FR3009788A1 - Oxygen therapy equipment - Google Patents

Oxygen therapy equipment Download PDF

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Publication number
FR3009788A1
FR3009788A1 FR1358133A FR1358133A FR3009788A1 FR 3009788 A1 FR3009788 A1 FR 3009788A1 FR 1358133 A FR1358133 A FR 1358133A FR 1358133 A FR1358133 A FR 1358133A FR 3009788 A1 FR3009788 A1 FR 3009788A1
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France
Prior art keywords
means
pressure
gas
instantaneous
measuring
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Legal status (The legal status 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 status listed.)
Withdrawn
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FR1358133A
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French (fr)
Inventor
Angelo Augusto
Philippe Bernard
Amelie Carron
Geraldine Thiebaut
Claude Weber
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Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Application filed by Air Liquide SA, LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Priority to FR1358133A priority Critical patent/FR3009788A1/en
Publication of FR3009788A1 publication Critical patent/FR3009788A1/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Application status is Withdrawn legal-status Critical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
    • A61M16/06Respiratory or anaesthetic masks
    • A61M16/0666Nasal cannulas or tubing
    • A61M16/0672Nasal cannula assemblies for oxygen therapy
    • A61M16/0677Gas-saving devices therefor
    • 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
    • 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
    • A61M16/06Respiratory or anaesthetic masks
    • A61M16/0666Nasal cannulas or tubing
    • A61M16/0672Nasal cannula assemblies for oxygen therapy
    • 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
    • A61M16/10Preparation of respiratory gases or vapours
    • A61M16/1005Preparation of respiratory gases or vapours with O2 features or with parameter measurement
    • A61M16/101Preparation of respiratory gases or vapours with O2 features or with parameter measurement using an oxygen concentrator
    • 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
    • A61M16/10Preparation of respiratory gases or vapours
    • A61M16/14Preparation of respiratory gases or vapours by mixing different fluids, one of them being in a liquid phase
    • A61M16/16Devices to humidify the respiration air
    • 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
    • A61M2016/0027Accessories therefor, e.g. sensors, vibrators, negative pressure pressure meter
    • 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

Abstract

An oxygen therapy equipment includes a nasal cannula (20) adapted and adapted to be worn at the nose of a patient (30) to deliver a breathing gas to the nostrils of said patient (30), said nasal cannula (20) being supplied with gas by a flexible duct (21) for supplying breathing gas, and a measuring and data-processing device (1) comprising an internal passage (13) of gas fluidly connected to said flexible duct supplying (21) gas, pressure measuring means (2) for determining at least one instantaneous pressure value (P) relative to the atmosphere by measuring the pressure of the gas in said passage (13), flow measurement means (3) for determining at least one instantaneous flow rate (Q) by measuring the gas flow in said passage (13), and data processing means (5) implementing at least an analysis algorithm (6) suitable for and designed for processing the instantaneous pressure (P) and instantaneous flow rate (Q) values determined by the pressure measuring means (2) and the flow measuring means (3) and deriving at least one estimate of the pressure value instantaneous (PPat) gas exerted at said nasal cannula (20).

Description

The invention relates to equipment for monitoring an oxygen treatment at home to determine the patient pressure that it is fed gas by a cannula single or double feed pipe, so as to deduce the patient breathing, respiratory rate and / or treatment efficacy. Oxygen therapy is a treatment consisting in administering to a patient in need, an oxygen-rich gas, for example pure oxygen or a 02 / air mixture (O 2 content> 21% vol), so as to maintain or to restore his blood oxygen level. Oxygen therapy can help patients with certain respiratory conditions, such as chronic obstructive pulmonary disease (COPD), and improve their quality and life expectancy. The treatment with oxygen therapy is generally carried out at home, that is to say in the patient. Therefore, monitoring patients at home is necessary, even essential, in order to be able to evaluate the real effectiveness of the treatment which is closely related to the duration of daily oxygen consumption by the patients, that is to say tell how long he actually takes his oxygen therapy during the day. To this end, monitoring and remote monitoring devices have already been proposed. Some devices measure the gas flow in the oxygen circuit connecting the oxygen source to the patient. The flow signal enables them to detect the presence of an oxygen flow rate and to measure the flow delivered by the source. Other devices measure the pressure in the oxygen circuit connecting the source to the patient. A fine analysis of the pressure signal enables them to detect the presence of a flow of oxygen and in some cases, that is to say, for certain sources and at certain flow rates, the breathing of the patient. Still other devices are connected only to a nasal cannula or respiratory goggles of the double lumen type, that is to say comprising two distinct branches, the oxygen flowing in one of the branches, the other branch being connected to the pressure sensor of a fan.

