DE19737537C1 - Breathing apparatus with gas container with variable volume for gas feed - Google Patents

Abstract

The changeover valve is formed by a valve piston (11) axially movable in a bore, which has an end surface freely located to the gas container (2) and an end surface freely located to the valve chamber (14). The valve piston is extended by an end pin, which engages in a cutoff manner in a bore leading to the outlet (17). At least one of the end positions of the valve piston is provided with a securing device (5,6,9) which holds it, the holding force of which is such that when a predetermined pressure in the gas container is reached the valve opens to the lung connection.

Description

The invention relates to a ventilator according to the generic term of claim 1.

Such ventilators are widely used and have proven themselves on the whole; they serve for the ventilation of patients at risk of respiratory arrest and to supply anesthetic gas to patients. Lots known devices of this type are complex, pneuma trained table or other power-operated devices and intended for use in hospitals or the like. Simpler Devices serve the civil and military emergency supply or are used in developing countries. equipment However, this type has the following disadvantage that it If the inhalation pressure is low, the gas volume is too high, If the inhalation pressure is high, the gas volume is too low Take a breath. Furthermore, the amount of gas that the Pati ducks per unit of time, often by up to 20% from the setpoint, d. H. the patient contains too much or too little air, oxygen and / or anesthetic gas.

A ventilator of the type mentioned is from the DE-AS 10 64 695 known.

The object of the invention is a structurally particularly simple to create this type of ventilator for every application used or can be adapted to this and that is set up, the patient exactly the predetermined To supply gas throughput.

This object is achieved according to the invention solved by the features specified in claim 1.  

The breathing gas is precisely pre-selected for the gas container throughput, which is technically not difficult can be fulfilled by a gas flow regulator.

This amount of gas is inevitably delivered to the patient where the valve piston by the different pressure conditions is caused to switch; a certain Throttling effect of the connection between the valve chamber and Gas container and the outflow from the valve chamber into the The patient's lungs ensure that the front of the container prevailing pressure not be both ends of the valve piston hits and thus paralyzes it.

It can open the second one to the valve chamber end surface larger than the first, to the gas tank exposed end face. The size ratio of the end surface Chen is broad according to the respective requirements Limits selectable.

The valve piston can also be arranged such that it can move vertically be net, and the second end face exposed to the valve chamber che can be above the first, exposed to the gas tank End surface to be arranged. The weight of the Ven tilkolbens be used to him in the exhalation position hold until there is sufficient pressure in the gas container has built up.

One of the end positions of the Ven  tilkolbens is associated with a locking device holding this. So it is possible to have a very light valve piston to use, so that the use of the invention Ventilator is also possible in an inclined position without that the switching pressures change significantly.

Special embodiments of the invention are in the subclaims Chen specified.

Each end position of the valve piston can have a rest be assigned to the device, and the end position of the Valve piston in which the lung connection with the outlet is associated with a higher locking holding force than the other end position. So is the holding force for each endla can be determined independently.

Preferably two locking devices are provided, de in the end position of the valve piston, in which the lung is connected to the outlet, both are effective and only one is effective in the other end position.

The holding force of the or each locking device could be adjustable so that the switching pressure, which is a switching valve, adjustable in every end position is.

The locking devices can in principle be any forms his; the ineffective rest in the other end position device may have a freewheel.

However, each latching device is preferred by one latch ball formed, which rests on the valve piston and by a to this radial spring is loaded on the outside Acts at the end of an adjusting screw. In the valve piston two circumferential grooves are introduced, one of which is in the end position of the valve piston in which the lung connection with the  Outlet is connected to a locking ball takes. In the second end position there is a latching seat gel in the other circumferential groove, while the other Rastku gel rests on the stem of the valve piston. So is one structurally simple and accordingly reliable detent of the valve piston.

The second one, which is exposed to the valve chamber, is preferred End face of a meme attached to the valve piston bran formed, with the one discharged from the valve chamber opposite side of the membrane arranged a back pressure chamber is through a leak hole with the outside of the Ventilator is connected. That way it is with simple means achieved that the valve piston on small ne pressure differences in the valve chamber and large in Gas container responds. The leakage hole prevents this a sometimes undesirable change in response tens.

