U.S. patent number 3,703,172 [Application Number 05/056,073] was granted by the patent office on 1972-11-21 for heated vaporizer anesthesia machine.
This patent grant is currently assigned to Airco, Inc.. Invention is credited to Wayne W. Hay.
United States Patent |
3,703,172 |
Hay |
November 21, 1972 |
HEATED VAPORIZER ANESTHESIA MACHINE
Abstract
An anesthesia machine which utilizes a plurality of vaporizers,
each individually adapted to be heated to a constant temperature
when in use and governed by a shut-off valve assembly. The oxygen
carrier passes from a source through a pressure regulator, needle
valve, flowmeter calibrated in flowrate of oxygen to a by-pass
valve and, thereafter, to a gas fluid circuit in parallel, one
branch of which permits unadulterated oxygen flow therethrough when
the pressure exceeds a predetermined level and the other branch of
which is divided into three subbranches in parallel via a manifold,
each sub-branch including a needle valve, flowmeter calibrated in
flowrate of vapor, and a vaporizer containing liquid anesthetic
agent. All branches join for passage through an altitude
compensator valve operating on a back pressure principle to
maintain the pressure in the upstream side of the compensator at a
predetermined amount above average sea level atmospheric pressure
by damping the effect of pressure fluctuations occurring in the
downstream portion of the system on the upstream portion.
Inventors: |
Hay; Wayne W. (Madison,
WI) |
Assignee: |
Airco, Inc. (N/A)
|
Family
ID: |
26734941 |
Appl.
No.: |
05/056,073 |
Filed: |
June 26, 1970 |
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
671741 |
Sep 29, 1967 |
|
|
|
|
Current U.S.
Class: |
128/200.13;
128/204.17 |
Current CPC
Class: |
A61M
16/18 (20130101); A61M 16/104 (20130101); A61M
16/109 (20140204) |
Current International
Class: |
A61M
16/10 (20060101); A61M 16/18 (20060101); A61m
017/00 () |
Field of
Search: |
;128/188,186,204,145.8,142.2,192,191 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Oechsle; Anton O.
Assistant Examiner: Shapiro; Paul E.
Parent Case Text
This is a continuation of application Ser. No. 671,741, filed Sept.
29, 1967, and now abandoned.
Claims
Having thus described my invention, what I claim as new and desire
to secure Letters Patent of the United States is:
1. An anesthesia machine comprising an oxygen source, a supply line
leading from said source to a by-pass valve, said supply line
including a pressure regulator, a needle valve, and flow meter
adapted to measure flow rate of oxygen, said by-pass valve
comprising a body having a through-bore and a partial bore
transverse to said through-bore, said partial bore communicating
with said through-bore and an exterior surface of said valve,
pressure responsive means reversibly closing said partial bore,
said supply line being secured to said valve at one end of said
through-bore, a first outlet line being secured at one end to said
valve at the other end of said through-bore, a second outlet line
being secured at one end to said valve at the point of
communication of said partial bore with said valve exterior
surface, said first outlet line including a needle valve, a flow
meter adapted to measure flow rate of oxygen, said first line being
secured at its other end to a first opening in a vaporizer, said
vaporizer including a liquid anesthetic agent, means for
introducing said agent into said vaporizer, means maintaining said
agent at a given constant temperature, means for bubbling oxygen
received from said first outlet line through said agent, and a
second opening in said vaporizer, a third outlet line being secured
at one end in said second opening for removal of oxygen and
vaporized agent, said third outlet line merging with said second
outlet line, said merged line communicating with a breathing
circuit directly feeding a patient and altitude compensator means
in said merged line for maintaining the pressure in said merged
line at a predetermined amount above average sea level atmospheric
pressure by damping the effect of pressure fluctuations occurring
in the downstream side of said compensator means upon the upstream
side of said compensator means.
2. The combination set forth in claim 1 wherein said first outlet
line further includes secondary outlet lines connected thereto and
being secured to a plurality of vaporizers, each vaporizer having
first means independent of the other vaporizers to open and close
said first vaporizer opening, and second means joining said first
means and preventing use of more than one vaporizer at a time.
3. The combination set forth in claim 1 wherein said predetermined
amount above average sea level atmospheric pressure is about 40 mm.
Hg.
