US3734092A - Medical respirator - Google Patents

Medical respirator Download PDF

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Publication number
US3734092A
US3734092A US00113279A US3734092DA US3734092A US 3734092 A US3734092 A US 3734092A US 00113279 A US00113279 A US 00113279A US 3734092D A US3734092D A US 3734092DA US 3734092 A US3734092 A US 3734092A
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United States
Prior art keywords
gas
liquid
volume
patient
pressure
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Expired - Lifetime
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US00113279A
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English (en)
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B Kipling
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Honeywell BV
US Philips Corp
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US Philips Corp
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Assigned to HONEYWELL B.V. RIJSWIJKSTRAAT reassignment HONEYWELL B.V. RIJSWIJKSTRAAT ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: PYE(ELECTRONIC PRODUCTS)LIMITED
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/14—Preparation of respiratory gases or vapours by mixing different fluids, one of them being in a liquid phase
    • A61M16/16—Devices to humidify the respiration air
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/14—Preparation of respiratory gases or vapours by mixing different fluids, one of them being in a liquid phase
    • A61M16/18—Vaporising devices for anaesthetic preparations

Definitions

  • ABSTRACT A liquid injector for medical respirators in which a predetermined quantity of patient gas is stored at higher than atmospheric pressure in a known volume during an expiratory period of a respiratory cycle and discharged to a patient during the next following inspiratory period of the cycle.
  • the injector includes a movable member the displacement of which from a datum position controls the quantity of liquid injected into the patient gas in each cycle. This displacement is directly proportional to the pressure of the stored patient gas and the movable member is displaced by driving means which is driven as a result of the pressure.
  • MEDICAL RESPIRATOR This invention relates to liquid injectors for medical respirators in which a predetermined quantity of patient gas is stored at higher than atmospheric pressure in a known volume during an expiratory period of a respiratory cycle and discharged to a patient during the next following inspiratory period of the cycle.
  • respirators of the type described sometimes referred to as tidal volume" respirators
  • the quantity of gas passed to a patient per respiratory cycle i.e. the tidal volume
  • This quantity may therefore be varied by controlling the pressure of the patient gas fed to and storedin the known volume.
  • liquid injector In medical respirators, it is sometimes required that a quantity of liquid be added to the patient gas in each respiratory cyele; this being effected by a liquid injector.
  • the quantity of liquid normally used per cycle is very small in relation to the tidal volume and must be accurately controlled.
  • the quantity per cycle is usually expressed as a ratio of liquid, or liquid vapor, to patient gas.
  • An object of the invention is the provision of a liquid injector for respirators of the type described in which alteration of the patient gas pressure to adjust the tidal volume also affects the quantity of liquid injected by the injector such that the liquid/gas ratio of the mixture discharged to the patient is held constant.
  • the injector includes a movable member the displacement of which from a datum position controls the quantity of liquid injected into the patient gas in each cycle; the said displacement being directly proportional to the pressure of the stored patient gas.
  • spring means are provided which control the displacementof the movable member by exerting a force tending to oppose the displacement.
  • a liquid injector for a medical respirator of the typedescribed, in which patient gas at the said pressure is appliedduring the expiratory or inspiratory period to displace a movable member to transfer liquid from a reservoir to the predetermined quantity of patient gas, and in which spring means control thedisplacement of the movable member to hold the liquid/- gas ratio in the mixture of liquid and gas fed to the patient constant with change of the said pressure.
  • FIG. 2 shows one embodiment of the invention in which the injector and drive system operate in the inspiratory period of a Tidal Volume Respirator
  • FIG. 3 shows an alternative to FIG. 2 in which liquid is delivered to stored patient gas during an expiratory period","tliemixture of liquid and gas being delivered in the next following inspiratory period.
  • a'p'ressure driven motor M which may be a cylinder enclosing a piston or bellows, giving linear movement with applied pressure, is coupled by a mechanicallink ML to aninjector I of a type in which displacement of liquid is proportional to displacement of a movable member.
  • An extension E of link ML is engaged with one end of a spring SP, whose other end is fixed.
  • the motor input is connected by a line 11 to a switch SW, which, in the shown position, connects the input of the motor M to atmosphere as indicated by an arrowhead A. In the shown position spring SP is unstressed.
  • a liquid reservoir LR supplies injector I via a line 12 and a one way valve D1, and liquid from injector I is passed to atmosphere, arrowhead A, via a second one way valve D2 and line 13.
