Static Respirator For Artificial Respiration

Abstract

A static respirator free of movable members having components to operate on demand by simple suction applied by a patient and components for automatic application of a controlled respiration to a patient. The apparatus is provided with components for setting respiratory parameters for individual patients.

Description

BACKGROUND OF THE INVENTION

This invention relates to static respirators and pressure release apparatus operating "one request" and used chiefly in the treatment of lung diseases or respiratory assistance and also for respiratory re-education.

DESCRIPTION OF PRIOR ART

Respirator apparatus are used in hospitals and also at home by the patients themselves at the end of a treatment and re-educational period at the hospital or a sanatorium. These apparatus are generally rather expensive and since they operate mechanically they are also objectionable on account of the maintenance required therefor.

SUMMARY OF THE INVENTION

It is a principal object of the invention to provide an improved static respirator characterized essentially in that it is free of any movable members, so that it is particularly reliable and maintenance-free. On the other hand, the cost of this apparatus is considereably lower than that of similar apparatus having the same adjustment possibilities and range. Finally, its consumption is particularly low (about 2 liter/minute).

The apparatus according to the present invention, in spite of its great simplicity, can operate either at the patient's demand, i.e., by a simple suction effected through the mouthpiece, or automatically, and in this last case the expiration pause time is adjustable. All the other respiratory paramaters are also adjustable at will, so that the respirator according to this invention can be adpated to any type of respiration. Thus, under normal operating conditions the demand effort is adjustable. This constitutes in certain cases an extremely valuable feature. Likewise, the blowing-in pressure and the ventilatory output are adjustable. Finally, a very simple device is provided for retarding the patient's expiration, if necessary, and furthermore it is possible to connect this device to a spirometer for measuring the volume expired or breathed in by the patient.

The apparatus constructed according to the teachings of this invention is actuated in a particularly simple manner by means of two miniature units of known type called "wall-effect amplifiers" comprising a monostable element and a bistable element.

BRIEF DESCRIPTION OF THE DRAWINGS

Various forms of embodiment of the present invention will now be described by way of example with reference to the attached diagrammatic drawings in which:

FIG. 1 is a diagram illustrating the basic principles of the static pneumatic respirator according to the invention;

FIG. 2 is an elevation view of the apparatus of this invention with its accessories;

FIG. 3 is a diagram similar to FIG. 1 illustrating a modified form of embodiment of the apparatus of this invention;

FIG. 4 is a section view on a larger scale a pneumatic relay utilized in the apparatus of FIG. 3, in the position obtaining during the insufflation period, and

FIG. 5 is a section view similar to FIG. 4 but showing the pneumatic relay in the position obtaining during the expiration period.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The apparatus according to this invention, as exemplified in the diagram of FIG. 1, is connected to a source 1 of fluid under pressure such as compressed oxygen air under a pressure of, say, three bars (about 43-45 p.s.i.). Between the apparatus proper and this source 1 a miniature pressure-regulator 2 is interposed which is adapted to deliver at its outlet the fluid under reduced and constant pressure, irrespective of the fluid inlet pressure as delivered by said source, so that this last-named pressure is, therefore, variable from about 2.3 to about 4.5 bars (33 to 65 p.s.i.) without impairing the operation of the apparatus. Thus, the adjustments are made with a view to deliver fluid under a pressure of 3 bars (about 43.5 p.s.i.). This value is selected preferably because it is the one most frequently adopted for gas supply pipe systems.

The outlet of the pressure regulator is fluidally connected on the one hand to an inlet PS of a monostable fluid amplifier 3 through a throttling passage 4 permitting reduction of the pressure at the inlet of the amplifier 3, and on the other hand to an inlet PS of a bistable fluid amplifier 5 through a valve 6 permitting regulation of the insufflation pressure.

The monostable fluid amplifier 3 comprises two asymmetric outlets 0 and 1 corresponding to the inoperative and operative positions, respectively of this amplifier and first and second opposite control inlets C3 and C4 located on the side of outlets 0 and 1, respectively. The principle of operation of this monostable fluid amplifier is well known: when the amplifier is in its normal or inoperative position the gas fed under pressure to the inlet PS emerges normally through the aligned circuit leading to the outlet 0. On the other hand, if a gaseous impulse is fed to the left-hand control inlet C3 or if an aspiration is produced at C4, this impulse or suction will be attended automatically by the deflection of the main gaseous jet towards the outlet 1 and the gaseous current will thus remain directed towards this outlet 1 as long as the control impulse is maintained at C3 or the suction is maintained at C4. If the gaseous impulse fed to the control inlet C3 or the aspiration produced at the control inlet C4 is discontinued, the gaseous jet is restored automatically in the initial circuit so as to flow through the outlet 0.

