FR3085831A1 - METHOD FOR SIMULATING A BREATHING PROFILE OF A PATIENT ON A TEST BENCH - Google Patents

Abstract

The invention relates to a method for simulating (20) a respiratory profile of a patient on a test bench (1) comprising at least one artificial lung (6) and a model for simulating upper airway obstruction ( 10), and it also relates to the corresponding test bench and an associated communicating device program. The method comprises at least one step of identifying the quality of the modifications of the respiratory profile by determining at least one level of obstruction of the upper airways in the zones of modifications of the respiratory profile, so as to distinguish the periods linked to the obstructions in the upper airways of those related to the alteration of the central control as well as a step of calculating operating parameters of the artificial lung and / or the simulation model of obstruction of the upper airways of the test bench in based on the results of the identification stage of the quality of changes in the respiratory profile.

Description

METHOD FOR SIMULATING A BREATHING PROFILE OF A PATIENT ON A TEST BENCH

The invention is in the field of medical devices and in particular devices that can be used in the context of treatment of respiratory profiles considered to be pathological. Among other things, it aims to allow the evaluation of medical devices adapted to a patient profile, for example in the field of sleep apnea treatment.

There are several types of respiratory profile changes, the causes of which are distinct and therefore difficult to treat with any medical device. In particular, one can distinguish modifications of the respiratory profile linked to obstructive causes and modifications of the respiratory profile which are directly related to the central control. Changes in respiratory profile related to obstructive causes are caused by an obstruction in the upper airway, which prevents air from passing between the lungs and the atmosphere through these upper airways. Changes in the respiratory profile linked to a change in central control can be due to an alteration of the nervous message or to a contraction of the diaphragm altering the function of the respiratory muscles.

It is for example classically accepted that obstructive sleep apnea-hypopnea syndrome (OSAHS) is mainly due to obstruction of the respiratory tract, due to an imbalance between the pressures inside and outside the upper airway. The machines, circuits and masks intended to treat this sleep apnea are configured to generate an air pressure during sleep, high enough to prevent collapse of the upper airways.

It should be noted that the terminology of sleep apnea is intended to cover both the apnea phases, during which the patient does not breathe for at least 10 s, and the phases of significant reduction in respiratory flow, or hypopnea, when the event lasts at least 10 s and is associated with a physiological repercussion.

Furthermore, the profile of a patient suffering from modifications of the respiratory profile other than sleep disorders can be simulated by the invention. For example, a patient may have asthma or Chronic Bronchopneumonia

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Obstructive (COPD). Some COPD patients requiring oxygen therapy are prescribed an appropriate dosage which may depend on the results of a walk test, for example of the order of six minutes. Patients should be assigned oxygen delivery devices that meet the specifics of their respiratory profiles.

There is therefore a need to adapt the machines to the particular changes in the respiratory profile and to test the machines to ensure that the medical device processes the corresponding change in the respiratory profile optimally.

Increasingly, the machines developed by the manufacturers integrate algorithms aimed at modulating the air injection according to the needs of the patient (apnea or reduction of the respiratory flow like hypopnea) and possibly according to the phases of sleep.

These machines can be tested on benches that reproduce physiological characteristics representative of sleep apnea.

A bench may include in particular an artificial lung and a simulation model of upper airway obstruction to which are connected pressure measurement means and pressure regulators, a flow measurement system and a connection for connection of the machine. .

A first need identified in this context is to best configure the test benches so that the machine tests are as representative as possible of their effectiveness in modifying the respiratory profile, for example sleep apnea, of patients. It is therefore a question of configuring the bench so that it reproduces the respiratory profile of the patient, in particular by configuring the artificial lung and the obstruction simulation model according to the data collected in a prior collection step.

In addition, it should be noted that in France in particular, these medical devices must be subject to a medical prescription and to use under certain prescribed conditions for the purchase and use of the device to be taken. supported by social security. However, given the profusion of machines and settings available on the market, the most appropriate choice can prove to be complex. In this context, a second identified need is to provide these doctors with a tool allowing them to help with

2018ID00317 appropriate and specific decision of the patient who comes to request them, the tool being configured to relate a given respiratory profile of a patient and a machine and an adapted setting.

Therefore, the present invention aims to propose a method of simulating a respiratory profile of a patient on a test bench comprising at least one artificial lung and a simulation model of upper airway obstruction, during which stores in the memory of an electronic control unit a plurality of data recorded by appropriate sensors and among which at least one data relating to the patient's air flow.

The simulation method according to the invention comprises at least:

- an analysis of the data to identify areas of modification of the respiratory profile, by taking into account at least the data relating to air flow;

a step of identifying the quality of the modifications of the respiratory profile by determining at least one level of obstruction of the upper airways in the zones of modifications of the respiratory profile, this identification step being carried out as a function of at least one parameter making it possible to assess the obstruction by analyzing the variation in respiratory flow or by analyzing the variation in respiratory effort, said step of identifying the quality of the modification in respiratory profile making it possible to distinguish the related periods obstructions in the upper airways from those related to impaired central control;

- a step of calculating operating parameters of the artificial lung and / or the upper airway obstruction simulation model based on the results of the step of identifying the quality of the changes in the respiratory profile.