However, these devices have a number of disadvantages. Many of these devices have a mode of operation based on measurement at a single point, that is to say near the gas source or in the middle of the duct of the cannula, mainly the gas pressure. Therefore, the gas flow signal from the gas source and the patient's breathing signal which is formed by alternating inspiratory and expiratory phases are often difficult to separate. This requires the use of reduced operating ranges and leads to high inaccuracies or measurement uncertainties. For example, the patient may be considered by the tracking device as 'present' when in reality there is only the source of branch gas and the patient is absent and / or unrelated to the monitoring system. gas delivery. Other devices use dual lumen cannulas. However, because of their high cost, double lumen cannulas are little used and are much less diversified than single lumen, i.e. single duct cannulas. In addition, some oxygen sources with oxygen delivery via a demand valve need to be connected to the second conduit of a double lumen cannula and, in this case, the tracking device can not be used because the second conduit is not connected to the on-board pressure sensor and the device no longer detects the patient's breathing. The problem then is to propose an improved equipment for monitoring an improved home oxygen treatment that will solve all or some of the problems mentioned above, in particular to determine the patient pressure that it is feeding. in gas by a cannula single or double feed pipe, so as to deduce the breathing of the patient, the respiratory rate and / or the effectiveness of treatment. The solution of the invention relates to equipment for monitoring an oxygen treatment at home, more simply called oxygen therapy equipment, comprising: a) a nasal cannula, also called "respiratory goggles", suitable for and designed for being carried by a patient so as to deliver a breathing gas to the nostrils of said patient, said nasal cannula being supplied with gas by a flexible breathing gas supply line, and b) a measuring and data processing device comprising an internal gas passage fluidly connected to said flexible gas supply duct; pressure measuring means making it possible to determine at least one relative instantaneous pressure value P by measuring the pressure of the gas in said passage; flow measurement means for determining at least one instantaneous flow rate value Q by measuring the flow rate of the gas in said passage; using at least one analysis algorithm adapted to and designed to process the instantaneous pressure P and instantaneous flow rate values Q determined by the pressure measuring means and the flow measurement means and to deduce from them at least one estimate the instantaneous pressure value PPat of gas exerted at the level of said nasal cannula.

In fact, the device for measuring and processing data of the equipment according to the invention makes it possible to make an estimate of the instantaneous value of pressure PPat exerted at the level of said nasal cannula, that is to say of the relative pressure (relative to the pressure of the atmosphere) at the end of the cannula which is either the nose pressure if the cannula is carried by the patient (who breathes and therefore expels gas under pressure through his nostrils) ), the atmospheric pressure if the cannula is not worn. In the context of the present invention, relative pressure is used to designate a pressure measured or estimated by difference with atmospheric pressure (which is of the order of 1 bar or 101325 Pa), that is to say relative to at atmospheric pressure. In other words, the device for measuring and processing data of the equipment according to the invention estimates the instantaneous pressure at the level of the nasal cannula or PPat which represents the relative pressure of the gas, that is to say gas pressure relative to that of the atmosphere, which is exerted at the end of the cannula, which makes it possible to determine when the patient is using his oxygen therapy well and when he does not do so, and the respiratory gas source does or does not release respiratory gas into the nasal cannula.

