U.S. patent number 3,811,800 [Application Number 05/271,011] was granted by the patent office on 1974-05-21 for blood pump.
Invention is credited to Karl Shill.
United States Patent |
3,811,800 |
Shill |
May 21, 1974 |
BLOOD PUMP
Abstract
This invention relates to a pump for an "artificial kidney
machine", or hemodialysis device; and primarily is designed for the
pumping of blood for purification in such a system using the
recently announced procedure of "single needle" dialysis, whereby a
single needle is temporarily inserted into a vein or artery of a
patient through which blood is withdrawn from the vein for
purification and returned to the patient through the same needle.
Such a dialysis system requires, in addition to the filter and
pump, a device commonly called an "occluder" by means of which
purified blood from the filter is prevented from flowing to the
needle during the suction stroke of the pump when blood is
withdrawn from the patient and is open to flow during the pumping
stroke.
Inventors: |
Shill; Karl (Fremont, CA) |
Family
ID: |
23033809 |
Appl.
No.: |
05/271,011 |
Filed: |
July 12, 1972 |
Current U.S.
Class: |
417/317; 417/478;
604/153; 604/6.05; 417/394; 417/479 |
Current CPC
Class: |
A61M
1/30 (20130101); A61M 60/43 (20210101); A61M
1/302 (20140204); A61M 60/435 (20210101); A61M
60/40 (20210101); F04B 7/0275 (20130101); A61M
60/284 (20210101); F04B 43/113 (20130101); A61M
1/307 (20140204); A61M 60/122 (20210101); A61M
60/113 (20210101); A61M 60/892 (20210101) |
Current International
Class: |
A61M
1/10 (20060101); A61M 1/30 (20060101); F04B
7/02 (20060101); F04B 7/00 (20060101); F04B
43/113 (20060101); F04B 43/00 (20060101); F04b
043/10 (); F04b 045/06 (); A61m 005/00 () |
Field of
Search: |
;128/DIG.3,214B,214R,214.2 ;417/317,394,479,474,478,395 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Freeh; William L.
Assistant Examiner: Gluck; Richard E.
Attorney, Agent or Firm: Wilcox; Robyn
Claims
1. A surgical pump comprising:
1. a casing;
2. a longitudinal duct through said casing adapted to receive a
blood tube;
3. an inlet valve member in said casing adjacent one end of said
duct and an outlet valve member in said casing adjacent the other
end of said duct each of said valves comprising:
a. a cylinder within said casing,
b. a piston operating in said cylinder, said piston having a
projection engaging said blood tube; and
c. means for alternately supplying fluid under pressure to and
draining fluid from said cylinder;
4. a pressure tube within said duct and lying adjacent said blood
tube;
5. means for supplying fluid under pressure to said pressure tube
substantially simultaneously with the opening of said outlet valve
and the closing of said inlet valve and for draining said pressure
tube and substantially simultaneously opening said inlet valve and
closing said outlet valve; and
6. resilient tube adapted to lie in said duct and leading into a
discharge
2. The apparatus of claim 1 comprising also an occluder in the
discharge line of said pump and means for operating said occluder
to open said discharge line to flow simultaneously with the opening
of the outlet valve to flow and closing the occluder to flow
simultaneously with the closing
3. The apparatus of claim 1 comprising also means for measuring the
flow
4. A dialysis pumping system for use in connection with a single
needle dialysis technique in a kidney machine in which blood is
taken from a patient and returned to the patient after treatment
through a single needle, said pumping system comprising:
1. a casing,
2. a longitudinal duct through said casing, said duct being adapted
to receive a flexible blood tube,
3. a power supply conduit in said casing for supplying fluid under
pressure,
4. a drain conduit in said casing for draining fluid,
5. an inlet valve at one end of said longitudinal duct and a