The simulation method further includes a step of configuring the test bench with said previously calculated operating parameters.

According to the invention, the analysis of the respiratory flow can consist of an analysis by the technique of forced oscillations (known by the acronym FOT for “Forced Oscillation Technique”) which consists in sending forced pressure oscillations and measuring the flow response.

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The analysis of the variation in respiratory effort can be carried out by processing the RIP parameter, that is to say the variation in the thoracic or abdominal perimeter. The parameter can be analyzed instantaneously, depending on the value of this perimeter, or else consider a phase shift in the thoracic signal and the abdominal signal. The analysis of the variation of the respiratory effort can also be made via an EMG, i.e. an electromyogram allowing the measurement of the diaphragmatic muscular activity, or by an indirect measurement of sussternal pressure derived from sound and / or pressure at the level of the trachea indicating the passage of air.

Such a simulation method can in particular be implemented as part of a treatment for a patient's sleep apnea, in order to simulate on the test bench the respiratory profile of the patient during sleep and to be able to test the effectiveness of such or such treatment conditions for this specific respiratory profile. It is understood that the method according to the present invention also makes it possible to consider the respiratory profiles of patients under various conditions such as physical exercise, to treat for example cases of modifications of the respiratory profile during physical activities.

It should be noted that the device and the determination method according to the invention make it possible to take into account different causes of modifications in the respiratory profile and to thus ensure that the response which must be given by the medical device is appropriate. More particularly, the invention makes it possible to highlight the periods when the respiratory events of sleep are caused by an obstruction of the upper airways, nasal or oral, and the periods where these events are central, that is to say caused by altering the central control at a given time. Therefore, the invention aims to prevent the simulation of a modification of the respiratory profile caused by a central problem from being simulated as a modification of the respiratory profile caused by an obstruction of the upper airways.

According to various characteristics of the present invention, taken alone or in combination, provision may be made for:

- the analysis of the data to identify areas of modification of the respiratory profile includes a first step of comparison of the amplitude of the air flow

2018ID00317 over a given period in relation to a first threshold value and the classification of the respiratory profile over this given period into a period of apnea if the amplitude of the air flow is less than the first threshold value, and includes a second step of comparison of the amplitude of the air flow over a given period compared to a second threshold value and the classification of the respiratory profile over this given period into a period of hypopnea if the amplitude of the air flow is between the first threshold value and the second threshold value and if an additional physiological parameter is detected. The additional physiological parameter can in particular be a rate of pulsed oxygen saturation (SPO2), which if it is falling compared to a standard value for the patient is indicative of a desaturation, and / or the detection of a phase of micro-awakening. The given period can in particular be between 3 and 15 ms.

- the identification of the quality of the modification of the respiratory profile is such that for a period of apnea, a period of modification of the respiratory profile due to an obstruction of the upper airways is identified when the variation of the thoracic perimeter and / or the abdominal perimeter, or when the variation of the resistance of the upper airways measured indirectly, is beyond a defined parameter, the apnea period being otherwise identified as a period of modification of the respiratory profile due to the alteration of the central control.

- the identification of the quality of the modification of the respiratory profile is such that for a period of hypopnea, a period of modification of the respiratory profile due to an obstruction of the upper airways is identified when these events are accompanied by at least one phase shift of the thoracic signal and the abdominal signal or the presence of snoring or the detection of an aggravation of respiratory limitation of flow or when the variation of the resistance of the upper airways measured indirectly, is beyond a parameter defined.

- a step of identifying the beginnings of the respiratory cycle is carried out on all or part of the data relating to the patient's air flow, at least by analyzing the variation in the thoracic or abdominal perimeter or any means of determining the respiratory effort when the amplitude of variation of the air flow data is weakly distinctive. As mentioned earlier, the effort analysis

2018ID00317 respiratory can be performed by a treatment of the RIP parameter, by EMG, that is to say an electromyogram allowing the measurement of diaphragmatic muscle activity, or by a measurement of susternal pressure derived from sound and / or pressure at level of the trachea showing the air passage.

the step of recording the data comprises recording an additional measurement of the patient's movements while he is sleeping, via an accelerometer, during which the step of analyzing the data and the step of determining the '' at least one qualifying parameter is preceded by a step of calculating a patient movement parameter, during which periods of agitation are identified if the amplitude of the movements is greater than a critical threshold, the data corresponding to a period of agitation being excluded from the processing in the analysis and determination stages.

the air flow measurement consists of a measurement of a nasal, buccal or nasobuccal flow during which the step of recording the data includes recording an additional measurement, for example tracheal sound or a measurement thermistor, the data analysis step comprising an analysis of the additional measurement value in addition to the analysis of nasal, buccal or nasal-oral flow, the zones of modification of the respiratory profile corresponding to the periods during which are detected simultaneously a nasal, buccal or nasal-oral flow lower than a determined threshold and an additional measurement value lower than a given threshold. In particular, in the case where the additional measurement is a thermistor value, it is understood that the additional measurement aims to ensure the presence of a breath of the patient when he sleeps, via a temperature sensor placed opposite the face of the patient, and that one then seeks to confirm the existence of a modification of the respiratory profile by ruling out a variation in flow rate linked to an opening of the mouth in the case where the air flow recorded is a nasal flow.

