U.S. patent number 3,841,327 [Application Number 05/376,075] was granted by the patent office on 1974-10-15 for anesthesia ventilator apparatus.
This patent grant is currently assigned to Airco, Inc.. Invention is credited to Wayne W. Hay.
United States Patent |
3,841,327 |
Hay |
October 15, 1974 |
ANESTHESIA VENTILATOR APPARATUS
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.
Inventors: |
Hay; Wayne W. (Madison,
WI) |
Assignee: |
Airco, Inc. (New York,
NY)
|
Family
ID: |
23483608 |
Appl.
No.: |
05/376,075 |
Filed: |
July 2, 1973 |
Current U.S.
Class: |
128/204.28;
128/205.15 |
Current CPC
Class: |
A61M
16/00 (20130101); A61M 16/104 (20130101); A61M
16/0081 (20140204); A61M 16/0075 (20130101) |
Current International
Class: |
A61M
16/00 (20060101); A61M 16/10 (20060101); A61m
016/00 () |
Field of
Search: |
;128/188,202,203,142.2,142.3,142.4,145.5,145.6,145.8 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Recla; Henry J.
Attorney, Agent or Firm: Rathbun; Roger M. Bopp; E. W.
Mathews; H. H.
Claims
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.
Description
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 patient's
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 patient's 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
harmlessly. In consequence of these construction features, the
sensitivity of the ventilating apparatus to the patient's
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 external 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 40 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 journaled 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 patient's 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.
* * * * *