Depending on the case, the invention may comprise one or more of the following technical characteristics: the measurement and data processing device comprises signal filtering means. the data processing means of the measurement and data processing device are adapted to and designed to estimate at least one pneumatic resistance value R of the cannula by calculating the following ratio: R = Pmoy / Qmoy where: Pmoy is a pressure value obtained by filtering by said signal filtering means of at least one instantaneous pressure value P measured by the pressure measuring means, and. Qmoy is a rate value obtained by filtering by said signal filtering means of at least one instantaneous flow rate value Q measured by the flow measurement means. the data processing means of the measurement and data processing device are capable of and designed to assign to PPat the instantaneous pressure value P measured (PPat = P), when Qmoy <Qmini where Qmini is a threshold value prefixed non-zero minimum. In other words, the calculation of the resistor R is carried out only if the average value of the rate Qmoy has a value greater than a set threshold value Qmini, with Qmini> 0, otherwise it is that is, when Qmoy <Qmini, the value of Ppat is obtained directly by assigning the instantaneous pressure value P measured, ie: PPat = P. - the signal filtration means comprise a low-pass filter, preferably a low-pass filter having a response time of a given duration D with D <1 minute. the data processing means are adapted to and designed to estimate at least one instantaneous pressure value Ppat exerted at a given instant t, at the level of said nasal cannula from said pneumatic resistance value R by calculating the difference following: Ppat = P - AP with AP = R x Q 20 where:. P is an instantaneous pressure value measured at time t by the pressure measuring means, and. Q is an instantaneous flow rate value measured at time t by the flow measurement means. The flow measurement means comprise a differential pressure sensor and means capable of creating a pressure drop in said passage. - The measuring device and data processing further comprises power supply means, in particular one or more batteries or electric batteries. the measuring and data processing device furthermore comprises storage means, in particular an extractable memory card or not. the measurement and data processing device further comprises communication means, in particular a radiofrequency antenna. the means for measuring flow and pressure, the data processing means, the electrical current supply means, the storage means and the communication means are arranged in a single box, the said box being crossed in the internal passage; . - It comprises a source of respiratory gas fluidly connected to the internal gas passage of the measuring device and data processing. - The internal gas passage of the measuring device and data processing is supplied with gas by a gas supply line, for example a gas conduit, fluidly connected to the source of breathing gas. the source of respiratory gas delivers oxygen in a volume proportion of at least 21% vol. the source of respiratory gas is a bottle of oxygen. - the source of breathing gas is a portable or portable oxygen concentrator - the source of breathing gas is a reserve of liquid oxygen. the communication means comprise a transmitter module associated with a transmitting antenna, in particular adapted to and designed to operate a radio frequency communication in GPRS mode. the measurement and data processing device (1) further comprises signal filtering means, and the data processing means (5) are adapted to and designed to estimate at least one quadratic pneumatic resistance value (Rquad ) of the cannula (20) by calculating the following ratio: R = Pmoy / Q2moy Where:. Pmoy is a pressure value obtained by filtering by said signal filtering means of at least one instantaneous pressure value (P) measured by the pressure measuring means (2), and. Q2moy is the average value of the square of the flow rate value obtained by filtering by said signal filtering means of at least one instantaneous flow rate value Q measured by the flow measurement means (3). the signal filtration means comprise a low-pass filter, preferably a low-pass filter having a response time of a given duration D with D <1 minute. the data processing means (5) are adapted to and designed to estimate at least one instantaneous pressure value (Ppat) exerted at a given instant t, at the level of said nasal cannula from said pneumatic resistance value; (R) by calculating the following difference: Ppat = P - 4P with 4P = Rquad x Q2 Where:. P is an instantaneous pressure value measured at time t by the pressure measuring means (2), and Q is an instantaneous flow rate value measured at time t by the flow measurement means (3). The present invention will now be better understood thanks to the following explanations given with reference to the appended figures among which: FIG. 1 represents an embodiment of the architecture of a device for measuring and processing data of a device oxygen therapy according to the present invention; FIGS. 2a and 2b schematize the oxygen therapy equipment according to the present invention shown worn by a patient in combination with single or double lumen respiratory goggles; FIG. 3 schematizes the different pressure signals generated by the gas source (02) and the patient's breathing, and the pressure signal that can be measured by the device according to the present invention; FIGS. 4 to 11 represent simulation curves obtained according to the invention. FIG. 1 schematizes an embodiment of the architecture of a device for measuring and processing data 1 of oxygen therapy equipment according to the invention making it possible to monitor compliance with a treatment of In particular, the measurement and data processing device 1 of the oxygen therapy equipment according to the present invention comprises a housing 11 traversed by an internal passage 13 of gas, such as a gas conduit, fluidly connected, upstream, to a gas supply pipe 22 conveying a breathing gas containing oxygen from a source of breathing gas, such as an oxygen cylinder or a fan, and, downstream, to a flexible conduit 21 for supplying gas to the patient 30 for feeding a nasal cannula 20, as explained below. The housing 11 of the measurement and data processing device 1 further comprises pressure measuring means 2, such as a pressure sensor, making it possible to determine at least one instantaneous pressure value P relative to the atmosphere by measuring the pressure. gas pressure in the passage 13, as well as flow measurement means 3 for determining at least one instantaneous flow rate value Q by measuring the flow rate of the gas in said passage 13. Preferably, the flow measurement means 3 comprise a differential pressure sensor and means capable of creating a pressure drop in said passage 13, for example a diameter restriction or the like, such as a calibrated orifice or a venturi. Data processing means 5 are also provided, such as a microcontroller, implementing at least one analysis algorithm 6 for processing the instantaneous pressure P and instantaneous flow rate values determined by the pressure measurement 2 and flow rate measurement means. 3 and deduce therefrom an estimate of the instantaneous pressure value PPat of gas exerted at the nasal cannula 20 which is carried by a patient 30 at the nose of said patient 30 so as to deliver the respiratory gas to the nostrils of said patient 30. The nasal cannula 30 is supplied with gas by the flexible duct 21 for breathing gas to which is connected the internal passage 13 of the housing 11. The pressure and flow measurements made by the measuring device and data processing 1 detect the use of the device 1 by the patient 30 and thus the effectiveness of the oxygen therapy treatment. Optionally, it is also possible to determine also the physical activity of the patient by incorporating in the housing 11, an acceleration measuring device 4, that is to say an accelerometer designed to measure the physical activity of the patient 30, to knowing the exercise time, stillness, sleep ... Once measured, these measured values or raw data of pressure, flow, and possibly acceleration, are converted into electrical signals and then transmitted to the data processing unit. 5, such as a microcontroller, which operates one (or more) analysis algorithm 6 for processing the raw measurement data (pressure, flow ...) to obtain processed measurement data, which can then be recorded by storage means 8, such as a data storage unit, for example a memory chip, and / or can be transmitted by data transmission means 7. In fact, the data transmission means 7 are adapted to and designed to transmit the raw measurement data and / or measurement data processed by the analysis algorithm 6 to at least one remote data receiving device, such as a remote server where they can be processed, stored ... The transmission by the data transmission means 7 is done with or without wire, or via removable media. For example, the transmission can be done by radio frequency communication, in the GPRS mode, by writing data to an SD card which can then be read on a PC, by a connector on which for example a USB cable or RS232 or other can come connect and connect the device to a computer, or by a system capable of automatically transmitting the data to the remote data receiving device, such as a remote server. To do this, the data transmission means 7 comprise an antenna, an electronic connector, a memory card reader or any other suitable data transmission system or device. In summary, the device 1 incorporating the pressure and flow measurement means 2, 3 and the processing means 5 are used to process these measurements via one (or more) algorithm 6 and to deduce the information relating to the use and the effectiveness of the treatment. The information and / or measurements and / or raw data are stored in storage means 8. Data transmission means 7 make it possible to communicate them subsequently for example to a remote server at which the data can be exploited, analyzed, edited ... by medical staff, especially to produce reports, graphs, charts or other.

