherein the controller is configured to control operation of the flow generator, and at intervals, perform the steps of: receiving or determining a patient parameter indicative of the patient's respiratory rate based on data from one or more sensors, determining whether to adjust or maintain the operating flow rate based on comparing at least the patient parameter indicative of the patient's respiratory rate to one or more thresholds, and based on determining that said operating flow rate be adjusted, adjusting the operating flow rate by an increment, and based on determining that said operating flow rate be maintained, maintaining the operating flow rate at the present operating flow rate.
PCT/US2023/085431 2022-12-22 2023-12-21 Respiratory support control using respiratory rate WO2024137988A2 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US63/476,730 2022-12-22

Publications (1)

Publication Number Publication Date
WO2024137988A2 true WO2024137988A2 (en) 2024-06-27

Family

ID=

Similar Documents

Publication Publication Date Title
US12005186B2 (en) Closed loop oxygen control
CN108290018B (en) Monitoring respiratory pressure therapy
EP2651478B1 (en) System for customizable automated control of fraction of inspired oxygen and/or positive end expiratory pressure to maintain oxygenation
US20220331548A1 (en) Methods and systems for controlling oxygen delivery in a flow therapy apparatus
JP7463389B2 (en) Adjustable Exhalation Relief in Respiratory Therapy
US20190175857A1 (en) Bilevel respiratory therapy system, controller and method
US20240024602A1 (en) A breathing assistance apparatus
US20230022107A1 (en) Alarm for respiratory therapy system
US20240082521A1 (en) Determining inspiratory and expiratory parameters in respiratory flow therapy systems
WO2024137988A2 (en) Respiratory support control using respiratory rate
US20230241336A1 (en) A respiratory support apparatus having a high temperature mode
WO2024057241A1 (en) A breathing assistance apparatus for providing resipratory therapy
WO2024089654A1 (en) Determining work of breathing in respiratory flow therapy systems
WO2023111914A1 (en) Measurement device and system for breathing assistance apparatus and/or performing diagnostics
AU2022235156A1 (en) A respiratory apparatus and control methods
NZ739771B2 (en) Monitoring respiratory pressure therapy