However, such a change is sometimes not unheard of wishes; then the leakage hole is particularly preferred shut off by a shut-off or pressure relief valve cash or throttled. It can also leak the leak bore so that it may be from The operator's finger can be covered when it is at is desirable for diagnostic reasons, for example Inflate the patient's lungs.

When used stationary, the gas container is more flexible Breath bag trained to the gas flow regulator one Compressed gas supply is connected. The gas flow regulator ensures a continuous flow of mass into the respiratory tract tel, and its elasticity and size determine the Size of the gas volume enclosed in the breathing bag, the  reaches the trigger pressure of the valve piston, d. H. a larger or more resilient breathing bag becomes a larger one Take up volume before the release pressure is reached, than a smaller or stiffer breathing bag.

For outpatient use, or in developing countries, but can also be used as a self-priming gas container Hand compressible breathing bag to be formed a back open to the outside of the ventilator has a check valve. In this case, the size determines of the breathing bag is the volume of air absorbed during each stroke and the operator squeezing the bag by hand Respiratory person determines the respiratory rate. It is also possible Lich to change the volume by breathing not fully compressed. The squeeze If necessary, the breathing bag can also be powered take over the same facility so that it is possible a salvaged accident patient who is sent to the hand-operated respirator was connected to it ben breathing apparatus in the rescue vehicle powered to beat men, so that the medical personnel perform other tasks can dedicate.

However, the breathing bag, for example, can equally well be replaced with a pressurized gas has conclusion.

A particularly simple and reliable, preferred design of the ventilator according to the invention is that

• - The changeover valve is a housing with a central axis has that assembled transversely to this in two Housing parts is divided,  
• - Between them the membrane with its circumference is tense
• - The first housing part has a continuous central bore has, in which the valve piston is movably guided is
• - to the outer end of the center hole of the gas tanks connected,
• - The inner end of the center hole under the membrane in the counter pressure chamber opens,
• - The second housing part that adjoins the membrane Valve chamber surrounds
• A nozzle is arranged in the center of the valve chamber, the bore of which communicates with the outlet and which faces the valve piston, the end pin facing the nozzle,
• - the end pin for sealing entry into the socket is trained, and
• - At least one gas in each of the two housing parts channel is formed, which are aligned are and of which the one in the valve chamber and the another opens into the path of movement of the valve piston.

The second housing part preferably points to that of a side facing away from the valve chamber, in which has a manometer attached to it with the valve chamber is connected to the pressure prevailing in this demonstrate. Thus, the proper function of the inventions can ventilator according to the invention are effortlessly monitored.

Each ventilator could have multiple, by size and / or extensibility different, interchangeable gas container or breathing bag to allow it to Optimal for every patient and every application  paint to choose breathing bag. The Be are more preferred respirator and all eligible breathing bags in one a common packaging, such as an emergency case.

The object of the invention is set out in the schematic drawing, for example, explained in more detail tert; in this shows:

Fig. 1 is an elevation of the invention Beatmungsgerä tes,

Fig. 2 shows an elevation through the ventilation valve according to the invention, in the exhalation position, and

Fig. 3 is an elevation through the ventilation valve according to the invention as in Fig. 2, however, in the inhalation position.

The same reference numbers are used throughout the figures same elements.

The reference number 2 designates a resiliently stretchable breathing bag, which is interchangeable and is selected and fitted appropriately depending on the operating mode and patient.

As shown, this breathing bag 2 can have a connection to a compressed gas supply, which is indicated here by a gas flow regulator 1 . This gas flow regulator leads to a constant gas flow with adjustable pressure. The gas flow can in turn be composed of several components, each of which can be individually metered, for example from air and oxygen, as shown in the example, from oxygen and anesthetic gas or the like. A device for moistening the gas flow can be connected to the outlet of the gas flow regulator be. The size of the gas flow corresponds to the patient's tidal volume per unit of time, but may slightly exceed this depending on the leakage currents that may occur. This breathing volume is strictly observed; the ventilator only changes the respiratory rate when there is increased resistance in the patient's airways, without reducing this tidal volume or significantly reducing it when leakage occurs.

