FR2459053A1 - RESPIRATOR - Google Patents

Abstract

RESPIRATOR OF THE TYPE COMPRISING A CHAMBER 3 OF BREATHING GAS WITH FLEXIBLE WALLS AND VARIABLE VOLUME, SURROUNDED BY A RIGID CHAMBER 4 OF CONTROL GAS. THE BREATHING GAS CHAMBER IS CONNECTED TO A SOURCE 6 OF BREATHING GAS WITH A VIEW TO SEND IT THROUGH AN INSPIRATION DUCT 9 AND A PIPE 10 INTO A PATIENT'S RESPIRATORY TRACT. THE CONTROL GAS CHAMBER 4 IS CONNECTED TO A DEVICE 13-15, 16-18 WHICH SENDS AIR TO THE CONTROL GAS CHAMBER 4 SO THAT THE BREATHING GASES THAT ARE COLLECTED ARE SENT TO THE PATIENT. THE AIR INTAKE IN THE CONTROL GAS CHAMBER 4 IS CONTROLLED BY A CENTRAL CONTROL UNIT 8 WHICH FORMS A CONTROL SIGNAL FOR CONTROL MEANS 15, 18 ELECTRICALLY CONTROLLED CLEAN TO CONTROL THE AIR SUPPLY OF THE CONTROL GAS CHAMBER 4, AND THEREFORE THE PRESSURE IN THE PATIENT'S RESPIRATORY TRACT.

Description

The present invention relates to a respirator or ventilator

of lungs, of the type comprising a breathing gas chamber

  carrying at least partially flexible walls and a variable volume and which is enclosed in a control gas chamber provided with rigid walls, the breathing gas chamber being

connected by a supply line to a source of breathing gas

  ration and being intended to receive and collect the breathing gases

ration by increasing volume, and being able to be connected to the res-

  a patient's respiratory tract by an inspiration line, while the control gas chamber is connected to air supply means making it possible to compress the breathing gas chamber and entrain the breathing gases collected at the inside of it

  to the patient via the inspiration line, this

the pick being provided with a check valve which allows gases to pass only towards the patient, the apparatus comprising an exhalation pipe which can be connected to the patient's airways

  and in which is mounted an expiration valve opening

  during the expiration phase of the patient's respiratory cycle and

  allowing gases to pass only from the patient.

We know various and varied embodiments of ventilation

lung readers of this general type belonging to the prior art.

  Examples of known lung ventilators of the type mentioned include

take the ER300 and ECS 2000 respiratory systems sold by Engs-

  trëm Medical AB, and the respiratory system described in the patent

Swedish 388.127.

  A problem common to all lung ventilators is

moved by the very large number of breathing modes of treatment

different roofs that current doctors want to have at their disposal

sition, as well as the desire to be able to modify the various parameters of the treatment within wide limits. Thus, one may wish to be able to subject the patient to controlled mechanical ventilation (CMV), that is to say continuous mechanical or forced ventilation of the patient, with a variable inspiration frequency, a variable relationship between the duration of the phase of inspiration and expiration phase, a variable flow volume, and if possible a variable pressure curve in the airways (hereinafter referred to as

the expression: respiratory tract) of the patient during the

piracy. You may also wish to subject the patient to

VMC with variable positive terminal expiratory pressure

(PETP), the pressure in the airways of the lungs of the pati-

  ent being maintained at the end of the expiration phase at a su-

  lower than atmospheric pressure instead of returning to zero. Another form of respiratory treatment that doctors would like to have is forced and intermittent ventilation

(PFD) during which the patient spontaneously aspirates through the ventila-

lung regulator a predetermined and precisely controlled amount of breathing gas, but to which is occasionally sent

  a forced inspiration of given and regulated volume of ebb and flow

  ble at a given frequency, predetermined and adjustable (shape in which

  it will be referred to below by the expression of forced breathing).

  We often wish to subject a patient to the PFD process with a

Continuous Positive Airway Zion (CPAP) while breathing

spontaneously, that is to say with an overpressure of the respiratory tract

  continuous, predetermined and adjustable rakes to facilitate breathing

spontaneous ration at this pressure level. It is also desirable, in a breathing process of this type, that the shape of the pressure and the shape of the current passing through the patient's airways

  have a predetermined given profile during each forced breath.