4. An anesthesia machine comprising an oxygen source, a gas fluid
system supply line running from said source into at least one
vaporizer and from said at least one vaporizer to a breathing
circuit, said supply line including at least one needle valve,
by-pass means associated with said gas fluid system supply line
adapted to direct a portion of the oxygen from said oxygen source
to the breathing circuit, a flow meter adapted to measure total
flow rate of oxygen from said oxygen source, a flow meter in said
supply line adapted to measure flow rate of oxygen for vaporizing
liquid anesthetic agent, means maintaining said liquid agent at a
predetermined constant temperature, and altitude compensator means
located between said at least one vaporizer and said breathing
circuit for maintaining the pressure in said supply line at a
predetermined amount above average sea level atmospheric pressure
by damping the effect of pressure fluctuations occurring in the
downstream side of said compensator means upon the upstream side of
said compensator means.
5. An anesthesia machine comprising an oxygen source, a gas fluid
system supply line running from said source into a plurality of
vaporizers and from said plurality of vaporizers to a breathing
circuit, first means associated with each of said plurality of
vaporizers for permitting flow therethrough, second means joining
said first means and preventing use of more than one of said
plurality of vaporizers at a time, said supply line including at
least one needle valve, by-pass means associated with said gas
fluid system supply line adapted to direct a portion of the oxygen
from said oxygen source to the breathing circuit, a flow meter
adapted to measure total flow rate of oxygen, a flow meter adapted
to measure flow rate of oxygen for vaporizing liquid anesthetic
agent, means maintaining said liquid agent at a predetermined
constant temperature; and altitude compensator means in said gas
fluid supply system immediately upstream of said breathing circuit
for maintaining the pressure in said supply line at a predetermined
amount above sea level atmospheric pressure by damping the effect
of pressure fluctuations occurring in the downstream side of said
compensator means upon the upstream side of said compensator
means.
6. An anesthetic machine comprising a gas fluid system supply line
adapted to receive oxygen from an oxygen source and to supply an
anesthetic fluid combined with the oxygen to a breathing circuit,
said supply line including at least one valve means adapted to
control the total flow of oxygen from the oxygen source, by-pass
means associated with said gas fluid system supply line adapted to
direct a portion of the oxygen from the oxygen source to the
breathing circuit, a flow meter in said supply line adapted to
measure total flow rate of oxygen from the oxygen source, an
anesthetic vaporizer in said supply line containing a liquid
anesthetic agent, a flow meter in said supply line adapted to
measure flow rate of oxygen for vaporizing the liquid anesthetic
agent, an electrical resistance heater adapted to heat the liquid
agent within said vaporizer, control means adapted to sense the
temperature of the liquid agent for controlling the resistance
heater whereby the liquid agent is maintained at a predetermined
constant temperature and, altitude compensator means in said gas
fluid supply system immediately upstream of the breathing circuit
for maintaining the pressure in said supply line at a predetermined
amount above sea level atmospheric pressure by damping the effect
of pressure fluctuations occurring in the downstream side of said
compensator means upon the upstream side of said compensator
means.
7. An anesthetic machine as defined in claim 6 wherein said
predetermined amount above average sea level atmospheric pressure
is about 40 mm. Hg.
8. An anesthetic machine comprising a vaporizer adapted to contain
an anesthetic liquid therein, said vaporizer having an inlet and an
outlet, an electrical resistance heater within said vaporizer,
means responsive to the temperature of the anesthetic liquid within
said vaporizer to control said heater to maintain the anesthetic
liquid at a predetermined constant temperature, a first supply line
having one end thereof adapted to connect to a source of oxygen and
having the other end thereof connected to said vaporizer inlet,
valve means in said first supply line for controlling the total
flow of oxygen from the oxygen source, a flow meter in said first
supply line adapted to measure the total flow rate of oxygen from
the oxygen source, a flow meter in said first supply line adapted
to measure flow rate of oxygen for vaporizing the liquid anesthetic
agent, an outlet line having one end connected to said vaporizer
outlet to receive anesthetic vapor therefrom for delivery to a
patient circuit, by-pass means in said first supply line adapted to
direct a portion of the oxygen from the oxygen source to said
outlet line, a second supply line having one end adapted to be
connected to a source of second fluid and the other end
communicating with said outlet line, said second supply line having
a valve means to control the flow of the second fluid and a flow
meter to measure the flow of said second fluid, and altitude
compensator means in said outlet line immediately upstream of the
patient circuit for maintaining the pressure in said outlet line at
a predetermined amount above average sea level atmospheric pressure
by damping the effect of pressure fluctuations occurring in the
downstream side of said compensator means upon the upstream side of
said compensator means.