The invention also relates to a medical device test bench treating respiratory ailments, comprising at least one artificial lung and a simulation model of upper airway obstruction, an artificial lung control and a resistance value of the simulation model. obstruction

2018ID00317 upper aerials being configured during the digitalization step of the simulation method according to one of the preceding claims.

According to a characteristic of the invention, the test bench can be such that a value corresponding to a minimum resistance of the simulation model of upper airway obstruction is applied in the periods of the digitalized respiratory profile during which no obstructive disorder n 'is detected or a modification of the respiratory profile linked to the alteration of the central control is identified.

The invention also relates to a communicating mobile device program comprising portions of program code launched or downloaded on the communicating mobile device, for the execution of a method according to which a medical device is chosen according to data, collected. by said program or retrieved by said program, representative of a respiratory profile of a patient, said program comprising a database with reference respiratory profiles and for each reference respiratory profile a suitable medical device. The association in the database of such a medical device with such a reference respiratory profile is made on the basis of tests carried out via the test bench as described above, the program first associating said respiratory profile of the patient with the 'one of the reference respiratory profiles loaded into the program database and indicating in a second step the medical device to be associated with this respiratory profile of the patient.

Other characteristics, details and advantages of the invention will appear more clearly with the aid of the following description and the drawings, among which:

FIG. 1 is a general schematic view of a test bench for a treatment apparatus for respiratory problems, comprising in particular an artificial lung and a model for simulating airway obstruction;

Figure 2 is a representative flowchart of an embodiment of the simulation method according to one aspect of the invention;

- Figure 3 is a schematic representation of a step in the process relating to the identification of respiratory cycle beginnings, making it visible that this aspect of the invention makes it possible to identify cycle beginnings for both periods

2018ID00317 respiratory and resulting flow only for periods with respiratory effort without resulting flow;

- Figures 4 and 5 schematically illustrate the identification of cycle starts for the periods with muscular effort and resulting flow respectively as for the periods with muscular effort without resulting flow;

- Figures 6 to 9 schematically illustrate a step in the process relating to the qualification of changes in the respiratory profile, and in particular chosen between apneas / hypopneas of obstructive / central causes, on an air flow signal curve;

FIGS. 10 to 13 illustrate steps for calculating the operating parameters of the components of the test bench of FIG. 1 as a function of the analysis of the signal carried out in accordance with the illustrations of FIGS. 2 to 9.

Figure 1 illustrates a test bench 1 according to one aspect of the invention.

This test bench 1 includes software components and hardware capable of reproducing the respiratory profile of the patient, in order to be able to test in real time the treatment machine 2 for this respiratory problem encountered by the patient.

This treatment machine, which may in particular consist of an automatic positive pressure device (known by the acronym AP AP), is illustrated in FIG. 1, which notably makes visible a ventilation device 3 in known positive pressure, and a mask 4 and similar can be worn by the user of this device.

A first component of the bench is an artificial lung 6, produced for example by means of a piston generating an air flow at the outlet of the lung.

A central control unit 8 is configured to control the operation of the artificial lung, in a standard back and forth mode in periods when no modification of the respiratory profile is to be reproduced, and in an alternative back and forth mode in the periods identified as periods of changes in respiratory profile. More particularly, and as will be described in more detail below, the invention makes it possible to configure the bench so that the artificial lung is

2018ID00317 ordered in alternating back-and-forth mode only in periods which correspond, for the patient whose respiratory profile is simulated, to periods of changes in the respiratory profile due to central causes, i.e. due to a impaired brain control.

Another component of the bench is a simulation model of obstruction of the upper airways 10, that is to say of the nasal and oral passages. Such an obstruction simulation model can in particular consist of a Starling box, in which the passage section of an air circulation duct at the outlet of the artificial lung is modified by the action of pressure regulators 12, which provide positive pressures and negative pressures to change the overall pressure in the sealed chamber of the Starling box through which the air blown by the artificial lung must pass.

According to a characteristic of the invention, the adjustment of the level of obstruction generated by the Starling box is adjusted at each start of the respiratory cycle, in synchronization with a TTL pulse signal transmitted by the artificial lung.

