WO2019121257A1

WO2019121257A1 - System for controlling the exhalation pressure of a diver for diving ventilation equipment

Info

Publication number: WO2019121257A1
Application number: PCT/EP2018/084611
Authority: WO
Inventors: Mathieu COULANGE; Pierre MICHELET
Original assignee: Universite d'Aix-Marseille (AMU); Assistance Publique Des Hopitaux De Marseille (Ap-Hm)
Priority date: 2017-12-19
Filing date: 2018-12-12
Publication date: 2019-06-27
Also published as: US20210086883A1; EP3728017A1; FR3075160A1

Abstract

System for controlling the exhalation pressure of a diver for diving equipment with a ventilation circuit, comprising a unidirectional valve acting on an exhalation outlet of the ventilation circuit, and a brake configured to exert an adjustable constraint on the unidirectional valve in order to control the pressure of the gas from the exhalation outlet so as to generate a positive exhalation pressure in the ventilation circuit of the equipment and thus prevent or treat immersion pulmonary edemas.

Description

PLUNGER EXPIRY PRESSURE CONTROL SYSTEM FOR DIVING VENTILATION EQUIPMENT

The invention relates to diving devices and more particularly to a device for the ventilatory part of diving systems for preventing and participating in the treatment of pulmonary edema of immersion.

Immune pulmonary edema is an increasingly common pathology secondary to cardiac decompensation following the impact of a constraining environment on a diver. Indeed, immersion causes a phenomenon of soft tissue compression, that is to say the lower limbs and the abdomen, with redistribution of peripheral blood volumes to the thorax. The cold, related to the immersion causes a closing of the vessels and slows the heart rate. Increasing the amount of oxygen caused by the increase in ambient pressure as the diver descends aggravates the aforementioned phenomena and decreases the contraction force of the heart muscle. These respective mechanisms generate cardiac overload which, when the cardiovascular system is defective or aging, causes early leakage of the blood fluid into the lungs. Pulmonary congestion, also known as pulmonary edema, leads to a decrease in blood oxygenation, which can quickly lead to discomfort.

A better knowledge of this pathology and the recent development of recreational diving are at the origin of a clear increase in the number of pulmonary edema of immersion. This becomes even the second cause of diving accident, just behind the desaturation accident, and is also the leading cause of death for the diver. Immune pulmonary edema is responsible for approximately 45% of cardiac arrests. The genesis of pulmonary edema of immersion occurs during the first twenty minutes of the dive and worsens during the ascent with the change of position of the diver and therefore the ventilation pressure regimes.

The physiopathology of pulmonary edema of immersion remained for a long time little known. However, the demonstration of the cardio-circulatory part in the physiopathology (Louge et al., "Pathophysiological and diagnostic the implications of cardiac biomarkers and antidiuretic hormone release in the differentiating pulmonary edema from decompression sickness ", Medicine (Baltimore), 95 (26): e4060, June 2016), the rapid worsening of the symptomatology during verticalization of the diver, which leads to a loss of expiratory back pressure (Coulange et al., "Pulmonary oedema in healthy SCUBA various: new physiopathological pathways", Clin Physiol Funct Imag., 30 (3): 181-186, 2010), as well as similarities with drowning made it possible to show the interest of considering the prevention and treatment of pulmonary edema of immersion by the generation of a positive expiratory pressure (Michelet et al., "Acute respiratory failure after drowning: a retrospective multicenter survey ", Eur J. Emerg Med., 2015). The positive expiratory pressure is the exhalation pressure maintained in the airways. It prevents the formation of a collapse (collapse of lung tissue due to pressure exerted by a pleural effusion, tumor or pneumothorax). Moreover, by increasing the period of time during which the gas exchanges between cell and capillary occur, it also makes it possible to avoid the formation of atelectases (retraction of the pulmonary alveoli).

US 1984/4436090 discloses a ventilation control device comprising a piston which can exert pressure on a valve, the valve serving to control the flow of gas upon inhalation and the expiration of a person for an application. medical (respirator or resuscitator). This device can provide a positive expiratory pressure and is also usable for aeronautical ventilation assistance applications. US 2004/035414 discloses a ventilatory device for diving equipment, especially for a snorkel, which can provide a positive expiratory pressure. This device makes it possible to slow down the ventilation cycle of the diver, to balance the ventilation work between inspiration and expiration and to minimize the risk of development of atelectases. However, neither of these devices can prevent or treat pulmonary edema immersion.

