GB2062476A - Artificial respiration apparatus - Google Patents

Abstract

An apparatus for automatic and manual artificial respiration has an artificial respiration bellows (13) in a pressure chamber for automatic artificial respiration and a respiration bag (20) for manual artificial respiration. The apparatus operates either as a "half-closed" system or as a "half-open" system, the changeover from one system to the other being effected by switching a changeover valve (30). During automatic use when operating as a "half-closed" system, the respiratory gas, impelled by the bellows (13), passes through an inhalation branch (43) for inhalation into the lungs (18) and upon exhalation returns via an exhalation valve (22) and the changeover valve (30) to the respiration bellows (13). During manual use when operating as a "half-closed" system, the respiratory gas is passed by pressure on the respiration bag (20) via a bypass line (42) into the lungs (18) and upon exhalation returns via the changeover valve (30) to the respiration bag (20). During both manual and automatic use when operating as a "half-open" system, the respiratory gas flows along the same inhalation path, and, during exhalation, passes via the exhalation valve (22) and the changeover valve (30), now switched over, into a waste gas line (32). The apparatus is used e.g. for anaesthesia. <IMAGE>

Description

SPECIFICATION Artificial respiration apparatus The invention relates to an artificial respiration apparatus.

Anaesthetic artificial respiration systems should be as comprehensive in their application as possible and should enable the known methods of artificial respiration to be carried out using them. They should, furthermore, be able to adapt as quickly as possible to the possibly changing circumstances in the gas and energy supply, and this adaptation should be capable of being made without loss of time and without extensive changeover procedures.

A known artificial respiration apparatus, described in German Offenlegungsschrift No. 2,601,902, for anaesthesia and long-term artificial respiration can operate either as a half-closed system or as an halfopen system. During operation as a half-closed system, respiratory air flows from the pressure chamber of a pneumatically driven diaphragm pump via an inhalation valve to the patient's lungs, and then via an exhalation valve and a diaphragm valve, connected to and driven by the pneumatic pump, and via a C02 absorber and an inlet valve, back to the pressure chamber of the diaphragm pump. Between the CO2 absorber and the inlet valve there is a buffer bag. In this section also, oxygen and anaesthetic gas is continuously introduced. Disposed in the exhalation line between the exhalation valve and the diaphragm valve is a safety valve.A gas deficit valve which connects the pressure chamber to the atmosphere enables the patient to inhale spontaneously and directly if there should be a deficiency of respiratory gas. During operation as a half-closed system, the apparatus may be operated both automatically and by spontaneous respiration of the patient. For operation as a half-open system, the safety valve is opened. The patient may then inhale spontaneously via the gas deficit valve and exhale via the safety valve. This apparatus has the disadvantage of the lack of a facility for manual artificial respiration which in an emergency upon failure of automatic respiration is vital to the life of the patient.

A further known artificial respiration apparatus, more particularly an anaesthetic apparatus, is described in German Offenlegungsschrift No.

2,554,674. This apparatus which operates as a halfclosed system, may operate either in an automatic mode or in a manual mode. By means of a switching mechanism, a changeoverfrom one mode of operation into the other may be made. Apart from the changeover common to both modes, the storage and drive elements for the respiratory gas differ in these two modes. For the automatic mode of operation, bellows moved and controlled by a pneumatic supply device are used and for the manual mode of operation a respiratory bag is used. The respiratory gas for inhalation flows from the storage and drive element via a C02 absorber and an inhalation valve to the patient, and the exhaled respiration gas then flows back via an exhalation valve into the storage and drive element.To replace the amount of respiratory gas used by the patient, fresh gas is continuously supplied to the system in the inhalation branch between the CO, absorber and the inhalation valve. The surplus of respiratory gas thereby arising in the system is removed in the automatic mode of operation via a diaphragm valve controlled so as to be open during exhalation, and in the manual mode of operation via a spring-loaded excess pressure valve. The outlets of the two valves combine into a common waste gas line. The automatic-manual switching mechanism constitutes a complete changeover according to which, by means of an axially displaceable bar, in the set mode of operation, the bellows in the case of the automatic mode and the respiration bag in the case of the manual mode are connected to or cut off from the respiratory circuit.In the manual mode of operation, spontaneous respiration by the patient is possible, the respiration bag acting as a buffer in this case. The possibilities for application of this artificial respiration apparatus are limited becaue operation as a half-open system is impossible. In half-closed automatic operation the quantity of respiratory gas cannot be determined by the bellows since additional fresh gas is continuously supplied to the patient.

