WO1985002104A1

WO1985002104A1 - Quick occlusion controlled device

Info

Publication number: WO1985002104A1
Application number: PCT/FR1984/000258
Authority: WO
Inventors: Jean-Pierre Speich; Pierre Joseph Zouloumian
Original assignee: Centre National De La Recherche Scientifique; Universite Louis Pasteur (Strasbourg I)
Priority date: 1983-11-15
Filing date: 1984-11-12
Publication date: 1985-05-23
Also published as: FR2554706B1; FR2554706A1

Abstract

A quick occlusion controlled device particularly intended to evaluate the sensitivity of respiratory centres comprises a body (1) connected to the respiratory apparatus of the patient through a buccal connector (2), provided with a pressure tap (3). According to the invention, the device is characterized in that the body (1) comprises an inspiration connector (4) which opens into the inner volume of the body (1) through a valve (5), as well as a respiration connector (6) which opens into the inner volume of the body (1) through a second valve (7), said device being further provided with an occlusion means of both/either of the valves (5) and (7).

Description

Controlled rapid occlusion device.

The invention relates to a controlled device for rapid and silent occlusion, in particular for evaluating the sensitivity of the respiratory centers, which comprises a body connected to the patient's respiratory system by means of an oral connector provided with a pressure tap. .

It will in particular find its application in the medical field, in particular for evaluating the sensitivity of the respiratory centers of a patient by means of the technique known as "occlusion pressure" and also for carrying out tests of pulmonary mechanics requiring repeated interruptions. ventilated flows.

For a long time, the evaluation of the sensitivity of the complex neurological unit constituted by the respiratory centers was approached by the study of the overall ventilatory response to various stimulations. The stimuli used were either chemical (modification of PC02 or P02), or mechanical (addition of resistance beyond the buccal space). But these modes of evaluation, valid in the normal subject, are debatable in patients, whose overall ventilatory response is strongly conditioned by the properties of the entire inert neuro-muscular mechanical system that constitutes the respiratory system: the tests carried out in these conditions are not specific to respiratory centers.

On the other hand, research carried out by different authors in animals and humans seems to show that under certain conditions the variation in pressure measured at the mouth during the one hundred to three hundred milliseconds following the sudden obstruction of the airways, the efferent neurogenic intensity of the respiratory centers and is independent of neuro-mechanical factors which could be associated with various thoracic affections. For clinicians, the measurement of occlusion pressure seems to be, at present, the most specific test of the sensitivity of the respiratory centers.

So that proper measurements of this pressure can be made occluded, the occlusions must be produced by means of a very silent obturating valve, the maneuver having to be done without the subject's knowledge. In addition, this valve must, outside the occlusion phases, offer a low and constant resistance to breathing, be etanehe and sufficiently rigid, and have a low internal volume (the pressure signals, must not be damped).

Unfortunately, the devices currently in existence suffer from various drawbacks which affect the quality of the results obtained:

In that described by WHITELAW, the occlusion is carried out by means of taps; the volume of the circuits involved is significant, and one can wonder about the consequences of their buffer effect on the pressures measured.

Another existing device is that described by CAMPORESI which uses an electromagnet to ensure the occlusion of the circuits.

The disadvantage of the latter device is the inertia attached to a magnetic valve whose operation, not silent, remains dependent on the position.

We can also cite the device described by GUENAKD, the production of which requires careful machining, and in which the movable flaps used move a considerable volume of air.

The object of the present invention is to remedy these drawbacks. The invention, as characterized in the claims, solves the problem of creating a controlled device for rapid and silent occlusion, in particular intended for evaluating the sensitivity of the respiratory centers comprising a body connected to the patient's respiratory system by by means of a buccal connector fitted with a pressure tap and comprising an internal volume into which an inspiratory connector opens via a valve and a respiratory connector via a closed valve l one and / or the other by means of occlusion. The advantages obtained thanks to this invention consist essentially in that the device of the present invention, described hereinafter, turns out to be simple to make and its operation, not dependent on a position, guarantees switching and / or interruptions. fast and silent flow without setting in motion large volumes of organs or fluids and without inducing a significant variation in the internal volume which can disturb pressure and flow measurements. It has a dead volume and a low resistance to flow, conditions which should be met if one wants to avoid disturbing the patient's natural breathing outside the occlusion phases. During these, the device is perfectly waterproof. On this subject, the results of experiments carried out are attached to the description and confirm the forecasts.

