U.S. patent number 3,566,865 [Application Number 04/736,427] was granted by the patent office on 1971-03-02 for anesthesia system.
This patent grant is currently assigned to Air Reduction Company, Incorporated. Invention is credited to Wayne W. Hay.
United States Patent |
3,566,865 |
Hay |
March 2, 1971 |
**Please see images for:
( Certificate of Correction ) ** |
ANESTHESIA SYSTEM
Abstract
An anesthesia system having a main circuit and a sample bypass,
said bypass being manually opened and closed to gas flow from the
main circuit by a zeroing valve and having an oxygen analyzer, an
anesthetic analyzer and automatic controllers associated
therewith.
Inventors: |
Hay; Wayne W. (Madison,
WI) |
Assignee: |
Air Reduction Company,
Incorporated (New York, NY)
|
Family
ID: |
24959811 |
Appl.
No.: |
04/736,427 |
Filed: |
June 12, 1968 |
Current U.S.
Class: |
128/203.14;
73/863.83; 137/625.62; 137/870; 73/1.06 |
Current CPC
Class: |
A61M
16/104 (20130101); A61M 16/0066 (20130101); Y10T
137/86598 (20150401); Y10T 137/87772 (20150401) |
Current International
Class: |
A61M
16/10 (20060101); A61M 16/00 (20060101); A61m
017/00 () |
Field of
Search: |
;128/188,191,194
;250/43.5 ;307/235 ;137/610,625.62,(Inquired),362 ;73/1 (A)/
;73/422 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Dunne; G. F.
Parent Case Text
CROSS-REFERENCES TO RELATED APPLICATIONS
This application relates to the subject matter of application Ser.
No. 688,480, filed on Dec. 6, 1967 for "Automatic Vaporizer
Controller" and assigned to the same assignee.
Claims
I claim:
1. An anesthesia system comprising a flow stream to and away from a
patient and source means of oxygen and anesthetic, said stream
having a sample bypass, said bypass receiving a sample of the flow
in said stream and having analysis means for determining the
concentration of certain constituents in said sample flow, and
valve means connected to said bypass and adapted to cut off sample
flow to said bypass and open said bypass to a second flow of known
concentrations to permit the bypass to sample said second flow and
check the accuracy of the analysis means, said valve means
comprising a pair of parallel plates, one of said plates has means
slidably receiving the other of said plates and stop means to limit
sliding movement, each plate has a pair of nipples connected to
respective bypass tubes and extending perpendicularly to the plates
with each extending oppositely and having the same spacing, and one
of said plates has a hole therethrough between its pair of nipples
so that when the pairs of nipples are aligned in a first position,
the bypass will sample flow from said stream and when the pairs of
nipples are nonaligned in a second position, the opening of said
one plate is aligned with a nipple of the other plate to permit the
bypass to sample said second flow.
2. An anesthetic system comprising a flow stream to and from a
patient and source means of oxygen, nitrous oxide and vaporizable
anesthetic agent, said stream having a sample bypass, said bypass
receiving a sample of flow in said stream and having analysis
means, said analysis means including oxygen analysis means for
determining the oxygen content of the sample flow and anesthetic
analysis means for determining the concentration of said
vaporizable anesthetic agent in said sample flow, vale means
connected to said bypass and adapted to cut off flow to said bypass
and open said bypass to a second flow of known concentrations to
permit the bypass to sample said second flow and check the accuracy
of the analysis means, said valve means comprising a pair of
parallel plates, one of said plates has means slidably receiving
the other of said plates and stop means to limit siding movement,
each plate has a pair of nipples connected to respective bypass
tubes and extending perpendicularly thereto with each pair
extending oppositely and having the same spacing, and one of said
plates has a hole therein between said nipples so that when the
pairs of nipples are aligned in a first position, the bypass will
sample flow from said stream and when the pairs of nipples are
nonaligned in a second position, the opening of said one plate is
aligned with a nipple of the other plate to permit the bypass to
sample said second flow.
3. In an anesthetic system having a flow stream for delivering
anesthetic to a patient, a bypass system comprising a first tubing
means for withdrawing fluid from the flow stream, a second tubing
means for returning withdrawn fluid to the flow stream, analysis
means intermediate said first and second tubing means for
determining the anesthetic content of the withdrawn fluid, and a
valve means connected to said first and second tubing means, said
valve means comprising a pair of parallel plates, one of said
plates having a pair of holes in alignment with said tubing means
and the other of said plates slidingly received in said one plate
and having three holes therein, said other plate being movable
between a first position wherein two of its holes are aligned with
said tubing means to introduce withdrawn fluid to said analysis
means, and a second position wherein the third hole is aligned with
said first tubing means whereby a second fluid is allowed to enter
said first tubing to said analysis means.
