Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3831596 A
Publication typeGrant
Publication dateAug 27, 1974
Filing dateNov 7, 1972
Priority dateNov 10, 1971
Publication numberUS 3831596 A, US 3831596A, US-A-3831596, US3831596 A, US3831596A
InventorsCavallo R
Original AssigneeSynthelabo
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Control device for a respiratory apparatus
US 3831596 A
Abstract
Respiratory apparatus having an electromagnetically operated valve for controlling the flow of respirable gas from a source thereof to a mouthpiece has a control arrangement for opening and shutting the valve in accordance with pressure changes appearing during periods of inhalation and exhalation by a patient using the apparatus. Alternatively, the valve can be opened and shut according to a predetermined cycle.
Images(2)
Previous page
Next page
Description  (OCR text may contain errors)

D United States Patent 1 1 1111 3,831,596 Cavallo Au 27 1974 [54] CONTROL DEVICE FOR A RESPIRATORY 3,357,428 12/1967 Carlson 137/4875 q q 3,456,643 7/1969 Koch 128/1458 APP TUS 3,508,542 4/1970 Browner 128/1422 Inventor: Roger Paul Charles Cavallo, 3,611,178 10/1971 McConnell 128/1422 Bourg-la-Reine, France 1 S th 1 M p F Primary ExaminerRichard A. Gaudet [73] Asslgnee yn e a ans rance Assistant Examiner-Henry J. Recla Flledi 1972 Attorney, Agent, or Firm-Karl F Ross; Herbert 211 App]. No.2 304,487 Dubno [52] U.S.Cl. ..128/145.8, 128/145.5 [57], ABS CT 51 11m. (:1 A61m 16/00 Resplratory apparatus havlPg electromagnetlcally [58] Field of Search 128/1453 1463 1464 operated valve for controlling the flow of resplrable 128/146 51 5 1422 1423 gas from a source thereof to a mouthpiece has a con- 37 4 14 1 trol arrangement for opening and shutting the valve in accordance with pressure changes appearing during [561 References Cited periods of inhalation and exhalation by a patient using the apparatus. Alternatively, the valve can be opened UNITED STATES PATENTS and shut according to a predetermined cycle. 2,376,348 5/1945 Fox 128/1458 2,863,287 12/1958 Berkman 137/4875 10 Chums, 3 Drawing Flgures CONTROL DEVICE FOR A RESPIRATORY APPARATUS This invention relates to control devices for respiratory apparatus. Respiratory apparatus for assisting natural respiration is normally controlled to operate at a fixed frequency or rhythm by a clock mechanism operated electrically or pneumatically but this is not satisfactory when the respiratory rhythm of a patient to be treated is irregular.

The present invention concerns means for supplying air to patient according to the demand of his lungs, in other words means to control the apparatus by shutting air supply as soon as the lungs are full of air and by opening the air supply as soon as patient begins an inhalation.

A control device for a respiratory apparatus comprising a source of respirable gas connected to a mouthpiece by a conduit provided with a control valve, according to the invention includes a pressure sensor connected to said conduit between said valve and mouthpiece, said sensor comprising a housing closed by a membrane, the outer face of which exposed to ambient air is partly applied against a rigid sustaining member, a first detector of a predetermined outward distortion of said membrane for controlling closing of said valve and a second detector of a predetermined inner distrotion of said membrane for controlling opening of said valve. Thus owing to the membrane outer sustaining member, outward displacement of a given point on the membrane due to gas over pressure inflating the lungs and prevailing in the housing may be of the same order as inward displacement of the same point due to under pressure in said housing produced by the inhalation effort of the patient.

Preferably an adjustable flexible flat member is connected to a point of the flexible membrane, so as to respond to the flexure of the latter and both faces of the member are provided with strain gauges which are connected in a Wheatstone bridge with reference resistors. Hence by adjusting the initial shape of the member, the bridge may be exactly equilibrated when the same pressure prevails on both faces of the membrane, so that an over pressure in the housing provides a current of one direction in the bridge detecting diagonal and an under pressure a current of the other direction, in the same diagonal.