discharge valve at the other end of said duct, said valves
comprising:
a. cylinders in said casing communicating with said duct, and
b. pistons within said cylinders, said pistons having projections
bearing against said blood tube,
6. an enlarged chamber adjacent to, and communicating with, said
duct between said inlet valve and said outlet valve,
7. a resilient pressure tube in said enlarged chamber,
8. branch conduits leading from said power supply conduit to said
inlet valve cylinder, said pressure tube and said discharge valve
cylinder,
9. branch conduits leading from said inlet valve cylinder, said
pressure tube and said discharge valve cylinder to said drain
conduit,
10. flow valves in said branch conduits,
11. means for operating said flow valves,
12. a timer for operating said last mentioned means in sequence to
connect said inlet valve and said pressure tube to said pressure
supply conduit and close them to drain and simultaneously opening
said discharge valve to drain and closing it to the pressure supply
conduit; and alternately open the inlet valve and the pressure tube
to drain while closing them to the pressure conduit and
simultaneously opening the discharge valve to the pressure conduit
while closing it to drain;
13. means for operating an occluder valve simultaneously and in
parallel phases with said discharge valve; and
14. a blood tube adapted to lie in said duct and having a strongly
resilient tube encompassing and cemented to the portion of said
blood tube adapted to lie within said duct, whereby a vacuum will
be applied to said
5. The pumping system of claim 4 wherein the inlet and discharge
valves are operated by water pressure which is controlled by
respective solenoids.
Description
BACKGROUND OF THE INVENTION
One of the important medical advances of our time is the invention
and development of the "artificial kidney machine" referred to in
medical circles as a "hemodialysis machine," by Dr. Willem Kolff,
now associated with the University of Utah. The dialysis machine
was invented by Dr. Kolff about 25 years ago. While a modern
hemodialysis system for purifying blood is often categorized as "an
artificial kidney machine," it is in fact an assemblage of
specialized laboratory or clinical apparatus which can be made to
filter out waste material normally processed by the kidneys and
expelled from the body through the urine. Such a system generally
comprises:
A. A MEANS FOR CONDUCTING WASTE LADEN BLOOD FROM THE PATIENT AND
THE PURIFIED BLOOD BACK TO THE PATIENT;
B. A FILTER HAVING A MEMBRANE THROUGH WHICH WILL PASS WASTE SOLUTES
WHILE PREVENTING THE PASSAGE OF BLOOD, AND THEREBY SEPARATE THE
WASTE FLUIDS FROM THE BLOOD;
C. A DIALYSATE FLUID WHICH ACTS THROUGH THE MEMBRANE OF THE FILTER
IN ORDER TO WITHDRAW THE FLUID WASTES IN THE BLOOD FROM THE
BLOOD;
D. A DIALYSATE PROPORTIONING AND DELIVERY SYSTEM;
E. means for propelling the blood through the filter and the
associated apparatus, i.e., a specialized blood pump. Preferably
the pump should exert a pressure greater than that supplied by the
body so as to force the purified blood back into the body and
permit the withdrawal of waste laden blood from the body;
F. A HEPARIN PUMP WHICH INJECTS A MINUTE QUANTITY OF ANTI-COAGULANT
INTO THE BLOOD BEING PURIFIED TO CONTROL THE BLOOD CLOTTING WHICH
WOULD OTHERWISE OCCUR;
G. MUCH MISCELLANEOUS HARDWARE SUCH AS BUBBLE TRAPS, MEDICINE
INJECTION CUFFS, METERING DEVICES, HEATERS AND CONTROLS FOR
MAINTAINING THE DIALYSATE AND BLOOD WITHIN CLINICAL LIMITS,
MONITORING DEVICES TO SOUND AN ALARM AND/OR CONTROL THE PROCEDURE
SO AS TO PROTECT THE PATIENT, AND THE INSTRUMENTS NORMALLY USED BY
A DOCTOR IN SUCH A PROCEDURE.
This invention is concerned with item (e), the specialized blood
pump which performs an auxiliary heart function for a prolonged
period, and preferably does so with minimal damage to the
blood.
