FR2987274A1 - Ventilating device for detecting respiratory cycles of patient, has signal processing unit attached with sensor to determine average gas leak value and inspiratory flow value from measured signal flow - Google Patents

Ventilating device for detecting respiratory cycles of patient, has signal processing unit attached with sensor to determine average gas leak value and inspiratory flow value from measured signal flow Download PDF

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Publication number
FR2987274A1
FR2987274A1 FR1251734A FR1251734A FR2987274A1 FR 2987274 A1 FR2987274 A1 FR 2987274A1 FR 1251734 A FR1251734 A FR 1251734A FR 1251734 A FR1251734 A FR 1251734A FR 2987274 A1 FR2987274 A1 FR 2987274A1
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France
Prior art keywords
value
flow rate
patient
signal
patient circuit
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Withdrawn
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FR1251734A
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French (fr)
Inventor
Eric Jacquot
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Air Liquide Medical Systems SA
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Air Liquide Medical Systems SA
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Priority to FR1251734A priority Critical patent/FR2987274A1/en
Publication of FR2987274A1 publication Critical patent/FR2987274A1/en
Application status is Withdrawn legal-status Critical

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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61MDEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/021Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes operated by electrical means
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Detecting, measuring or recording for diagnostic purposes; Identification of persons
    • A61B5/08Detecting, measuring or recording devices for evaluating the respiratory organs
    • A61B5/087Measuring breath flow
    • A61B5/0876Measuring breath flow using means deflected by the fluid stream, e.g. flaps
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61MDEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00Devices for influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes
    • A61M16/0003Accessories therefor, e.g. sensors, vibrators, negative pressure
    • A61M2016/003Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter
    • A61M2016/0033Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical
    • A61M2016/0039Accessories therefor, e.g. sensors, vibrators, negative pressure with a flowmeter electrical in the inspiratory circuit
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61MDEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M2205/00General characteristics of the apparatus
    • A61M2205/15Detection of leaks
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61MDEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M2205/00General characteristics of the apparatus
    • A61M2205/50General characteristics of the apparatus with microprocessors or computers
    • A61M2205/502User interfaces, e.g. screens or keyboards

Abstract

The device has a ventilator (1) fluidly connected to a patient circuit (2) for generating gas under positive pressure to feed the patient circuit with the gas under pressure. The patient circuit comprises respiratory branches. A single flow sensor (3) is connected with the respiratory branches of the patient circuit to determine signal flow representing the output gas circulating in the respiratory branches. A signal processing unit (4) is attached with the sensor to determine an average gas leak value and an inspiratory flow value from the measured signal flow. An independent claim is also included for a method for determination an average gas leak value and an inspiratory gas flow value between a ventilating device and a patient.

Description

The present invention relates to a device for detecting the respiratory cycles of a patient during ventilation by a ventilation machine with patient circuit to one or more branches, and to estimate gas leaks between the machine and the patient. In the case of Positive Airway Pressure (PAP) type assisted ventilation, that is, positive airway pressure, a patient is connected to a machine delivering a breathing gas under a positive pressure, by example of air, oxygen enriched air or a mixture 02 / N2. The patient is master of the ventilation since he breathes at his own pace (volume, frequency, cyclic ratio ...) and the machine only follows the patient's breathing.

The patient is connected to the ventilation machine, also called fan, using a mask and a patient circuit, that is to say one or more pipes carrying the pressurized gas delivered by the machine or fan. However, the masks are often equipped with an intensional leak and no mask is perfectly adjusted to the patient, that is to say, completely sealed, which generates additional leaks that vary over time. So there is always a leak rate that should be taken into account. Another difficulty is found on the patient circuits since there are 3 types of patient circuits, namely double branch, single branch valve and single branch leaking, each with its own characteristics in terms of leakage rate in particular .

However, a respirator must be able to work with all these different circuits. In fact, the respirator must follow, ie monitor, the patient's respiratory parameters in order to follow the patient's breathing and provide follow-up information to the medical profession, which must be as accurate as possible and truly reflect the gas exchange entering and leaving the patient's lungs.

