US3841327A

US3841327A - Anesthesia ventilator apparatus

Info

Publication number: US3841327A
Application number: US00376075A
Authority: US
Inventors: W Hay
Original assignee: Airco Inc
Current assignee: Airco Inc
Priority date: 1973-07-02
Filing date: 1973-07-02
Publication date: 1974-10-15
Anticipated expiration: 1991-10-15
Also published as: DE2429541C3; FR2235706A1; DK353874A; FR2235706B1; GB1431739A; JPS5438438B2; IT1014963B; DE2429541A1; SE7408336L; DE2429541B2; JPS5037292A

Abstract

An improvement is disclosed for anesthesia ventilating apparatus of the type including a patient breathing circuit, a bellows in the breathing circuit which by its expansion and contraction regulates the volume of gas cycled to the patient, a chamber surrounding the bellows, a pneumatic powering system for cyclically pressurizing and depressurizing the chamber to effect expansion and contraction of the bellows, and a highly flexible diaphragm which serves to separate, fluidly, the patient circuit from the pneumatic powering system, yet which transmits a negative pressure signal from the patient upon an attempt to inhale to trigger cycling of the pneumatic system. In the improvement, the highly flexible diaphragm, called a pucker plate, is mounted in an enclosed chamber located exterior of the bellows chamber, preferably above the chamber, and which has only its under surface in communication with the patient circuit, thus precluding moisture from accumulating on the upper surface of the flexible diaphragm, thereby assuring indefinite service without response changes due to the accumulation of such moisture on the flexible diaphragm.

Description

United States Patent [191 u :1 3,841,327 Hay 1 Oct. 15, 1974 ANESTHESIA VENTILATOR APPARATUS apparatus of the type including a patient breathing cir- [75] Inventor, Wayne w. Hay, Madison Wis cuit, a bellows in the breathing circuit which by its expansion and contraction regulates the volume of gas [73] Asslgneer 'CO, New York, NY. cycled to the patient, a chamber surrounding the bellows, a neumatic owerin s stern for c clicall res- [22] Filed. July 2, 1973 P P g y Y y P surizing and depressurizing the chamber to effect ex- PP 376,075 pansion and contraction of the bellows, and a highly flexible diaphragm which serves to separate, fluidly, [52] us CL l 128/188 the patient circuit from the pneumatic powering sys- [51] Int. 1....11111....1.11111111111111111111111111?2am 16/00 an ya wanna nananna a naaaava nanal [58] Field of Search 128/188, 202, 203, 142.2, the Patient attempt inhale trigger 128/1423 142.4, 145.5 145.6 1458 cycling of the pneumatic system. In the improvement, the highly flexible diaphragm, called a pucker plate, is [56] References Cited mounted in an enclosed chamber located exterior of the bellows chamber, preferably above the chamber, 3 046 979 STATES PATENTS and which has only its under surface in communica- Andreasen 128/1458 Primary ExaminerRichard A. Gaudet Assistant Examiner-Henry J. Recla Attorney, Agent, or FirmRoger M. Rathbun; E. W. Bopp; H. H. Mathews [57] ABSTRACT An improvement is disclosed for anesthesia ventilating tion with the patient circuit, thus precluding moisture from accumulating on the upper surface of the flexible diaphragm, thereby assuring indefinite service without response changes due to the accumulation of such moisture on the flexible diaphragm.

5 Claims, 2 Drawing Figures PATEME um 5 1914 sum 1 or 2 FIG.1

ANESTHESIA VENTILATOR APPARATUS BACKGROUND OF THE INVENTION This invention relates generally to anesthesia apparatus, and more specifically relates to the anesthesia ventilating apparatus which are in common use for providing adequate ventilating for a patient during surgery.

The anesthesia ventilating apparatus to which the present invention has application, includes devices which have found wide application in hospital operating rooms and similar environments. These ventilators are designed to replace or augment the function of a breathing bag. In particular, the said ventilators are designed to either supplement the respiratory effort of a patient who is breathing spontaneously, or in an alternate mode of functioning, take over the entire effort of respiration for a patient.

Devices of the type cited above commonly utilize a bellows as part of the breathing circuit for the apparatus, which bellows is commonly mounted in vertical orientation within a surrounding chamber. Its displacement in an upward (contraction) and downward (expansion) direction serves to control the flow and quantity of gases in the breathing circuit to the patient. The displacement of the bellows in a downward direction is commonly effected by gravity acting upon a weight mounted within the lower part of the bellows body, and its upward displacement is enabled by pneumatic powering means which pressurizes the surrounding chamber in which the bellows is mounted. The chamber pressure, so raised, causes contraction of the bellows, thereby forcing gas from the bellows to the patient circuit. Again, the degree of such powering pneumatic pressure may be controlled for a specific patients requirements.