9. An anesthetic vaporizer as defined in claim 8 wherein said
predetermined amount above average sea level atmospheric pressure
is about 40 mm. Hg.
10. An anesthesia machine as defined in claim 8 wherein said
altitude compensator comprises a body having an inlet means and an
outlet means, and having a central opening intermediate said inlet
means and said outlet means, a resilient diaphragm disposed
opposite said central opening movable toward and away from said
central opening to change the restriction of fluid flow passing
therethrough, spring biased operating means adapted to move said
resilient diaphragm to a selected position with respect to said
central opening whereby a predetermined backpressure is established
in the fluid flow.
Description
BACKGROUND OF THE INVENTION
Vaporized liquid agents play an important role in anesthesia either
alone or in combination with some other agent. For proper use,
knowledge of the precise concentration of vapor for introduction to
the patient should be available to avoid over-dosage and danger to
the patient.
The concentration of vapor for introduction to the patient is a
function of the temperature of the liquid in the vaporizer, the
surface area of contact between the gas carrier and the liquid to
be vaporized and the time of such contact.
A practical way to achieve saturation of the gas carrier by the
vapor is by bubbling the gas through the liquid to be vaporized.
This provides a substantial area of contact which makes the
exposure time required a negligible factor under normal gas flow
rates.
Anesthesia machines of the prior art have commonly used the
external environment as a source of heat for the liquid within the
vaporizer and sometimes thermal compensation means to compensate
for vaporizer temperature variations due to changes in the
environment. The flowrate of vapor could only be determined by
calculation, and this was subject to error due to differences in
atmospheric pressure.
SUMMARY OF THE INVENTION
It is a primary object of the present invention to provide an
anesthesia machine in which the flowrate of vapor can be read
directly from a flowmeter and in which only a single oxygen flow
reading is required so as to facilitate a determination of the
vapor concentration.
It is a further object of this invention to provide a vaporizer
including a heater and thermostat to maintain the liquid to be
vaporized at a constant, known temperature.
It is also an object of this invention to provide a means built
into the system for easy adjustment to compensate for reductions in
ambient pressure.
It is still another object of this invention to provide a novel
interlock for the shut-off valve assemblies which can preclude the
use of more than one vaporized agent at a given time.
Other objects and advantages of the invention will become apparent
from a consideration of the following description and claims, taken
together with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a flow diagram of the system;
FIG. 2 is a cross-sectional view of the by-pass valve;
FIG. 3 is a cross-sectional view of the vaporizer;
FIG. 4 is a partial cross-sectional view of the shut-off valve
assembly;
FIG. 5 is a cross-sectional view of the altitude compensator
valve;
FIG. 6 is a rear perspective view of the vaporizer housing;
FIG. 7 is an exploded view of the interlock mechanism; and
FIG. 8 is a planar view of the interlock mechanism in
operation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in more detail and by reference characters to the
drawings, in FIG. 1, pressure regulated oxygen 1 enters split
circuit 2 having needle valves 3 and flowmeters 4 calibrated in
flowrate of oxygen. The oxygen flow reunites into line 5 and passes
to a second circuit 6. Circuit 6 comprises branches 7 and 22 in
parallel with branch 7 receiving flow through by-pass valve 8 and
branch 22 receiving direct flow from line 5. By-pass valve 8 shown
in FIG. 2 comprises cap 9, body 10, yoke 11 and ball 12. Cap 9
includes a stop flange 13 abutting the free edge 14 of the body,
peripheral groove 15 receiving an O-ring gasket 16 and central
through-bore 31, and is threadedly received in body 10 in sealed
relation thereto. Body 10 is cylindrical in cross-section and has a
hollow upper portion 18 and a solid lower portion 19 which has
extending therein a pair of partial bores 20 with major axes
parallel to the major body axis. Lower portion 19 also includes a
transverse through-bore 21 which provides a passage for oxygen into
branch 22 of circuit 6 from line 5. Bore 23 in lower portion 19
provides a communication between bore 21 and upper portion 18. Yoke
11 comprises a plate 17 having aligned openings 24 and 25 and a
pair of opposed downwardly extending flanges 29 shown in dotted
lines. Openings 24 receive the reduced ends 26 of cylindrical bars
27 which have enlarged base portions 28. The bars 27 of the yoke
are received within bores 20 of body lower portion 19, said bores
containing a viscous fluid 30 which dampens sliding movement of
bars 27 in bores 20 in response to oxygen flow through bore 23.