Since the original invention, much time and effort has been spent
in trying to improve the operation of these devices in order to
make them more efficient, to make the complete system truly
portable and less expensive, and to develop one that could be used
in the home rather than requiring treatment in a hospital or
clinic. One of the defects of prior machines has been the fact that
they have been very large, very expensive and required expert
medical attention under clinical or surgical conditions. This made
treatment not only expensive, but also required the patient to go
to a hospital or clinic every two or three days for treatment -
which automatically limited patients to an urban area and to those
who could spend considerable time in travel to and from the
hospital or clinic. Thus, most patients were financially unable to
get treatment because such machines could be supplied only by large
hospitals or well-endowed clinics. Many people just don't have the
time or resources necessary for such a procedure. In the past, for
dialysis treatment, a patient had to undergo a surgical procedure
by means of which an artificial "plug-in" connection, or "canula,"
was placed in the artery and also in a vein, blood being withdrawn
from the artery for treatment in the machine and then returned to
the vein. Since there are relatively few spots in the body where an
artery is close to the skin, the number of places where such a
canula could be placed in an artery was very limited. The life of
such a canula is quite short, as the natural bodily processes make
it unuseable (a period sometimes as short as 6 weeks and seldom as
long as a year) and a new, costly and painful surgical procedure
was required. Eventually there is no place left to place such a
canula, and the patient is doomed.
In 1971 the researchers under the direction of Dr. Kolff developed
a new technique called the "single needle dialysis technique"
whereby the canula problems are eliminated. In this procedure a
single needle is inserted into a vein (many of which are quite
close to the skin and therefore readily accessible, for withdrawing
blood samples, taking blood for a transfusion or storage in a blood
bank, etc.) and after this blood is purified in the machine, it is
injected into the patient through the same needle. Dr. Kolff, at
the University of Utah, has very recently announced a truly
inexpensive dialysis machine which would be within the price range
of most American families and, which is more important, could be
utilized in the home. Such a system requires that a very small
amount of blood be withdrawn through any suction stroke in order to
avoid collapsing the vein. The volume of each stroke is usually
within the range of 1.5 to 2.5 cc. per stroke at the rate of
between 60 and 120 strokes per minute, depending upon the age, size
of the patient, and size of the available vein. During the suction
stroke of the pump, the blood is taken from the body of the patient
through the single needle and one leg of a Y-connection; and then
during the pumping stroke, passes through the filter and back into
the patient's body through the other leg of the Y-connection and
through the same needle. Patients can be readily trained to insert
the needle themselves.
Such a system requires the use of at least one valve device, or
occluder, which preferably is located in the tube delivering
purified blood to the patient, and is operative to shut off the
flow of purified blood to the patient during the suction stroke of
the pump. Furthermore, this occluder, as it is commonly called,
must operate in timed sequence to the operation of the pump.
Obviously, the occluder must be open for the passage of blood
during the time that the pump is pushing blood through the filter
and back into the body of a patient, but should completely close
the purified blood delivery line during that portion of the cycle
in which the pump is withdrawing blood from the body of a
patient.
One of the features of the present invention is that the volume of
blood pumped in each stroke is variable through a wide range and
adjustments can be made easily and accurately while the pump is in
operation. Another feature is that the force applied to the blood
in the conduit is also variable over a considerable range, and
again adjustments can be made while the pump is in operation. More
important is the fact that the pump and occluder of the present
invention are isolated from the tubes carrying the blood from the
patient to the dialysis filter and returning it to the body, so
that neither the pump nor the occluder need to be sterilized
between uses. It will be understood that in such a procedure as
dialysis, the needle, the blood tubes, and the filter will have to
be sterilized or replaced between each use, and this is commonly
done; but it is unnecessary to sterilize either the pump or the
occluder of the present invention, as the sterilized tubes are
inserted through the pump and occluder and the blood does not come
into direct contact with these devices.
OBJECTS
It is a primary object of the present invention to provide a small,
light-weight pump for a dialysis machine.