Depending upon the desired mode of operation for the said ventilating apparatus, the pneumatic powering pressure for the chamber within which the bellows is mounted, may be provided on a predetermined cyclically timed basis, or the application of the powering pressure may be triggered by inspiratory effort on the part of the patient, i.e., the patient draws a slight negative pressure in an attempt to inhale. For the latter purposes, it has been common to provide at the bottom of the bellows a very light gauge flexible rubber diaphragm-This flexible diaphragm is commonly referred to as a pucker plate. In particular, the said diaphragm, located interior of the bellows, responds to a sufficient inhalation effort on the part of the patient by flexing, whereby a negative pressure is drawn on the opposite side of the pucker plate from the patient, that is, outside the bellows but within the bellows chamber. By this means the negative signal may be transmitted to a sensing device which is fluidly isolated from the patients circuit and thus cannot become contaminated by pathogens or the like within the patient circuit. The sensing device responds to the slight negative pressure communicated to the chamber to activate a suitable control valve in a pneumatic powering system to initiate a cycle of operation for the ventilator by pressurizing the bellows chamber, thus contracting the bellows itself.

Unfortunately, the construction described in the preceding paragraph, where the pucker plate is located at the bottom of the bellows, suffers from a defect tending to impair long-term efficient operation of the apparatus. That location within the bellows is convenient to isolate the patient circuit within the bellows from the sensing element, i.e., exterior of the bellows but within the chamber; however, its particular location is unfortunate in that moisture from the patient circuit collects on the internal surface of the bellows and drains to the bellows bottom, thereby eventually covering the upper surface of pucker plate with moisture and rendering it less sensitive to further attempts by the patient to inhale.

SUMMARY OF INVENTION Now, in accordance with the present invention, the aforementioned problem with moisture accumulation on the pucker plate has been overcome in an anesthesia ventilating apparatus by repositioning the highly flexible diaphragm constituting the pucker plate in an upper chamber overlying and exterior of the bellows chamber of the apparatus. The diaphragm is mounted within this upper chamber to fluidly separate first and second gas spaces therein on opposite sides of the diaphragm. The first gas space is formed underneath the flexible diaphragm and communicates with the patient circuit. The second gas space is formed above the flexible diaphragm and communicates with the space within the bellows chamber external of the bellows and thus to the pneumatic powering system. The relocation, in effect,

creates parallel gas spaces and frees the pucker plate from any substantial loading with accumulating moisture within the bellows. The diaphragm is so mounted within the said upper chamber that the first gas space communicating with the patient circuit. lies beneath the diaphragm, which is preferaly oriented in a generally horizontal direction, whereby any moisture in the patient circuit which may contact and condense on the diaphragm forms only on the underside thereof and drains off harrnlessly. In consequence of these construction features, the sensitivity of the ventilating apparatus to the patients inspiratory efforts is not impaired, and the apparatus may be operated for extended periods of time without changes in the performance characteristics. At the same time, the construction utilized is such that the pucker plate chamber may be readily opened, in order to gain access to the interior thereof, for inspecting or servicing the diaphragm and other components.

BRIEF DESCRIPTION OF DRAWINGS The invention is diagrammatically illustrated, by way of example, in the drawings appended hereto, in which:

FIG. 1 is-an elevational view of the ventilating apparatus constructed in accordance with the present invention; and

FIG. 2 is a vertical cross-sectional view of the ventilating apparatus depicted in FIG. 1, taken along the line 2-2 thereof.

DESCRIPTION OF PREFERRED EMBODIMENT In FIGS. 1 and 2 herein, there is shown a ventilating apparatus 10 constructed in accordance with the present invention. A conventional pneumatic powering system, not shown, may be used which responds to inspiratory effort on the part of a patient by instituting a cycle of operation of the ventilator. Such control systems are well known and include valving means to sense a predetermined negative pressure in the bellows chamber extern'al of the bellows, whereupon a main valve is actuated to pressurize the bellows container, as will be described. Such apparatus and control means are presently marketed commercially. Accordingly, these various conventional portions of the overall ventilator are not illustrated herein, but their function will become clear in the course of the ensuing description. The ventilator apparatus 10, shown, includes a frame 12, including a frame cross plate 14, and two or more vertical frame members 16 which engage at their bottom ends with a support base 18 (shown only in part). Frame 12 and support base 18 provide support for a bellows chamber 22 which is preferably formed out of clear cylindrical plastic or the like and may be enclosed within a cage 20, which is best seen in FIG. 2. The lower periphery of cylinder 22 is sealed against the support base 18 by means of a sealing ring 24 so that the gas volume within the cylinder 22 may not leak from the ends thereof.