The outlet 0 of the monostable fluid amplifier 3 is fluidally connected to its control inlet C3 through a valve 7 in order to permit the adjustment of the request effort, as will be explained hereinafter.

The bistable fluid amplifier 5 comprises in addition to the inlet PS two symmetric outlets 0 and 1, and first and second opposed control inlets C3 and C4. Finally, the bistable amplifier 5 comprises two other control members, namely either third and fourth opposed control inlets C1 and C2 (FIG. 1) or first and second opposed vent ports E1 and E2 (FIG. 3), the third inlet C1 or the first vent port E1 being disposed on the side of the first control inlet C3 and of the outlet 0.

Considering the case of the bistable amplifier 5 having symmetrical outlet walls 0 and 1, the main gas jet fed to PS is deflected towards the outlet 0 under the control impulse applied to C4 or C2, or as a consequence of the closing of vent port E2. A control jet or impulse at C3 or C1, or the closing of the other vent port E1 causes the jet to be deflected towards the outlet 1, the jet remaining directed towards this outlet after the removal of the control impulse at C3 or the closing of port E1.

The chief advantage of these two miniature pneumatic units of known type, made mainly of ceramic glass, lies in the fact that they are free of any movable elements. Their functions are based on the so-called "COANDA effect" phenomenon defining the flow of a fluid as tending to adhere to any adjacent wall if the latter forms a sufficiently small angle with respect to the main direction of the fluid jet.

Referring again to FIG. 1, the outlet 0 of the bistable fluid amplifier 5 is fluidally connected to its left-hand control inlet C1 through a circuit comprising, in series, a valve 8 for adjusting the expiratory pause time, a pneumatic switch 9 permitting the setting into operation of the automatic circuit, and a constant-volume vessel 10. The left-hand control inlet C3 of the bistable fluid amplifier 5 is connected directly to the outlet 1 corresponding to the operative condition of the monostable fluid amplifier 3.

The outlet 1 of the bistable fluid amplifier 5 is connected on the one hand to the control inlet of a pneumatic power relay 11 and on the other hand through a pipe line 12 to the interior of a valve-forming bladder 13. The power relay 11 is fluidally connected in series in a circuit extending from the outlet of pressure regulator 2 to a non-return valve 14 connected via a flexible hose 15 to a mouthpiece 16. The aforesaid circuit comprises in succession, between the power relay 11 and valve 14, a valve 17 for adjusting the ventilatory output and a venturi device 18 having its outlet connected via a pipe line 19 to the non-return valve 14.

The non-return valve 14 comprises a venting or expiration orifice or vent hole 20 communicating with the inlet orifice under the control of the aforesaid valve-forming bladder 13, and another orifice 21 constantly communicating with the interior of valve 14 and mouthpiece 16. This orifice 21 is connected in turn through a pipe line 22, having connected thereto a pressure-vacuum meter or gauge 23, to the two control inlets C4 of amplifiers 3 and 5.

Now the operation of the respirator according to this invention will be described in detail with specific reference to the case wherein this operation is obtained "on request," and assuming that the apparatus is supplied with oxygen. To this end, the control handle of switch 9 is set on the "Stop" or "Off" position corresponding to the closed condition of this switch. The request effort and the ventilatory output are adjusted by actuating the valves 6, 7 and 17 the insufflation pressure, respectively.

In the inoperative condition, the gas jets penetrating into the two amplifiers 3 and 5 through the inlets PS are directed towards the outlets 0. The gas jet appearing at the outlet 0 of monostable amplifier 3 is communicated to its inlet C3 through the valve 7, but in this case the pressure prevailing in the control inlet C3 is not sufficient to deflect the gaseous jet towards the outlet of the monostable amplifier 3. When the patient demands gas, he aspirates through the mouthpiece 16 and a vacuum is produced in valve 14 and transmitted via pipe line 22 to the control inlets C4 of amplifiers 3 and 5. Due to the vacuum applied to the right-hand control inlet C4 of the monostable fluid amplifier 3, the action exerted by the gas flow applied to the left-hand control inlet C3 of this amplifier becomes preponderant and sufficient to deflect the main gas jet towards the outlet 1 of amplifier 3, therefore towards the left-hand control inlet C3 of bistable amplifier 5. In this amplifier the main gas jet is then deflected towards the outlet 1. This gas jet is then transmitted through a pipe line 12 to the interior of bladder 13 and the latter is inflated so as to close the expiration orifice 20 of valve 14. On the other hand, the gas jet appearing at the outlet 1 of the bistable amplifier 5 is also transmitted to the power relay 11 so as to open the same. Thus, a gas flow is produced through this relay 11 and then through the output adjustment valve 17 before it penetrates into the venturi device 18. In this last dvice 18, atmospheric air is caused to penetrate through orifice 18a and is carried along by induction so that the venturi device 18 will deliver at its outlet end a mixture comprising fifty per cent air and 50 percent oxygen. This mixture is subsequently introduced into the non-return valve 14, then into the flexible hose or line 15 and through the mouthpiece 16 to the patient's respiratory tract.