Again, a control unit, advantageously the central control unit 8 previously described, is configured to control the operation of the upper airway obstruction simulation model 10, in an obstruction mode in periods identified as periods of modification of the respiratory profile with obstruction and in an alternative mode in the periods where no obstruction is to be reproduced. More particularly, and as will be described in more detail below, the invention makes it possible to configure the bench so that the upper airway obstruction simulation model 10 is controlled in obstruction mode only in periods which correspond, for the patient whose respiratory profile is simulated, to periods of modifications of the respiratory profile due to obstructive causes, that is to say due to an obstruction of the upper airways.

The bench also includes a flow measurement device 14 arranged between the mask or equivalent device and the simulation model of obstruction of the channels.

2018ID00317 upper air, in order to record the air flow likely to be brought to the patient by the mask or equivalent device.

As illustrated, the central control unit is configured to additionally recover a pressure value 16 measured at the output of the upper airway obstruction simulation model.

We will now describe with reference to FIG. 2 and the following figures a method for simulating a respiratory profile of a patient according to one aspect of the invention, it being understood that it is appropriate here to implement this simulated respiratory profile in the test bench 1 so that the machine is brought to show its efficiency in a context identical to its context of application. In particular, it is particularly important that the machine provides an adequate response to phases of modification of the respiratory profile of obstructive cause and an adequate response to phases of modification of the respiratory profile of central cause according to their appearance during treatment, and it is It is therefore noteworthy according to the invention that the simulated respiratory profile reliably presents these different phases and allows the corresponding configuration of the artificial lung and of the upper airway obstruction simulation model.

More particularly, the method according to the invention makes it possible to reliably characterize a phase of apnea or obstructive hypopnea in the respiratory profile of the patient, and it therefore makes it possible to reliably configure a standard back and forth mode of the lung. artificial and a mode of obstruction of the Starling gearbox for a corresponding duration on the associated test bench, which requires the device tested on this test bench to respond effectively to this situation, in particular by performing a counter pressure to clear the upper airway.

And in a similar way, this method according to the invention makes it possible to reliably characterize a phase of apnea or central hypopnea in the respiratory profile of the patient, and it therefore makes it possible to reliably configure an alternate back and forth mode. of the artificial lung and a mode released from the Starling box for an adequate duration on the associated test bench, which requires the device tested on this test bench to respond effectively to this situation, in particular by avoiding performing

2018ID00317 back pressure when it is not necessary, which could have negative impacts on the patient.

As illustrated in FIG. 2, the simulation method 20 according to one aspect of the invention comprises a first step 21 of recovering data during a diagnostic examination, for example carried out in a sleep center or on an outpatient basis . A polygraph or polysomnographic device can be used, sensors being positioned on the body of the sleeping patient.

This data recording makes it possible in particular to detect an air flow, that is to say a nasal, buccal or bucco-nasal flow or pressure of the patient, and therefore the development over a determined period of a respiratory profile of the patient, and it makes it possible to recover data relating to the measurement of the respiratory effort. More particularly, in the example illustrated, the data relating to the measurement of the respiratory effort consists of a measurement of the thoracic and / or abdominal perimeter of the patient, and for example a variation of the thoraco-abdominal perimeter. It will be understood that other measures of respiratory effort could be implemented within the framework of a variant of the invention, without however departing from the context of the invention.

This data recording also makes it possible to recover other additional information, including the detection of the tracheal or ambient sound, to have in particular if the patient is snoring, or the position of the patient via the data captured by an accelerometer, to know in particular if the patient moves at night.

It is advantageous to determine at this stage the rate of pulsed oxygen saturation (SPO2), to determine the level of oxygen in the blood: if the patient is no longer breathing, the supply of oxygen is cut, and the patient's metabolism draws on oxygen from the blood, so there is a desaturation.

We can also determine if the patient is in a micro-arousal phase: if the patient no longer breathes or breathes little, he may be the victim of a micro-arousal.

It is also possible to envisage measuring the thermistor, in particular in the cases where the measurement carried out beforehand is a measurement of nasal flow, this measurement of thermistor making it possible to validate if the patient breathes by the mouth, that is to say validate

2018ID00317 cases where the nasal discharge is zero but there is no apnea. This is a qualitative determination more than a quantitative one. We understand that the measurement of respiratory sound or RIP flow aims to provide the same type of additional information and which can be used in a similar way.

The method can then have a second step of preprocessing the signals 22. As will be understood on reading the description which follows, this second step is optional and the method could be implemented without this pretreatment of the signals. This second step can consist in particular of a treatment of the respiratory profile established in the previous step to detect and select stable periods of the patient's activity, for example stable periods of sleep when the simulation is made as part of the treatment of sleep apnea, excluding certain values.

On the basis of an activity signal defined from the three dimensional signals measured by a triaxial accelerometer during the data acquisition phase, the aim is to calculate frames of fixed duration, for example 5 seconds, by overlapping 50% step by step and to be determined on each of these frames if the patient's activity is above a determined threshold.

Data recovered during one of the frames identified as disturbed, that is to say with an activity above the determined threshold, can then be left aside in the simulation. The data corresponding to these unstable periods is then deleted.