Thus the bridge arrangement is a part of the first and second detectors.

By comparison of each of both currents with respective adjustable thresholds, control of a flip-flop at predetermined amplitudes of the currents (i.e. definite levels of membrane distortions) may be obtained for the alternate control of the .valve.

In one particular form of the control device according to the invention the the flow control valve is electro-magnetically operated by one output of a flipflop device triggered by signals derived from the strain gauges.

For reasons of security after control of the valve to close position, the flip-flop is again triggered to control open position of the valve by the output of a timing device a predetermined time after closing of the valve.

For allowing the weak inhalation effort of the patient to entail a negative pressure in the conduit portion the flow control valve is adapted, when in its closed position, to place the pipe in communication with atmosphere via a light exhaust valve.

In a further embodiment of the apparatus, means are provided for operating the flip-flop according to a predetermined time cycle. Such means may comprise resistorcapacitor combinations of which the resistors are variable.

By way of example only, an embodiment of the invention will now be described in greater detail with reference to the accompanying drawing in which:

FIG. 1 is a plan view of part of one embodiment,

FIG. 2 is a section on the line lI-Il of FIG. 1, and,

FIG. 3 is a circuit diagram partly in block or schematic form of the respiratory apparatus,

The component shown in FIGS. 1 and 2 is a pressure change detector and it comprises a flat circular membrane 1 attached to a plate 2 concentrically with an ap erture 3 in the latter. The membrane is clamped between the plate and a cup-shaped housing 4 attached to the plate by screws 5 which also pass through the membrane adjacent its periphery.

The membrane 1 is made of metal or of a plastic material, for example that known as Stabilene.

The plate 2 is of laminated glass/resin construction and is extended to provide support for other components described below.

Extending externally of the housing 4 and centrally from the base thereof is a coupling 4a by means of which connection is made to a pipe supplying a patient with respirable gas.

Connected to the center of the membrane 1 is one end of a bolt 6 whose other end is fixed to a flexible strip 7 clamped cantilever fashion between small clamping plates 8 bolted to plate 2.. The free end of the strip 7 rests resiliently on an adjusting screw 9, which sets the zero position of the strip 7, and of the membrane.

To the upper and lower faces of the strip 7 are fixed strain gauges 10, 11 respectively. The gauges are connected in a Wheatstone bridge including reference resistors l2, 13 (FIG. 3) for supplying control signals.

Increase of pressure within the housing 4 causes the central part only of the membrane 1 to flex upwardly as indicated by the dotted line la whereas a reduction in pressure below atmospheric causes the membrane to flex downwardly over a much greater area as indicated by the dotted line 1b. In this way, a pressure reduction which is only one tenth of the maximum pressure to which the membrane is likely to be exposed produces, in the strip 7 a flexure equal in amplitude but opposite in sense to that produced by that maximum pressure.

A manometer 20 is joined to thepipe 18 as shown and the latter also has a branch connection to the housing 4 via the coupling 4a.

In use, flexure of the strip 7 causes signals to be transmitted from the bridge whose amplitude and polarity depend upon the extent to which and the direction in which the strip is flexed and thus, this flexure indicates the pressure in the housing 4 and so in the pipe 18. Owing to the screw 9 output of the bridge is adjusted to zero when both faces of the membrane are submitted to the same pressure.

The bridge output is applied to an amplifier 31 having thus one output on which appear positive signals representing positive pressure in housing 4 and another output on which appear negative signals representing negative pressures in that housing. The two outputs are connected to respective differential amplifiers 32 32 B each with a reference input controlled by the respective potentiometers 33, 33

Amplifier 32, and its potentiometer 33,, are adapted to deal with positive pressures and by adjustment of the potentiometer 33,, can be set to deal with a range of from +100 mb as indicated by the manometer 20. This range is selected so that a supply pressure can be selected which suffices to fill the lungs of a patient without smothering him.