When the pre-adjusted or preset insufflation pressure is attained, this pressure is exerted from the patient's respiratory tract to the control inlets C4 of both amplifiers 3 and 5, through the medium of a pipe line 22. This pressure causes the gas jet to be deflected in the bistable amplifier 5 towards its outlet 0. The power relay 11 is then closed and the bladder 13 deflated to free the expiration orifice 20 of valve 14, so that the patient can expire freely.

The insufflation pressure is adjusted by means of valve 6. By more or less opening this valve the supply of gas to the bistable amplifier 5 takes place under a more or less accentuated pressure. The higher this pressure, the higher the pressure required at the control inlet C4 of amplifier 5 in order to switch the gas jet to the outlet 0 of his amplifier.

Now the automatic operation of the respirator according to this invention will be described with reference to the same type of apparatus. To this end, the pneumatic switch 9 is set in its operative or "ON" position, in which this switch is open. Under these conditions, the gas jet issuing from the outlet 0 of the bistable amplifier 5 flows through the pause-time adjustment valve 8 and through switch 9 to fill up the vessel 10. The latter is filled more or less rapidly according as the valve 8 is more or less open. Thus, the vessel 10 introduces a pressure time-lag at the left-hand control inlet C1 to which the vessel 10 is connected.

When this vessel 10 is filled completely with gas, the pressure at the control inlet C1 of the bistable amplifier 5 rises and causes the jet therein to be deflected towards its outlet 1. The power relay 11 is then opened and the bladder 13 re-inflated. As far as the monostable amplifier 3 is concerned the circuit is still directed from the outlet 0 to the control inlet C3 through the valve 7.

FIG. 2 illustrates a typical form of embodiment of the respirator according to this invention. This apparatus comprises a casing provided on its front face with control knobs 6a, 7a, 8a, 9a and 17a for controlling the insufflation pressure adjustment valve 6, the request effort adjustment valve 7, the expiratory pause time adjustment valve 8, the switch 9 controlling the request or automatic operation of the apparatus and finally the ventilating output adjustment valve 17, respectively. The casing of the apparatus further comprises the dial 23 of a pressure and vacuum meter or gauge unit 23. The top wall 24 of the casing contains a carrier handle 25. On the other hand, the apparatus comprises a pipe fitting 26 for the ventilation outlet, which is connected to the outlet of the venturi device 18. Also connected to the fitting 26 is a humidifier 27 having its outlet connected through a flexible hose 19 to the non-return valve 14. The casing further comprises a pipe fitting 28 for connecting the control outlet of bladder 13 to the pipe line connecting the outlet 1 of the bistable amplifier 5 to the power relay 11. This fitting 28 is also connected to the bladder 13 through the medium of pipe line or hose 12 having the same length as the hose 19 to which it is connected.

When the apparatus is operating on a supply of compressed air and oxygen, it is connected to a special compressor supplying clean, oil-free compressed air. On the other hand, a source of oxygen 29 must be provided. This source has an output meter 30 disposed at its outlet, together with a bladder 31. This bladder is then connected through a flexible hose 32 to an aspiration fitting 33 provided on the apparatus and connected to an inlet nozzle 18a of the venturi-device 18.

According to the desired concentration, the air output and correlatively the oxygen output are then adjusted by means of valve 17. At each insufflation, compressed air flowing through the venturi device 18 carries along by induction the oxygen contained in bladder 31 and the patient is thus ventilated with the desired or preset mixture.

Now reference will be made to FIGS. 3, 4 and 5 to describe a modified form of embodiment of the respirator of this invention. In FIG. 3 the component elements similar to or identical with those shown in FIG. 1 are designated by the same reference numerals. This modified construction is advantageous notably in that it permits replacing the fixed vessel 10 intended for introducing a pressure time-lag at the control inlet C1 of the bistable amplifier 5.