To do this, it must be possible to extract the gas flow delivered by the machine, the inspirations, expirations, leaks, inspired volume, respiratory rate .... Currently, as part of a "PAP" type ventilation , the estimation of leaks is at the heart of monitoring. It is usually made from inspired volumes or averaged flows, from which volumes expired over a given time are subtracted.

This technique therefore also requires measuring the exhaled volume of the patient, which is usually done using a second flow sensor.

This technique is therefore not usable with fans connected to a patient circuit of the single branch type, that is to say using only one conduit or pipe for the gas, to supply the patient with gas. Another known technique is to estimate the leakage by applying a low-pass filter, as recalled by US-A-2002023645A, to the patient flow rate signal. However, since the respiratory rate can regularly drop to about 0.1 Hz, it is necessary to use a low-pass filter with a very low cutoff frequency, which has the major disadvantage of leading to a leakage measurement. very slow. It is therefore easy to understand that the existing techniques are not ideal and present each of the disadvantages. In other words, the problem that arises is therefore to propose a device and a method for detecting the patient's breathing cycles and especially for estimating leaks between the device and the patient, whatever the configuration of the respirator and the patient circuit, that is to say one or more branches, so that the patient flow can be determined in real time and as reliably as possible. The solution of the invention is a ventilation device comprising: a fan capable of generating a positive pressure gas fluidly connected to a patient circuit so as to be able to supply said patient circuit with said gas under pressure, said patient circuit comprising one or more several respiratory branches, - a single flow sensor connected to one of said respiratory branches of said patient circuit so as to determine at least one flow signal Q representative of the flow rate of the gas flowing in said respiratory branch, and - treatment means of signal cooperating with the flow sensor to determine at least one average gas leakage value and at least one inspiratory flow value from said at least one measured flow rate signal. Depending on the case, the device of the invention may comprise one or more of the following technical characteristics: the signal processing means comprise a band-pass filter or a high-pass filter. the signal processing means are adapted to and designed to determine at least one inspiratory flow value by processing by said bandpass filter or a high pass filter of said at least one measured flow signal. the signal processing means are adapted to and designed to determine at least one average gas leakage value from at least one inspiratory flow rate value and at least one measured flow rate signal. the signal processing means furthermore comprise an electronic card equipped with an analog / digital converter, a microcontroller-type calculation element, a microprocessor, a processor or a signal processor. the patient circuit is at a single or double respiratory branch. the or one of the respiratory branches of said patient circuit comprises a respiratory mask. - It comprises display means for viewing one or more curves representative of the variations of the average gas leakage values, inspiratory flow rate and measured flow rate, for a given period of time. the signal processing means are included in the fan. The invention further relates to a method for determining at least one average gas leakage value (Fmoy) and at least one inspiratory flow rate value (Qinsp) comprising the steps of: a) generating a positive pressure gas (> 1 atm) by means of a ventilator fluidly connected to a patient circuit comprising one or more respiratory branches, and supplying said patient circuit with said gas under pressure, b) determining at least one flow rate signal (Q) representative of the flow rate circulating gas in said respiratory branch, by means of a single flow sensor connected to one of said respiratory branches of said patient circuit, c) processing the flow signal (Q) measured in step b), and d) deducing from the treatment of step c), at least one average gas leakage value (Fmoy) and at least one inspiratory flow value (Qinsp). Depending on the case, the method of the invention may comprise one or more of the following technical characteristics: in step c), at least one inspiratory flow rate value (Qinsp) is determined by treatment with a bandpass filter or a high-pass filter of said at least one measured flow rate signal (Q). in step c), at least one average gas leakage value (Fmoy) is determined from at least one inspiratory flow value (Qinsp) and at least one measured flow rate signal (Q). The invention will now be better understood thanks to the following description given with reference to the appended figures in which: FIG. 1 shows a block diagram of an embodiment of a ventilation device according to the present invention; FIG. 2 represents the curves obtained on a patient circuit with a branch, FIG. 3 represents the curves obtained on a patient circuit with two Y-shaped branches, and FIG. 4 is an algorithm for estimating the flow inspired by FIG. the patient in the presence of a leak. Figure 1 is a block diagram of a possible embodiment of a ventilator device of a patient P according to the present invention which comprises a medical ventilator 1, also called respirator or ventilation machine, which generates a gas under positive pressure fluidly connected to a patient circuit 2 so as to supply the patient circuit 2 with the gas under pressure. The patient circuit 2 comprising one or more respiratory branches, that is to say pipes or pipes carrying the gas. When it has two branches, as shown in Figure 1, they form a circuit "Y", one of the branches used to supply the patient with fresh gas and the other to evacuate the exhaled gas by the patient P , which are enriched in CO2. The interface between the patient P and the patient circuit 2 is typically formed of a breathing mask 6 from covering the patient's nose P, his mouth or both, depending on the type of mask used. Such a medical ventilator 1 makes it possible to provide assisted ventilation of "PAP" type to the patient P which is connected to the machine 1 delivering the respiratory gas under a positive pressure, that is to say at a pressure greater than the pressure. atmospheric (ie> 1 atm), for example a gas such as air, air enriched with oxygen or a mixture 02 / N2. The patient is therefore master of the ventilation since he breathes at his own pace and the machine only follows the patient's breathing.