It is a further object of the present invention to provide a small,
light-weight pump which can be operated by hydraulic pressure that
does not need to be as great as that ordinarily supplied in a city
water supply, and in fact can be operated from a portable hydraulic
supply, such as those found in many recreational vehicles.
It is a further object of the present invention to provide an
artificial kidney pump with an infinitely variable volumetric
adjustment.
It is another object of the present invention to provide a pump for
a dialysis machine that is adapted to be used with a single needle
dialysis system, i.e., one in which a single needle is used to
withdraw blood from, and return it to the patient.
It is still another object of the present invention to provide a
quiet and positive operation for an occluding device which controls
the flow of the patient's blood from, and the delivery of the
purified blood back to, the patient through a single hypodermic
needle.
It is a further object of the present invention to provide a
surgical pump, which may include an occluder, that does not have to
be sterilized, since only the tubes through which the blood passes
and the filter needs to be sterile since the tube or tubes may be
readily inserted through the above-mentioned devices.
A still further object of the present invention is to provide a
blood pump which may be used for prolonged periods of time without
causing blood cell rupture known as "hemolysis."
These and other objects of the present invention will be apparent
from the specification which follows taken in conjunction with the
accompanying drawings in which:
FIG. 1 is a diagrammatic view of the dialysis system with which the
present invention is designed to be associated, showing the pump of
the present invention interposed between the supply tube to the
dialysis filter for withdrawing blood from the patient and passing
it to the filter.
FIG. 2 is a cross-sectional view through one of the valves of the
pump, such as taken along the plane indicated by the line 2--2 of
FIG. 1.
FIG. 3 is a cross-sectional view of the power section of the
present invention showing also the means for supplying hydraulic
power and releasing it.
FIG. 4 is a diagrammatic cross-sectional view of the pump of the
present invention showing the various hydraulic supply valves in
the positions they would occupy at the start of the suction phase
of a cycle of operation during which blood is to be withdrawn from
the body of a patient.
FIG. 5 is a timing diagram showing the operation of the three
important valves and the supply of hydraulic fluid to the pressure
chamber.
The single needle dialysis system with which the pump of the
present invention is particularly adapted to control is shown in
FIG. 1. The usual surgical hypodermic needle 10 can be inserted
into any suitable vein of the patient. A Y-member 11 is affixed to
the needle 10, and a suction hose 12 leads from one leg of the
Y-member 11 to and through the pump 40, the section of the suction
tube 12 leading from the pump to a dialysis filter 15 being
indicated by the reference character 14. It will be understood that
the tube 12 and 14 is integral, the two reference characters being
used to indicate the two sections of a single tube. The other leg
of the Y-member 11 is connected to the delivery tube 13 leading
from the filter 15.
It is conventional in an apparatus of this kind to pass blood
through the filter 15 in two or more diverging and converging
streams, and accordingly the section 14 of the tube 12 is provided
with a Y-member 16 which divides the blood flowing therethrough
into two tubes 14-a and 14-b. Similarly, the blood discharged from
the filter passes through discharge tubes 13-a and 13-b to a common
Y-member 17 and thence to a bubble trap 18. Since the filter 15 and
bubble trap 18 are of known construction, it is believed
unnecessary to refer further to them. It can also be noted that it
is conventional practice to inject a very minute amount (usually in
the order of 1.5 milliliters per hour) of heparin (an
anti-coagulant) into the suction tube 12 as by means of a heparin
pump 21 operated from a source of power 22, the heparin passing
through tube 23 to a suitable T-connection 24 in the suction tube
22. It is customary in this art to form the tubes 12, 14, 14-a,
14-b, 13-a, 13-b and 13 of surgical plastic tubing, as such tubing
under treatment conditions does not cause blood to coagulate, and
is quite flexible while being of sufficient strength to withstand
any pressure to which it need be subjected. Such tubing also can be
readily sterilized, packed in sealed containers and sold quite
inexpensively.