  • Movement of switch SW to its alternative position connects gas at adjustable pressure in line 15, supplied from pressure regulator PR fed via line 14 from a source PS of gas at higher than atmospheric pressure, to the motor input, and motor M will be driven.
  • Such drive will move link ML and the movable member of the injector by an amount depending on the gas pressure and the opposed force from the now compressed spring SP. Adjustment of gas pressure may therefore control the amount of liquid displaced from injector I.
  • a quantity of liquid will be delivered from injector I immediately after switch SW connects the motor M to gas pressure.
  • the delivery may be prolonged by the inclusion of resistance to flow, as for example, by a flow control FC in line 13 from the outlet of the injector I.
  • a pneumatically operated spool valve 60 is controlled by air pressure supplied by air lines connected to control ports 29 and 66, the arrangement being such that a pneumatic timing circuit supplies pressure to port 29, with port 66 vented to atmosphere, during an inspiration period, and supplies pressure to port 66, with port 29 vented, during an expiration period.
  • a cylinder 50 contains a piston 54, having unequal area end faces 52 and 51 (the area of latter being greater than the former) which divides the cylinder into two volumes V1 and V2.
  • valve 60 establishes a passage as shown between ports 48 and 55, and gas passes from volume V1 via pipe lines 49 and 56 to a flow control 57 and thence to a patient via line 58.
  • pressure in pipe line 56 is substantially constant due to the movement of piston 54 to the right under the influence of gas pressure from regulator 45 applied to volume V2 via pipe lines 46 and 53.
  • the pressure in pipe line 56 is utilized by applying it to a piston 20, within a cylinder 20A, via a pipe line 21; the resulting movement of piston 20 under the influence of the pressure being transferred by a piston rod 20B to a plunger 22, working within a cylinder 22A, which together comprise an injector.
  • Piston 20 is preferably of larger diameter than plunger 22 and of much smaller diameter than piston 54.
  • a recessed collar 20C is secured to piston rod 20B and engages one end of a spring blade 23 attached to an anchoring bar 23A.
  • Fluid from a reservoir not shown, is supplied to the injector cylinder 22A via a fluid line 24 and a one way valve D1 and may leave the injector by way of fluid line 25 having a one way valve D2 therein.
  • Valve D2 is very lightly spring loaded so that the head of fluid within the reservoir and injector does not of itself cause liquid to flow beyond it.
  • a liquid flow control 26 receives liquid from line 25 and passes it to a patient via a line 27 joined to the patient gas line 58.
  • Movement of bar 23B relative to bar 23A may be by any conventional control means, and, as such movement alters the spring rate and therefore the deflection for a given applied force, the control may be calibrated in terms of liquid ejected.
  • Alteration of pressure, by regulator 45 not only alters the deflection and amount of liquid ejected for a given position of bar 238, but also the quantity of gas stored per expiratory period; the tidal volume of gas being delivered to a patient in the next following inspiratory period.
  • the control for movement of bar 23 may therefore be calibrated in terms of the ratio of liquid to patient gas per respiration or, for a given temperature and with a volatile liquid, in terms of the ratio or percentage of liquid vapor to patient gas, such ratios remaining constant during changes of tidal volume caused by alteration of gas pressure.
  • the volume of gas in cylinder 20A discharges substantially exponentially to the patient through flow control 57 after piston 54 has reached its extreme right hand position and/or valve 60 has operated to terminate an inspiratory period.
  • This advantage may be made negligible by arranging that the maximum volume within cylinder 20A and piston 20 is small and also small relative to the maximum capacity of volume V1. As the maximum quantity of liquid to be injected is small, this is readily achieved.
  • Liquid flow control 26 must be adjusted, in addition to the pneumatic timing controls and gas flow control 57 of the respirator, so that transfer of liquid from the injector to line 58 and the patient occurs within the set inspiratory period.
  • walls 74, 75 and 76 contain two rigid diaphragms and 72, connected by a spacing member 79 fixed thereto and having respective flexible surrounds 71 and 73, to define two volumes V1 and V2 with respective entry ports 83, 83A and 82.
  • Parts concerned with liquid injection are a bellows 30, sealed in a container 30A to define a volume V3, which drives a plunger 32 within a cylinder 32A by means of a linking piston rod 308 when gas pressure is introduced into volume V3 by a pipe line 31C; plunger 32 and cylinder 32A forming at least part of an injector.
  • Liquid for the injector is supplied from a reservoir, not shown, via liquid pipe line 34 containing a one way valve D1, and leaves the injector by line 35 containing a second one way valve D2 which is lightly spring biased to the closed position.
  • a spring 33 has one end attached to an anchoring member 33A which carries, in slidable engagement, a fulcrum member 33B. Pivoted on fulcrum 33B is a bar 33C to one end of which is attached the other end of spring 33. The other end of bar 33C is bifurcated to embrace piston rod 308, a pin 30C therein engaging the upper surface of bar 33C.
  • Patient gas at pressure is applied to a port 36 of the tidal volume respirator and is passed on line 37 to a pressure regulator 38 from whence it issues on a line 31 to port 82 of volume V2.
  • Branches 31A and 31B of line 31 respectively feed ports A of two spool valves 39 and 40.