The invention is set out below in more detail with the aid of drawings representing only one embodiment.

FIG. 1 represents, in section, an exploded view of the various elements making up the controlled rapid occlusion device according to a preferred embodiment of the invention.

FIG. 2 represents the test apparatus of the device of the present invention.

FIG. 3 represents the comparative diagram of the results of the test carried out with the apparatus of FIG. 2.

FIG. 4 represents the device of the present invention adapted to the case where hypercapnic / hypoxic stimulation is superimposed on the occlusions.

Figure 5 shows a second embodiment of the present invention.

FIG. 6 represents the behavior of the flow and pressure measurement chains used, when a stationary gas flow (constant flow) is interrupted by means of the device described in FIG. 5. FIG. 7 represents the signals obtained during repeated interruptions of a sinusoidal flow generated by a BTPS pump through a pressure drop constituted by a pipe.

The controlled rapid occlusion device of the present invention is in particular intended to evaluate the efferent neurogenic sensitivity of the respiratory centers. The oral pressure measured during the first three hundred milliseconds following an inspiratory occlusion has been shown to reflect the force generated by the isometric contraction of the inspiratory muscles.

The present invention aims to present a device capable of causing occlusions in a circuit connected to the respiratory system of a patient, and making it possible to very quickly measure the static pressure prevailing after the occlusion.

However, it has been shown that, under penalty of distorting the results of the measurements, it was essential to perform the occlusions silently so as not to influence the patient. In addition, a low resistance to flow is compulsory and a reduced dead volume varying very slightly during operation is necessary to guarantee the accuracy of the results.

The preferred embodiment of the controlled occlusion device shown in FIG. 1 comprises a body 1 connected to the patient's respiratory system (not illustrated) via a buccal connector 2 provided with a pressure tap 3 connected to a pressure measuring device.

The body 1 further comprises an inspiratory connection 4 opening into the interior volume of the body 1 by means of a valve 5.

The body 1 is, moreover, connected to an expiratory connector 6 communicating with the interior volume of the body 1 by means of a valve 7.

The connection of all the parts is sealed so as to avoid any leakage. According to the invention, the controlled occlusion device is also provided with means for occluding one and / or the other valve. The occlusion means make it possible to prevent the operation of one and / or the other valve, causing an abrupt cessation of the flow of the respiratory flow, as well as a variation of the instantaneous pressure measurable at the level of the pressure tap 3.

According to a first embodiment of the occlusion means, these are in the form of a controlled disc 8 capable of coming to bear on a diaphragm 9 of the valve 5 and thus immobilizing it in the closed position. The example chosen above applies to the inspiratory part of the device, it is however obvious that the same arrangement can be applied to the expiratory part.

The articulated disc 8 comes to rest in particular on the periphery of the diaphragm 9 and thus applies it to its seat in order to guarantee the sealing of the assembly.

The example chosen applies to a valve 5 with a diaphragm 9, that is to say that it is a one-way device in the case of exhalation, ie when the internal pressure of the body 1 is higher than atmospheric pressure, the diaphragm 9 remains applied to its seat, on the other hand a diaphragm 10 of the valve 7 opens so as to let out the breath of the patient. By cons, during inspiration, that is to say when the pressure inside the body 1 is lower than atmospheric pressure, the diaphragm 10 of the valve 7 is pressed against its seat while the diaphragm 9 of the valve 5 s opens to allow the patient to breathe.

According to another embodiment of the present invention, it is possible to imagine that the valves 5 and / or 7 are devoid of diaphragms and, on the other hand, provided with a flexible seat. In this way, the controlled disc 8 comes directly to bear on the seat of the valve and itself obstructs the passage of the air flow.

The occlusion disc 8 is controlled by means of a semi-rigid operating wire 11 which can be in the form of a needle or a cable. It is desirable to use a semi-rigid wire, on the one hand, so that the wire is capable of ensuring the transmission of a certain thrust force on the disc 8 to ensure the closing of the valve 5 and, on the other hand, it is necessary to allow a certain orientation of the disc 8 so that it can be articulated and come to be applied over the entire periphery of the valve, this despite the mechanical positioning defects.

The operating wire 11 may, for example, slide in a mandrel 12, similar to a sheath and pass through a plug 13 secured to the body 1 of the device.

So that the operation of the occlusion disc only slightly modifies the internal volume of the body 1, the diameter of the wire 11 used for the control will be small, of the order of a few tenths of a millimeter.