In addition, it is naturally desirable to have total control over the volumes of gas inhaled by the patient during spontaneous breathing. Another type of respiratory treatment consists of intermittent ventilation on demand (VID) in which the patient is forced to be subjected to a forced breathing volume flow and

  adjustable and predetermined backflow and a current and pressure profile

  adjustable and predetermined time each time the patient himself tries to breathe, that is to say when the patient himself determines the start of forced breathing and establishes the frequency of the

breathing. It is often desirable, even with this type of milking

breathing, that breathing takes place at a positive pressure

tive and continuous in the respiratory tract (PPCV) predetermined.

  It is desirable that all respiratory treatments will

mentioned above, and other processing methods not mentioned-

  born, can be realized, with their different parameters varying

by using a single lung ventilator, or at least lung ventilators whose essential components

are constructed in the same way, but are supplemented or modified

  relied upon during their manufacture with various different components and

  different control functions, so that they can

come to various types of respiratory treatments. This would simplify

  the overall manufacturing of these lung ventilators and the

  would be less expensive to produce, which would reduce their cost. In addition, the lung ventilator equipment would be easier to handle and maintain in a hospital because all the equipment would have

  at least the same basic design.

  It is also desirable that a lung ventilator be

of the simplest possible mechanical design, because this simplifies

  would highly trust manufacturing, thereby making it less expensive,

  and would further increase the reliability and efficiency of the device.

  It would also be very advantageous if the lung ventilator is constructed so that it can function in various forms

  mentioned and with the possibilities of variations desired in function

tion of different parameters by constructing or programming an appropriate central electronic control unit, since this control unit can be produced relatively inexpensively and with a high degree of reliability thanks to current technologies. This

  control unit can also be easily changed or reprogrammed

  even for the various desired forms of operation of the lung ventilator, and this for moderate sums. This electronic control unit requires only a small space and is relatively light, which is an advantage when considering that current lung ventilators must be as small and light as possible since it is often necessary to be able to move these fans

from one location to another.

Accordingly, the object of the present invention is to provide

  rer an improved lung ventilator of the type described in the intro

  duction and satisfying the requirements and desiderata which have just been mentioned. To this end, it is proposed that in a lung ventilator of the type indicated, the device intended for supplying air to the

  control gas chamber includes control means with

  electric command to modify the effective air supply, and therefore the pressure, of the control gas chamber as a function of a control signal which is applied to them, and that a control unit constituted is provided to generate a command signal of predetermined shape during each forced breath, and to send

  this signal to said regulation means.

By providing the means for supplying air to the control gas chamber with a lung ventilator according to the invention with electrically controlled regulation means capable of modifying the effective air intake in the control gas chamber , and therefore the pressure generated in this chamber, as a function of an electrical signal which is applied to them, we obtain the possibility of determining the pressure prevailing in the control gas chamber, of varying it, of controlling it and / or to adjust it, and therefore that prevailing in the breathing gas chamber, depending on what is desired, during the different phases of a respiratory treatment, thus bringing a high degree of flexibility compared to the type of respiratory treatment applied and the pace of treatment. It has been found that such an air supply can be obtained which can be controlled or regulated in the gas chamber of

relatively simple control when the supply device

air intake includes an ejector mounted between the control gas chamber and the surrounding atmosphere, and includes a control nozzle

  connected to a source of compressed air via a valve -

  regulating the electrically controlled current and forming said regulating means, or when this device comprises a fan arranged between the surrounding atmosphere and the chamber, and an outlet putting this chamber in communication with the surrounding atmosphere,

this output including a variable throttle device with

electric control forming said regulation means. This last dis-

positive has this important advantage that there is no need for a pressurized air source, so a lung ventilator constructed in this way can also

  be used in places where there is no compressed air network

  or where the air supplied by an existing air network does not

not a quality in terms of its purity and dryness allows

  both to a lung ventilator to be able to be connected to the network.

A number of embodiments of the invention will now be described, given by way of examples and with reference to the appended schematic drawings in which: FIG. 1 is a schematic view showing by way of example

  the construction of a lung ventilator according to the invention, and

taking an embodiment of an air supply device for the control gas chamber and for controlling the pressure prevailing in this chamber; and FIG. 2 is a partial view of a lung ventilator according to the invention provided with another device for supplying air to the gas chamber for controlling and controlling the prevailing pressure

in this room.