The supply of the system is done by means of supplying electric current, such as (one or more) battery, battery or accumulator 9, having an autonomy of at least 1 year, preferably greater than 1 year, or may be rechargeable either by induction or via a power socket. Finally, the measurement and data processing device 1 is equipped with an information means 10 making it possible to inform the patient of his use of the treatment. This information means 10 may comprise, for example, one or more light indicators, such as LEDs, indicating to the patient when he is using his treatment or if he has already taken his treatment according to his prescription, or a digital screen allowing the patient to display information to the patient giving an overview of his daily use of the treatment and the effectiveness of his treatment, and possibly allowing, and if necessary, also to transmit to the patient messages to motivate him to follow his treatment . Moreover, FIGS. 2a and 2b show the equipment according to the invention comprising the device 1 and the cannula 20 carried by a patient 30. As can be seen, the cannula 20 on arranged on a simple respiratory-type device 14 or double 15 lumen. As can be seen, the measurement and data processing box 1 is supplied with gas by a pipe or supply duct 21 conveying the oxygen-rich respiratory gas from the oxygen source 12 which can be fixed or portable. A flexible hose 21 makes it possible for the device 1 to be connected to single lumen 14 (FIG. 2a) or double lumen type respiratory goggles 15 (FIG. 2b) feeding the nasal cannula 20 which delivers the oxygen-rich gas to the airways. of the patient, particularly to the nostrils of the patient 30. A double limb may be necessary, when the oxygen source 12 requires it, especially when equipped with a demand valve. In this case, the branch that allows the detection is connected directly to the source 12 via a suitable connector. The administration of the oxygen passes through the housing 1 comprising the flow 3 and pressure sensors 2 via the supply pipe 22 connected between the source 12 and the housing 1. Note that a gas humidifier (Not shown) can be optionally installed at the outlet of the oxygen source 12. The device 1 can be worn around the stroke of the patient 30 with a strap or the like, or attached to the belt with a suitable fastening system .