Other documents (EP 1500586, US 1993/5259374) present adjustable regulating devices of the ventilation of the diver upon inhalation, but they do not generate positive expiratory pressure and therefore do not make it possible to prevent or treat oedemas Immersion pulmonary The invention aims to remedy the aforementioned problems of the prior art and more particularly, it aims to provide a device for preventing and treating pulmonary edema immersion by generating a variable positive expiratory pressure. According to the invention, this prevention device can generate an adjustable positive expiratory pressure and thus control the expiratory pressure of the plunger for diving ventilation equipment. It comprises a one-way valve acting on the expiratory outlet of the ventilation equipment and a brake configured to exert an adjustable stress on the valve so as to control the pressure of the gas from the expiratory outlet, therefore the exhaled gas by the plunger. With the invention, the diver may for example benefit from a greater or lesser resistance to expiration to prevent the risk of pulmonary edema immersion during an effort immersed in cold water and deep. Conversely, the diver can immediately cancel this resistance to exhalation in case of panic rise to prevent a risk of thoracic barotrauma (or overpressure) related to the sudden expansion of the gas in the lungs.

An object of the invention is therefore a system for controlling the expiratory pressure of a plunger for diving equipment having an expiratory circuit. The system includes a one-way valve acting on an expiratory outlet of the ventilator circuit, and a brake configured to exert an adjustable stress on the one-way valve to control the exhalation outlet gas pressure to generate a positive pressure in the ventilator. breathing circuit of the diving equipment.

According to particular embodiments of the invention:

- The brake may be an adjustable discharge valve comprising a hardening spring and a set screw for adjusting the spring resistance;

- The system may include a disengaging system for disabling the brake, which may consist of a central tubular shaft and coaxial with the set screw;

- The system may include a pressure sensor in the expiratory circuit of the ventilatory circuit;

- The brake may be a solenoid valve;

- The solenoid valve can be controlled electronically following measurements provided by the pressure sensor; - The brake may include grommets, shutters or a diaphragm;

- The opening level of the eyelets or shutters or the diaphragm can be controlled electronically following measurements provided by the pressure sensor;

- The system generates at least two discrete levels of positive expiratory pressure;

- The system can generate positive expiratory pressure levels among the levels (0; 2,5; 5; 7,5 and 10 mbar).

Another object of the invention is an expander whose second stage comprises an expiratory pressure control system as claimed in any one of the embodiments of the invention.

Yet another object of the invention is a recycler, the recycler comprising an expiratory pressure control system as claimed in any one of the embodiments of the invention.

The invention also relates to a scuba apparatus comprising a system for controlling the expiratory pressure of a plunger as claimed in any one of the embodiments of the invention.

Other characteristics, details and advantages of the invention will emerge on reading the description made with reference to the appended figures given by way of example and which represent, respectively:

- Figure 1, an illustration in top view of the implementation of an expiration control system on a pressure regulator according to one embodiment of the invention;

- Figure 2, a sectional illustration of the implementation of an expiration control system on a pressure regulator according to one embodiment of the invention;

- Figure 3, an illustration of the implementation of an expiration control system on a rebreather according to one embodiment of the invention.

As is generally accepted, diving equipment may comprise all or part of a set of equipment for practicing diving including an isothermal suit, a mask, fins, a ballast, a stabilizing vest and at least one bottle of diving containing a mixture of respiratory gas, such than nitrox, heliair, hydrox, trimix, heliox and hydreliox. Most often, the gaseous mixture is compressed air. The diving equipment within the meaning of the invention comprises an expander or a rebreather allowing the diver to breathe via a mouthpiece.

A regulator is an open-circuit diving equipment that allows a diver to breathe the gas contained in his diving bottle at the pressure at which he is moving.

A rebreather is a closed-circuit dive equipment that recycles exhaled gas from a diver to lengthen the dive time and reduce the weight of the dive tanks.

A self-contained breathing apparatus is generally defined as an individual device allowing the user to breathe and freely move underwater with a supply of compressed breathable gas.