The lung ventilator shown in FIG. 1 comprises,

in a manner known per se, a rigid tank 1 divided into a chamber

  bre of breathing gas 3 and a control gas chamber 4 by means of a diaphragm or a flexible membrane 2 movable between the two main and opposite walls of the reservoir. The breathing gas chamber is connected to a source 6 of breathing gas by a pipe 5. The source 6 is only shown diagrammatically and can

be of any suitable type of construction. The gas source

piration 6 is designed to supply breathing gases of compound

  desired or having any other desired properties, in particular

  which concerns for example their temperature and the degree of humidity.

The source of breathing gas is suitably designed to provide a constant stream of breathing gas which can be set in advance to a desired value. The supply line 5 may include a shut-off valve 7 kept open or closed in a controlled manner by a central control unit 8. The chamber

  of breathing gas 3 is also connected by an

  ration 9 to a pipe 10 which puts it in communication with the res-

piratory of the patient, in an appropriate manner known per se.

  The inspiration line 9 comprises, in a conventional manner, a stop valve 11 which allows gases to pass only in the direction of the patient, and it can also comprise, according to the invention, a

  flow meter 12 which detects the passage of the breathing gases which

come through line 9 to the patient and which sends a measurement signal

re corresponding to the control unit 8. The flow meter 12 can be of any suitable model and advantageously comprise means

throttle valves arranged in line 9 and a pressure transducer

  differential pressure detecting the pressure drop in the means

  throttling, this drop in pressure being proportional to the cost

  gaseous rant, in a well known manner.

  The control gas chamber 4 is connected to a supply device.

air ment which sends the air into the room so as to increase

  ter the volume of this chamber and / or generate a desired pressure inside thereof so as to compress the breathing gas chamber and the breathing gases which are collected therein to send them passing through the inspiration 9 to the pipe 10 and thereby to the patient's airways, and also in such a way that a desired pressure corresponding to the pressure prevailing in the control gas chamber 4 is obtained in the breathing gas chamber 3 In the embodiment of the invention shown in FIG. 1, the air supply device comprises a

ejector 13 comprising an ejector tube 13a communicating with the atmos-

surrounding sphere, and a control nozzle 13b connected to a source of compressed air 14 by means of an electrically controlled current control valve 15 comprising throttling means

or constriction that can be changed from one to-

fully closed to a fully open position according to the amplitude of the electrical control signal applied to it, so that

the drive current passing through the nozzle 13b of the ejector can-

to have changed. The compressed air source 14 is only shown

  schematically and normally includes a fixed distribution network

  tion of air present at the site where the lung ventilator is used

  read, this network being connected to the control valve 15 via the

  medium of filtering and pressure regulation devices

  dealers. The regulating valve 15 is controlled by the central control unit 8. The stream of pressurized air coming from the control nozzle 13b of the ejector, which current can be modified by means of the valve 15, carries with it the air from the surrounding atmosphere passing through the ejector tube 13a, which amplifies the current and which sends a greater air flow in the control gas chamber, so that this chamber can be expanded and that the breathing gas chamber 3 can be compressed to a corresponding degree, which passes the breathing gases through line 9 to the airways of the patient connected to the ventilator. It will be understood that the pressure prevailing in the breathing gas chamber 3 coincides with the pressure prevailing in the chamber

  control gas 4 due to the fact that the flexible diaphragm 2 can

  place substantially freely without developing any force. The resulting current from the ejector 13 which reaches the control gas chamber 4 depends on two factors: namely the current from the control nozzle 13b, which current is determined

  by adjusting the regulating valve 15, and the back pressure

gaining in the control gas chamber 4. The higher the pressure prevailing in the control gas chamber 4, the lower the total flow coming from the ejector] 3 is low for a given flow coming from the control nozzle 13b, c of a given control signal

  sent to the control valve 15. When a certain pressure

gene in chamber 4, the so-called stagnation pressure of the ejector, there is no resulting current coming from the ejector and arriving in chamber 4; all the kinetic energy of the compressed air stream and coming from the nozzle 13b of the ejector is consumed by

  the formation and maintenance of the stagnation pressure in the cham-

  bre 4. The greater the flow of compressed air from the control nozzle

  13 of the ejector is important, that is to say more the regulating valve

lation 15 is strongly open, the higher the stagnation pressure

important. This feature of the ejector device is used

  sée, according to the invention, to generate the desired pressure and current profiles of the breathing gases sent to the patient. When the regulating valve 15 is completely closed and when the flow of compressed air sent to the control nozzle 13b of the ejector is thus interrupted, the chamber 4 is put into communication with the surrounding atmosphere by the tube 13a of the ejector, so that the pressure in the chamber 4 becomes equal to atmospheric pressure. Under certain conditions, the ventilation capacity passing through the tube 13a of the ejector may however be too low, and this is why an additional vent valve 26 can be provided. This vent valve is kept closed by the pressure supply sent to the control nozzle 13b of the ejector, and therefore this valve opens automatically when the control valve 15 is closed

and when the ejector is stopped.