The empty breathing bag 2 is initially inflated by this gas flow, the pressure and thus the amount of gas inside increasing depending on its elasticity. For patients with a low breathing volume, such as children, a stiffer breathing bag 2 can be selected than for a patient with a normal breathing volume, since the stiffer breathing bag 2 already reaches a release pressure when it contains a smaller amount of gas than a breathing bag 2 for patients with normal tidal volume.

The breathing bag 2 can also be replaced by a known, self-sucking breathing bag if no compressed gas supply is available, such as when used in mountain rescue, in developing countries or the like. In this case, the self-sucking breathing bag 2 has a check valve 3 on, which, as is known, can be designed as a diaphragm valve and prevents air from escaping from the breathing bag 3 unused to the outside. In addition, the connection to the gas flow regulator 1 is missing .

This self-sucking breathing bag 2 is compressed and released again by the person performing the breathing in the rhythm of the breathing frequency; the ventilation pressure can be read on a manometer 18 described in more detail later.

The outlet of the breathing bag 2 opens into the inlet of a breathing valve which has a substantially cylindrical housing which is formed from a lower housing part 7 a and an upper housing part 7 b.

The lower housing part 7 a has a cylindrical Mittelboh tion, in which a valve piston 11 is arranged practically smoothly; Because of the necessary fit for this, which can have a small clearance, a small Lec kage gas flow can take place around the valve piston.

The central bore is extended downwardly over the housing-Un terteil 7a out continuously in a ventilator inlet port 16, which a starting projects and from the housing bottom 7 down on the respiratory bag 2 screws as by In is fixed gas-tight.

The lower housing part 7 a has a flat recess on its upper side. The valve piston 11 protrudes with its upper end portion into this depression from below and has a radially outwardly projecting circumferential flange which a short end pin of the valve piston 11 projects upwards.

On the top of this circumferential flange sits a circular membrane 12 , which is centered and preferably sealingly centered from the end pin of the valve piston 11 and whose circumference is held between the lower housing part 7 a and an upper housing part 7 b. The diameter of the end pin can differ from that of the valve piston 11 and in particular be smaller than this water. The diaphragm 12 can in turn be designed to be resilient so that in the first position (exhalation position) shown in FIGS. 1 and 2 the valve piston 11 is not loaded or is loaded downwards or in the second position shown in FIG. 2 ( Inhalation position) downward.

The membrane 12 is preferably made of rubber or a similar union elastomer.

The membrane 12 limits together with the upper, shallow recess of the lower housing part 7 a a practically closed back pressure chamber, which is connected to the outside of the lower housing part 7 a through a leakage hole 19 in United, the dashed lines in FIGS . 2 and 3 is shown. This leakage hole 19 prevents a Luftpol ster that forms in the back pressure chamber, the movement of the diaphragm 12 obstructs. Insofar as a leakage flow from the ventilation air inlet connector 16 passes past the valve piston 11 into the counter-pressure chamber, this can also escape through the leakage bore 19 without the movement of the membrane 12 being impaired.

On the outside of the leakage bore 19 , a shut-off valve or a pressure-limited shut-off valve can be arranged, which prevents the escape of gas from the back pressure chamber completely or up to an adjustable pressure when the membrane 12 moves upward by an overpressure acting on it or held up who should.

The valve piston 11 has on its inside the middle bore of the lower housing section two superimposed circumferential grooves with an arcuate cross-sectional contour, which extends over an angular range which is below 180 °. In the area of these order grooves, the lower housing part 7 a has two radially and axially offset threaded or fine-thread bores into which a knurled screw 4 or 5 (only indicated) is screwed. On the inner end of each knurled screw 4 , 5 there is a helical compression spring 8 or 6 (only indicated), which is supported with its respective inner end on a locking ball 10 or 9 . The springs 8 , 6 and the locking balls 10 , 9 are arranged as smoothly as possible in the respective bore. The radius of the locking balls 10 , 9 corresponds to the radius of the cross section of the annular grooves in the valve piston. The axial offset of the two locking balls 10 , 9 corresponds to the axial distance between the two ring grooves.