The simulation method according to the invention then comprises a step 24 of identification of all the respiratory cycles present in the respiratory profile established previously, and therefore over the so-called stable periods depending on whether there has been a pretreatment step beforehand. The aim here is to identify in particular the beginning of the cycle, whether these respiratory cycles belong to a normal or standard breathing period or to a period of modifications in the respiratory profile such as a period of apnea or a period of hypopnea. Such identification of the beginning of the respiratory cycle then makes it possible, during the configuration of the components of the test bench which must reproduce the respiratory profile of the patient, to synchronize the events to be configured.

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The simulation method according to the invention also comprises a step 26 of qualifying events of respiratory profile modification by detection, on the air flow signal, of periods of breathing profile modification, this qualification step being carried out in parallel or in series of the stage of identification of the cycle beginnings. This qualification step aims to qualify the type of changes in the respiratory profile and in particular to identify periods of apnea or hypopnea and to distinguish them according to whether they are due to obstructive or central causes.

The data acquired in the identification step 24 and in the qualification step 26 are then processed in a step of digitalization and configuration of the test bench 28.

We will now describe in more detail and one by one the main steps of the process, namely the step of identifying the beginnings of cycle 24, then the step of qualifying periods of modification of the respiratory profile 26, then the step of digitalization and configuration 28.

The step of identifying all the respiratory cycles is done, as illustrated in FIG. 3, by a first analysis of the patient's air flow. A signal S representative of an air flow of the patient is here represented over a period of approximately one minute, and a first identification sub-step SE1 consists in the detection of the zones with reduced flow amplitude 29 making it difficult to identify the beginning of the cycle by the sole study of air flow.

Consequently, as illustrated in FIG. 4, a second identification sub-step SE2 consists in identifying the start of the cycle for the time segments which have not been identified as zones with reduced flow amplitude 29. These time segments "Easy to identify" 30 each correspond to a period in which the amplitude of the cycles is greater than 35% of the average of the amplitudes over the previous two minutes, without there being a respiratory pause of more than 3 sec. Of course, these threshold values are taken here by way of example, having been determined empirically by the inventors' tests, but it will be understood that other threshold values could be implemented without leaving the context of the invention.

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In these easy-to-identify time segments, the airflow values are distinctive enough to identify the start of the cycle, which corresponds to an inflection point between a trough and a top of the airflow value curve. In FIG. 4, the air flow end values have been illustrated, which correspond to a maximum value 31i, j, k of flow at a vertex of the curve or to a minimum value 32i, j, k of flow at a trough of the curve, and the instants of cycle beginnings 34i, j, k corresponding to the point of inflection mentioned previously, relative to two corresponding end values 31i, j, k, 32i, μ.

In parallel, and as illustrated in FIG. 5, without the simultaneity of the actions being limiting of the scope of the invention, a third sub-step of identification of the beginnings of cycle SE3 takes place for the periods with very small variation amplitude of flow nevertheless accompanied by respiratory effort 29, the beginnings of the cycle being here more difficult to distinguish because of the amplitude less than 35% and the possibility of respiratory pauses of a duration greater than three seconds. This third identification sub-step SE3 is carried out by using a RIP parameter, namely a parameter corresponding to the variation in the thoracic and / or abdominal perimeter, or by using another signal making it possible to distinguish a respiratory effort.

Carrying out this third identification sub-step makes it possible to avoid the simplification of the analysis of the patient's air flow by which one could be led to estimate that the periods in which the variations are small, that is to say say in which the amplitude of each cycle is less than 35% of an average value of amplitudes for a duration greater than three seconds, are equivalent to a constant cycle period.

More particularly, if we refer to FIG. 5, the value of variation of the thoracic perimeter (“RIP thorax”) and the value of variation of the abdominal perimeter (“RIP abdomen”) are taken into account for a first time zone 291t, 291a corresponding to a first period with very small variation in air flow amplitude 291 and for a second time zone 292t, 292a corresponding to a second period with very small variation in air flow amplitude 292. A reference signal is chosen between these two perimeter variation values, for example by considering a

2018ID00317 possible time difference between these signals and the air speed signal and then choosing the most phase signal, or advantageously considering the perimeter variation signal whose amplitude of relative variations is the largest and therefore the most exploitable.

In the example illustrated, the first time zone of the signal for variation of the abdominal perimeter 291a is chosen to define the start of the cycle in the first period with very small amplitude variation 291 and the second time zone of the signal for variation of the thoracic perimeter 292t is chosen to define the cycle starts in the second period with very little variation in air flow amplitude 292. In each case, an arrow illustrates the way in which the cycle starts identified in the movement of the movement are reported by temporal analogy thorax or abdomen in the air flow signal, in addition to the cycle beginnings identified in the second identification sub-step.

After carrying out the second and third identification sub-steps, a data collection sub-step SE4 makes it possible to centralize the information recovered and to list all the cycle starts on the whole of the signal S.