Figure 3 schematizes pressure signals generated by the gas source 12 (left signal in Fig. 3) and patient 30 (right signal) at both ends of the oxygen circuit, as well as the pressure signal in FIG. resulting (central signal) as measured at the device 1 for measuring and processing data according to the present invention. As can be seen, the pressure signal of the source 12 greatly disturbs the pressure signal measured by the device 1. This explains why the devices of the prior art, the operation of which is based mainly on an analysis of the pressure signal alone, present limits for the detection of respiration, in particular limitations on the sources of gas with which these devices can function effectively since some sources of pressure generate a signal that is too disturbed, and moreover as to the flow ranges for which the devices are functioning correctly because the higher the flow rate, the more the signal generated by the pressure source is disturbed and then hinders the detection of the patient's breathing. However, with the system or device 1 for measuring and processing data according to the present invention, as shown diagrammatically in FIG. 1, these limitations no longer exist or are greatly minimized, and it is therefore possible to make an effective determination and monitoring. the use of the equipment according to the invention and the effectiveness of the oxygen therapy treatment undertaken by the patient 30 and possibly its physical activity, and this, thanks to the values of pressure, flow and possibly acceleration measured and processed by the measurement and data processing system 1 as explained above. Indeed, the device 1 of the equipment according to the invention makes it possible to subtract an estimated value of the pressure signal from the gas source from that of the measured signal to obtain only the signal coming from the patient and then to use this signal to deduce therefrom the daily use of the treatment and the effectiveness of the treatment, The processing of these different signal values is operated by means of the algorithm 6 (or several algorithms if necessary) of the device 1 of FIG. 1 so as to overcome the The limitations of the prior art devices based solely on pressure signal analysis. More specifically, the data measuring and processing device 1 further comprises signal filtering means, such as a low-pass filter. Preferably, the low-pass filter has a response time of a given duration D with D <1 minute. The data processing means 5 then estimate at least one pneumatic resistance value R of the cannula 20 by calculating the ratio R = Pmoy / Qmoy where Pmoy is a pressure value obtained by filtering by said signal filtering means. one (or more) instantaneous pressure value P measured by the pressure measuring means 2, and Qmoy is a flow rate value also obtained by filtering by the signal filtering means of one (or more) instantaneous flow rate value Q measured by the flow measurement means 3.

Then, the data processing means 5 estimate at least one instantaneous pressure value Ppat exerted at a given instant t, at the level of the nasal cannula 20 from the tire resistance value R obtained above, by calculating the following difference: Ppat = P - 4P with 4P = R x Q, where P is an instantaneous pressure value measured at time t by the pressure measuring means 2, and Q is an instantaneous flow rate value measured at instant t by the flow measurement means 3. In general, the flow rate of the oxygen source 12 can be continuous or on demand. The flow is rarely constant. The pressure measured in the cannula 20 is generated both by the consequence of the flow of gas in this cannula 20 and the nasal pressure of the patient 30. It is therefore not easy to reconstruct from the measured pressure signal the nasal pressure signal. Thus, the source may provide a periodically oscillating flow rate, the consequence of which on the pressure signal may resemble the impact of a breath. The device 1 is then able to detect a breath that does not exist.