In this fall in in Fig. 1 and 2 shown position, both locking balls 10, 9 into the transverse grooves, while the upper detent ball 10 is incident as shown in Fig. 2 position to the lower transverse groove, while the bottom detent ball 9 of the circumference Valve piston is seated. There must therefore be two Ra to trigger the upward movement of the valve piston, the downward movement only one rest must be overcome.

The two knurled screws 4 , 5 have on their radially outer end a knurled head or other handle and carry a z. B. in the knurled head, a pointer to which a scale can be attached on the outside of the lower housing part, so that by metered, readable on the scale of the respective knurled screw 4 , 5 whose radial distance from the ball and thus the length and thus bias of the associated spring 8 , 6 is adjustable, which this exerts on the associated ball 10 , 9 .

Furthermore, in the lower housing part 7 a forms a gas channel 13, which starts from a section of the central bore, which in the first position shown in FIGS . 1 and 2 is blocked by the valve piston 11 and in the second, in FIG. 2 ge showed location is released, and opens into the top of the Ge housing lower part 7 a. There the Gaska nal 13 continues in the upper housing part 7 b and opens into a valve chamber 14 surrounded by this.

The gas channel 13 may consist of several branches, each of which connects the central bore to the valve chamber 14 , so as to ensure the lowest possible flow resistance.

The upper housing part 7 b is tightly attached to the lower housing part 7 a by pinching the membrane 12 and aligning with the mouths of the gas channel 13 just called ge and continues its cylindrical outer contour upwards. In the top, an upwardly open recess is made, which is bounded at the bottom by a bottom wall. In this recess sits a manometer 18 , the load cell is connected via a drilling through the bottom wall tion with the valve chamber 14 .

This valve chamber 14 is limited upwards from the bottom wall, outwardly from the peripheral wall of the housing upper part 7 b and downwardly from the membrane 12 and has a first radial opening that one continues in the bore outwardly projecting lung stub 15, to which a ventilation tube or the like can be connected.

In the valve chamber 14 is also a starting from the top of the bottom wall, central nozzle is arranged, which has an axial bore into which you tend from below the end pin of the valve piston 11 can enter if this in the second, in fig. 2 shown position is: in the first, shown in Fig. 1 and 2, the end pin is outside the axial bore, which is then then in free flow communication with the Ven tilkammer 14 .

The upper end of the axial bore is connected to a Radialboh tion, which extends outward in a protruding exhalation connector 17 .

The lower end of the axial bore lies clearly below the confluence of the gas channel or the gas channels 13 and still further below the confluence of the lung socket 15 in the valve chamber 14 ; If liquid should accumulate in the valve chamber 14 , such as condensate in a winter outdoor use, it is pressed out of the ventilator by exhalation via the axial bore and exhalation connector 17 before it runs the risk of entering a gas channel 13 or even the lung connector 15 to arrive, presupposes that the ventilator is held in a somewhat correct position, as is also shown in the drawing.

At the exhalation 17 , a pressure relief valve can be connected, which maintains a residual pressure in the valve chamber 14 , in order to prevent the lungs from collapsing completely.

Instead of a leakage bore 19 or in addition to this, piston 11 can also be relieved of pressure in the back pressure chamber by a play between membrane 12 and valve.

At the lung stub 15 , a line can be connected to a throttling point, at which pressure, volume, frequency and throughput (P, V, F, F) are measured and displayed on a monitor (MONT).

The effect of the beat described above device is as follows:

The starting point is the one shown in FIG. 1. Gas flows from the gas flow regulator 1 into the breathing bag 2 and inflates it. The downstream of this ventilation valve is closed because the valve piston 11 closes the mouths of the gas channels 13 in the central bore ver. The gas pressure which forms in the breathing protection bag 2 as it increases in inflation, acts on the lower end face of the valve piston 11 and seeks to move it upward. But it is held by a grip of the two locking balls 10 , 9 in circumferential grooves of the valve piston 11 .

The holding force of these locking balls 10 , 9 depends on the force F of the springs 8 , 6 , which in turn depends on the amount by which the knurled screws 4 , 5 are screwed into the associated Ge threaded bore. These knurled screws are screwed in according to the operating instructions in such a way that when a predetermined maximum pressure is reached, the holding force that is exerted on the valve cylinder 11 via the two locking balls 10 , 9 is overcome.