The single needle technique above-mentioned requires the use of an
occluder which is operative to prevent flow of blood from the
dialysis filter to the patient during the period of time that the
pump 40 is in its suction phase and is withdrawing blood from the
patient. In FIG. 1 the occluder 19 is shown associated with the
delivery tube 13. In that situation, the occluder 19 is timed to
close the delivery tube 13 to the flow of blood during the suction
portion of a pumping cycle and is open to permit the flow of blood
during the pumping phase of that cycle. It will be obvious,
however, that the occluder 19 could be placed in the suction tube
12, in which event it would have to operate in exact time with the
pump, so that the tube 12 would be open to the passage of blood
during the time that the pump was in its suction phase and closed
to the passage of blood during the pumping phase of pump 40, which
is the reverse of the preferred form shown in FIG. 1.
PUMP
The pump 40 of the present invention will be contained in any
suitable casing which, preferably, can be constructed of three
sections: a pressure, or operating, section 41; a section 42
containing the passages for supply of hydraulic fluid under
pressure, and 43 a simple casing for enclosing the control
solenoids to be hereafter mentioned. Preferably, casing sections 41
and 42 are formed of some readily extrudable material, such as
aluminum or some forms of plastic, so that longitudinal passageways
can be formed therein and thereby avoid the expensive drilling
operation required when such passageways are drilled longitudinally
through the casing.
The power, or operating, section 41 is provided with a longitudinal
bore 44 for the blood tube 12 and a parallel bore 45, the two
communicating throughout their length, as shown in FIGS. 2 and 3.
The bore 44 is somewhat larger than the tube 12, preferably as much
as one-quarter or three-eighths of an inch larger in diameter than
the tube 12. The parallel bore 45 is partially contained within the
casing 41 and thereby provides an open slot, not identified,
throughout the length of the casing block 41. This bore is adapted
to permit the ready insertion of the blood tube 12 and its
encompassing rubber tube 50 from the outside without the necessity
of threading the tube therethrough. The bore 45 is also adapted to
receive a locking member 46 provided with a suitable handle 47 so
that the member 46 can readily be inserted into or removed from the
bore 45. The locking member 46, when positioned in the bore 45,
holds the blood tube 12 and its encompassing rubber tube 50 within
the block 41 and also provides an anvil against which the tubes 12
and 50 can be pressed during operation of the pump, whereby the
tubes can be completely compressed by a hydraulic pressure tube 56
described below. The alternate contraction and relaxation of the
tubes 12, 50 forces blood from the pump 40 and suction of blood
thereinto.
The central, or supply, section 42 of the casing is provided with
two longitudinal bores: a tube 48 for supplying hydraulic fluid
under pressure, and a drain 49.
The casing members 41 and 42 will have auxiliary passageways
drilled therein, as will be described more in detail hereafter. It
will readily be understood that the three sections of the casing
41, 42 and 43 can be rigidly attached one to another by any
suitable means, such as by means of bolts, not shown, cementing, or
other suitable procedure.
As mentioned before, the blood tube 12 is, throughout its length
adapted to be inserted in the pump 40, encompassed within a larger
tube 50. Preferably, the tube 50 is formed of soft but strong
rubber and is of sufficient thickness to rather strongly resist
collapsing and has such resiliency that once pressure is released
it will resume its natural round shape with a force sufficiently
strong and rapid to create a negative, or suction pressure.
Preferably, the two tubes are cemented together so that they must
act as one, particularly when pressure is released from against the
tubes and the tube 50 resumes its normal round shape shown in both
FIGS. 2 and 3.
Throughout the major portion of the length of the tubes 12 and 50
within the casing 41, an enlargement 55 is milled into the casing
adjacent the bore 44. This can readily be done by a milling machine
operating through the sides of the two bores 44 and 45 (see FIG.