As has been described above, the step of identifying the beginning of the cycle which has just been described is carried out before, simultaneously or after a step of qualifying events of changes in the respiratory profile by detection, on the air flow signal, periods of modification of the respiratory profile, this qualification stage being described in what follows with reference to FIGS. 6 to 9.

More particularly, for each given period of nasal flow signal, as illustrated in FIG. 6, the qualification step follows the process illustrated in FIG. 7. The nasal flow values are considered in a first test phase T1. , during which it is determined whether the respiratory excursion, or in other words the amplitude of the air flow signal, is less than 70% of an average value of amplitudes, calculated for example over the last two minutes of acquisition of the signal.

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If this first test step T1 is positive, that is to say if the air flow signal amplitude is less than this first threshold value of 70%, a second test step T2 is carried out, to determine whether this situation is sufficiently significant, that is to say what lasts beyond 10 seconds. If, on the other hand, the first test step is negative, that is to say if the signal amplitude of the nasal flow is greater than this first threshold value of 70%, the process starts again at the beginning.

When it takes place, if the second test step T2 is positive, that is to say if the amplitude of the nasal flow signal is less than the first threshold value of 70% for a duration greater than 10 seconds, a third test step T3 is carried out, to qualify whether it is an apnea phase, that is to say to determine whether the amplitude of the air flow signal is actually less than the value 10% threshold. If, on the other hand, the second test step is negative, that is to say if the amplitude of the nasal flow signal is less than this threshold value of 70% but over a short, non-significant period, the process starts again at the beginning.

When it takes place, if the third step of T3 test is positive, that is to say if one has identified a phase of apnea, a fourth step of T4 test is carried out to more precisely qualify which type apnea it is, namely apnea of obstructive cause due to an obstruction of the upper airways, or apnea of central cause due to an impairment of the specific cerebral control. This fourth step of test T4 aims to compare to a reference value a value for variation of thoracic perimeter or a value for variation of abdominal perimeter, or even any value representative of respiratory effort, such as suprasternal pressure for example, or even any signal making it possible to appreciate the obstruction, such as a signal resulting from an analysis by the technique of forced oscillations (FOT). By way of example, the fourth test step consists in checking whether the average value of variation in thoracic perimeter over the period considered at least greater than 10 seconds is a value greater than 10% than an average value of variation in thoracic perimeter for a reference period, of significant duration for example equal to two minutes, and preceding the period considered. If the result of this fourth T4 test step is positive, that is to say that the small variation in air flow is accompanied by a

2018ID00317 Acceptable change in thoracic perimeter, the event of modification of the respiratory profile is qualified as an obstructive apneic AO cycle, that is to say a phase of apnea due to problems with obstruction of the upper airways. If on the other hand the result of this fourth test step is negative, that is to say that the small variation in the air flow is accompanied by a small variation, or zero variation of the thoracic perimeter and the abdominal perimeter, we qualify l event of modification of the respiratory profile like a central apneic cycle AC, that is to say a phase of apnea due to an alteration of the cerebral control without obstruction of the upper airways.

If, on the other hand, the third test step T3 is negative, that is to say that it has been identified that one is not confronted with an apnea phase, a fifth test step T5 is carried out for qualify if it is a hypopnea phase and we then test the rate of pulsed oxygen saturation (SP02). If this rate is reduced by at least 3% compared to a period preceding the period of completion of this third test step, the period is qualified as a phase in which the patient is in hypopnea. Of course, other parameters can be taken into account to validate the existence of hypopnea, for example the detection, of a phase of micro-arousal close to a reduction in air flow.

If the result of the fifth test step T5 is negative, and we are therefore neither in the presence of an apnea phase nor in the presence of a hypopnea phase, the process starts again from the beginning.

When the result of the fifth step of T5 test is positive, that is to say if a phase of hypopnea has been identified, a sixth step of T6 test is carried out to more precisely qualify what type of hypopnea it is, namely hypopnea of obstructive cause due to an obstruction of the upper airways, or hypopnea of central cause due to an alteration of the cerebral control. This sixth test step T6 aims to detect the existence of at least one parameter among the presence of snoring, a flow profile characteristic of the flow limitation or the phase shift between the parameter for variation of the abdominal perimeter and the parameter variation in the thoracic perimeter. If one of these phenomena occurs, we qualify the event as

2018ID00317 Modified respiratory profile as a phase of HO obstructive hypopnea due to problems with upper airway obstruction. If on the other hand none of these phenomena occurs, the event of modification of the respiratory profile is qualified as a phase of central hypopnea HC, that is to say a phase of hypopnea due to an alteration of the cerebral control. without obstruction of the upper airways.

It follows from the above a modeling of the air flow signal in accordance with that illustrated in FIG. 8, with the different phases framed in solid lines. By way of example, there have been chronologically illustrated three first phases of obstructive apnea AO, and a fourth phase of mixed apnea AM, namely a phase of apnea during which both central and obstructive causes have been detected. .