In order to be able to detect the respiratory cycles of the patient P and to estimate the leaks between the apparatus and the patient P, in particular at the level of the mask 6, and this, whatever the configuration of the ventilator 1 and the patient circuit 2, it is that is to say that the circuit 2 comprises one or more branches, also called gas lines, for the ultimate purpose of determining the patient flow in real time and as reliably as possible, according to the present invention, it is proposed to put a single flow sensor 3 connected to the patient circuit 2 so as to be able to measure the flow rate Q of the gas conveyed by said patient circuit 2. More precisely, this single flow sensor 3 is connected to one of said respiratory branches of the patient. patient circuit 2 so as to determine therein at least one flow signal Q representative of the flow rate of the gas flowing in the respiratory branch in question, in particular in the branch bringing the gas from the machine 1 to Fig. 1 is schematized a patient circuit 2 with a single limb or line. Furthermore, signal processing means 4, that is to say a processing device, comprising in particular a band-pass filter or a high-pass filter, cooperate with the flow sensor 3 so as to determine at least an average gas leakage value, called Fmoy, and at least one inspiratory flow value, called Qinsp, from the flow rate signal Q measured by the sensor 3 connected to the patient circuit 2. The signal processing device 4 is generally installed in the fan 1 but it can nevertheless, according to the embodiment chosen, be inserted into an external box connected to the sensor 3.

Different technologies can be used for the sensor 3, in particular of the mass flowmeter type or the debitimeter flowmeter. As an example of a sensor 3, it is possible to use the sensor referenced AWMP720 sold by Honeywell. The flow rate signal Q measured by the sensor 3 is transmitted to the signal processing means 4 via one (or more) conventional electrical connection.

From the flow rate signal Q measured by the single flow sensor 3 connected to the gas supply line 2 of the patient P, then the inspiratory flow rate of the patient Qinsp and the average leakage Fmoy of gas are determined by treatment. To do this, a decomposition of the signal Q into two parts is carried out: a DC component and an AC component. The DC component represents the average leak Fmoy, while the positive part of the AC component is the image of the inspired flow Qinsp by the patient P. To this end, a high pass filter or a band pass filter is used to extract the component signal alternative and thus determine the inspired flow Qinsp by the patient P.

The cutoff frequency of the high pass filter is generally between 0.05 and 0.5 Hz. It comes directly from the respiratory frequencies which are between 1 and 2 Hz. The filter can be made in analog using one or more resistance. However, it can also be realized in digital using a microcontroller. In this case, the signal of the sensor 3 is digitally converted using an analog / digital converter. In digital, a first order high pass filter is coded as follows: Output = A (Input - Input (.4)) + B (Output (.4)) with: _ (.4) representing the value when the previous sampling, - Output = Output of the filter - Input = Input of the filter - A and B are the coefficients of the filter considered. Then, as shown diagrammatically in FIG. 4, the DC component 14 is determined by subtracting 13 between the input rate signal values (Q) and the output signal 12 of the filter 11. The subtraction 13 is realized in analog using an operational amplifier and 4 resistors, or in digital. In the latter case, this involves subtracting each sampling period. The positive part of the signal 12 instantaneously represents the flow inspired by the patient Qinsp, while the signal 14 represents the average leakage Fmoy on the cycle. In numerical terms, the algorithm used is, for example, of the type: Qpatient = A (Q-Q (n-1)) + B (Qpatient (n-1)) Fmoy = Q - Qpatient Where: - A and B are the coefficients of the filter - Q = input flow rate measured by the sensor 3 during a given breathing cycle. - Q (11-1) = input flow rate measured during the previous cycle The advantages of such a device is that it implements only one sensor and therefore not only its response time is very low since we can know the leakage value of the first breath cycle, but also the necessary computing power is also very low since a simple first order high pass filter can largely be sufficient to process the signal. Once the average leakage values of gas Fmoy, inspiratory flow Qinsp and measured flow Q have been determined, for example during a given period of time T, it is possible to visualize them, that is to say to display them. , for example in the form of curves 8, on display means 7, that is to say a display device, such as a monitor or the like. Thus, Figures 2 and 3 show curves obtained with a device according to the invention in the case of a patient circuit 2 with a branch (Figure 2) and, alternatively, a patient circuit 2 with two branches. Y-shaped (Fig. 3).