Now the valve cylinder snaps up and reaches the position shown in FIG. 3. In this position, the detent ball 10 falls into the lower circumferential groove and stops the upward movement of the valve piston 11 . The other locking ball 9 sits on the outer circumference of the valve piston 11 and does not hinder its movement.

An additional stop can also be provided be the further upward movement of the valve piston prevented.

Due to the upward movement, the valve piston 11 has undergone ren, it releases the openings of the gas channels 13 into the central bore; The pressure gas collected in the breathing bag 2 can now flow through the gas channels 13 into the valve chamber 14 and through this into the lungs 15 and into the patient's lungs.

During the upward movement of the valve piston 11 , its top end, the end pin, has also entered the overlying de axial bore and has blocked it, so that no compressed air introduced for ventilation can get into the breathing nozzle 17 . Due to flow losses in the gas channels 13 , the pressure in the Ven tilkammer 14 may be significantly lower than in the breathing bag 2nd

The movement of the membrane 12 , which separates the back pressure chamber from the valve chamber 14 , is unimpeded because the pressure in the back pressure chamber can be compensated for via the leakage bore 19 .

If the breathing bag 2 has emptied, then the pressure in all gas-carrying parts of the breathing valve drops until the holding force, which results from the pressure force of the gas pressure acting from below on the end face of the valve piston 11 from the breathing bag 2 and the holding force Locking ball 10 results, is overcome by the pressure force that the pressure in the valve chamber 14 exerts on the arrangement of the valve piston 11 and the membrane 12 . Then the valve piston 11 jumps back into the position shown in FIGS. 1 and 2, only the Hal tekraft of the upper locking ball 10 must be overcome. By throttling or blocking the leakage bore 19 , the triggering time of the valve piston can be delayed.

The exhalation can now take place through the lung connection 15 , the valve chamber 14 , the released axial bore and the exhalation connection 17 .

When using a self-aspirating breathing bag 2 , its internal pressure is produced by compressing the breathing bag 2 ; in the exhalation phases, the breath bag is released, so that it is soaked again due to its own suspension through the check valve 3 from the ambient air.

It can be seen that, apart from the potential energy of the respiratory gas or the compression of the Atembu tels 2, no additional energy is required to operate the ventilator according to the invention. The gas throughput through the gas flow regulator 1 is always kept constant in compressed gas operation; increases the breathing resistance of the patient, then the pressure in the valve chamber 14 will increase more quickly because now the gas can flow there more slowly, and there will be a switchover faster, ie the respiratory rate increases, but the gas throughput, ie the The amount of gas delivered to patients per unit of time remains constant.

If spontaneous breathing occurs in the patient during the course of ventilation, this is immediately supported by the ventilator shown: if, for example, in the exhaled position of the ventilator ( Fig. 1, 2) the patient draws air spontaneously, the pressure in the valve chamber 14 drops, and the valve immediately switches to the position of FIG. 3, so that the spontaneous inhalation process is supported by additional, phasenglei che ventilation. A complete or partial shutdown of the leakage line supports this process because the pressure then occurring in the back pressure chamber has a pushing effect on the membrane 12 and the flange of the valve piston 11 .

3 begins to exhale men in the valve position of FIG. 3, the pressure in the valve chamber 14 immediately rises, and the valve piston 11 is pressed down so that the exhalation can take place with little resistance. The fact that the membrane 12 is very much larger than the lower end surface of the valve piston 11 ensures that the valve also responds to very small changes in pressure in the valve chamber 14 .