Amplifier 32 B and its potentiometer 33 are adapted to deal with negative pressures and by adjustment of the potentiometer 33,, can be set to deal with a range of pressures of from -1 mb to l0 mb which pressure can also be indicated by manometer 20. In practice, the pressure is determined by the comfort of the patient in that a signal is emitted when the latter breathes undue without effort.

By means of the contact arms 26,,, 26 of a doublepole changeover switch, the outputs of the differential amplifiers 32,,, 32 can be applied to the inputs of an electronic flip-flop circuit represented by block 34. The flip-flop has a single output corresponding with the output of amplifier 32,, which is used, after amplification by power amplifier 35, to energise the winding 16 and so open valve 15.

The output of differential amplifier 32A is also applied to a timing device 37 which, in response to an input, produces an output after a predetermined delay within the range of from 2 to seconds, for example 3 seconds. The output of timing device 37 is connected to the output of differential amplifier 32 The general arrangement is such that when the predetermined positive pressure is reached pipe 18, a signal is sent to the flip-flop 34 which responds by a change in its other stable state and as a result valve is closed. At the same time, the timing device 37 is set into operation.

The patient then exhales and after a certain time inhales again providing a negative pressure in housing 4 and this produces a signal that is applied via amplifier 32,, to the flip-flop 34 which switches to its other stable state with the result that valve 15 is opened.

In inhaling is insufficient to produce the necessary negative pressure or if the latter appears after the end of the predetermined delay to which device 37 is set, the latter produces a signal atthe end of the delay and this causes flip-flop 34 to switch to its other state and valve 15 opens. The cycle then repeats, timing device 37 being ready then to receive a further signal from amplifier 32,, when the pressure in pipe 18 again rises to the predetermined positive value.

It has already been stated that valve 15 is a three-way valve. In the open position of valve 15, pipe 18 is placed in communication with source 14 only while in the closed position source 14 is shut off from pipe 18 but the latter is placed in communication with the atmosphere via an outlet 38 normally closed by a light exhaust valve 39, for example a flexible elastomeric disc with a central fastening positioning the valve over outlet 38. Thus, when valve 15 closes, the positive pressure then existing in pipe 18 flexes valve 39 away from the outlet 38 and the pressure rapidly drops to ambient pressure. As the patient inhales exhaust valve 39 is closed and negative pressure appears in pipe 18 and housing 4.

The double pole switch can be manually actuated to disconnect the amplifiers 32,,, 32,, from the flip-flop 34 to connect the latter to capacitive devices 40,, 40,, which with their respective potentiometers 41 A and 41 3 convert the flip-flop into a multivibrator.

The setting of the potentiometers 41 41 B is such that the ratio of the switching times of the multivibrator is 2:1 so that the valve 15 is open and shut cyclically, the closed time being twice the open time, this giving a time period for expiration that is twice the time period for inhalation.

For medical use, the frequency of the multivibrator can be set to a value within the range 10-60 exhalations and inhalations per minute. However, for veterinary use, a wider range of variation may be required and in practice, the respiratory rhythm is adjustable within the range of from to per minute.

What 1 claim is:

1. A device for the control of a respiratory apparatus comprising:

a source of a respirable gas connected to a patient through a conduit provided with an electrically operated control valve;

control means for operating said valve, said control means including a housing communicating with said conduit between said valve and the patient, a flat membrane spanning said housing and having an outer face exposed to the atmosphere and an inner face exposed to the breathing air supplied to said patient, a flat generally rigid member disposed proximal to said outer face for securing said membrane and provided with a central aperture of a surface area substantially less than the area of said membrane, a rigid element connected to a central portion of said membrane, and a distortion detec tor connected to said element; and

electrical means connected to said detector and to said valve for supplying a valve-closing signal to said valve upon distortion of the membrane in the direction of said central aperture and; for supplying a valve-opening signal to the latter upon distortion of the membrane in the other direction.

2. The device defined in claim 1, further comprising a flexible member overlying said membrane, said distortion detectors being formed as strain gauges applied to opposite faces of said flexible member and a wheatstone bridge circuit having reference resistors and said strain gauges connected therein.