In the general case, the occlusion disc 8 can be controlled manually or automatically, by mechanical, electro-mechanical, pneumatic or other means.

In the example chosen, the disc 8 is operated by a push button 14 secured to the wire 11 and a socket 15 secured to the mandrel 12. The push button 14 can slide in the socket and is pushed back by a spring device 16. In this way, by operating the push button 14 in the socket 15, the operator operates the operation of the occlusion device, that is to say of the disc 8.

The expiratory connector 6 advantageously has lateral openings 17 which will thus allow the air evacuated by the patient to escape. In a similar manner to the inspiratory device, a valve closure mechanism 7 may be mounted on the expiration portion 6 provided with a second plug 18 and a disc 19 for bearing on the valve 7 may be operated by a wire ( not shown) actuated similarly to that previously exposed and passing through said plug 18.

It will be noted that all the parts used for the construction of the controlled rapid occlusion device of the present invention may be made of synthetic materials which will ensure silent operation of the device and which can, moreover, easily be sterilized.

Tests of the occlusion device 46, described above, were carried out by means of a sinusoidal pump 32 (such as a BTPS pump) comprising, on the one hand, a tank 33 whose air volume 34 contained in this tank 33 is between one and four liters and, on the other hand, a piston 35. These tests are shown in Figure 2. The reference 36 represents the stroke of the piston 35. On the ordinate 37 are reported the pressures in cmH ₂ O, reference 38 corresponds to an occlusion. The tests represented in this figure 2 were carried out for frequencies 39, 40, 41, 42, 43 corresponding respectively to a given position of the piston 35.

By way of example, the tests were carried out by means of the sinusoidal pump BTPS 32 for frequencies of nine (mark 39 in FIG. 2) - twelve (mark 40 in FIG. 2) - eighteen (mark 41 on the figure 2) - twenty four (reference 42 on figure 2) and thirty six (reference 43 on figure 2) cycles per minute, cylinders of 1-0.5 and 0.25 liter, the volume of air 34 contained in the tank 33 of the pump 32 at the start of inspiration being between one and four liters.

The pressure measurements were made using an electromanometer connected to a fast and precise analog recorder.

The occlusions were performed using the device described above, during the inspiratory phases of the sinusoidal pump. The depression obtained after two hundred milliseconds of inspiration was noted for various displacements and frequencies and compared to the depression reigning theoretically in the tank in the simplified hypothesis of an isothermal transformation, that is:

with - P (t): pressure prevailing in the system - PB: barometric pressure - Vo: Chamber volume at the start of inspiration - C: pump displacement - T: Sinusoidal pump period (min)

FIG. 3 shows that in the domain corresponding to the rest ventilation, the pressures measured on the experimental device practically coincide with the theoretical pressures calculated. The occlusion device therefore seems to be suitable for the study of occlusion pressures in patients breathing spontaneously at rest. In particular, it is sufficiently rigid and waterproof. We have represented in this figure on the abscissa 44 the frequencies 39, 40, 41, 42, 43 therefore the frequencies of nine - twelve - eighteen - twenty four and thirty six cycles per minute and on the ordinate 45 the pressure in cmH ₂ O. In this figure are represented four curves A, B, C, D, the observed curves being in solid lines and the theoretical curves in mixed lines.

Displacement Total volume

A 1000 4000

B 500 4000

C 250 4000

D 250 1000

FIG. 4 illustrates a device allowing the measurement of occlusion pressure and minute ventilation in the presence of hypercapnic / hypoxic stimulation generated by breathing in a closed circuit.

The occlusion device 20 has an exhalation connector 6 connected to a flexible balloon 21 having a CO ₂ / O ₂ / N ₂ gas mixture itself connected to the inspiratory connector 4 via a rigid pipe 22. The flexible balloon 21 is placed in a sealed box 23. The preferably transparent box 23 opens onto a pneumotachographic measuring tip 24 whose operation is optimized by means of the tubes 25 and 26, the shape of the tube 25 avoiding any risk of obstruction by the ball. This end piece 24 is connected to a pneumotograph (not shown felt). On the rigid pipe 22 is provided a socket 47 of a gas analyzer (not shown). Likewise, a second tap 48 of gas analyzer is provided on the flexible balloon 21. In 49 is provided a shutter valve.

For certain medical applications, it is desirable for the device of the invention to allow brief and frequent interruptions of the ventilated flow rates.