Overall, the following advantages can be achieved with the automatic or manual ventilator according to the invention when ventilating or anesthetizing children and adults:

• 1. The gas flow into the breathing bag 2 takes place with a constant throughput and builds up a pressure there; If this pressure reaches a set value, the valve opens and the amount of gas in the breathing bag 2 empties into the patient's lungs. This value is primarily set using the knurled screw 5. The breathing bag 2 determines the tidal volume (the volume of a single breath).
• 2. This breathing stroke volume is adjustable and depends on the extensibility of the respiratory bag 2 used in each case and on the holding force of the notches, in particular the notch from parts 5 , 6 , 9.
• 3. The throughput of the breathing air through the patient is constant and corresponds to the adjustable throughput of the gas flow regulator 1 , regardless of the respiratory stroke volume set in each case. If the respiratory volume increases, the respiratory rate decreases, and vice versa.
• 4. Changes the flow resistance and the Nachgie lungs, then the gas flow rate (the breath minute volume) still constant; only the respiratory quenz adjusts itself automatically.
• 5. The patient's spontaneous breathing begins in this way on the ventilator valve so that it is Valve switches in a position in which it is the supports spontaneous breathing.
• 6. Since the pressure in the breathing bag 2 increases only gradually after the valve has switched to the position of FIGS. 1 and 2, it is possible to adjust the catches which hold the valve piston 11 in the corresponding position so that ultimately the Inhalation suction for switching the valve into the position of FIG. 3 leads so that this inhalation position is not activated prematurely and thus the hyperventila tion of the patient is prevented.
• 7. The ventilation pressure can be adjusted independently of the breathing air throughput by the catches, in particular by means of the knurled screw 4.
• 8. The breathing bag 2 is exchangeable for a self-sucking breathing bag, which sucks in ambient air after being compressed by hand via a check valve 3 .
• 9. If the self-priming breathing bag 2 is used for manual operation, the catches can be screwed through the knurled screws 4 and 5 to ineffectiveness; when the breathing bag 2 is released and thus during suction, the valve piston 11 is sucked into the lower position ( FIGS. 1 and 2).
• 10. By blocking or throttling the leakage bore, the membrane 12 can be held in its upper position ( Fig. 3) if it should be necessary to inflate the lungs; damage to the patient is not possible since the available breathing volume is limited by the size of the breathing bag 2 .
• 11. The breathing bag 2 can be designed so that it empties quickly and then slowly at first, so that an optimal pressure profile of the breathing gas is achieved.
• 12. By easily replacing the breathing bag 2 , the device can be easily adapted to the patient; For example, children and adults can be ventilated optimally.
• 13. In addition to pure ventilation and anesthesia ventilation, so-called "high-frequency ventilation" can also be carried out by using a stiffer breathing bag 2 .
• 14. The ventilator according to the invention can also be used drove the bellows of an anesthesia machine to this be closed.
• 15. The device according to the invention can also be used only for inspiration; in this case, the gas exhaled by the patient does not pass through the valve chamber 14.

All in the claims, the description and / or the Individual and combination features shown in the drawing are considered essential to the invention.

The scope of the invention not only extends on the features of each claim, but also on their combination.

The invention is not illustrated and described bene embodiment limited. Rather, the ses only an advantageous embodiment of the inven idea.

Reference list

1

Gas flow regulator

2nd

Breathing bag

3rd

check valve

5

Thumbscrew

5

Thumbscrew

6

Feather closed

5

7

a Housing lower part

7

bHousing upper part

8th

Feather closed

4th

9

Locking ball too

5

10th

Locking ball too

4th

11

Valve piston

12th

membrane

13

Gas channel

14

Valve chamber

15

Lung socket

16

Respiratory air inlet connector

17th

Exhalation nozzle

18th

manometer

19th

Leakage hole

Claims (10)