According to the present invention, there is provided an artificial respiratory apparatus comprising a bellows device and a respiration bag each connected to an inhalation line forthe supply of respiratory gas to a patient either automatically by the bellows device or manually by the respiration bag; an exhalation line for the return of exhaled respiratory gas from the patient to the bellows device and to the respiration bag; means for closing the exhalation line during the supply of repiratory gas to the patient and for opening the exhalation line during the return of exhaled respiratory gas; and switching means in the exhalation line for allowing the exhaled respiratory gas to be exhausted to the atmosphere rather than being returned to the bellows device and the respiration bag.

In an embodiment of the invention, there is provided an anaesthetic artificial respiration apparatus for automatic and manual artificial respiration when operating as a half-closed system, and including artificial respiration bellows in a pressure chamber for automatic operation and a respiration bag for manual operation, wherein, for automatic artificial respiration when the apparatus operates as a half-closed system, respiratory gas, impelled by the artificial respiration bellows, passes through an inhalation branch for inspiration into the lungs and upon expiration is passed, via an exhalation branch having an expiration valve and a closed-open changeover valve, past the connected respiration bag, which fills back to the respiration bellows; wherein, for manual artificial respiration when the apparatus operates as a half-closed system, the respiratory gas is passed by pressure on the respiration bag via a bypass past the respiration bellows into the lungs and upon expiration passes back via the changeover valve into the respiration bag; and wherein, for automatic and manual artificial respiration when the apparatus operates as a half-open system, the respiratory gas flows on the same inspiration path and is passed during expiration via the expiration valve and the changeover valve, suitably switched, into a waste gas collecting line.

Preferably, the means for closing and opening the exhalation line is a pneumatic valve operable by a control unit during automatic respiration and by the pressure generated in the inflateable bag during manual respiration. The control chamber of the pneumatic valve may be connected to an adjustable device for controlling the post exhalation excess pressure and for controlling the pressure in the event that the patient exhales deeply.

The apparatus preferably includes an inlet valve and inlet line for the supply of ambient atmosphere to the respiration bag via a bacteria filter and a nonreturn valve, and means for opening said inlet valve in the event of failure of supply of fresh respiratory gas to the apparatus.

The apparatus preferably includes pressure measuring means for measuring the-pressure in the inhalation line and means for exposing the pressure measuring means to the ambient atmosphere for calibration.

The apparatus preferably includes an excess valve for enabling excess respiratory gas supplied to the respiration bag to be discharge in a waste line, the excess valve having a lower opening pressure than a valve via which respiratory gas from the respiration bag flows to the inhalation line. In this case, the apparatus may include an adjustable release valve via which the respiration bag is connected to the waste line.

The apparatus preferably includes an adjustable pressure-limiting valve for allowing discharge of excess drive gas for the bellows device.

Fora better understanding of the invention, reference will now be made, by way of example, to the single Figure of the accompanying drawing, showing an apparatus of the invention.

The anaesthetic artificial respiration apparatus shown in the Figure is supplied at input 1 with electrical energy, at input 2 with a drive gas, e.g. compressed air, and at input 3 with a continuously flowing breathable fresh gas, e.g. an anaesthetic gas mixture. A control unit 4 controls according to adjustable values, the inspiration-expiration frequency and also the ratio of the times of the respiratory phases, and includes a changeover switch for changing from an atomatic mode or operation for automatic artificial respiration to a manual mode of operation for manual respiration and spontaneous respiration and vice versa.At outlets 5 to 9 of the control unit 4 the following conditions obtain: to outlet 5, drive gas under pressure is supplied during automatic operation but not during manual operation; to outlet 6, drive gas under pressure is supplied during manual operation but not during automatic operation; to outlet 7, drive gas under pressure is supplied during automatic operation in accordance with the respiration phase but not during manual operation; outlet 8 is connected to outlet 7 during automatic operation (and thus is supplied with drive gas under pressure in accordance with the respiration phase) and is closed during manual operation; and to outlet 9, during both automatic and manual operation, there is supplied drive gas under an adjustable pressure which, during automatic operation and in the event that the patient exhales deeply (e.g. if the patient sighs or groans), is automatica Ily switched to a higher pressure and then switched back again. If the supply of electrical energy to the control unit fails, the outlets 5 to 9 are automatically switched to the manual mode of operation.

The apparatus shown in the drawing operates as a half-closed system or as a half-open system, in each case in automatic mode, manual mode or spontaneous breathing mode, as follows.