Similarly, if the impact of breathing is too weak in the impact of flow, we can conclude that there is a flow but no patient. Knowing the flow rate, it is obviously not possible to isolate the effect of this flow on the pressure. Indeed, the glasses with cannula 20 feeding the patient 30 may comprise gas supply pipes of greater or lesser length and diameter larger or smaller. Similarly, the glasses with cannula 20 can be rolled up or unwound. The induced pneumatic head losses are therefore very variable depending on the glasses used. However, thanks to the present invention, it is now possible to obtain an approximate reconstruction of the nose pressure signal of the patient Ppat and this, regardless of size of the pipes, the positioning of the device 1 between the patient 30 and the oxygen source 12, the winding or not glasses 14, 15 ... Know this patient's nose pressure Ppat can follow and then effectively visualize the respiratory rate of the patient 30. Indeed, thanks to the equipment of the invention, in particular to the device 1, an estimation of the pneumatic resistance between the housing 11 and the patient 30 can be carried out on an ongoing basis, independently of the length of pipe 21 between the patient 30 and the device 1, and independently of the oxygen flow rate and therefore allows to know the respiratory rate of the patient even if the flow rate signal is variable. The estimate is made by realizing the ratio of the relative pressure average Pmoy in the sensor to the average of the flow Qmoy through the portion of the gas circuit comprising the pipe 21, the glasses 14, 15 and the cannula 2, namely R = Pmoy / Qmoy. This ratio R is analogous to a supposed linear resistance of this circuit portion. The nasal pressure of the patient Ppat is then provided from the pressure P measured by the pressure sensor 2 and the oxygen flow rate Q by the following formula: Ppat = P-RxQ As mentioned above, this equation is also expressed as: = P - 4P with 4P = R x Q. The averages are calculated over a time interval long enough to obtain a stable value R, typically at least 30 seconds, typically more than one minute, for example a range of 2 minutes time.

In fact, the average patient's nasal pressure tends to be negligible because this pressure is similar to the nasal flow, the average of which tends to zero since there is as much air inhaled by the patient as air exhaled by the patient. this one. The following simulation examples will better understand the invention. The simulation is calculated using a quadratic model that would be closer to reality. The input data of the simulator is a flow imposed by the source, as well as a breath performed by the patient. The flow rate imposed by the source is reflected in the first example in typical flow pulses of a valve on demand. In the other example, it is a sinusoidal flow whose average value is 2 l / min, which is a typical rate of supply of oxygen by a source of oxygen type portable cryogenic tank.

The breathing of the patient, meanwhile, is reflected in pressure in the nostrils related to inspirations and expirations. Expirations generate a positive pressure of a few mbar (4 mbar in the examples). The inspirations produce a negative pressure of a few mbar (8 mbar in the examples). The simulator obtains an estimate of the pressure that is read by the sensor following the quadratic model, as well as the pressure at the source.

The quadratic resistances chosen are such that the resistance between the patient and the sensor is 10 times greater than that between the source and the sensor. This corresponds to the situation where the sensor remains at the side, that is to say near the source, while the patient is separated from the source by a tube of about ten meters. This is not the general case that would be the opposite, but it is the most restrictive case that the simulation proposes to address. Example 1: Case of a Flow Delivered by a Demand Valve The quadratic model for performing the simulations is as follows. The downstream resistance Raval between the sensor 2 and the patient 30: 4P = Raval Q x Q = Pc - Pp -amont Similarly, a quadratic model is used for the upstream resistance R between the source 12 and the sensor 2: Ps - Pc = Ramont Q2 Where: - Raval is the quadratic resistance of the pipe between the sensor and the patient. - Ramont is the quadratic resistance of the pipe between the source and the sensor.

The values are here: - Raval = 10 mbar / (1 / min) 2 - Ramont = 1 mbar / (1 / min) 2 This corresponds to a tube between the sensor 2 and the source 12 much smaller than between the patient 30 and the sensor 2.