1. ventilator with a gas container ( 2 ) with variable volu men for gas injection, a valve chamber ( 14 ) and a switching valve to the verb, a lung connection ( 15 ) alternately with the gas container ( 2 ) and an outlet ( 17 ) for used breath , The changeover valve being formed by a valve piston ( 11 ) which can move axially in a bore and which has an end surface exposed to the gas container ( 2 ) and an end surface exposed to the valve chamber ( 14 ), characterized in that
that the valve piston is extended by an end pin which is designed to engage in a shut-off manner in a bore leading to the outlet ( 17 ),
that the potential energy of the respiratory gas or the energy resulting from compressing a replaceable breathing bag serving as a gas container ( 2 ) is provided for operating the respirator,
that at least one of the end positions of the valve piston ( 11 ) is associated with a locking device ( 5 , 6 , 9 ), the holding force of which is adjustable so that when a predetermined pressure in the gas container ( 2 ) is reached, the valve for the lung connection ( 15 ) opens,
and that a further latching device ( 4 , 8 , 10 ) is provided, the adjustable holding force of which is dimensioned such that when a predetermined pressure in the valve chamber ( 14 ) is exceeded, the valve piston ( 11 ) into which the latching device ( 5 , 6 , 9 ) defined end position. 2. Ventilator according to claim 1, characterized in that the latching devices ( 4 , 8 , 10 ; 4 , 6 , 9 ) in the axial direction of the Ventilko bens ( 11 ) are arranged axially spaced. 3. Ventilator according to claim 2, characterized in that the end position of the valve piston ( 11 ), in which the lung connection is connected to the outlet, is associated with a higher locking holding force than in the other end position. 4. Ventilator according to one of claims 1 to 3, characterized in that two locking devices ( 4 , 8 , 10 ; 5 , 6 , 9 ) are vorgese hen, of which in the lung connection ( 15 ) with the outlet ( 17 ) connecting end position of the valve piston ( 11 ) both ( 4 , 8 , 10 ; 5 , 6 , 9 ) are effective and in the other end position only one ( 4 , 8 , 10 ) is effective. 5. Ventilator according to one of claims 2 to 4, characterized in that each latching device is formed by a latching ball ( 10 ; 9 ) which rests on the valve piston ( 11 ) and is loaded by a radial spring ( 8 ; 6 ) , on the outer end of which an adjusting screw ( 4 ; 5 ) acts that two circumferential grooves are introduced into the valve piston ( 11 ), one of which in the end position of the valve piston ( 11 ), in which the lung connection ( 15 ) with the outlet ( 17 ) is connected, each a locking ball ( 10 ; 9 ) receives, and that in the second end position, the one locking ball ( 10 ) in the other order sits, while the other locking ball ( 9 ) on the smooth shaft of the valve piston ( 11 ) rests. 6. Ventilator according to one of claims 1 to 5, characterized in that the second to the valve chamber ( 14 ) exposed end surface is formed by a on the valve piston ( 11 ) attached membrane ( 12 ), on which of the valve chamber ( 14th ) Abgee NEN side of the membrane ( 12 ) a back pressure chamber is arranged, which is connected by a lockable or throttled leakage hole ( 19 ) to the outside of the ventilator. 7. Ventilator according to claim 6, characterized in that

• 1. the changeover valve has a housing ( 7 a, 7 b) with a central axis, which is divided transversely to this into two assembled housing parts ( 7 a, 7 b),
• 2. the diaphragm ( 12 ) with its circumference is clamped between them,
• 3. the first housing part ( 7 a) has a continuous central bore in which the valve piston ( 11 ) is movably guided,
• 4. at the outer end ( 16 ) of the central bore of the gas container ( 2 ) is closed,
• 5. the inner end of the central bore opens under the membrane ( 12 ) in the Ge counter-pressure chamber,
• 6. the second housing part ( 7 b) surrounds the valve chamber ( 14 ) adjacent to the membrane ( 12 ),
• 7. in the valve chamber ( 14 ) a nozzle is arranged in the center, the bore of which is connected to the outlet ( 17 ) and which faces the valve piston ( 11 ), the end pin of which faces the nozzle,
• 8. the end pin is designed for sealing entry into the socket, and
• 9. that in each of the two housing parts ( 7 a, 7 b) at least one gas channel ( 13 ) is formed, which are aligned with one another and of which one in the valve chamber ( 14 ) and the other in the path of movement of the valve piston ( 11 ) merges into the center hole.

8. Ventilator according to claim 7, characterized in that the gas container ( 2 ) is connected to a gas flow regulator ( 1 ) of a compressed gas supply. 9. Ventilator according to claim 7 or 8, characterized in that the gas container ( 2 ) has a check valve ( 3 ). 10. Respirator according to one of claims 7 to 9, characterized in that the second housing part ( 7 b) on the side of the Ven tilkammer ( 14 ) has a recess in which a manometer ( 18 ) is arranged, with the valve chamber ( 14 ) is connected to indicate the pressure prevailing in it.