  • Valves 39 and 40 work in unison and may be'driven either mechanically or by other means. Their operation from the shown beginning of an inspiratory period terminates such period and starts an expiratory period which, in turn, is terminated by reverting the valves to the shown position. The drive and timing means for these valves are not shown.
  • volume V2 expands volume V2 and drives the contents of volume V1 out of port 83A, via a line 41, ports B and C of valve 40, a line 56, a flow control 57 and a line 58, to a patient connected thereto.
  • volume V3 is reduced to a minimum, which may be substantially zero, due to the passage within valve 39 to atmosphere, indicated by an arrowhead issuing from port C, established from port B to which line 31C is connected.
  • a minimum volume V3 established the arrangement is such that neither bellows 30, which may be of metal, or spring 33, are stressed but pin 30C is in contact with bar 33C.
  • valves 39 and 40 On change over of valves 39 and 40 to their expiratory position, communication to the patient is closed at port C of valve 40 and gas at pressure is passed to volume V1 via ports A and B of that valve, driving the diaphragm assembly towards the position shown. At the same time a path is established in valve 39 between ports A and B, applying pressure to volume V3, so contracting bellows 30 and moving plunger 32.
  • the amount of such movement and of liquid ejected thereby is governed by forces acting in opposition to the pressure in volume V3 which comprise the tension in the now elongated spring 33 multiplied by any mechanical advantage given by the position of fulcrum 338 plus pressure from volume V1 acting on plunger 32 and any force exerted by compressed bellows 30.
  • Pressure in volume V1 may be regarded as substantially constant at the pressure set by regulator 38, which pressure is also applied to volume V3, so that movement of plunger 32 is proportional to the pressure determining tidal volume for any position of fulcrum 338, which may therefore be calibrated, as for FIG. 2, in terms of the ratio of liquid to patient gas.
  • Movement of fulcrum 33B may be controlled, as for FIG. 2, by known means, e.g. threaded rod and nut, rack-and-pinion gears or cam and spring.
  • the opposing force exerted by the spring 33 is proportional to Ds/Dp, where Ds is the distance between spring and fulcrum and Dp is the distance between fulcrum and pin 30C
  • the movement calibration of fulcrum 33B departs from linearity less than in the case of the cantilever spring blade of FIG. 2.
  • cam movement means are employed to linearize the scale a less steep profile is required.
  • FIGS. 2 and 3 a simple type of plunger operated injector is shown. It may be replaced in both figures by a more complex type as described and shown in FIG.
  • a broken line 31D represents a source of driving pressure for the cylinder 66 of FIG. 3 of US. application 6,846, broken line rectangles shown in both lines 31C and 31D indicating means e.g. restrictions and/or one way valves to control the required sequential action of the two moving parts of the more complex injector. With such an injector, one way valve D1 becomes superfluous and one way valve D2 is incorporated in the injector.
  • Gas from volume V3 discharged to atmosphere from port C of spool valve 39 represents wastage which may be small due to the small maximum capacity of volume V3. Such wastage may be eliminated by connecting port C of valve 39 to line 58 and so to the patient.
  • bellows 30 and container 30A may be replaced by the piston and cylinder of FIG. 2, as may be the tension spring arrangement by the equivalent cantilever or quarter elliptic spring system.
  • cylinder 32A may be within a wall of volume V1, e.g. wall 75 in FIG. 3.
  • liquid pipe line 25 may be taken instead to gas pipe line 56 downstream of the junction with line 21.
  • piston 20 must be of greater diameter than plunger 22 and preferably a third one way valve is inserted in line 56 between the junctions of lines 21 and 25 to prevent liquid passing into line 21.
  • Spring blade 23 also may have nonuniform dimensions throughout its length or be comprised of more than one blade to assist in obtaining a linear scale to the control for movement of bar 23B.
  • a medical respirator comprising a cylinder for containing patient gas at a storage pressure which is higher than atmospheric pressure, a piston having opposite end faces thereof of unequal areas movable within said cylinder and dividing said cylinder into first and second volumes, first connection means connected to a source of gas and to said first volume for supplying patient gas thereto during an expiratory period of said respirator, second connection means connected to said first volume for passing patient gas therefrom to a patient during an inspiration period of the respirator, switching means for connecting said first volume to said first or second connection means during expiration or inspiration periods, means connected to said switching means for cyclically operating said switch, means connected to said second volume for supplying gas thereto the pressure of which acts on said piston to expel the gas within said first volume, a liquid injector means for injecting an adjustably predetermined quantity of liquid into the patient gas to be passed to the patient comprising a variable volume container for the liquid, driving means connected to said variable volume liquid container and operable by said storage pressure of said gas to reduce the volume of said liquid container to cause liquid to be
  • variable volume container comprises a piston in a cylinder.
  • the spring is a helical spring.