In fact, the rate of filling of the vessel 10 is adjusted by means of a micrometric valve and constitutes therefore a difficult operation. Moreover, any modification occurring in the adjustment of valve 17 may have a certain influence on the pause time. The present modification is intended to provide a device permitting a considerably more accurate adjustment of the respiratory pause time period through means requiring lesser preliminary adjustments and also to provide an apparatus in which the pause time is completely independent of the adjustment of the other valves, such as valve 17.

It will be noted that in this case the bistable fluid amplifier 5 comprises, in addition to the two control inlets C3 and C4, a pair of vent orifices E1 and E2 opening into the central portion of the amplifier. These vent holes E1 and E2 are adapted to act as the third and fourth control members of the bistable amplifier 5, a function previously performed by the inlets C1 and C2.

The outlet 0 of the bistable amplifier 5 of FIG. 3 is connected to the vent port E1 through a circuit comprising a pneumatic relay 34 of which an exemplary form of embodiment is illustrated in detail in FIGS. 4 and 5. The vent port E1 of amplifier 5, to which the relay 34 is connected, lies on the same side as the control inlet C3 and outlet 0. The pneumatic relay 34 comprises a body formed with a chamber 35 containing an inflatable bladder 36, and normally connected to the atmosphere via multivarious orifices 37 so that atmospheric pressure is constantly exerted against the outer surface of the inflatable bladder 36 which is thus kept in the position shown in FIG. 4 during the insufflation period. Opening into this chamber 35 is a duct 38 connected to the vent port E1 and adapted to be closed by the bladder 36 when the latter is inflated (see FIG. 5). The interior of the bladder 36 communicates with another duct 39 connected to the pause time adjustment valve 8 and also to a chamber 40 communicating with the atmosphere via an orifice 41 adapted to be closed by a membrane 42. The chamber formed on the opposite side of this membrane 42 communicates via a duct 44 with the outlet 0 of bistable amplifier 5.

On the other hand, duct 22 is connected to the venturi device 18 instead of being connected to the body of the non-return valve 14 as in the case of the apparatus illustrated in FIG. 1. Similarly, a duct 45 connected the "inoperative" outlet 0 of monostable amplifier 3 to the inlet of the expiratory pause time adjustment valve 8. Finally, the basic diagram of FIG. 3 departs from that of FIG. 1 by the last element, namely, the provision of a humidifier 27 inserted in the pneumatic circuit between the venturi device 18 and non-return valve 14.

The apparatus illustrated in FIG. 3 operates as follows:

As in the case of the apparatus shown in FIG. 1, the insufflation pressure is preset by means of vlave 6, the "request" effort being adjusted on the other hand by means of valve 7 and the ventilation output by means of valve 17.

When demanded by the patient, i.e., when the latter breathes in through the mouthpiece 16, a vacuum is produced in the body of non-return valve 14 and also in duct 22. This vacuum is transmitted to the control inlets C4 of both amplifiers 3 and 5. As a consequence of this vacuum or negative pressure, the permanent control jet introduced into the monostable amplifier 3 via its control inlet C3 causes the main jet to be deflected towards the outlet 1 of amplifier 3 and, therefore, towards the control inlet C3 of the bistable amplifier 5. Then, the main gas jet issuing from this bistable amplifier 5 is deflected towards the outlet 1 to determine on the one hand the opening of the power relay 11 and on the other hand the inflation of the bladder contained in non-return valve 14. The gas issuing from the power relay 11 is directed on the one hand towards the atomizer of humidifier 27 and on the other hand through the valve 17 and then through the venturi device 18 in which its volume is doubled by the introduction of fifty per cent of atmospheric air. Then the gas flows through valve 14, the flexible hose 15 and mouthpiece 16 to the patient's respiratory tract.

When the insufflation pressure transmitted via duct 22 to the control inlets C4 of both amplifiers 3 and 5 exceeds the supply pressure of the bistable amplifier 5 as preset by means of vlave 6, it causes the main jet to be deflected in the bistable amplifier 5 from outlet 1 to the other outlet 0, thus closing the power relay 11 and deflating the bladder 13 in valve 14. Under these conditions, the expiration orifice of this valve is free, as in the case of the apparatus illustrated in FIG. 1.