4. An anesthesia system as set forth in claim 3 wherein said second
fluid is air.
5. An anesthesia system as set forth in claim 4 wherein said valve
means includes stop means to limit the relative movement of said
plates at said first and second positions.
6. In an anesthesia system having a flow stream for delivering
anesthetic to a patient, a bypass system comprising tubing means
for withdrawing fluid from the flow stream, analysis means for
determining the anesthetic content of the withdrawn fluid, and
valve means in said tubing for interrupting the flow of withdrawn
fluid to said analysis means, said valve means comprising first and
second parallel plates, said first plate having at least one
opening, said second plate having at least two openings, said
plates slidingly received with respect to each other between a
first position wherein one of said openings in said second plate is
aligned with said at least one opening in said first plate whereby
withdrawn fluid passes therethrough to said analysis means and a
second position wherein the other of said openings in said second
plate is aligned with said at least one opening in said first plate
whereby a second fluid is introduced to said analysis means.
7. An anesthesia system as set forth in claim 6 wherein said second
fluid is air.
Description
BACKGROUND OF THE INVENTION
Anesthesia is administered through nonrebreathing, partial
rebreathing, or rebreathing systems. The nonrebreathing system has
permitted the most accurate knowledge of the concentration of
anesthetic agent administered, since the concentration of new agent
administered is the concentration of agent inhaled. However, use of
the system is very costly because large amounts of anesthetic agent
are exhaled to the atmosphere.
Where partial rebreathing and rebreathing systems are used,
accurate knowledge of agent concentration is not readily available
because of the recirculation of exhaled anesthetic agent in
addition to that newly administered. The rebreathing systems
substantially eliminate waste, but require intensive observation of
the patient by the anesthetist and may employ extensive apparatus
for analysis and even automatic control.
The prior art has not provided efficient apparatus for anesthetic
concentration control in a rebreathing system, nor has the prior
art provided for oxygen analysis in a rebreathing system to
indicate the oxygen percentage reaching the patient. Presently,
control is accomplished solely by the anesthetist through
observation of the patient.
SUMMARY OF THE INVENTION
This invention relates to the analysis of the oxygen and anesthetic
concentration in an anesthesia system, the automatic control of
such concentrations, and the utilization of a unique valving
arrangement for permitting a check on the stability of the
analyzers employed.
The specific embodiment referred to hereafter relates to the
analysis and automatic control of the concentration of
1,1,1-trifluoro-2-bromo-2-chloroethane (Halothane), although other
embodiments are contemplated with different anesthetics and this in
no way is to limit the scope of applicant's invention.
Since nitrous oxide is a common complement of an oxygen/Halothane
mixture as well as other mixtures in chemical practice, users are
in need of an oxygen content monitor built into the system to
indicate oxygen content as well as provide a possible means for
automatically controlling the flow of a diluent anesthetic, such as
nitrous oxide or the oxygen itself. It is therefore an object of
the present invention to incorporate oxygen and anesthetic
analyzers with automatic concentration control into an anesthesia
system.
Since an anesthetic analyzer must be rezeroed to verify the
accuracy of the zero point of its meter, air can be sampled for
this purpose rather than the regular gas flow. The air sampling
also permits checking of the oxygen analyzer meter at, for example,
21 percent concentration.
It is, therefore, a further object of this invention to provide a
novel valving arrangement to permit checks on the accuracy of the
analyzers.
The foregoing objects and other objects, features, and advantages
will become apparent in the light of the following description and
claims taken with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a combined schematic illustration of the anesthesia flow
through the fluid analysis and anesthetic control sample bypass
with the zeroing valve in position.
FIG. 2 is a cross-sectional view of the zeroing valve in position
to permit flow from the anesthesia circuit through the
analyzers.
FIG. 3 is an end view of the zeroing valve showing the sliding
relationship .
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now in more detail and with reference characters to the
drawings, in FIG. 1, inhalation gas stream 1 leading to the patient
has a sample bypass 2 which includes main lines 23, 23a and 24, 24a
and branch line 2a which splits into a vaporizer flow line 3 and
analysis flow line 4. Main line 24, 24a is shown in FIG. 1
returning to stream 1, but it could return elsewhere, as, e.g. the
exhalation gas stream, not shown. Vaporizer flow line 3 includes a
pump 5, a first solenoid-operated valve 6, a vaporizer 7 including
liquid anesthetic 1,1,1-trifluoro-2-bromo-2-chloroethane
(Halothane) reservoir 8 through which the vaporizer flow is bubbled
for saturation with the Halothane vapor, and a second
solenoid-operated valve 9 before rejoining main line 24 at 10.