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  • Health & Medical Sciences (AREA)
  • Anesthesiology (AREA)
  • Emergency Medicine (AREA)
  • Pulmonology (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Hematology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Infusion, Injection, And Reservoir Apparatuses (AREA)
US00113279A 1970-03-18 1971-02-08 Medical respirator Expired - Lifetime US3734092A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB03064/70A GB1243765A (en) 1970-03-18 1970-03-18 Improvements in or relating to medical respirators

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US3734092A true US3734092A (en) 1973-05-22

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US00113279A Expired - Lifetime US3734092A (en) 1970-03-18 1971-02-08 Medical respirator

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US (1) US3734092A (cg-RX-API-DMAC10.html)
DE (1) DE2111691A1 (cg-RX-API-DMAC10.html)
FR (1) FR2083377B1 (cg-RX-API-DMAC10.html)
GB (1) GB1243765A (cg-RX-API-DMAC10.html)
NL (1) NL7103376A (cg-RX-API-DMAC10.html)
SE (1) SE366654B (cg-RX-API-DMAC10.html)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4587967A (en) * 1985-07-09 1986-05-13 Lifecare Services, Inc. Oxygen enriched reciprocating piston respirator
US4932401A (en) * 1988-04-01 1990-06-12 Perkins Warren E Two-gas variable ratio, variable dose, metering system and method of use
FR2825027A1 (fr) * 2001-05-22 2002-11-29 Draeger Medical Ag Recipient a anesthesique equipe d'elements doseurs
US20150352302A1 (en) * 2007-05-30 2015-12-10 Gilbert Jacobus Kuypers Electrically Operable Resuscitators

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4186737A (en) 1977-11-10 1980-02-05 Airco, Inc. Drug nebulizing system for medical ventilators of the volume-limited type
US4279250A (en) 1977-11-10 1981-07-21 Airco, Inc. Drug nebulizing system for medical ventilators of the volume-limited type
FR2597631A1 (fr) * 1986-04-22 1987-10-23 Corfa Yves Paul Doseur-evaporateur de liquide anesthesique

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4587967A (en) * 1985-07-09 1986-05-13 Lifecare Services, Inc. Oxygen enriched reciprocating piston respirator
WO1987000061A1 (en) * 1985-07-09 1987-01-15 Lifecare Services, Inc. Oxygen enriched reciprocating piston respirator
US4932401A (en) * 1988-04-01 1990-06-12 Perkins Warren E Two-gas variable ratio, variable dose, metering system and method of use
FR2825027A1 (fr) * 2001-05-22 2002-11-29 Draeger Medical Ag Recipient a anesthesique equipe d'elements doseurs
US20150352302A1 (en) * 2007-05-30 2015-12-10 Gilbert Jacobus Kuypers Electrically Operable Resuscitators
US11285281B2 (en) 2007-05-30 2022-03-29 Gilbert Jacobus Kuypers Electrically operable resuscitators

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Publication number Publication date
GB1243765A (en) 1971-08-25
FR2083377B1 (cg-RX-API-DMAC10.html) 1973-06-08
FR2083377A1 (cg-RX-API-DMAC10.html) 1971-12-17
DE2111691A1 (de) 1971-09-30
SE366654B (cg-RX-API-DMAC10.html) 1974-05-06
NL7103376A (cg-RX-API-DMAC10.html) 1971-09-21

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Owner name: HONEYWELL B.V. RIJSWIJKSTRAAT 175,AMSTERDAM,THE NE

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:PYE(ELECTRONIC PRODUCTS)LIMITED;REEL/FRAME:003927/0818

Effective date: 19810619