Half-closed system Automatic mode In the automatic mode of operation of the apparatus when set up for operation as a half-closed system, the drive gas flows during inhalation from tthe outlet of the control unit 4 via a non-return valve 10 into a pressure chamber 11 whose outlet to the atmosphere is blocked by a pneumatic control valve 12 which is closed by pressure from the outlet 8 of the control unit 4. Located in the pressure chamber 11 are weighted respiration bellows 13 which, during their expansion to an adjustable stop 14, fill with respiratory gas. The respiration bellows 13 are compressed by the drive gas flowing into the pressure chamber 11.Their contents, the volume required for one inhalation by the patient, then pass via an inhalation line 43 (which includes a spring-loaded nonreturn valve 15, an oxygen sensor 16 and a COn absorber 17) into the patient's lungs 18. An in-valve 19 prevents any flow of the contents of the bellows into respiration bag 20. At the same time, the pneumatic control valve 21 is closed by pressure from the outlet 5 and thus bypass line 42, bypassing the non-return valve 15, is closed.The respiratory gas from the bellows 13 is prevented from bypassing the lungs 18 by means of a pneumatic exhalation valve 22 which is closed during inhalation by virtue of the fact that its control member, connectible via a pneumatic control valve 23 and a PEEP (post exhalation excess pressure) and sigh control device 24 to the ambient atmosphere, is activated by the pressure of drive gas flowing to the control member from outlet 8 via a non-return valve 25, which drive gas pressure simultaneously closes the control valve 23.

During inhalation, any pressure peaks which occur are absorbed by an adjustable pressure limiting valve 26 which allows temporary discharge of drive gas into the ambient atmosphere without loss of respiratory gas and without changing the fixed volume of respiratory gas for one inhalation. Fresh respiratory gas is containuously supplied along input 3. This gas inflates the respiration bag 20.

With the changeover of the control unit 4 to the exhalation phase, the control valve 23 opens and allows discharge into the ambient atmosphere ofthe contents of the control chamber of the exhalation valve 22 (except for a residual amount fixed by the PEEP and sigh control device 24). The contents of pressure chamber 11 are similarly discharged by opening of the control valve 12. The respiration bellows 13 expand and fill, via the in-valve 19, with exhaled gas from the lungs 18, mixed with fresh gas from the resporation bag 22 and with directly supplied fresh gas. The exhaled gas thus passed from the lungs 18 via a volume measuring device 28, a non-return valve 29, the exhalation valve 22, a changeover valve 30 and a non-return valve 27 into the respiration bellows 13.The surplus from the overflow of fresh gas flows via an excess valve 31 into a waste gas collecting line 32.

The changeover valve 30 is a 3-way valve and is switched for operation as a half-closed system. The excess valve 31 has a lower opening pressure than the in-valve 19. This enables that the continuously inflowing fresh gas fills the respiration bag 20 and thereafter discharges via the excess valve 31 rather than entering the circuit via the in-valve 19.

In the case of a failure of the fresh gas supply, a return air control valve 33, closed by the fresh gas pressure, opens. The respiration bellows 13 and the respiration bag 20 then fill with air from the ambient atmosphere via a bacteria filter 34, the return air control valve 33 and a non-return valve 35.

To the inhalation branch 43, there is connected via a bactericidal delay line 36 and a solenoid valve 37, a pressure pick-up 38 connected to the control unit 4.

The pick-up 38 passes to the control unit 4 a signal relating to the prevailing artificial respiration pressure. In the event of spontaneous coughs or inhalation difficulties on the part of the patient, the signal switches the control unit 4 to the appropriate respiration phase. The spring-loaded non-return valve 15 ensures that even small impulses on the part of the patient have an effect on the pressure pick-up 38.

Upon control by the control unit 4, the solenoid valve 37 operates every two minutes to cut the connection between pressure pick-up 38 and the delay line 36 and to open to the ambient atmosphere. The zero value then ascertained is taken into account in the control unit 4 as a calibration value.

Haff-closedsystem Manual mode In the manual mode of operation, the control valve 21 and hence the bypass line 42 are opened. Inhalation is initiated by manual pressure on the respiration bag 20. The pressure generated closes servo valve 39. The pressure supplied by outlet 6 then controls, via a non-return valve 40, the valves 22 and 23.

Because of the servo effect of the servo valve 39, a low pressure from the respiration bag 20 is sufficient to close the exhalation valve 22. With further pressure on the respiration bag 20, the gas content thereof flows via the in-valve 19, the control valve 21 lying in the bypass line 42, the oxygen sensor 16 and the CO, absorber 17 into the patient's lungs 18. The non-return valve 27 prevents emptying of the respiration bag 20 via the excess valve 31 (which opens under a low pressure). An adjustable discharge valve 41 prevents the occurrence of excessive pressure in the patient's lungs 18. The respiratory gas then flows away via the waste gas collecting line 32. The con tinuouslyflowing fresh gas supplied from input 3 is discharged during inhalation via the excess valve 31 into the waste gas line 32.