It should be noted that the pump and two solenoid operated valves
operate simultaneously to permit flow in line 3 under a pressure
differential.
The analysis flow 4 enters sensor cell 11 at 14. Sensor cell 11 is
held fixedly in place by support bar 16 attached to support 17.
Drum 18 is adapted to rotate at a constant speed of approximately
120 r.p.m. on drive shaft 12 which is in drive relation to drive
shaft 19 of synchronous motor 13 by a worm gear arrangement
generally designated at 20. The flow exits cell 11 at 15 and
rejoins main line 23 at 21 through line 22.
Circulation fan 25 moves the flow through the main bypass lines 23,
24, and is driven by motor 13 through shaft 19 at approximately
3,600 r.p.m. The fan provides for circulation of a representative
sample of the rebreathing gas constituents.
Sensor cell 11 is of hollow rectangle box shape with opaque
sidewalls 26 and opposed light transparent windows 27 preferably
made of quartz. Drum 18 comprises a hollow cylindrical member
having diametrically opposed openings 28. Within one opening is
placed a phosphor-quartz material 29 having a light conversion peak
at a predetermined wavelength band while the other is left vacant.
Drum 18 further comprises a base plate 30 closing one end to which
the drive shaft 12 is connected and an open end through which is
received sensor cell 11.
In operation, an ultraviolet light source, lamp 31, emitting light
at the conversion peak of material 29 is placed to one side of the
drum and a photoresistor 32 having lead wires 33, 34 is placed
adjacent the diametrically opposed side of the drum. As the drum
rotates at a constant speed, each 180.degree. of drum rotation
presents a drum opening 28 adjacent the source 31 alternately
vacant as in FIG. 1 and then with the material 29. With cell
windows 27 in fixed position, the drum acts as a chopper to the
light source to each 180.degree. when the source 31, openings 28,
windows 27, and photoresistor 32 are aligned. Since the single cell
11 is used, there is a pulse-type output through the photoresistor.
The pulse-type output is a result of a reference pulse obtained
when material 29 is adjacent source 31 and a data pulse obtained
when vacant opening 28 is adjacent to the source.
The reference pulse is obtained when the source emits light in the
given wavelength band which light is converted by material 29 to
visible light which then passes through the sensor cell 11
undiminished in intensity and is "read" by photoresistor 32. The
data pulse is obtained when the source emits light in the given
wavelength band which light passes through vacant window 28 when
the chopper drum has rotated 180.degree. and, in passing through
cell 11, has its intensity diminished by absorption in the given
wavelength band by the gas sample present in the cell. The
diminished light intensity is then converted by material 29 to
visible light at the reduced intensity which is "read" by the
photoresistor.
The comparison between reference and data pulses determines the
concentration of anesthetic vapor agent in the gas sample since it
is only the vapor agent which is capable of light absorption in the
given wavelength band.
Conventional Reed switches 36 are positioned adjacent opposed drum
sides. The drum further comprises a permanent magnet 35 which is
positioned on said drum so that when said drum permits light to
pass to the photoresistor said magnet actuates one of said Reed
switches.
Although the electrical analysis and control circuitry for
Halothane is not being shown or disclosed herein in particularity,
it is shown and disclosed in application Ser. No. 688,480, referred
to hereinabove. For purposes of this application, Reed switches 36
lead to a pair of linear gates which separate the pulses for data
charge storage and reference charge storage. Photoresistor 32 has a
lead into the separator and supplies it with the pulses for
separation and later charge storage. The photoresistor also has a
lead to a Schmidt trigger which initiates the action of the charge
storage drain circuit which is responsive to drum rotation. The
trigger actuates the drains which drain the charge from the
capacitor storage systems for receipt of new pulse charges.
The storage systems each feed an amplifier through which a meter
reading can be obtained. The meter leads into a meter relay by
which the anesthetic vapor agent concentration is controlled. The
meter relay has a concentration control setting operated by the
anesthetist which setting actuates the vaporizer pump 5 and
solenoid operated valves 6 and 9 simultaneously to permit vapor
flow 3 and increase the vapor concentration if such should fall
below the setting. An additional control is provided to give the
anesthetist the choice of monitoring or controlling anesthetic
concentration. Vapor flow 3 provides increased Halothane vapor
concentration in the analysis flow 4 after circulation thus causing
a new meter reading eventually bringing the reading up to the
setting.