Ball 12 is positioned within flanges 29 and closes bore 23 and
opening 25. In operation, oxygen passes under pressure through bore
21 and exerts a force in opposition to the ball and yoke weight
less the bouyant effect of the viscous fluid. When the pressure
differential across the ball exceeds approximately 1 p.s.i., ball
12 is displaced vertically to open bore 23 and permit oxygen flow
through the spaces formed between the perimeter of plate 17 and the
internal diameter of hollow upper portion 18 to branch 7 through
bore 31.
Branch 22 of circuit 6 is basically a manifold having three outlet
sub-branches 32, 33, and 34. Each sub-branch includes needle valve
35, flowmeter 36 calibrated in flowrate of vapor, and vaporizers
37. Each vaporizer has an associated shut-off valve assembly shown
in FIG. 4 and interlock means provided, if desired, for precluding
the operation of more than one vaporizer at a time. The latter
means will be described more particularly hereinafter.
In FIG. 3, vaporizer 37 includes hollow casing 38 having inlet and
outlet openings 39 and 40, respectively; an electrical equipment
housing 45 separated from casing 38 by wall 112, thermometer 41,
nipple spigot 42 with movable plug 73 for drainage of liquid
anesthetic agent, openings 43 for filling funnel 74 as shown in
FIG. 6, and opening 44 which accommodates the electrical power
leads into the electrical equipment housing 45. within the casing,
inlet tube 46 is positioned between inlet opening 39 and heater
well 47. Heater well 47 comprises a hollow cylindrical member
having axial grooves 48 extending the length thereof and secured to
the casing at opening 110 with a heater 113 shown in dotted lines
inserted therein and communicating with housing 45. Tube 46 has at
its lower end an enlarged hollow cylinder 49 which fits snugly over
heater well 47. Opening 111 in wall 112 receives therethrough
closing same a thermostat assembly 114. Outlet tube 50 extends from
outlet opening 40 to the upper part of the casing interior which is
free of liquid anesthetic agent. After the oxygen passes through
inlet tube 46 down through grooves 48 to the bottom of the casing,
it bubbles upwardly through the liquid anesthetic agent to the
upper part of the casing interior, and, with the vaporized agent,
passes down outlet tube 50 and exits from the vaporizer at 40. It
should be noted that the casing openings at 51 and 52 are
capped.
A shut-off valve assembly, designated generally at 53 in FIG. 4,
extends between points a-a on each sub-branch as shown in FIG. 1 to
control on-off flow through each vaporizer. As shown in FIG. 4, the
assembly includes a body portion 54, a camshaft 55, a detent 56
with spring bias 57, a pair of thrust pins, 58, and balls 59. The
camshaft 55 comprises a cylindrical bar with pairs of opposed, flat
grooves 60 into which an end portion of a thrust pin is received.
Each thrust pin 58 is received within a guide 62 which is in sealed
relation at 63 to the body portion. The thrust pin is sealed within
the guide by O-ring 61.
The body portion has oxygen inlet and outlet openings 64 and 65,
respectively, shown in dotted lines, with inlet openings 64
communicating with their respective circuit sub-branch and outlet
openings 65 communicating with their respective vaporizer inlet
opening 39. Balls 59 are positioned in body portion bores 66 and
are spring biased at 67 to maintain them against thrust pin noses
68. When pins 58 are in grooves 60, balls 59 close the openings 69
in gasket 70, said gasket dividing the body portion between the
inlet and outlet openings into two sealed chambers. Spring-loaded
detent 56 is notched as at 71 at each quarter turn and is secured
to the camshaft so that every other quarter turn of the detent will
cam the thrust pins to force balls 59 from sealing engagement with
openings 69 and allow oxygen to flow between the inlet and outlet
openings of the body portion, thus making the vaporizer
communicating therewith available for use.
Camshaft 55 has an extension 72 which permits turning of the detent
by way of a control knob 80 which receives the end of the extension
in bore 121 and is fixedly held by set screw 122. As seen in FIGS.