These curves are the result of tests in which an intentional leak was created between the patient circuit 2 and the mouth of the patient P. With the aid of a sensor 3 external to the fan 1, the flow rate was measured as closely as possible. from the mouth of the patient P, upstream of the created leak. These curves represent, over time T, the variations (expressed in cl / min) of the flow rate measured by the sensor 3, the estimated inspiratory flow, the estimated leak and the patient flow measured upstream of the leak. More precisely, the curve: - Cl represents the flow rate measured at the fan output by the sensor 3. - C2 represents the flow rate measured upstream of the leak, close to the patient's mouth. - C3 represents the continuous component of the signal from the sensor 3. In inspiration, it corresponds to the estimated average leakage. - C4 represents the alternative component of the signal from the sensor 3. In inspiration, it corresponds to the flow inspired by the patient.

As seen on these curves, during inspiration, the flow measured at the mouth of the patient P is very close to the flow estimated by the algorithm, which shows the effectiveness of the method for determining the patient flow.

Claims (12)

  1. REVENDICATIONS1. Ventilation device comprising: - a fan (1) capable of generating a positive pressure gas fluidly connected to a patient circuit (2) so as to feed said patient circuit (2) with said pressurized gas, said patient circuit (2 ) comprising one or more respiratory branches, - a single flow sensor (3) connected to one of said respiratory branches of said patient circuit (2) so as to determine at least one flow signal (Q) representative of the flow of the circulating gas in said respiratory branch, and - signal processing means (4) cooperating with the flow sensor (3) so as to determine at least one average gas leakage value (Fmoy) and at least one inspiratory flow value ( Qinsp) from said at least one measured flow rate signal (Q).
  2. 2. Device according to the preceding claim, characterized in that the signal processing means (4) comprise a bandpass filter or a high-pass filter.
  3. 3. Device according to one of the preceding claims, characterized in that the signal processing means (4) are adapted to and designed to determine at least one inspiratory flow rate value (Qinsp) by treatment with said bandpass filter or a high-pass filter of said at least one measured flow rate signal (Q).
  4. 4. Device according to one of the preceding claims, characterized in that the signal processing means (4) are adapted to and designed to determine at least one average gas leakage value (Fmoy) from at least one inspiratory flow rate value (Qinsp) and at least one measured flow rate signal (Q).
  5. 5. Device according to one of the preceding claims, characterized in that the signal processing means (4) further comprises an electronic card equipped with an analog / digital converter, a microcontroller-type computing element, microprocessor, processor or signal processor.
  6. 6. Device according to one of the preceding claims, characterized in that the patient circuit (2) is a single or double respiratory branch.
  7. 7. Device according to one of the preceding claims, characterized in that the or one of the respiratory branches of said patient circuit (2) comprises a breathing mask (6).
  8. 8. Device according to one of the preceding claims, characterized in that it comprises display means (7) for viewing one or more curves (8) representative of the variations of the average gas leakage values (Fmoy ), inspiratory flow rate (Qinsp) and measured flow rate (Q) for a given period of time (T).
  9. 9. Device according to one of the preceding claims, characterized in that the signal processing means (3) are included in the fan (1).
  10. A method for determining at least one average gas leakage value (Fmoy) and at least one inspiratory flow rate value (Qinsp) comprising the steps of: a) generating a gas under positive pressure (> 1 atm) by means of a fan (1) fluidly connected to a patient circuit (2) comprising one or more respiratory branches, and supplying said patient circuit (2) with said gas under pressure, b) determining at least one flow signal (Q ) representative of the flow rate of the gas flowing in said respiratory branch, by means of a single flow sensor (3) connected to one of said respiratory branches of said patient circuit (2), c) processing the measured flow signal (Q) in step b), and d) deducing from the treatment of step c), at least one average gas leakage value (Fmoy) and at least one inspiratory flow value (Qinsp).
  11. 11. Method according to claim 10, characterized in that in step c), at least one inspiratory flow rate value (Qinsp) is determined by treatment with a band-pass filter or a high-pass filter of said at least one flow rate signal (Q) measured.
  12. 12. Method according to one of claims 10 or 11, characterized in that in step c), is determined at least a mean gas leakage value (Fmoy) from at least one inspiratory flow rate value (Qinsp) and at least one measured flow rate signal (Q).
FR1251734A 2012-02-27 2012-02-27 Ventilating device for detecting respiratory cycles of patient, has signal processing unit attached with sensor to determine average gas leak value and inspiratory flow value from measured signal flow Withdrawn FR2987274A1 (en)