It should be noted that in order to have a stable system, the
ultraviolet light source 31 should be maintained at a constant
intensity by means of regulating the lamp current such that the
reference pulse is of constant amplitude. Thus, a lamp starter for
initial use and regulator is provided so that if the intensity is
decreasing, the regulator can permit additional current flow to
maintain the lamp intensity.
Since the preferred embodiment is intended for use in closed
circuit anesthesia, it is not feasible to use anything but oxygen
and Halothane in the mixture unless the oxygen content of the
respired mixture is monitored. Nitrous oxide is a common complement
of an oxygen/Halothane mixture in clinical practice, and many users
would be reluctant to dispense with it and be unable to monitor the
oxygen concentration with a conventional oxygen analyzer not built
into the system.
An oxygen analyzer generally designated at 37 is positioned with a
conventional self-powered fuel cell 38 in flow relation to main
line 23 and further comprises a potentiometer 39 and a milliammeter
40. The current generated by the fuel cell 38 is proportional to
the oxygen concentration of the contacting fluid in line 23, and
the milliammeter is calibrated to read oxygen concentration.
As in the Halothane analyzer, the meter reading of oxygen
concentration can be fed to a meter relay (not shown) by which the
oxygen concentration can be controlled -- either by oxygen flow
control or nitrous oxide flow control of the needle valves
associated with the respective gas sources.
To permit a check on the zeroing of the Halothane analyzer and the
accuracy of the oxygen analyzer, a zeroing valve generally
designated at 40 is positioned as shown in FIG. 1.
More particularly, as shown in FIG. 2, the valve 40 comprises an
analyzer plate 41 having nipples 42 and 43 which are received
within lines 24 and 23, respectively, and bypass plate 44 having
nipples 45 and 46 which are received within lines 24a and 23a,
respectively.
As shown in FIG. 3, bypass plate 44 is slidably received within the
flanged recesses of plate 41. However, plate 41, as shown in FIG.
2, has stops 47, 48 to limit the sliding movement of plate 44 with
respect thereto.
Bypass plate 44 has an opening 49 between nipples 45, 46 with
nipples 45, 46 each having an internal recess adjacent plate 41
receiving an O-ring seal 50 therein to prevent the entry of air or
gas as the case may be.
In operation, when end 51 of plate 44 abuts stop 47, O-ring seals
50 prevent air from entering the nipples. Nipples 42 and 45 and
nipples 43 and 46 are aligned to permit gas flow from the gas
stream 1 through nipples 46 and 43, respectively, into bypass 2
through lines 23a and 23. After passing through the bypass
circuitry, the gas returns to the gas stream through lines 24 and
24a and nipples 42 and 45. The gas has been analyzed for oxygen and
Halothane concentration and, depending on the readings of each,
could be automatically controlled as to concentration of Halothane
and oxygen, the oxygen content being controlled through the needle
valves at the flow lines from either the oxygen or nitrous oxide
sources.
When the accuracy of the oxygen analyzer and the zeroing of the
Halothane analyzer is to be checked, the bypass plate 44 is moved
until the end 52 of plate 44 abuts stop 48. In this position,
nipple 42 is unopposed by nipple 45 since nipple 45 has moved to
the former position of opening 49 and is sealed against plate 41.
Opening 49 now is aligned with nipple 43 and nipple 46 is sealed
against plate 41. Thus, air will be introduced into bypass 2
through opening 49, nipple 43 and line 23 by the circulation fan
and returned to atmosphere through line 24 and nipple 42 which is
unopposed.
Since air contains no Halothane and a known concentration of oxygen
at a given location, the Halothane meter can be rezeroed on a
no-Halothane reading and the oxygen analyzer can be checked for a
reading of the known oxygen concentration of the air. Under these
checking circumstances, the anesthetist would terminate automatic
concentration control and merely monitor to minimize loss of
Halothane due to the zero air reading of the analyzer which would
be below the normal setting.
This valving arrangement minimizes the number of motions required
to check accuracy and also provides an important safety function in
retaining all tubing connections (23, 23a, 24, 24a) intact rather
than requiring removal with possible transposing of tubes on
reconnection.
The above description should be viewed as illustrative of a
preferred embodiment and not in a limiting sense.
* * * * *