  FIG. 2 represents another possible and advantageous embodiment of an air supply device for controlling and regulating the air supply to the control gas chamber 4. FIG. 2 represents only a part of the lung ventilator which is of most interest as far as it is concerned, namely the rigid reservoir 1 divided into the breathing gas chamber 3 and into the breathing chamber

control gas 4 by means of the diaphragm 2. The gas chamber of res-

  piration 3 is connected to the supply line 5 and to the inspiration line 9 in the manner described above. The air supply device which brings the air to the control gas chamber 4 to increase its volume and / or to generate the desired pressure at

the interior thereof, includes, in this embodiment of the in-

vention, a blower 16 intended to operate continuously and arranged so as to blow air from the surrounding atmosphere into the control gas chamber 4, this chamber being provided with

an outlet 17 communicating with the surrounding atmosphere and incorporating

rant a variable throttle device 18 controlled by an electrical control signal from the control unit 8. The controllable and variable throttle device 18 is arranged so

that when fully open it has a pass-through surface

wise flow whose size is such that there is no overpressure

in the control gas chamber 4 vis-à-vis the surrounding atmosphere

  humorous. The more the throttling device 18 is closed under the action of the electrical signal applied to it, the more the pressure generated and blocked in the control gas chamber 4 under the influence of the

  air current caused by blower 16 and reaching the chamber

bre 4 is high. This device presents compared to that represented

tee in Figure 1 the advantage that it is not necessary to have a compressed air network or any other form of source

  compressed air, which is an important advantage in many

breux case.

  The lung ventilator shown in FIG. 1 also includes a pressure comparator 19 of suitable design, connected to the control gas chamber 4 and to the breathing gas chamber 3, and is adjusted to compare the pressure prevailing in these two chambers and to send a signal to the control unit 8 when the pressure in chamber 4 tends to exceed the pressure prevailing in chamber 3. This increase in pressure occurs when the

breathing gas chamber 3 is completely empty and when the ejector

  tor 13 continues to send air into the control gas chamber 4. The lung ventilator according to the invention also comprises a pressure transducer 20 connected to the inspiration line 9 and which detects the pressure prevailing in this line , and therefore also in the hose 10 and the patient's airways, and

sends a measurement signal corresponding to the control unit 8.

Finally, the lung ventilator shown comprises an exhalation pipe 21 connected to the pipe 10 and comprising an exhalation valve 22 in the form of a pressure-controlled check valve, this valve allowing gases to flow only in

  a direction from the patient and opening only when the pressure

  reion prevailing in the exhalation line 21 and the pipe 10, and therefore also in the patient's respiratory tract, exceeds a control pressure applied to it and which is obtained by a control pressure line 23 from the room of

  breathing gas 3. The control pressure of the exhalation valve

  tion 22 thus coincides with the pressure prevailing at this time in the breathing gas chamber 3. It is advantageous that the control line 23 comprises a shut-off valve 24 controlled by the

control unit 8. Normally, the gases exhaled by the ex-

piration 22 pass to means (not shown) which measure the

volume of gas exhaled.

If the lung ventilator shown in Figure 1 is to be used for continuous mechanical or forced ventilation (VMC) treatment, the valve 7 located on the supply line 5

  of the breathing gas chamber 3 is kept constantly open

te, or else it is left out. In addition, the flow meter 12 mounted on the inspiration line 9 can also be omitted, as can

also, in the case of the simplest form of ventilation

  ple, the pressure transducer 20 and the shut-off valve 24 mon-

  tees on line 23 for pressure and control of the ex-

piration 22. The source 6 of breathing gas is adjusted to provide

  a current corresponding to the average volume of breathing gas at approx.

  yer to the patient per unit of time. This stream of breathing gas constantly flows into the breathing gas chamber 3. The unit

  control valve 8 is designed and adapted to control the control valve

  lation 15 periodically at a desired frequency which coincides with the desired respiration rate. During each inspiration phase, the control unit 8 sends to the control valve

  a control signal of predetermined shape, which causes the ejection

tor 13 to send air into the control gas chamber 4, the volume of which is therefore increased so as to compress the gas chamber