3. The device defined in claim 2 wherein said flexible member is a blade, further comprising means for clamping said blade at one end to said housing, adjustment means for varying the position of the opposite end of said blade with respect to the housing, and means connecting an intermediate location on said blade between said ends to said rigid element.

4. The device defined the claim 3 wherein said rigid member is a wall of electrically insulating material carrying said detectors and said blade.

5. The device defined in claim 1 wherein the firstmentioned and second electrical means are respective differential amplifiers having respective adjustable thresholds of opposite polarity, and a bistable flip-flop responsive to said differential amplifiers.

6. The device defined in claim 1 wherein said valve is a three-way valve and in its closed position connects said conduit to the atmosphere through an adjust valve.

7. The device defined in claim 6, further comprising a timing device for operating said valve independent of at least one of said detectors.

8. The device defined in claim ll, further comprising means for indicating visually the pressure in said conduit.

9. A device for the control of a respiratory apparatus comprising:

a source of a respirable gas connected to a patient through a conduit provided with an electrically operated control valve;

control means for operating said valve, said control means including a housing communicating with said conduit between said valve and the patient, a flat membrane spanning said housing and having an outer face exposed to the atmosphere and an inner face exposed to the breathing air supplied to said patient, a flat generally rigid member disposed proximal to said outerface for securing said membrane, a rigid element connected to a central portion of said membrane, and a distortion detector connected to said element; electrical means connected to said detector and to said valve for supplying a valve-opening signal to the latter upon distortion of the membrane in one direction; second distortion detector connected to said element for sensing deflection of said membrane in the opposite direction, and second electrical means responsive to said second detector and connected to said valve to apply a valve-closing signal to the latter, said control valve is electromagnetic, said detectors are strain gauges, and said electrical means include respective differential amplifiers having adjustable thresholds and connected to said strain gauges, a bistable flip-flop connected to said differential amplifiers and having an output applied to said valve, two resistor-capacitor combinations, each associated with said flip-flop, and switching means for selectively applying said resistorcapacitor combinations and said differential amplifiers to said valve for constituting a multivibrator from the flip-flop upon connection of a resistorcapacitor combination therewith.

10. The device defined in claim 9, further comprising variable resistors in said resistor-capacitor combinations for determining the switching time of the multivi- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,831,596 DATED 27 August 1974 INVENTOR(S) Roger Paul Charles CAVALLO It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, after line 1 insert:

-- Q Foreign Application Priority Data 10 November 1971 FRANCE 71 40291 17 October 1972 FRANCE 72 36666 Erigned and Scaled this A ttest:

RUTH C. MASON C. MARSHALL DANN iltcsling ()jfr'zer (mnmissz'uncr uflarents and Trademarks