Figure 1 shows a top view of the second stage of a pressure regulator according to one embodiment of the invention. The arrival of a medium pressure gas from the first stage of the regulator to the second stage is provided by a hose 100. A button 101 makes it possible to adjust the flow of gas arriving in the second stage by the hose 100. This medium pressure gas enters in the dry chamber 102 of the second stage of the regulator, and is then relaxed when arriving in the mouthpiece 104. This is the inspiration of the plunger in the mouthpiece 104 which triggers the passage of the gas from the dry chamber 102 to the mouthpiece 104. The inspiration or expiration of the plunger controls, for example, the opening of a valve that allows the gas to pass from the dry room 102 to the mouthpiece 104 when inhale or block the gas in the dry chamber 102 at expiration. The exhaled gas pressure is adjustable by means of a brake 105 and the exhaled gas is evacuated from the second stage of the regulator by the exhaust whiskers 106.

Figure 2 shows a sectional view of the second stage of an expander according to one embodiment of the invention. The arrows symbolize the movement of the gas in the second stage of the regulator. In this implementation, the brake 105 comprises a set screw 200 and a hardening spring 201. The brake 105 makes it possible to act on washers 202 which act on membranes 203. The 203 membranes and the washers 202 thus form a unidirectional valve 204. The plunger can act on the set screw 200 to adjust the resistance of the curing spring 201. During the inspiration phase, the gas present in the dry chamber 102 passes in the mouthpiece by the opening of the membranes 203. During the expiration phase, the membranes 203 close again, completely or in part according to the resistance of the hardening spring 201, and the exhaled gas is evacuated by the whiskers 106. Controlling by setting the resistance of the hardening spring 201 the closing level of the membranes, to have a complete or partial closure, the plunger can act on the pressure of the exhaled gas.

The clinical manifestations of pulmonary edema of immersion often appear during the ascent phase or during the extension of the diving session. They do not always appear at the same time depending on the divers or with the same intensity. It is therefore important to be able to adjust the positive expiratory pressure at the onset of symptoms, or even anticipate the genesis of edema by a preventive trigger as soon as environmental conditions become binding. In the embodiment described, the plunger acts directly on the calibration screw 200 according to its feel.

Moreover, during the ascent, the verticalization of the plunger causes a large pressure difference between the regulator that is in the mouth and the lungs of the plunger. It is then necessary to generate a stronger positive expiratory pressure than a descent to prevent pulmonary edema of immersion or to treat the symptoms.

The second stage of the regulator may also comprise a disengaging rod 205 which makes it possible to deactivate the brake, that is to say to cancel the resistance of the hardening spring 201. This disengaging rod 205 constitutes a safety as regards the level of solid obstruction of the system or panic lift requiring no obstacle to expiration. The disengagement rod 205 is central and coaxial with the set screw 200. The valve 204, the brake 105 and the disengaging rod 205 are held in place by a fixed housing 206. This fixed housing 206 also comprises a safety channel at the walkout 207. In an alternative embodiment of the invention, a pressure sensor is placed in the expiratory circuit to measure the pressure of the exhaled gas by the plunger. According to one embodiment, the sensor can be positioned at the mouthpiece 104.

Advantageously, the measurements can be retrieved in order to control the brake 105 electronically. An electronic brake control makes it possible to more effectively detect any symptom related to the appearance of pulmonary edema and to generate any pressure control action more rapidly. expiratory. In an embodiment with integrated sensor, the brake 105 is a solenoid valve or a solenoid valve. The brake may also be eyelets, shutters or a diaphragm, the eyelets, shutters and diaphragm being outlet orifices having a variable opening level. More generally, the brake can take any form to vary the level of closure of the exit surface.

Thus, the system comprises two operating modes: one said passive and the second said active. The passive mode is characterized by the absence of positive expiratory pressure and is the preferred mode for the descent of the diver or may be the mode imposed in case of emergency lift where the expiration must be facilitated. The other mode of operation, said active mode is characterized by the generation of a positive expiratory pressure by the implementation of the system of the invention. The active mode is used during the diver's ascent phase or during an extension of the dive session. The active mode can be operated semi-autonomously by the diver who can adjust the level of the positive expiratory pressure by the activation of the set screw, or be operated automatically by being for example connected to a dive computer worn by the diver. The dive computer records the diver's dive parameters and thus provides data on the symptoms experienced by the diver to activate the expiratory pressure control system. In an alternative embodiment, the dive equipment may include a plurality of sensors for providing data that can enhance the detection of symptoms indicative of pulmonary edema of immersion.

According to another embodiment of the invention, the brake 105 makes it possible to generate at least two discrete levels of positive expiratory pressure. The 0 mbar discrete level belongs to the possible levels of positive expiratory pressure. In order to meet the known standards, in one embodiment, the brake makes it possible to generate levels of positive expiratory pressure among the following levels:

- 0 mbar;

2.5 mbar;

- 5 mbar;

- 7.5 mbar; and

- 10 mbar

Advantageously, the levels of positive expiratory pressure are chosen from the following levels: 2.5 mbar; 5 mbar; 7.5 mbar and 10 mbar.