The automatic operation of the respirator illustrated in FIG. 3 will now be described in detail. To obtain the automatic operation of this apparatus the patient just opens the valve 8, more or less, according as it is desired to obtain a more or less extended expiratory pause time period. During the insufflation period, no pressure appears at the outlet 0 of the bistable amplifier 5 and the membrane 42 of the pneumatic relay 34 is unseated as shown in FIG. 4, so that orifice 41 is free. Under these conditions, the gas jet appearing at the outlet 0 of the monostable amplifier 3 is transmitted through valve 8 (now open) to the inlet duct 39 of the pneumatic relay 34. Since the orifice 41 is not closed by the membrane 42, the gas can escape to the atmosphere through this orifice 41 and chamber 40. The bladder 36 remains inflated. At the end of the insufflation period, due to the pressure prevailing in duct 22, the main gas jet in the bistable amplifier 5 appears at the outlet 0 thereof, whereby a pressure is transmitted via a duct 44 to a chamber 43. As a consequence, this pressure causes the membrane 42 to engage its seat, i.e., orifice 41. In this case, gas under pressure introduced through the duct 39 causes the bladder 36 to be inflated and thus close the orifice of the duct 38 connected to vent port E1 (FIG. 5). As a consequence of the closing of the vent port E1 the main jet in the bistable amplifier 5 is deflected towards the outlet 1 to begin another insufflation period. Then the pressure at the outlet 0 of the same bistable amplifier 5 is expanded and the bladder 36 is deflated due to the atmospheric pressure prevailing in chamber 35 and acting upon the outer surface of the bladder 36. The latter thus resumes the condition illustrated in FIG. 4 but the main jet within the bistable amplifier 5 remains deflected towards the outlet 1 thereof, notwithstanding the fact that the communication between the vent port E1 and the external atmosphere has been restored as a consequence of the basic principle of operation of this bistable amplifier 5.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and scope of the invention.

Claims

What I claim and desire to secure by letters patent is:

1. Static respirator for artificial respiration disposed in operation between a mouthpiece and a source of gas under pressure comprising: a monostable fluid amplifier having an inlet, two asymmetric outlets corresponding to inoperative and operative conditions of the amplifier, respectively, and first and second opposite control inlets disposed on the side of said outlets, respectively; a bistable fluid amplifier having an inlet, two symmetric outlets corresponding to the inoperative and operative conditions of the amplifier, respectively, and first and second opposite control inlets disposed on the side of said last-named outlets respectively, said amplifiers being both so disposed that their inlets are connectable in use to a source of gas under pressure and each operable to develop a main gas jet and deliver same from one of its outlets; means fluidally connecting one outlet of said monostable amplifier to the first control inlet of the same amplifier to form a control jet which, by interaction with the main jet, tends to deflect said main jet towards the other outlet of said monostable amplifier which corresponds to the operative condition thereof; means fluidally connecting said other outlet of said monostable amplifier to the first control inlet of said bistable amplifier; means connected to one outelt of said bistable amplifier for receiving therefrom the main jet and developing a control jet and applying same to said bistable amplifier after a predetermined time delay to deflect the main jet to the other outlet of said bistable amplifier; a pause time-adjustment valve connected to said bistable amplifier and cooperative with said last-mentioned means for adjusting the duration of said time delay; a non-return valve fluidally connected to the mouthpiece and having means therein defining an expiration orifice vented to the atmosphere; an inflatable bladder effective when inflated to seal said orifice; a fluid circuit comprising, in succession, a pneumatic power relay fluidally connected to said source of gas and having a control inlet, another valve for controlling the gas flow, and a venturi device having its outlet connected through a duct to said non-return valve; means fluidally connecting said other outlet of said bistable amplifier to both said control inlet of said pneumatic power relay and to the interior of said inflatable bladder; means fluidally interconnecting the two second control inlets of said amplifiers and providing direct communication between same and one of said venturi device and said non-return valve; and another valve for adjusting the demand effort exerted by a patient using the respirator and inserted in said means fluidally connecting said one outlet of said monostable amplifier to said first control inlet of the same amplifier, and wherein said means for developing a control jet comprises a control circuit having fluidally connected in series said pause time-adjustment valve, a pneumatic ON/OFF switch for controlling the automatic operation of the circuit and a constant-volume vessel.

2. A static respirator as set forth in claim 1 including a pressure regulator; and means connecting said inlet of said monostable amplifier to the outlet of said pressure regulator through a throttle passage permitting reducing the pressure at the inlet of said monostable amplifier.

3. A static respirator as set forth in claim 2 including a valve connecting said inlet of said monostable amplifier to the outlet of said pressure regulator for adjusting the insufflation pressure.