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2376348 *Apr 24, 1943May 22, 1945Clarence N EricksonResuscitator
US2863287 *Nov 9, 1956Dec 9, 1958Research CorpVacuum control system
US3357428 *Dec 23, 1963Dec 12, 1967Carlson David LRespiratory augmentor with electronic monitor and control
US3456643 *Dec 12, 1966Jul 22, 1969Drager Otto HControl system for breathing apparatus
US3508542 *May 3, 1967Apr 28, 1970Automatic Sprinkler CorpDual source breathing fluid supply system with alarm
US3611178 *Oct 13, 1969Oct 5, 1971Bourns IncPressure-sensing signal generator
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3961627 *Sep 3, 1974Jun 8, 1976Hoffmann-La Roche Inc.Automatic regulation of respirators
US3972327 *Nov 7, 1974Aug 3, 1976Hoffmann-La Roche Inc.Respirator
US4232668 *Feb 28, 1979Nov 11, 1980Strupat John PGas ventilating device
US4323064 *Jun 1, 1979Apr 6, 1982Puritan-Bennett CorporationVolume ventilator
US4357936 *Apr 14, 1980Nov 9, 1982Bear Medical Systems, Inc.Directional thermistor assist sensing
US4469097 *May 25, 1982Sep 4, 1984Kelman Charles DMedical breathing apparatus
US4538604 *Jun 20, 1983Sep 3, 1985Bunnel Life Systems, Inc.System for assisting respiration
US4567888 *Jun 24, 1983Feb 4, 1986Compagnie Francaise De Produits OxygenesDevice for treating respiratory deficiency of a patient
US4648395 *Aug 13, 1984Mar 10, 1987Sanyo Densihkogyo Co. Ltd.Synchronized feed type oxygen concentrator for use in an open breathing system
US4706664 *Apr 11, 1986Nov 17, 1987Puritan-Bennett CorporationInspiration oxygen saver
US4744356 *Mar 3, 1986May 17, 1988Greenwood Eugene CDemand oxygen supply device
US4848332 *Feb 25, 1988Jul 18, 1989L'air LiquideDevice for controlling the pressure of a fluid and injection system for this fluid employing this device
US5099836 *Jan 17, 1990Mar 31, 1992Hudson Respiratory Care Inc.Intermittent oxygen delivery system and cannula
US5099837 *Sep 28, 1990Mar 31, 1992Russel Sr Larry LInhalation-based control of medical gas
US5165397 *Jul 31, 1990Nov 24, 1992Arp Leon JMonitor/control the flow of gas to a patient
US5542416 *Jan 10, 1995Aug 6, 1996Societe D'applications Industrielles Medicales Et Electroniques (Saime)Apparatus for assisting ventilation including reduced exhalation pressure mode
US5570682 *Dec 14, 1993Nov 5, 1996Ethex International, Inc.Passive inspiratory nebulizer system
US6076519 *Nov 4, 1996Jun 20, 2000Ethex International, Inc.Passive inspiratory nebulizer system
US6244267 *Apr 10, 2000Jun 12, 2001DRäGER MEDIZINTECHNICK GMBHRespirator with a pressure relief valve
US7870858Sep 1, 2005Jan 18, 2011Ric Investments, LlcApparatus and method for driving a sensor in a ventilator
US8136527Mar 13, 2008Mar 20, 2012Breathe Technologies, Inc.Method and device for non-invasive ventilation with nasal interface
US8381729Aug 3, 2007Feb 26, 2013Breathe Technologies, Inc.Methods and devices for minimally invasive respiratory support
US8418694Apr 30, 2010Apr 16, 2013Breathe Technologies, Inc.Systems, methods and apparatus for respiratory support of a patient
US8464714 *May 2, 2005Jun 18, 2013Resmed ParisBreathing assistance device comprising a gas regulating valve and associated breathing assistance method
US8567399Sep 26, 2008Oct 29, 2013Breathe Technologies, Inc.Methods and devices for providing inspiratory and expiratory flow relief during ventilation therapy
US8573219Dec 9, 2011Nov 5, 2013Breathe Technologies, Inc.Method and device for non-invasive ventilation with nasal interface
US8677999Aug 21, 2009Mar 25, 2014Breathe Technologies, Inc.Methods and devices for providing mechanical ventilation with an open airway interface
US20100018529 *May 2, 2005Jan 28, 2010Philippe ChalvignacBreathing assistance device comprising a gas regulating valve and associated breathing assistance method
EP0131769A1 *Jun 15, 1984Jan 23, 1985Bunnell, Inc.System for assisting respiration
EP0183593A1 *Nov 8, 1985Jun 4, 1986L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges ClaudeRespiratory apparatus
WO1986000537A1 *Jul 9, 1985Jan 30, 1986Gerald P DurkanMethod and apparatus for supplying gas mixtures to an in vivo respiratory system
WO1987006142A1 *Apr 3, 1987Oct 22, 1987Puritan Bennett CorpMethod/apparatus for inspirational gas saving
WO2006024531A2 *Sep 1, 2005Mar 9, 2006Anagram Consultants AgApparatus and method for driving a sensor in a ventilator priority claim
Classifications
U.S. Classification128/204.23, 128/205.24
International ClassificationA61M16/20, A61M16/10, A61M16/12, A61M16/00
Cooperative ClassificationA61M2016/0021, A61M16/00, A61M16/12, A61M16/0066, A61M2016/202
European ClassificationA61M16/00