3). Within the enlarged bore 55 is placed a hydraulic pressure tube
56 which is sealed at its lower end as shown in FIG. 4. The tube 56
communicates with conduit 57 and thence to the hydraulic pressure
supply conduit 48 and the drain 49 through a two-position, two-way
flow valve 59, as will be described hereafter. It should be noted
at this point that in FIG. 3 the tube 56 is shown in its relaxed
position in which it communicates with the drain 49 and hence the
resilient force of the tube 50 forces the tube 56 to the
semi-collapsed position shown and expels pressure fluid therefrom,
FIG. 3 showing the relations of the parts during the suction phase
of a cycle of pump operation. It will be understood, however, that
when hydraulic fluid under pressure is admitted into tube 56 it
will assume a round shape throughout its length, thereby forcibly
displacing the tube 50 and its enclosed blood supply tube 12 to a
semi-collapsed position (the discharge valve 86 then being open)
and forcing blood through tube 12, 14 to the filter 15.
As shown in FIGS. 3 and 4, the conduit 57 communicates with the
pressure supply line 48 through a branch conduit 58 and a
two-position, two-way flow valve 59 (shown in these figures as
being in the drain position). For purposes of exemplification only,
the valve 59 is shown as having a diametric bore 60 and a radial,
or T-shaped, bore 61 extending from the periphery of the valve
member to the bore 60. In the position shown in FIGS. 3 and 4,
conduit 57 communicates with an auxiliary drain 62 which, in turn,
communicates with the drain 49, the bore 61 in the valve member 59
communicating with conduit 57 and bore 60 communicating with
conduit 62. If the valve member 59 is activated (rocked in the
exemplification shown) through an angle of 90.degree. (clockwise in
this figure), then conduit 58 will communicate with conduit 57
through bore 60 and the conduit 61 will be blocked by registering
with the interior wall of the valve casing. In the latter
condition, fluid under pressure from conduit 48 will pass through
conduit 58, bore 60, conduit 57, into tube 56 and compress the
blood tubes 50 and 12. However, in the position shown in FIG. 3,
the resiliency of the outer tube 50 tending to resume its round
shape will collapse the tube 56, forcing the immediate discharge of
the fluid in pressure tube 56 through conduit 61 and into drain 62.
The inherent resilient force in the tube 50 acts with such strength
and with such speed that it not only collapses tube 56 to permit
blood to enter tube 12, but it does so with some negative pressure
to suck blood from the patient into the pump.
The activation of the valve 59 is readily secured by operation of a
small solenoid 115, as will now be described. The solenoid 115 is
mounted in the casing section 43 and comprises the usual winding
116 and armature 117. In the exemplification shown, the armature
117 normally lies in the position shown in FIG. 3 whereby its link
118 rocks the valve member 59 90.degree. counter-clockwise so that
the bores 61, 60 register with ducts 56 and 62, respectively. Upon
energization of the solenoid, the solenoid armature 117 moves to
the right, rocking valve member 90.degree. clockwise so that bore
60 registers with ducts 58 and 57 and liquid under pressure is
allowed to enter the pressure tube 56, whereby it will compress the
blood tube 12, 50. The solenoid is supplied with power through
suitable leads 119 from a circuit in a timer 120 (FIG. 1) of
conventional construction. The timing of the device will be
described in a subsequent section. It will be understood that
instead of valves 59 and 101 being rotary as shown, one can use any
two-way, two-position valve, such as the straight line valves known
in this art.
In connection with all dialysis techniques, it is necessary to know
the volume of blood being pumped per minute. Since the volume of
pressure fluid entering and leaving tube 56 is a measure of the
throughput of blood through tube 12, the amount of blood pumped can
readily be measured by measuring the output from the tube 56.
Normal procedure is to collect this throughput for six seconds and
multiply it by "10." This can readily be accomplished in the
present invention by means of a graduate 70 (FIG. 4) provided with
suitable indicia for volumetric measurement thereon. Such a
graduate 70 communicates with the drain line 62 by means of a
bypass conduit 71 which communicates with drain 62 by means of a
two-position, two-way flow valve 72. The valve member includes a
diametric bore 73 and a perpendicular radial bore 74 communicating
with the periphery of the valve member and the diametric bore 73.