4. A static respirator as set forth in claim 3, wherein said venturi device comprises an atmospheric air intake, the atmospheric air being carried along by induction in order to provide at the outlet end of said venturi device a mixture comprising equal volumetric amounts of air and oxygen.

5. Static respirator for artificial respiration disposed in operation between a mouthpiece and a source of gas under pressure comprising: a monostable fluid amplifier having an inlet, two asymmetric outlets corresponding to inoperative and operative conditions of the amplifier, respectively, and first and second opposite control inlets disposed on the side of said outlets, respectively; a bistable fluid amplifier having an inlet, two symmetric outlets corresponding to the inoperative and operative conditions of the amplifier, respectively, and first and second opposite control inlets disposed on the side of said last-named outlets respectively, said amplifiers being both so disposed that their inlets are connectable in use to a source of gas under pressure and each operable to develop a main gas jet and deliver same from one of its outlets; means fluidally connecting one outlet of said monostable amplifier to the first control inlet of the same amplifier to form a control jet which, by interaction with the main jet, tends to deflect said main jet towards the other outlet of said monostable amplifier which corresponds to the operative condition thereof; means fluidally connecting said other outlet of said monostable amplifier to the first control inlet of said bistable amplifier; means connected to one outlet of said bistable amplifier for receiving therefrom the main jet and developing a control jet and applying same to said bistable amplifier after a predetermined time delay to deflect the main jet to the other outlet of said bistable amplifier; a pause time-adjustment valve connected to said bistable amplifier and cooperative with said last-mentioned means for adjusting the duration of said time delay; a non-return valve fluidally connected to the mouthpiece and having means therein defining an expiration orifice vented to the atmosphere; an inflatable bladder effective when inflated to seal said orifice; a fluid circuit comprising, in succession, a pneumatic power relay fluidally connected to said source of gas and having a control inlet, another valve for controlling the gas flow, and a venturi device having its outlet connected through a duct to said non-return valve; means fluidally connecting said other outlet of said bistable amplifier to both said control inlet of said pneumatic power relay and to the interior of said inflatable bladder; means fluidally interconnecting the two second control inlets of said amplifiers and providing direct communication between same and one of said venturi device and said non-return valve; and another valve for adjusting the demand effort exerted by a patient using the respirator and inserted in said means fluidally connecting said one outlet of said monostable amplifier to said first control inlet of the same amplifier, and wherein said means for developing a control jet comprises a pneumatic relay connected to the outlet of said pause time-adjustment valve, and a duct connecting the inlet of said last-named valve to said one outlet of said monostable amplifier.

6. A static respirator as set forth in claim 5, wherein said pneumatic relay comprises a body defining a chamber, said chamber enclosing an inflated valve-forming bladder and communicating normally through a plurality of holes with the surrounding atmosphere, a duct connected to said vent port opening into said chamber and closed by the valve-forming bladder when the latter is inflated, the interior of said bladder communicating with said pause time-adjustment valve and with another chamber connecting said bladder interior to the surrounding atmosphere through an orifice adapted to be closed by one face of a flexible membrane, the other face of said membrane being disposed in front of another chamber communicating via a duct with said one outlet of said bistable amplifier.

7. A static respirator as set forth in claim 6, including a pressure regulator; and means connecting said inlet of said monostable amplifier to the outlet of said pressure regulator through a throttle passage permitting reducing the pressure at the inlet of said monostable amplifier.

8. A static respirator as set forth in claim 7, including a valve connecting said inlet of said monostable amplifier to the outlet of said pressure regulator for adjusting the insufflation pressure.

9. A static respirator as set forth in claim 8, wherein said venturi device comprises an atmospheric air intake, the atmospheric air being carried along by induction in order to provide at the outlet end of said venturi device a mixture comprising equal volumetric amounts of air and oxygen.

10. A static respirator as set forth in claim 9, including a fitting provided for the ventilation output, said fitting being connected to the outlet end of said venturi device and comprising a branch pipe incorporating a humidifier having its outlet connected to said non-return valve and the outlet of said venturi device to said non-return valve.

11. A static respirator as set forth in claim 10, wherein said respirator comprises a casing having on a front face control means associated with said insufflation pressure adjustment valve, said pause time adjustment valve, said demand effort adjustment valve and said ventilatory output adjustment valve, respectively, said casing further comprising a pressure-vacuum gauge connected to the said amplifiers, to said venturi device, and said non-return valve, and a carrier handle disposed at the top of said casing.