This is shown in FIG. 4 where the curve with peaks oscillating between 0 and 2 l / min corresponds to the gas flow and the linear curve between 0 and less than 0.5 l / min which corresponds to the average of the flow computed over the wire. time. FIG. 5 represents the pressure P measured by the sensor, in this example obtained by simulation, as well as the mean pressure Pmoy obtained by low-pass filter. For indication, the curve also represents the pressure provided by the source calculated by simulation Ps. We have: - P: Pressure measured by sensor. This value is obtained by simulation, that is to say calculated by the quadratic model from flow 02 and Pp. - Pmoy: average pressure obtained by filtering - Ps: Pressure supplied by the simulated source. It is calculated by the quadratic model from flow 02 and Pc. FIG. 6 represents the estimate of the linear resistance R over time, whereas FIG. 7 represents on two curves the value of the estimated nose pressure juxtaposed with the representation of the nose pressure, input data of the simulator. The representation is carried out on an area where the stabilization of the calculation of averages is effective: - Pp: Narcotic pressure of the patient (input data of the simulation). It oscillates between 8 mbar and 5 mbar. - Ppat: Recurrent patient pressure (calculated by linear model from flow 02, Pc and linear resistance estimate R). This signal is compared to the signal Pp in order to test the quality of the estimate. The Ppat reconstruction of the patient's pressure closely follows the patient's pressure Pp supplied to the simulation as input data, except in the time intervals where a gas pulse is sent. However, this is not a problem for approximating the amplitude of the signal and its frequency. Example 2: Flow rate which oscillates around an average value of 2 l / min provided by an oxygen concentrator FIG. a flow rate that oscillates around an average value of 2 l / min (top curve) and the filtered average value of this flow over 2 minutes which increases between 0 and 2 l / min, Figure 9 represents the pressure P measured by the sensor, in this example, obtained by simulation, and the mean pressure Pmoy obtained by low-pass filter. For indication, the curve also represents the pressure provided by the source calculated by simulation Ps. - P: Pressure measured by sensor (Value obtained by simulation, calculated by the quadratic model from flow 02 and Pp) -Pmoy: average pressure obtained by filtering - Ps: Pressure provided by the simulated source (calculated by the quadratic model from the flow 02 and Pc) Figure 10 represents the estimate of the linear resistance R over time, while Figure 11 represents over two curves the value of the estimated nasal pressure juxtaposed with the representation of the nostril pressure, input data of the simulator. The representation is carried out on an area where the stabilization of the calculation of averages is effective: - Pp: Narcotic pressure of the patient (input data of the simulation) It oscillates between -8 mbar and 5 mbar. - Ppat: Recurrent patient pressure (calculated by linear model from flow 02, Pc and linear resistance estimate R). This signal is compared to the signal Pp in order to test the quality of the estimate. The estimator approximates the value of the patient's nostril pressure. It can be seen that a calibration error of a few mbar remains in the estimation of the patient pressure Ppat, related to the sinusoid of the flow rate Q. The result obtained according to the invention nevertheless makes it possible to estimate the amplitude of the signal PPat and its frequency by signal processing via for example an amplitude calculation by difference of maximum and minimum over a period of one minute, and / or a calculation of frequency by high threshold detection by rising edge with reset by low threshold However , the estimate of the Ppat pressure can also be performed using a quadratic model.

In this case, it is a question of considering not a linear resistance but a quadratic resistance Rquad, with: Rquad = Pmoy / Q2moy where: Q2moy is the average value of the flow Q squared established on the same rincipe that Qmoy with a filter lowpass. We then have: 4P = Rquad Q x Q and Ppat = P- 4P = P-Rquad Q x Q This second method also allows to have results approaching the nostril pressure.

Claims (13)