4, 6, and 7, extensions 72 extend through cover 75 which has
aligned holes 76 and slot 78. Under cover 75 can be slidably
mounted a plate 77 having aligned openings 115, 116, and 117 with
keying slots 118, 119, and 120, respectively. Each control knob 80
has a grip 79 and key 81 which is of a thickness and length to fit
through holes 76 and openings 115, 116, and 117 and into desired
keying slots. It should be noted, however, that the holes 76 are
spaced apart a greater distance than openings 115, 116, and 117.
Thus, for example, as shown in FIGS. 7 and 8, opening 116 is
properly concentrically aligned with an associated hole 76 so that
the control knob key therein can rotate 90.degree. in the opening
116 and open the vaporizer. The other two knob keys can not be
rotated since they are in slots 118 and 120 as seen in FIGS. 4 and
8. This interlock mechanism prevents the possible erroneous or
careless use of more than one vaporizer at a time. A pin 123
extends through slot 78 to slide the plate 77 below cover 75 so
that the knob above the desired vaporizer can be rotated. If such
is consciously desired, the plate 77 can be removed entirely and
the knobs operated without restriction. Once the knob has been
rotated 90.degree. in the hole 76 and opening 116, the plate 77 as
seen in FIG. 8 cannot be slided to permit another knob to be
rotated until the first knob returns to off position. Other gases,
e.g., nitrous oxide or helium, can be introduced to the system
through supply lines 107 as shown in FIG. 1. Each supply line 107
includes needle valve 105 and flowmeter 106 calibrated in flowrate
of the specific gas.
With any one vaporizer open, oxygen passes therethrough, becomes
saturated with vaporized anesthetic agent and reunites in line 108
with the unadulterated oxygen flow and other gas. The united flow
then passes through altitude compensator valve generally designated
in FIG. 1 as 83 and into the circuit leading directly to the
patient.
The altitude compensator valve, shown in FIG. 5, includes inlet
elbow 84 received within body portion 85 and communicating with
diaphragm 87, and pressure relief elbow 86 also received within the
body portion. Diaphragm 87 is held in place at 88 by pressure
contact between the lower part of body portion 85 and the upper
part of cap 89 caused by clamp 94. Body portion 85 has central
opening 91 which communicates with central opening 92 of outlet 93
which is mounted on the body portion and secured thereto by bolts
90. The outlet and body portions are secured in sealed relation by
"O" ring gasket 95. Cap 89 includes an open end receiving a hollow
piston 96 having a closed end 97 adjacent the diaphragm and secured
thereto by adhesive 98, and a substantially closed end 99.
Compression spring 100 is received within piston 96 and has one end
abutting the piston closed end 97 and the other end attached to
seat 101. Adjusting screw 102 extends through an opening in
substantially closed end 99 and has a neck portion 103 received
within an opening in seat 101. Hex nut 104 is threaded onto screw
102 and securely abuts end 99.
In operation, the system is designed to flow at a pressure of
approximately 800 mm of mercury absolute. In order to reduce this
pressure to ambient pressure where used, the screw 102 varies the
spring force against diaphragm 87 to produce a back pressure equal
to the difference between 800 mm of mercury and the ambient
pressure of the environment. Thus, the back pressure affects both
branches 7 and 22 of circuit 6 with branch 7 pressure being 1
p.s.i. below the back pressure at the by-pass valve inlet so that
ball 21 can be displaced vertically and oxygen can flow into branch
7. As the back pressure in the breathing circuit will have a
negligible effect on the difference between the pressure in the
anesthesia machine and the atmospheric pressure with which the
machine is surrounded, the compensator means acts to dampen the
effect of pressure fluctuations occurring at its downstream side
upon the upstream side of the compensator.
Temperature in the vaporizer should be held constant at 75.degree.
F. by means of thermostat regulated heater 47.
Thus, the system provides a single oxygen flow reading at 4, a
constant pressure differential regulated by the altitude
compensator valve, and constant temperature in the vaporizers.
With a known constant temperature in the vaporizer, a known vapor
pressure results. Flowmeters 36 can, therefore, be calibrated
directly in flowrate of vapor for oxygen flow in branch 22 through
flowmeters 36. Knowing the volume of vapor by reading flowmeters 36
and the volume of oxygen by reading flowmeters 4 and other gases by
reading flowmeters 106, the concentration of vapor entering the
system directly feeding the patient breathing circuit can be
determined.
It is intended that all matter contained in the above description
or shown in the accompanying drawings shall be interposed as
illustrative and not in a limiting sense.
* * * * *