Normally, the valve is in the position shown in FIG. 4 in which
drain 62 communicates through a primary drain tube 75 that
communicates with the main drain 40 through the bore 73. However,
if the valve member is rocked counter-clockwise through an angle of
90.degree., then drain 62 communicates with the radial bore 74,
one-half of drain 73 and the flow passes into conduit 71 and
graduate 70. This valve can be operated by any suitable means, such
as the pushbutton 76 shown in FIGS. 1 and 3. The valve will be held
in the position to pass flow into the graduate 70 for a period of
six seconds and then returned to its normal position. A glance at
the graduate 70 will show the amount of volume of liquid contained
therein, and this if multiplied by "10," gives the flow per minute.
A tiny bleed drain 77 preferably is provided between the graduate
70 and the main drain 49. This permits the liquid in the drain to
slowly drain therefrom so that it will be empty for again
registering the amount of flow whenever it is desired to do so. It
will be understood, of course, that when the graduate 70 is empty,
the conduit 71 will be full of liquid as it cannot drain from the
system.
VALVE CONSTRUCTION
It is obvious to those skilled in the art that a pump such as that
herein described requires two valves: an inlet valve 85 and an
outlet valve 86. When the pump of the present invention is utilized
for single needle dialysis, a third valve is required in the
occluder. Since in the preferred construction all three valves are
identical in construction, only one will be described in detail,
and for this purpose the outlet valve shown in FIGS. 2 and 4 will
be used for exemplification. The various valves, such as outlet
valve 86 shown in FIG. 2, comprise a piston 87 operating within
elongated cylinder 88. The piston 87 is provided with an elongated
nipple 89 which, in the retracted position of the cylinder 87
(shown in FIG. 2) registers with the outer surface of the outer
tube 50, and in the projected, or operative, position so deforms
the tubes 50 and 12 that they are completely closed to the flow of
blood therethrough. It should be noted at this point that both
FIGS. 2 and 4 show the position of the parts at the start of the
valve-closing operation, and that FIG. 4 shows in dotted line its
fully projected, or closed, position. Preferably, the piston 87 is
provided with a peripheral depression 90 in which is seated an
O-ring or other piston ring to prevent leakage of fluid past the
piston.
The piston is operated by hydraulic pressure through a
two-position, two-way flow valve 101 which, for purposes of
exemplification, is shown as including a diametrical bore 102 and a
perpendicular T-bore 103. In the closing position shown in FIGS. 2
and 4, the diametrical bore 102 registers with a short auxiliary
inlet 104 which communicates with the power supply conduit 48, and
with a short conduit 105 that leads to the cylinder. In the valve
open position in which the piston 87 is retracted to permit flow of
blood through tube 12, duct 105 registers with T-duct 103, part of
duct 102, which then registers within duct 106 that leads to drain
49. This draining position is secured by rotating a valve
counter-clockwise through an angle of 90.degree.. The rocking of
the valve member 101 counter-clockwise from the position shown in
FIGS. 2 and 4, is preferably secured by the operation of a solenoid
115, such as was described in connection with valve 59 above.
The inlet valve 85 is of the same construction as valve 86 just
described, its cylinder 87-a being supplied with fluid under
pressure by branch ducts 125 and 126, flow through the system being
controlled by a two-position two-way flow valve 127. The valve 127
also registers with an auxiliary drain duct 128 which communicates
with the main drain 49. The valve is operated by a solenoid 115 and
in the same manner as that described above.