  1. REVENDICATIONS1. Oxygen therapy equipment comprising a) a nasal cannula (20) adapted and adapted to be worn at the nose of a patient (30) so as to deliver a breathing gas to the nostrils of said patient (30), said nasal cannula ( 20) being supplied with gas by a flexible duct (21) supplying respiratory gas, and b) a measuring and data processing device (1) comprising: - an internal passage (13) of gas fluidly connected to said duct gas supply hose (21); pressure measuring means (2) for determining at least one instantaneous pressure value (P) relative to the atmosphere by measuring the gas pressure in said passage (13); ), flow measuring means (3) for determining at least one instantaneous flow rate (Q) by measuring the flow rate of the gas in said passage (13), and - data processing means (5) setting at least one analysis algorithm (6) suitable for and designed for milking r the instantaneous pressure (P) and instantaneous flow rate (Q) values determined by the pressure measuring means (2) and the flow measurement means (3) and deriving at least one estimate of the instantaneous pressure value; (PPat) gas exerted at said nasal cannula (20).
  2. 2. Equipment according to the preceding claim, characterized in that the measuring device and data processing (1) further comprises signal filtering means, and the data processing means (5) are adapted to and designed for estimating at least one pneumatic resistance value (R) of the cannula (20) by calculating the following ratio: R Pmoy / Qmoy where: - Pmoy is a pressure value obtained by filtering by said signal filtering means of at least an instantaneous pressure value (P) measured by the pressure measuring means (2), and Qmoy is a flow rate value obtained by filtering by said signal filtering means of at least one instantaneous flow rate value Q measured by the flow measurement means (3).
  3. 3. Equipment according to one of the preceding claims, characterized in that the signal filtering means comprise a low-pass filter, preferably a low-pass filter having a response time of a given duration D with D <1 minute.
  4. 4. Equipment according to one of the preceding claims, characterized in that the data processing means (5) are arranged to estimate at least one instantaneous pressure value (Ppat) exerted at a given instant t, at the level of said nasal cannula from said pneumatic resistance value (R) by calculating the following difference: Ppat = P - AP with AP R x Q Where: - P is an instantaneous pressure value measured at time t by means of pressure measurement (2), and - Q is an instantaneous flow rate value measured at time t by the flow measurement means (3).
  5. 5. Equipment according to one of the preceding claims, characterized in that the flow measurement means (3) comprises a differential pressure sensor and means adapted to create a pressure drop in said passage (13).
  6. 6. Equipment according to one of the preceding claims, characterized in that the measuring device and data processing further comprises: - power supply means (9), - storage means (8) and - communication means (7).
  7. 7. Equipment according to one of the preceding claims, characterized in that the flow measurement means (3) and pressure (2), the data processing means (5), the electric power supply means (9) , the storage means (8) and the communication means (7) are arranged in a single housing (11), said housing (11) being traversed in the internal passage (13).
  8. 8. Equipment according to one of the preceding claims, characterized in that it comprises a source of respiratory gas (12) fluidly connected (22) to the internal passage (13) of the gas measuring and data processing device (1). ).
  9. 9. Equipment according to one of the preceding claims, characterized in that the respiratory gas source (12) delivers oxygen in a volume proportion of at least 21% vol.
  10. 10. Equipment according to one of the preceding claims, characterized in that the communication means (7) comprise a transmitting antenna. 15
  11. Equipment according to claim 1, characterized in that the data measuring and processing device (1) further comprises signal filtering means, and the data processing means (5) are suitable for and designed for estimating at least one quadratic pneumatic resistance value (Rquad) of the cannula (20) by calculating the following ratio: R = Pmoy / Q2moy where: - Pmoy is a pressure value obtained by filtering by said signal filtering means d at least one instantaneous pressure value (P) measured by the pressure measuring means (2), and 25 - Q2moy is the average value of the square of the flow rate value obtained by filtering by said signal filtering means of at least one instantaneous flow rate value Q measured by the flow measurement means (3).
  12. 12. Equipment according to one of the preceding claims, characterized in that the signal filtering means comprise a low-pass filter, preferably a low-pass filter having a response time of a given duration D with D < 1 minute.
  13. 13. Equipment according to one of claims 1 or 11, characterized in that the data processing means (5) are arranged to estimate at least one instantaneous pressure value (Ppat) exerted at a given instant t, at level of said nasal cannula from said pneumatic resistance value (R) by calculating the following difference: Ppat = P - 4P with 4P = Rquad x Q2 where: - P is an instantaneous pressure value measured at time t by the pressure measuring means (2), and - Q is an instantaneous flow rate value measured at the instant t by the flow measurement means (3).
FR1358133A 2013-08-23 2013-08-23 Oxygen therapy equipment Withdrawn FR3009788A1 (en)

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EP0714670A2 (en) * 1994-12-02 1996-06-05 RESPIRONICS Inc. Breathing gas delivery method and apparatus
US20050121033A1 (en) * 1998-02-25 2005-06-09 Ric Investments, Llc. Respiratory monitoring during gas delivery
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EP3369452A1 (en) * 2017-03-03 2018-09-05 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Medical treatment apparatus with fluid oscillation flowmeter and long-distance communication module
FR3063433A1 (en) * 2017-03-03 2018-09-07 Air Liquide Medical treatment apparatus with fluidic oscillation flowmeter and long distance communication module

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