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FR1251734A FR2987274A1 (en) 2012-02-27 2012-02-27 Ventilating device for detecting respiratory cycles of patient, has signal processing unit attached with sensor to determine average gas leak value and inspiratory flow value from measured signal flow

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FR1251734A FR2987274A1 (en) 2012-02-27 2012-02-27 Ventilating device for detecting respiratory cycles of patient, has signal processing unit attached with sensor to determine average gas leak value and inspiratory flow value from measured signal flow

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016174318A1 (en) * 2015-04-28 2016-11-03 Air Liquide Medical Systems Artificial ventilation apparatus able to deliver ventialtion and monitoring which are specific to the patients receiving cardiac massage

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020023645A1 (en) * 1989-09-22 2002-02-28 Respironics, Inc. Breathing gas delivery method and apparatus
US20030066528A1 (en) * 1999-06-15 2003-04-10 Respironics, Inc. Average volume ventilation
US6675797B1 (en) * 1993-11-05 2004-01-13 Resmed Limited Determination of patency of the airway
FR2908975A1 (en) * 2006-11-15 2008-05-30 Weinmann Gerate Fur Medizin Gm Method for acquiring the reaspire expiry gas volume in a power-assisted breathing system
WO2011145014A1 (en) * 2010-05-17 2011-11-24 Koninklijke Philips Electronics N.V. System and method for estimating upper airway resistance and lung compliance employing induced central apneas

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020023645A1 (en) * 1989-09-22 2002-02-28 Respironics, Inc. Breathing gas delivery method and apparatus
US6675797B1 (en) * 1993-11-05 2004-01-13 Resmed Limited Determination of patency of the airway
US20030066528A1 (en) * 1999-06-15 2003-04-10 Respironics, Inc. Average volume ventilation
FR2908975A1 (en) * 2006-11-15 2008-05-30 Weinmann Gerate Fur Medizin Gm Method for acquiring the reaspire expiry gas volume in a power-assisted breathing system
WO2011145014A1 (en) * 2010-05-17 2011-11-24 Koninklijke Philips Electronics N.V. System and method for estimating upper airway resistance and lung compliance employing induced central apneas

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016174318A1 (en) * 2015-04-28 2016-11-03 Air Liquide Medical Systems Artificial ventilation apparatus able to deliver ventialtion and monitoring which are specific to the patients receiving cardiac massage
FR3035591A1 (en) * 2015-04-28 2016-11-04 Air Liquide Medical Systems Artificial ventilation apparatus for delivering specific ventilation and monitoring to patients receiving cardiac massage
EP3323459A1 (en) * 2015-04-28 2018-05-23 Air Liquide Medical Systems Artificial ventilation apparatus with expiratory valve which can be used during cardiac massage
EP3323460A1 (en) * 2015-04-28 2018-05-23 Air Liquide Medical Systems Artificial ventilation apparatus with ventilation mode selection which can be used during cardiac massage

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