The modeling of the air flow signal is then completed, over the duration of the phase of modification of the respiratory profile identified in FIG. 9 by the arrow D, by a qualification of the transition zones ZT, represented in FIG. 9 by zones in dotted. In the example illustrated, each of the transition zones is identified as a zone corresponding to a modification of the respiratory profile of obstructive cause, due to its presence in the vicinity of at least one apnea phase of obstructive cause. In the case where a transition zone is only directly adjacent to the apnea or hypopnea phase (s) of central cause, it is understood that this transition zone would be qualified as an zone corresponding to a modification of the respiratory profile caused by a central problem.

The next step is to digitize the data, in particular to configure the functioning of the artificial lung and the upper airway obstruction simulation model, for example a Starling box, from the test bench.

FIG. 10 illustrates a period of nasal flow signal V ′ analyzed by the various process steps previously described, so that the various beginnings of respiratory cycle are associated with the curve both in periods of small amplitude variations and in periods of greatest variation, and so that periods of apnea, or hypopnea, obstructive (shaded bands in Figure 10) and / or

2018ID00317 periods of apnea, or hypopnea, central (white bands in Figure 10) are identified.

In the example illustrated, a first period of modification of the respiratory profile 101 consists of a phase of obstructive apnea AO and a second period of modification of the respiratory profile 102 consists of a sequence of a phase of obstructive apnea AO and a central apnea phase of AC.

On the basis of this information, a calculation module associated with the simulation method of the invention is configured to define an air flow, here a nasal flow, hypothetical V'h describing an absence of obstruction of the airways at any point of the signal. It is understood that for the period of modification of the respiratory profile corresponding to a central apnea phase AC, the reference air flow V ', that of the patient, illustrated in FIG. 10, is identical to the hypothetical flow V'h since the phase central apnea is not due to an obstruction of the airways but to an impairment of cerebral control.

The calculation module then performs a calculation of the effort pressure of the patient's respiratory muscle APmus necessary to achieve this hypothetical air flow, based on the following equation:

APmus = -J V’h.dt / C - V’h * R,

With:

V’h, the hypothetical air flow

R, the resistance of the simulated pulmonary system without obstruction of the upper airways

C, pulmonary compliance.

This value is used to configure the artificial lung 6, so that it can simulate inspiration and expiration over the entire respiratory cycle so as to obtain an air flow equivalent to that breathed by the patient if he did not have d obstruction of the upper airways. Of course, this muscle effort pressure

2018ID00317 respiratory APmus is null for the period of modification of the respiratory profile corresponding to a phase of central apnea AC. This perfectly simulates the respiratory functioning of the patient whose diaphragm is not involved in the phases of central apnea.

FIG. 13 finally illustrates the configuration of the simulation model for obstruction of the upper airways 10. This is achieved here by the use of abacuses defined by prior experimentation with the Starling box or another simulation model of obstruction of the upper airways. More particularly, it is understood that this model consists schematically of a duct whose diameter is varied - therefore the degree of obstruction - and whose amplitude of the flows is measured with the minimum degree of obstruction and the amplitude of flow resulting of different degrees of obstruction. These data are stored in a memory block of the calculation module, and this calculation module can then retrieve information on the degree of obstruction to be applied to the flow rate of the central control (V'h), that is to say the flow estimated as having been produced by the patient's lung if there were no obstruction in the upper airway, taking into account its amplitude and the reference air flow V '. It can be observed in FIGS. 12 and 13 that it follows that for the period of modification of the respiratory profile corresponding to a phase of central apnea AC, the effort pressure of the respiratory muscle APmus is equal to 0 cmH2O and the degree obstruction to exercise is minimal, since the setting of the central apnea phase implies that the artificial lung does not generate air likely to pass through the upper airway obstruction simulation model.

The method according to the invention, as just described and illustrated, allows, by the implementation of simple and inexpensive means, to carry out an effective and reliable simulation of the respiratory profile of a patient, who s '' applies as well to a simulation of a respiratory profile during a sleep phase of a patient treated for sleep apnea as during a stress phase of another patient subjected to asthma or COPD for example.

2018ID00317

This process therefore makes it possible to effectively test the apnea treatment machines which can be prescribed for different patients. In other words, according to the method of the invention, we process the various signals to establish a digital respiratory profile which can be implemented in the bench, then we test all the machines to determine which is the most effective.

The invention also fits into the context where the results of the tests carried out on the test bench configured according to the method described above, that is to say particularly reliable test results, are organized in a database allowing to associate the ideal apnea treatment machine with a given respiratory profile.

Therefore, the invention also relates to an application, or program, intended to be implemented on a communicating device, whether it consists of a mobile device such as a laptop, smartphone or tablet or whether it consists of a computer. desktop, the application consisting in allowing the choice of a medical device according to data, collected by said program or recovered by said program, representative of a respiratory profile of a patient.