Exhalation is initiated by the discharging of the respiration bag 20. By means of the servo valve 39, the respiration valve 22 is opened. The exhalation gas from the lungs flows via the volume measuring device 28, the non-return valve 29, the exhalation valve 22 and the changeover valve 30, and, together with the inflowing fresh gas, then flows via the non return valve 27 into the respiration bag 20. The surp lus, produced by the inflow of the fresh gas, is dis charged via the excess valve 31. The respiration pressures are determined by the pressure pick-up 38.

Half-Closed System~Spontaneous Breathing Mode In the manual mode of operation, spontaneous breathing is also possible. The circulation of the respiratory gas is effected by the lung power of the patient. This is possible because without pressure on the respiration bag 20 the exhalation valve 22 is permanently set to exhalation.

Half-Open System By turning the changeover valve 30 by 900 in a clockwise direction from the position represented, a changeover to operation as a half-open system is effected. The supply with fresh gas is effected on the paths described from input 3, in automatic, manual and spontaneous breathing modes. The exhaled gas is not passed into the apparatus via the changeover valve 30, however, but is conveyed into the waste gas collecting line 32.

The advantage of the apparatus shown in the drawing is that it is possible in a simple manner, both in terms of apparatus and of the operation, to apply all of the procedures usual in anaesthesia.

Furthermore, if the electrical energy supply fails, artificial respiration may be continued manually simply by pressure on the respiratory bag, without the need of any switching procedure. Loss of time, and thus risk to the patient, as a result of switching procedures do not arise. The respiration bag contains the required respiratory gas mixture at all times because of the continuous inflow of fresh gas into the respiration bag. The path into the bag ensures a good mix to rue with the exhalation gas. The inflow of fresh gas, upstream of the respiration bellows, into the flow of respiratory gas ensures that the respiration volume is specifically determined by the adjustable artificial respiration bellows. The servo control allows the anaesthetist to apply sensitiive manual artificial respiration to the patient. If the supply of fresh gas fails a connection to the ambient atmosphere is automatically made, so that the patient is safeguarded in all circumstances. There is also the safeguard that it is impossible for possibly damaging inhalation pressure peaks to occur, since the inspiration volume is fixed by the volume of respiratory gas supplied by the respiration bellows.

Claims (9)

1. An artificial respiratory apparatus comprising a bellows device and a respiration bag each connected to an inhalation line for the supply of respiratory gas to a patient either automatically by the bellows device or manually by the respiration bag; an exhalation line for the return of exhaled respiratory gas from the patient to the bellows device and to the respiration bag; means for closing the exhalation line during the supply of respiratory gas to the patient and for opening the exhalation line during the return of exhaled respiratory gas; and switching means in the exhalation line for allowing the exhaled repiratory gas to be exhausted to the atmosphere ratherthan being returned to the bellows device and the respiration bag.

2. An apparatus as claimed in claim 1, wherein the means for closing and opening the exhalation line is a pneumatic valve operable by a control unit during automatic respiration and by the pressure generated in the respiration bag during manual respiration.

3. An apparatus as claimed in claim 2, wherein the control chamber of the pneumatic valve is connected to an adjustable device for controlling the post exhalation excess pressure and for controlling the pressure in the event that the patient exhales deeply.

4. An apparatus as claimed in any of claims 1 to 3, including an inlet valve inlet line for the supply of ambient atmosphere to the respiration bag via a bacteria filter and a non-return valve, and means for opening said inlet valve in the event of failure of supply of fresh respiratory gas to the apparatus.

5. An apparatus as claimed in any of claims 1 to 4, including pressure measuring means for measuring the pressure in the inhalation line and means for exposing the pressure measuring means to the ambient atmosphere for calibration.

6. An apparatus as claimed in any of claims 1 to 5, including an excess valve for enabling excess respiratory gas supplied to the respiration bag to be discharged in a waste line, the excess valve having a lower opening pressure than a valve via which respiratory gas from the respiration bag flows to the inhalation line.

7. An apparatus as claimed in claim 6, includinging an adjustable release valve via which the respiration bag is connected to the waste line.

8. An apparatus as claimed in any of claims 1 to 7, including an adjustable pressure-limiting valve for allowing discharge of excess drive gas for the bellows device.

9. An artificial respiration apparatus substantially as hereinbefore described with reference, to, and as shown in, the accompanying drawing.