Several investigative methods, widely described in the literature, use air current interruptions to demonstrate the mechanical properties of the respiratory system. In particular, that characterized by brief and frequent interruptions makes it possible to roughly assess the total dynamic resistances that oppose breathing; resistance of the airways to flow and resistance of tissues with movement.

FIG. 5 represents an embodiment of the present invention, very particularly suitable for the pulmonary mechanics test. We find in this embodiment the main elements constituting the device, namely the mouthpiece 2, the pressure tap 3, the body 1, a disc 8.

On this subject, it should be noted that the occlusion is carried out according to the second mode described above, that is to say that the valve is deprived of diaphragm but, on the other hand, is equipped with a flexible seat 27 on which comes directly support the disc 8 to ensure sealing.

In the present case, the operating wire 11 of the disc 8 is actuated by means of an electromagnet 28, for example of the type with plunger core provided with a return spring. The electromagnet is controlled by means of a logical servo allowing the duration and frequency of recurrence of occlusions to be set at will. This logic can be used independently or be triggered from signals from other devices, such as measuring devices, IT or other means. The gas flow is routed to the oral connector 2 by means of a single bidirectional connector 29 or also unidirectional valves 30 and 31 can be installed on either side of the body 1, so to route the inspiratory and respiratory flow to separate ducts.

Tests have been carried out with the device described and the performance of this device is as follows. The valve is closed in approximately eight milliseconds, broken down as follows: - four milliseconds of dead time (pure delay)

- four milliseconds of actual closing time.

FIG. 6 illustrates the behavior of the flow rate 50 and pressure 51 measurement chains used when interrupting a static gas flow (constant flow) by means of the device described.

FIG. 7 illustrates the signals obtained during repeated interruptions of a sinusoidal flow generated by the BTPS pump through a pressure drop constituted by a pipe. The envelopes of the curves representing the pressures 52 and the flows 53 have sinusoidal shapes, and the coefficient of similarity linking these profiles generally characterizes the resistance opposed by the pipe to the gas flow.

The resistance thus measured also includes that opposed by the valves. The minimization of the latter can be obtained in particular by the realization on a suitable scale of the device described.

In general, the present invention can be applied to any use which requires a rapid interruption of a fluid flow.

Claims

claims

1. A controlled device for rapid and silent occlusion, in particular intended for evaluating the sensitivity of the respiratory centers, which comprises a body (1) connected to the respiratory system of the patient by means of an oral connection (2) provided with a pressure tap (3), characterized in that in the internal volume of said body (1) open an inspiratory connection (4) by means of a valve (5), as well as a respiratory connection (6) by through a second valve (7), said device being further provided with occlusion means closing one and / or the other valve (5) and (7).

2. Controlled occlusion device according to claim 1, characterized in that the occlusion means are in the form of controlled discs (8) and (19) capable of coming to bear on the diaphragms (9) and (10) of the valves (5) and (7) respectively, and thus immobilize them in the closed position.

3. controlled occlusion device according to claim 1, characterized in that the valves (5) and (7) are themselves formed by discs (8) and (19) controlled, capable of coming to bear on a flexible seat to ensure a good seal.

4. Controlled rapid occlusion device according to claim 2, characterized in that the disc (8) is integral with a wire (11) for semi-flexible operation.

5. Controlled rapid occlusion device according to claim 4, characterized in that the operating wire (11) slides in a mandrel (12) through a plug (13) secured to the body (1) of the device.

6. Controlled rapid occlusion device according to claim 5, characterized in that the operation of the disc (8) is operated by a push button (14) secured to the wire (11) and a socket (15) secured of the mandrel (12).

7. Controlled rapid occlusion device according to claim 4, characterized by the fact that the diameter of the operating wire (11) is very small, of the order of a few tenths of a millimeter.

8. Controlled rapid occlusion device according to claim 1, characterized in that the exhalation connector (6) has lateral openings (17) opening into the open air.

9. Controlled rapid occlusion device allowing in particular the measurement of occlusion pressure and minute ventilation in the presence of hypercapnic / hypoxic stimulation generated by breathing in a closed circuit, according to claim 1, characterized in that the expiration connector (6) is connected to a flexible balloon (21), itself connected to an inspiratory connector (4), said flexible balloon (21) being placed in a sealed box (23).

10. A controlled device for rapid occlusion of pulmonary mechanical tests according to claim 4, characterized in that the disc (8) is actuated by means of an electromagnet (28) itself controlled by a control logic. .