A doctor can, on the basis of data collected during respiratory tests on the patient on an outpatient basis or in a sleep center, find the closest profile in the database and retrieve information concerning the name of the machine that has was the most effective for the treatment of apnea of the profile closest to his patient.

The invention cannot however be limited to the means and configurations described and illustrated, and it also applies to all means or equivalent configurations and to any combination of such means. In particular, it will be clearly understood that if the invention has been described and illustrated here preferentially in its application to the simulation of modifications of the respiratory profile relating to sleep apnea, it applies to

2018ID00317 any simulation allowing further processing of other respiratory profile changes.

Claims (9)

1. Method for simulating (20) a respiratory profile of a patient on a test bench (1) comprising at least one artificial lung (6) and a model for simulating upper airway obstruction (10), during which a plurality of data recorded by appropriate sensors is recorded in the memory of an electronic control unit and among which at least one data item relating to the patient's air flow, said method comprising at least: an analysis of the data to identify areas of modification of the respiratory profile, by taking into account at least the data relating to air flow; a step of identifying the quality of the modifications of the respiratory profile (26) by determining at least one level of obstruction of the upper airways in the zones of modifications of the respiratory profile, this identification step being carried out as a function of '' at least one parameter making it possible to assess the obstruction by analyzing the variation in respiratory rate or by analyzing the variation in respiratory effort, said step of identifying the quality of the modification in the respiratory profile making it possible to distinguish the periods related to obstructions in the upper airways from those related to impaired central control; a step of calculating (28) operating parameters of the artificial lung (6) and / or the simulation model of upper airway obstruction (10) of the test bench as a function of the results of the step of identifying the quality of changes in respiratory profile. 2. The simulation method according to claim 1, during which the analysis of the data to identify zones of modification of the respiratory profile comprises a first step of comparing the amplitude of the air flow over a given period with respect to a first value. threshold and classification of the respiratory profile over this given period into an apnea period if the amplitude of the air flow is less than the first threshold value, and includes a second step of comparing the amplitude of the air flow over a given period relative to a second threshold value and the classification of the respiratory profile over this given period into a hypopnea period if the amplitude of the air flow is between the first threshold value and the second threshold value and if an additional physiological parameter is detected . 3. Simulation method according to the preceding claim, during which the identification of the quality of the modification of the respiratory profile (26) is such that for a period of apnea, a period of modification of the respiratory profile due to an obstruction of the upper airway is identified when the variation in the thoracic perimeter and / or the abdominal perimeter, or when the variation in the resistance of the upper airway measured indirectly, is beyond a defined parameter, the apnea period being in otherwise identified as a period of modification of the respiratory profile due to the alteration of the central control. 4. A simulation method according to claim 2 or 3, during which the identification of the quality of the modification of the respiratory profile (26) is such that for a period of hypopnea, a period of modification of the respiratory profile due to a obstruction of the upper airways is identified when these events are accompanied by at least one phase shift of the chest signal and the abdominal signal or the presence of snoring or the detection of an aggravation of respiratory limitation of flow or when the variation of the resistance of the upper airways measured indirectly, is beyond a defined parameter. 5. Simulation method according to one of the preceding claims, in which a step of identifying the beginning of the respiratory cycle (24) is carried out on all or part of the data relating to the patient's air flow, at least by analysis of the variation of the thoracic or abdominal perimeter or any means of determining the respiratory effort when the amplitude of variation of the data relating to the air flow is slightly distinctive. 6. Simulation method according to one of the preceding claims, during which the step of recording the data comprises recording an additional measurement of the patient's movements while he sleeps, via an accelerometer, during which the step of analyzing the data and the step of determining at least one qualifying parameter are preceded by a step of calculating a patient movement parameter, during which periods of agitation are identified if the amplitude of the movements is above a critical threshold, the data corresponding to a period of agitation being excluded from the processing in the analysis and determination steps. 7. Simulation method according to one of the preceding claims, during which the air flow measurement consists of a measurement of a nasal, buccal or nasobuccal flow during which the step of recording the data includes the recording of '' an additional measurement, for example of the tracheal sound or a thermistor measurement, the data analysis step comprising an analysis of the additional measurement value in addition to the analysis of nasal, buccal or nasal-oral flow , the zones of modification of the respiratory profile corresponding to the periods during which a nasal, buccal or naso-buccal flow rate is less than a determined threshold and an additional measurement value less than a given threshold. 8. Medical device test bench for respiratory conditions comprising at least one artificial lung and an upper airway obstruction simulation model, an artificial lung control and a resistance value of the airway obstruction simulation model upper aerials being configured during a digitalization step of the simulation method according to one of the preceding claims. 9. Test bench according to claim 8, characterized in that a value corresponding to a minimum resistance of the upper airway obstruction simulation model is applied in the periods of the digitalized respiratory profile during which a modification of the linked respiratory profile at the alteration of the central control is identified.