Referring particularly to FIG. 2, it is seen that a control head 26 encloses the upper end of cylinder 22, with the walls of the head 26 being sealed with the periphery of the upper end of cylinder 22 by means of sealing ring 28. A depending flange 30 flares outwardly from head 26 within cylinder 22, and a bellows 32 is secured at its open upper end to the flange 30. The open upper periphery of the flexible bellows is sealed in gas-tight contact to the head flange 30. Bellows 32 is made of rubber or other flexible material, and is contractable and expandable in a vertical direction. In particular, in accordance with the well-known operation of this type of ventilating apparatus, positive air pressure from a pneumatic powering system is introduced to the interior of cylinder 22 surrounding the bellows 32 to force the bellows 32 to collapse upwardly, thereby forcing a volume of gas contained within the bellows outwardly through holes 33 and 35 in the head 26 and thence through passageways 34 and 31 to the patient breathing circuit via the conduit 36.

The bellows 32 carries at its lowermost convolution a weight of metal or the like, which functions to return the bellows to its lowermost, expanded position, upon completion of the inspiratory portion of the breathing cycle. During the expansion of bellows 32, the interior of the cylinder 22 is vented to atmospheric pressure through an exhaust valve in the pneumatic powering system.

in order to regulate the tidal volume or overall linear travel of the bellows, a chain 42 is secured to the bottom of the bellows 32, such as at 44, and thence is led upwardly through opening 46 in head 26 to cylinder 48, which is engaged by pin 50 to rotatable shaft 52. The shaft 52 is joumaled in head 26 and may be rotated by the control knob 54, secured to the external portion of shaft 52. Depending on patient requirements, shaft 52 is rotated to wind chain 42 about the cylinder 48 to thereby establish an adjustable limit to set the lowermost travel of bellows 32. Once set at the desired tidal volume, the control knob 54 is held by friction through O-ring 56 against flange 58 on head 26 by means of spring 60. A scale 62 is mounted externally of the apparatus, in order to provide an indication of the resultant tidal volume to the operator of the apparatus.

In accordance with the present invention, it will be seen that the uppermost portion of control head 26 is provided with an upstanding circular shoulder 64 forming at its top a rim 66. A thin flexible rubber diaphragm 68 is secured across rim 66 and then turned downwardly and sealed about the rim 66 so as to form a first gas space or chamber 70 beneath the diaphragm 68. A perforated plate 72 encloses the first gas space 70 by extending across head 26 beneath the flexible diaphragm 68. The plate 72 has its outer periphery bearing against the internal surface of head 26 as shown, and is secured by a retaining ring 73.

A second gas space or chamber 74 is formed above the diaphragm 68, enclosed within a cover 76 which is fitted over and sealed to the head 26 via sealing ring 78. The cover 76 is held in place by a retaining screw 82, which is threaded through an opening in cross plate 14, and has a lower end 84 which bears against a receiving opening in the said cover 76.

It may now be seen that the cover 76 serves together with portions of head 26 to define a pucker plate chamber 86, which chamber is divided by the flexible diaphragm 68 into a first gas space 70, and a second gas space 74. It is further seen that the second gas space 74 above the diaphragm 68 communicates via passages 88, shown in shadow, with the gas volume within cylinder 22 exterior of the bellows 32. Accordingly, it will be evident that the second gas space 74 and the gas volume within cylinder 22 exterior of bellows 32 are isolated completely from possible contamination from the patient circuit. This isolated space may then communicate with conventional pressure sensitive control means which also will remain free from contamination.

The first gas space 70, on the other hand, is seen to be in communication, through the head 26, with the conduit 36 by means of passageways 34 and 31. Conduit 36 is, in use, coupled to the patient breathing circuit. It will thus be evident that a negative pressure such as is induced by a patients inspiratory effort, will be directly communicated to the first gas space 70 beneath flexible diaphragm 68. The diaphragm 68 is caused to flex downwardly, thus transmitting the negative pressure signal to the second gas space 74 above the flexible diaphragm 68, through passages 88, to the interior of cylinder 22 and thus to a pressure sensitive control means which is then triggered to pressurize the interior of cylinder 22 to collapse bellows 32 upwardly and expel the fluid contained therein to the patient through conduit 36.

Before the increased pressure within cylinder 22 forces bellows 32 upwardly, the pressure is also transmitted to the second gas space 74 via'passages 88. The increased pressure is then transmitted through a duct 92 to inflatable exhaust valve 38 to close the exhaust valve 38. After the bellows 32 has reached its uppermost contracted position, the pneumatic controller conventionally senses the increased pressure and shifts the ventilator to exhalation phase where the bellows 32 drops freely. When the bellows reaches its lower limit the reduced pressure in the bellows cylinder 22 allows exhaust valve 38 to open and vent the breathing circuit to atmospheric pressure.