These values of positive expiratory pressure given by way of non-limiting example, correspond to the levels likely to prevent the genesis of pulmonary edema in emergency medicine while not reaching levels likely to create pulmonary overpressure and to respect the pressure regime limits for pressure reducers (see standard NF EN 250, June 2014). Figure 3 shows the implementation of one of the embodiments of the invention on a diving rebreather. The arrows symbolize the movement of the gas in the rebreather. When the diver inhales, the rebreather supplies gas to the diver from the inspiratory lung 300. This gas arrives at the mouthpiece 301 through a hose 302. In the mouthpiece 301, the inspired gas passes through a check valve. of inspiration 303 before reaching the mouth of the diver. When the diver expires, the exhaled gas is found in the mouthpiece 301 and passes through the exhalation check valve 304. A brake 305 adjustable by the plunger can act on the opening of the valve 304. In limiting its opening, the brake 305 can generate a positive expiratory pressure in the mouthpiece 301, to prevent or treat pulmonary edema immersion.

After having passed through the exhalation check valve 304, the exhaled gas arrives in the expiratory lung 306 via a hose 302. One or more 307 respiratory gas bottles supply the expiratory lung 306 with respiratory gas (feed symbolized by reference 308). in Figure 3). The gases then present in the expiratory lung 306 pass through a filter 309. This filter 309 makes it possible to filter the carbon dioxide so that the gases that then penetrate into the inspiratory lung 300 no longer contain carbon dioxide. The invention has been described for several embodiments in order to present the general principle. However, those skilled in the art will be able to adapt the invention to other embodiments without departing from the essential features described herein. More generally, the invention can be used on any type of open or closed dive circuit. The described embodiments should be considered in all respects as merely illustrative and not restrictive.

Claims

claims

A diver's expiratory pressure control system for diving equipment having a ventilatory circuit, comprising:

a unidirectional valve acting on an expiratory outlet of the ventilatory circuit; and

a brake configured to exert an adjustable stress on the unidirectional valve in order to control the pressure of the gas coming from the expiratory outlet so as to generate a positive expiratory pressure in said breathing circuit.

The expiratory pressure control system of a plunger according to claim 1 wherein said brake is an adjustable relief valve comprising a hardening spring and a set screw for adjusting the resistance of said spring.

3. system for controlling the expiratory pressure of a plunger according to claim 1 or 2 further comprising a disengaging system for disabling said brake.

4. A system for controlling the expiratory pressure of a plunger according to claim 3 wherein the disengaging system comprises a central tubular shaft and coaxial with said set screw.

The expiratory pressure control system of a plunger according to any one of the preceding claims further comprising a pressure sensor in the expiratory circuit of said ventilator circuit.

6. The expiratory pressure control system of a plunger according to claim 5 wherein the brake is a solenoid valve, the solenoid valve being controlled electronically following measurements provided by the pressure sensor.

7. The expiratory pressure control system of a plunger according to claim 6 wherein the brake comprises eyelets or shutters or a diaphragm.

The expiratory pressure control system of a plunger according to claim 7 wherein the opening level of the eyelets or shutters or the diaphragm is electronically controlled following measurements provided by the pressure sensor.

9. The expiratory pressure control system of a plunger according to any one of the preceding claims wherein the brake generates at least two discrete levels of positive expiratory pressure.

The expiratory pressure control system of a plunger according to any one of the preceding claims wherein the brake is operative to generate positive expiratory pressure levels among the levels (0 mbar, 2.5 mbar, 5 mbar; , 5 mbar and 10 mbar).

11. Regulator for diving with at least:

a first stage for expanding a high pressure gas so as to obtain a medium pressure gas, and

a second stage for receiving said medium pressure gas and lowering the pressure of said medium pressure gas to supply low pressure gas to a ventilatable plunger, characterized in that the second stage of the expander comprises a system according to any one of the claims 1 to 1 0 to control the expiratory pressure of the diver.

12. A diving rebreather comprising a system for controlling the expiratory pressure of a plunger according to any one of claims 1 to 10.

13. Scuba apparatus comprising a system for controlling the expiratory pressure of a plunger according to any one of claims 1 to 10.