  3 and to force the amount of breathing gas to collect

  wheat in this room during the expiration phase of the cycle of

  previous breathing to the patient's airways in step-

  health through line 9 and hose 10. This continues until the breathing gas chamber 3 is completely empty, this state of the chamber being detected by the pressure comparator 19 in the manner previously mentioned and sent by a signal corresponding to the unit

  8 which, in the simplest embodiment of the fan,

lator, thereby interrupts the control signal sent to the valve

  regulator 15 so as to close this valve. This brings the eject-

  tor 13 to stop and as a result the pressure in the

control gas chamber 4 quickly drops to atmospheric pressure

  risk. Thus the pressure prevailing in the breathing gas chamber 3 is also equal to atmospheric pressure and the breathing gases

  ration from source 6 again begin to fill the chan-

  bre 3. At this time, the inspiration phase is also interrupted

  and the patient can exhale through the exhalation line 21 and the

  exhalation valve 22, the closing pressure of which is reduced to atmospheric pressure due to the decrease in pressure in the

bedroom 3.

The profile of the current and pressure of the supply of breathing gas sent to the patient's airways during the inspiration phase can be determined by means of the shape and amplitude of the control signal generated by the unit. 8 and sent by the latter to the regulating valve 15 during the inspiration phase. If the control signal is such that it determines a relatively weak current coming from the ejector 13 towards the chamber 4, and therefore a low stagnation pressure in this chamber, the current of breathing gas coming from the chamber 3 and reaching the patient's airway drops as the pressure in the airway increases. If on the other hand the control valve 15 receives a control signal determining a

  high current in the ejector 13, and therefore a stag-

high nation in chamber 4, the fall in the breathing gas stream

  ration from 4th chamber 3 and reaching the patient's respiratory tract is also, considerably lower, or only

very reduced as the pressure in the airways rises

roofs. The control valve 15 can also be supplied with a control signal which increases linearly and determines a continuously increasing current between the ejector and the chamber 4. In this case, the breathing gases flow from the chamber 3 to the patient's airway under linearly increasing pressure

  in said respiratory tract. The rate at which the increase

The pressure takes place, that is to say the inclination of the pressure ramp, depends on the resistance and elasticity of the patient's lungs. These different current and pressure profiles intended for supplying breathing gas in the respiratory tracts of the

patient during each inspiration phase can therefore be obtained

  without using a closed control loop, and only by generating an appropriate control signal of desired shape and by applying this signal to the control valve 15. If it is desired to obtain a predetermined pressure curve with precision in the tracks respiratory system of the patient during the inspiration phase, whatever the state of the patient's lungs, this can be achieved by providing the lung ventilator with a pressure transducer which detects the pressure prevailing in the respiratory tract

  patient and sends a corresponding measurement signal to the control unit 8

laying on the pressure detected. The measurement unit 8, in this case, is formed to generate during each inspiration phase a

  reference signal which is representative of the pressure curve

sirea in the patient's airways, this reference signal

being compared in a conventional manner to the measured signal received from the trans-

  pressure conductor 20, and a control signal being generated and sent to the control valve 15, which brings the difference between

the two signals compared to be kept substantially zero.

As mentioned earlier, we often want to apply a

  respiratory treatment with terminal expiration pressure po-

sitive, and called PETP. This result can easily be obtained with a lung ventilator according to the invention by constructing the control unit 8 so that it is also sent to the regulating valve 15, during the expiration phase of each cycle of

breathing, a given command signal, giving rise to a pressure

  predetermined sion in the corresponding control gas chamber 4

to the desired value of the PETP treatment. So, and as mentioned before-

  previously, the pressure in chamber 3 coincides with the pressure

  zion prevailing in chamber 4, and it follows that a pressure con-

controlled or a closing pressure corresponding to said PETP value

  is sent to the exhalation valve 22 during the expiration phase.

The patient therefore performs an exhalation at the desired terminal pressure.

value, whose value can be changed by modifying the com-

command sent by the control unit 8 to the regulating valve 15.

Since the breathing gas chamber 3 is completely empty during each inspiration phase, the patient is supplied with

during each forced breath with a constant volume predeter-

mined with breathing gas corresponding to the volume of breathing gas

  tion supplied by source 6 to chamber 3 during the period of a

complete breathing cycle.