It is again pointed out that the general operational techniques utilized in the presently depicted apparatus, are conventional in the sense that a flexible diaphragm has been previously used for coupling the pressure signal induced by the patient's inspiratory effort at the breathing circuit, to the conventional pneumatic control system which communicates with the interior of the bellows chamber to effect operation of the bellows.

In accordance with the present arrangement, however, it will be evident that such moisture as may be introduced from the patient breathing circuit will enter the first gas space 70 beneath diaphragm 68, and should it condense at all on the diaphragm 68, will merely drip from the under surface thereof and hence have no effect on the sensitivity of the diaphragm. The moisture from the patient circuit thus can only condense on the underside surface of the pucker plate, yet the pucker plate still serves to effectively isolate the patient circuit, including the bellows interior, from all pneumatic controls used with the ventilator.

While the present invention has been particularly set forth in terms of specific embodiments thereof, it will be understood in view of the instant disclosure, that numerous variations upon the invention are now enabled to those skilled in the art, which variations yet reside within the scope of the instant teaching. Accordingly, the invention is to be broadly construed, and limited only by the scope and spirit of the claims now appended hereto.

I claim:

1. In anesthesia ventilating apparatus of the type including a patient breathing circuit; a bellows in said breathing circuit adapted to expand and contract to cycle gas to the patient circuit, a bellows chamber surrounding said bellows; a pneumatic powering system for cyclically pressurizing said chamber to cause the expansion and contraction of said bellows; and a highly flexible diaphragm mounted intermediate the said patient circuit and said pneumatic powering system and adapted to be displaced by a negative pressure signal from said patient circuit to effect a negative pressure signal to said pneumatic powering system for triggering cycling of said pneumatic system; the improvement comprising a diaphragm chamber containing said flexible diaphragm, said diaphragm separating said chamber into first and second separate gas spaces, said first gas space being located above said flexible diaphragm and communicating with said pneumatic powering system, and said second chamber being located below said flexible diaphragm and communicating with said patient circuit whereby moisture within said patient circuit collects on the bottom of said flexible diaphragm and drains downwardly therefrom.

2. Apparatus in accordance with claim 1 wherein said diaphragm chamber is mounted above and exterior of said bellows chamber.

3. Apparatus in accordance with claim 1 wherein said flexible diaphragm is circular and has its periphery sealed to the interior of said enclosed chamber.

4. An anesthesia ventilator for delivering gas to a patient comprising:

a patient circuit;

a head;

a cylindrical bellows chamber depending from said head, having its upper peripheral rim sealed to said head and being closed at its lower end;

a collapsible bellows suspended within said chamber for delivering fluid to said patient circuit and having its upper open end sealed to said head;

a flexible diaphragm mounted on top of said head, having its bottom surface in communication with said patient circuit, and its top surface in communication with said bellows chamber, said flexible diaphragm adapted to flex upon sensing a negative pressure in the patient circuit to transmit the negative pressure to said bellows chamber;

a pneumatic powering system communicating with said bellows chamber and adapted to respond to a negative pressure in said bellows chamber to pressurize said bellows chamber and thereby force said bellows to collapse whereby gas within said bellows is forced into the patient circuit;

normally open valve means venting the patient circuit, said valve means adapted to sense the increased pressure in said bellows chamber to close said valve means.

5. In anesthesia ventilating apparatus of the type including a patient breathing circuit; a bellows in said breathing circuit adapted to expand and contract to cycle gas to the patient circuit; a bellows chamber surrounding said bellows; a pneumatic powering system communicating with said bellows chamber for cyclically pressurizing said chamber to cause the expansion and contraction of said bellows; the improvement comprising: a diaphragm chamber, a flexible diaphragm separating said chamber into an upper gas space and a lower gas space, the upper gas space communicating with the pneumatic powering system and the lower gas space communicating with the patient breathing circuit wherein moisture from said patient circuit collects on the lowermost side of said flexible diaphragm, said diaphragm being responsive to a negative pressure signal in said patient circuit to transmit said signal to said pneumatic powering system.

Claims

4. An anesthesia ventilator for delivering gas to a patient comprising: a patient circuit; a head; a cylindrical bellows chamber depending from said head, having its upper peripheral rim sealed to said head and being closed at its lower end; a collapsible bellows suspended within said chamber for delivering fluid to said patient circuit and having its upper open end sealed to said head; a flexible diaphragm mounted on top of said head, having its bottom surface in communication with said patient circuit, and its top surface in communication with said bellows chamber, said flexible diaphragm adapted to flex upon sensing a negative pressure in the patient circuit to transmit the negative pressure to said bellows chamber; a pneumatic powering system communicating with said bellows chamber and adapted to respond to a negative pressure in said bellows chamber to pressurize said bellows chamber and thereby force said bellows to collapse whereby gas within said bellows is forced into the patient circuit; normally open valve means venting the patient circuit, said valve means adapted to sense the increased pressure in said bellows chamber to close said valve means.