Preferably, the occluder 19 is a valve similar in all respects to
those heretofore described, except that it is located near the
Y-member 11 and needle 10. It can be supplied with fluid under
pressure from the supply line 48 by means of a branch duct 135
(FIG. 4), a valve 136, and a tube 137 which leads from the casing
of the pump 40 to the occluder 19. It should be noted, however,
that the valve 136 operates out of phase with valve 127 and in
phase with valve 101, as shown in FIG. 4. In fact, it would be
possible to connect tube 137 to supply duct 105 leading from valve
101 to cylinder 88, but it is believed that the use of a separate
valve 136 will be more readily understood. That is, the valve 136
is open to the flow of fluid under pressure to apply pressure to
the occluder valve from conduit 137 simultaneously with the
operation of valve 101 to supply fluid under pressure to the
cylinder 87, at which time valve 127 is positioned to permit the
flow of water from its cylinder 87 to drain 128, 48. It should also
be noted that when the valve 136 is rocked counter-clockwise from
the position shown in FIG. 4, fluid can pass from tube 137 to the
drain duct 138 which connects to drain 128 and thence to main drain
49.
It will be understood that a preferred liquid fluid for operating
the various valves and the pressure tube 56 will be water from a
residential or hospital supply, such as that provided by water line
145. Since most water supplies have greater pressure than is needed
or desired for operation of the pump of the present invention, it
is expected that a pressure regulating valve 146 will be interposed
between the water line 145 and the pump supply line 48. It is
expected that water will normally be used in the operation of the
pump of the present invention, as it is not only relatively cheap,
but is available in practically all homes and all hospitals.
TIMING
As indicated above, the various valves and the pressure tube 56 are
operated through their respective two-way flow control valves 127,
101, 136 and 59. These valves are operated by electric power
through a sequence timer 120. The timer is supplied with power
through any suitable electrical conduit 121 which can be connected
to any suitable power supply. The timing sequence is so set that
the respective solenoids are operative to open the outlet and
occluder two-way control valves 101 and 136 to drain and to
position inlet valve 127 and pressure chamber valve 59 to conduct
enough water under pressure to chamber 87-a and tube 56,
respectively. Conversely, the pressure chamber and inlet flow
valves 59 and 127 are positioned to conduct water from the pressure
tube 56 and inlet valve cylinder 87-a to drain substantially
simultaneously with positioning the outlet and occluder valves 101
and 136 to conduct water under pressure from power supply duct 48
to their respective valves. This timing is shown in FIG. 5 and in
the table below. It can be noted that the inlet valve 127 starts to
close shortly before outlet and occluder valves 101 and 136 are
opened to drain and before pressure tube 56 comes to position of
equilibrium between suction and pressure.
The timing chart shown in FIG. 5 is shown to include a single cycle
of operation beginning with the start of positioning outlet and
occluder valves 101 and 136 to conduct water under pressure to
their respective valve-operating devices, which is the beginning of
the suction phase of a pump cycle. At this moment inlet valve 127
is being positioned to conduct water to drain, as is valve 59,
which permits the flow of water from pressure tube 56 to drain. At
this time the resilient strength of the outer tube 50 rapidly
forces the tube 56 to the partially closed position shown in FIG. 3
and creates a suction on the blood supply line 12. At the end of
this phase the valves reverse their position and valves 101 and 136
are opened to drain and valves 127 and 159 are positioned to
conduct pressure fluid to their respective chambers.
This can perhaps better be explained by a table showing the valve
conditions in which the phase "open to pressure" is used to
indicate that the diametrical bore of the respective valves is
positioned to conduct water under pressure from main supply duct 48
to the respective chambers and the phrase "open to drain" is used
to indicate that the valve is positioned to pass water from the
respective chamber to drain: ##SPC1##
It will be understood that it is conventional to provide means for
adjusting the length of the various phases of a timing cycle so
that the number of strokes per minute and the amount of blood per
cycle can be changed at the discretion of the operator. Since this
is a conventional feature of many timers, it is not deemed
necessary to explain it herein.
It is believed that the hereinbefore stated and other advantages of
the pump of the present invention will be obvious to those skilled
in the art. It is also obvious that the pump of the present
invention can be used in connection with other organs, excised
organs in banks, for open heart and heart transplant surgery, and
the like. Accordingly, it is intended that all modifications which
lie within the scope of the underlying inventive concepts are to be
included within the scope of the claims and that the invention is
not to be limited to the particular forms herein shown and
described.
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