  Following the supply of the patient's respiratory tract with the desired volume of breathing gas during an increase in pressure in the respiratory tract, it is often desirable that the quantity of gas sent is momentarily distributed in all parts of the lungs of the patient, so that all the alveoli

  have time to fill with breathing gas before it

  begins the expiration phase. This equalization plateau between the phase

  inspiration and the expiration phase can be obtained with a

  lung tilator according to the invention by providing the line with pressure

  control valve 23 of the exhalation valve 22 of a closing valve 24 which is normally kept fully open but which, under the action of the control unit 8, is closed at the same time as the inspiration is interrupted, by interrupting the control signal sent to the regulating valve 15, or by reducing this signal to a value corresponding to the desired PETP value,

  then keeping said valve closed for a corresponding period

laying on the desired pressure equalization plate. While the sou-

Pape 24 is kept closed in this way, the pressure prevailing at the end of the inspiration phase in the line 23 between the valve 24 and the exhalation valve 22 is maintained, and the valve 22 is thus always kept closed and prevents air being exhaled from the patient's airways, causing the volume of gas to

  sent respiration can be distributed in said respiratory tracts

res. Following the end of the desired plateau interval, the valve 24 is again opened by the control unit 8, which causes the control pressure sent to the exhalation valve 22 to drop to the pressure then prevailing in breathing chamber 3 (atmospheric pressure or desired PETP pressure), after which the patient can

exhale in the normal way.

  In other types of respiratory treatment, for example when it is a spontaneous breathing of patients and when

VOI and VID treatments are used, the volume of breathing gas

  tion obtained by the patient during each breath is not known beforehand but varies for example depending on the patient's ability to breathe on his own, and also varies from breath to breath. In this case, the breathing gas chamber 3 does not

  does not empty completely with each breath, and in this case the

  the lung tiler is therefore provided with a flow meter 12 which measures

continuously the stream of breathing gas passing through the container

  pick 9 and sent to the patient's airway, and

* channels a measurement signal corresponding to the control unit 8 which includes appropriate means for integrating this current signal for desired periods of time and establishing the volume of breathing gas sent to the patient. In these respiratory treatments,

  the source 6 of breathing gas is adjusted for a sufficient flow

high enough to match the maximum demand positively.

  To save breathing gas, the closing valve 7 mon-

  ted on the supply line 5 going to the chamber 3 is controlled

  given by the control unit 8 in response to the current signal sent

  from the flow meter 12 so that there is always a minimum required amount of breathing gas in the chamber 3. But in this case, the breathing gas chamber 3 could be filled to its maximum volume from the source of breathing gas, and even more than filled. To prevent this from causing an uncontrollable rise in pressure in the chamber 3, the membrane 2 of the embodiment of the invention illustrated is provided with a leak valve 25 which opens automatically when the breathing gas chamber

3 reaches its maximum volume and when the diaphragm 2 is then

  dried against the upper wall of the tank 1. When the valve 25 opens, the breathing gases can escape from the chamber 3 and

get to room 4.

When it comes to spontaneous breathing treatments, it is possible by means of the lung ventilator of the invention to obtain

  continuous and desired positive overpressure in the airways

  patient's so-called PPCV, making sure that the patient unit

  command 8 generates a spontaneous signal during spontaneous breathing

  rence corresponding to the desired PPCV processing, this signal being compared with the pressure signal coming from the pressure transducer 20, the control signal sent to the regulating valve 15 being adapted so that the difference between the two compared signals is maintained substantially at zero . The patient's spontaneous breathing is

  then proceeds relative to the PPCV determined by the control unit 8.

  To further improve the patient's spontaneous breathing and to determine a very small deviation from the level of

PPCV desired, and at the same time so that the trend of oscillations-

the automatic control system is insignificant, the

  signal from flow meter 12, in addition to the pressure signal

coming from the pressure transducer 20, can also be returned to

the control unit to be compared to the corresponding reference signal

  corresponding to the desired PPCV value. The signal from the transducer-

  pressure sensor 20 and the signal from flow meter 12 are amplified

  relied on at different levels during the feedback before they

  are added and the summation signal is compared to the

general reference.

When applying forced ventilation and inter-

  mittent, says PFD, forced breaths are started at a

adjustable frequency determined by the control unit 8, due to the fact that this control unit 8 generates a corresponding control signal

in one of the modes described above, and sends this signal to the valve

regulating pe 15, that is to say tput to be quite simply either in app-

plicating a desired shape control signal to the control valve

lation 15, either by generating a reference signal corresponding to the desired pressure curve in the patient's airways during said breathing, and by comparing this reference signal with the measurement signal received from the pressure transducer 20, the signal command sent to the control valve 15 now the difference

  between the signals compared substantially to zero. The duration of the respi-

  forced ration is determined here by the current signal from

  from the flow meter 12, this signal being integrated in the control unit

  command 8 during breathing which is interrupted by the action of the

  control signal sent to the control valve 15 when the

  lume breathing gases sent to the patient during each breath

  tion coincides with a desired and predetermined volume of ebb and flow set in the control unit 8. It will be understood that it is also possible to obtain a pressure equalization plate as described above after each forced breathing by temporarily closing

valve 24.

  When a patient is subjected to VID treatment, each breath

  The forced action is triggered by the efforts made by the patient to inhale, because the control unit 8 detects the current signal from the flow meter 12 and detects the increase in current which occurs when the patient begins to draw gases from breathing of the chamber 3 in the inspiration line 9, the control unit 8 being designed to initiate breathing in any of the ways described above and in response to an increase in current.

It will be understood that the arrangement illustrated in FIG. 2 can-

operate in a manner corresponding to that illustrated on the

  FIG. 1 and described previously, the throttling device varies

ble 18 of the embodiment of FIG. 2 being controlled by the unit

  control tee 8 in a manner corresponding to the manner in which

the control valve 15 of the embodiment of Figure 1

2459053

is ordered. It will be noted in this connection that the result of the farm-

  ture of the variable throttle device 18 of FIG. 2 corresponds to

  pond to that obtained when opening the regulating valve of the

figure 1.

  It will also be understood that the embodiments of the information

  vention described above are not limiting and that it is pos-

  likely to design other embodiments and other modifications of the lung ventilator of the invention while remaining in the camps

  of application of the appended claims.

_o O_ O_ O_ O_ O

O O O O O

Claims (12)

  1 - Lung ventilator or respirator of the type comprising a breathing gas chamber (3) comprising at least partially flexible walls (2) and a variable volume and which is enclosed in a control gas chamber (4) provided with walls rigid, the   breathing gas chamber being connected by a supply duct   tion (5) to a source of breathing gas (6) and being intended to receive and collect breathing gases by increasing your lume, and can be connected to the respiratory tract of a patient by an inspiration conduit (9), while the control gas chamber (4) is connected to means (13-15; 16-18) for supplying air compressing the breathing gas chamber and entraining the breathing gases collected therein towards the patient via the inspiration conduit, this conduit being provided with a check valve (11) which allows gas to pass only in the direction of the patient, the apparatus comprising an exhalation duct (21) which can be connected to the respiratory tracts of the patient and in which is mounted an exhalation valve (22) opening during the expiration phase ration of the patient's respiratory cycle and allowing gases to pass only from the patient, characterized in that the device intended for supplying air to the control gas chamber (4) comprises means (15; 18 ) electrically controlled regulation to modify the actual air supply, and therefore the pressure.,   of the control gas chamber (4) as a function of a control signal applied to them, and that a unit of   control (8) suitable for supplying a control signal of predeter shape-   mined during each forced breath, and to send this signal to said regulation means.   2 - Lung ventilator according to claim 1, characterized in that the air supply device comprises an ejector (13) mounted between the chamber of the control gases and the surrounding atmosphere,   and includes a control nozzle (13b) connected to a source of compressed air award-winning (14) via a valve (15) for regulating the rant electrically controlled and forming said regulation means. 3 - Lung ventilator according to claim 1, characterized   in that said air supply device comprises a fan   (16) disposed between the surrounding atmosphere and the chamber, and an outlet   tie (17) putting this chamber in communication with the surrounding atmosphere   running, this outlet comprising a throttling device (18) electrically controlled variable forming said regulation means. 4 - Lung ventilator according to claim 2, characterized in that the control gas chamber (4) also comprises   means for connecting this chamber to the surrounding atmosphere by the   through a valve (26) urged by pressure and maintained   closed by a pressure derived from the supply pressure approx. yée to the control nozzle (13b) of the ejector. - Lung ventilator according to any one of claims 1 to 4, characterized in that the exhalation valve (22) has the form of a non-return valve urged by pressure and kept closed by a control pressure derived from the pressure in the breathing gas chamber (3); and in that the unity of   control (8) is set up so that during the expiration phase tion of each forced breath and during the spontaneous breathing of the patient, it generates a constant control signal of predetermined amplitude corresponding to a substantially constant pressure and   predetermined prevailing in the control gas chamber, which is inferior   lower than the pressure generated in the control gas chamber during during the inspiration phase of forced breathing, and to send this signal to said regulation means (15, 18). 6 - Lung ventilator according to any one of the claims 1 to 5, caYactérisé in that it comprises means (19) for de- tect and compare the pressures prevailing in the gas chamber mande (4) and in the breathing gas chamber (3) and to send to the control unit (8) a signal which is a function of this comparison reason, said unit (8) being adapted to interrupt, in response to this signal, an inspiration phase in progress for forced breathing by changing the control signal sent to the regulating means (15, 18) when the pressure prevailing in the control gas chamber (4)   tends to exceed the pressure in the breathing gas chamber tion (3). 7 - Lung ventilator according to any one of the claims 1 to 5, characterized in that it comprises means (12) for measuring   the flow of breathing gas passing through the breathing line   ration (9) and generate a corresponding gas current signal sent to the control unit (8) which is clean, in response to said signal of current, to interrupt an inspiration phase during a breath   forced ration by changing the control signal sent to the regulating means (15, 18) when the volume of breathing gases passing   through the inspiration duct during the inspiration phase in question tion has reached a predetermined value. 8 - Lung ventilator according to any one of the claims   catipns 1 to 7, characterized in that it comprises a pressure transducer (20) connected to the inspiration duct (9) to detect a   pressure in the patient's airways and for   generate a corresponding pressure signal and send this signal to the control unit (8) which is capable of providing a reference signal   which is representative of the desired pressure in said channels at this time and to compare said reference signal with said pressure signal and keep the control signal sent to the regulating means (15, 18) constant at a level such that the difference between the two compared signals is kept substantially at zero. 9 - Lung ventilator according to any one of the claims   cations 1 to 7, characterized in that it comprises a pressure transducer (20) connected to the inspiration line (9) to detect the pressure in the patient's airways and for set a corresponding pressure signal sent to the control unit (8); and means (22) for measuring the current of breathing gas passing through the inspiration duct (9) and for providing a corresponding gas current signal sent to the control unit (8) this control unit being able to supply, during spontaneous breathing   of the patient, a reference signal representative of the level of   desired pressure in the patient's airways - and to compare   rer this reference signal to a weighted sum of said press signals ion and current, and in response to this comparison, to maintain the control signal sent to the regulating means (15, 18) at a value such that the difference of this comparison is shifted by direction of zero.   10 - Lung ventilator according to claim 7, characterized in that the control unit (8) is provided in response to the gas current signal, to trigger the inspiration phase intended for forced breathing by a corresponding modification of the signal of   command sent to the regulating means (15, 18) when an increase   temporary gas flow in the inspiration duct (9) indicates an attempt to inhale the patient.   11 - Lung ventilator according to claim 7, characterized in that the supply duct (5) connected to the gas chamber of   breathing (3) ccrrprendunes closing valve (7) can be com-   ordered by the control unit (8); and in that the control unit is such that in response to said current signal it keeps said valve respectively open or closed during the time intervals during which the breathing gas chamber (3) operates   always a minimum predetermined volume of breathing gas.   12 - Lung ventilator according to any one of claims 1 to 11, characterized in that a flexible wall (2) is provided for the breathing gas chamber (3), this wall comprising   a valve (25) normally closed and constituted to be automatic   only open to allow the passage of breathing gases from the breathing gas chamber when this flexible wall assumes the position corresponding to the maximum volume of said breathing gas chamber, thereby preventing excessive filling of this chamber.   13 - Lung ventilator according to any one of the claims   cations 1 to 12, characterized in that the exhalation valve (22) has the form of a pressure-stressed check valve which   is kept closed by a control pressure applied by the through a control pressure conduit (23) connected to said breathing gas chamber (3), this conduit (23) comprising mounted on it a shut-off valve (24), normally open and controlled by the control unit control (8), which determines at the end of the forced breathing the closing of this valve at the same time as the control signal sent to the regulating means (15, 18) is modified to reduce the pressure prevailing in the gas chamber control (4) and thereby in the breathing gas chamber (3), and to maintain the valve (24) closed for a predetermined period during which   the volume of breathing gas sent during this period to the respiratory tract of the patient can be distributed in said respiratory tract before the expiration phase begins, since the valve (24) is again opened so that the pressure of ordered   of the exhalation valve (22) drops and so that the exhalation valve   tion can be opened by the overpressure prevailing in the res- piratory of the patient. 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