U.S. patent number 3,902,490 [Application Number 05/455,179] was granted by the patent office on 1975-09-02 for portable artificial kidney system.
This patent grant is currently assigned to University of Utah. Invention is credited to Stephen C. Jacobsen, Willem J. Kolff, Clifford Kwan-Gett.
United States Patent |
3,902,490 |
Jacobsen , et al. |
September 2, 1975 |
Portable artificial kidney system
Abstract
An artificial kidney system includes a dialyzer element through
which blood of a patient and dialysate solution are circulated to
enable transfer of waste, electrolytes, water and other components
from the blood to the solution (and in some cases from the solution
to the blood), blood pump and circulation apparatus for withdrawing
blood from the patient and applying it to the dialyzer element and
for returning blood from the dialyzer element to the patient, and
dialysate pump and circulation apparatus for transporting dialysate
solution from a dialysate source to the dialyzer element and from
the dialyzer element to a dialysate sink. The blood and the
dialysate pump apparatus each includes a flexible casing which,
when compressed, forces fluid from the casing and which, when
released, draws fluid into the casing. The dialysate circulation
apparatus includes a variable volume accumulator jacket for
receiving dialysate solution when the pump casing is compressed and
for discharging dialysate solution when the pump casing is
released. A pump actuator operates the blood pump apparatus and the
dialysate pump apparatus to circulate blood and dialysate solution
through the dialyzer element.
Inventors: |
Jacobsen; Stephen C. (Salt Lake
City, UT), Kwan-Gett; Clifford (Salt Lake City, UT),
Kolff; Willem J. (Salt Lake City, UT) |
Assignee: |
University of Utah (Salt Lake
City, UT)
|
Family
ID: |
23807707 |
Appl.
No.: |
05/455,179 |
Filed: |
March 27, 1974 |
Current U.S.
Class: |
210/321.65;
128/DIG.3; 417/478; D24/169; 210/929; 604/6.05 |
Current CPC
Class: |
A61M
1/308 (20140204); A61M 1/1649 (20140204); F04B
43/086 (20130101); F04B 43/08 (20130101); A61M
60/562 (20210101); A61M 1/302 (20140204); A61M
1/1696 (20130101); A61M 1/30 (20130101); A61M
1/304 (20140204); Y10S 210/929 (20130101); A61M
60/892 (20210101); A61M 60/894 (20210101); A61M
60/50 (20210101); A61M 60/40 (20210101); A61M
60/268 (20210101); Y10S 128/03 (20130101); A61M
60/113 (20210101) |
Current International
Class: |
A61M
1/16 (20060101); A61M 1/30 (20060101); F04B
43/00 (20060101); F04B 43/08 (20060101); A61M
1/10 (20060101); A61M 005/00 (); A61M 001/03 () |
Field of
Search: |
;128/214R,214B,214E,214F,214.2,213,273,DIG.3,214 ;210/321,416 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Truluck; Dalton L.
Attorney, Agent or Firm: Criddle & Thorpe
Claims
What is claimed is:
1. A hemodialyzer comprising
a dialyzer element through which blood of a patient and dialysate
solution are circulated to enable transfer of waste and water from
the blood to the solution,
blood transporting means for transporting blood from the patient to
the dialyzer element and from the dialyzer element back to the
patient,
first pump means coupled into said blood transporting means, said
pump means including a flexible casing which, when alternately
compressed and released, causes blood to flow in said blood
transporting means,
a dialysate source and dialysate sink,
dialysate transporting means for transporting dialysate solution
from the dialysate source to the dialyzer element and from the
dialyzer element to the dialysate sink,
second pump means coupled into said dialysate transporting means,
said second pump means including a flexible casing which, when
alternately compressed and released, causes dialysate solution to
flow in the dialysate transporting means, and
means common to the first and second pump means for compressing and
releasing the casings of said first and second pump means to
produce a pumping action in the blood transporting means and the
dialysate transporting means.
2. A hemodialyzer as defined in claim 1 wherein said dialysate
source and sink include
a canister coupled in the dialysate transporting means and through
which dialysate solution flows, and
filter means disposed in the canister for collecting waste from the
dialysate solution when the solution flows through the
canister.
3. A hemodialyzer as defined in claim 2, comprising an accumulator
means which includes
a jacket, and
means for coupling the jacket into said dialysate transporting
means to enable passage of dialysate solution from said dialysate
transporting means into said jacket and from said jacket to said
dialysate transporting means.
4. A hemodialyzer as defined in claim 3 wherein said jacket is a
flexible jacket.
5. A hemodialyzer as defined in claim 3 further comprising a
collector means which is coupled into said dialysate transporting
means for receiving excess dialysate solution.
6. A hemodialayzer as defined in claim 5 wherein said collector
means includes a collapsible bladder.
7. A hemodialyzer as defined in claim 6 wherein said collector
means further includes a check valve for allowing the flow of
solution from said dialaysate transporting means into the bladder
and for preventing the flow of solution from the bladder to said
dialysate transporting means.
8. A hemodialyzer as defined in claim 6 further including feeler
means positioned to engage the collector bladder when the bladder
fills to a predetermined volume, and switch means for generating a
signal when the bladder engages said feeler means.
9. A hemodialyzer as defined in claim 5 wherein said accumulator
means and collector means are interposed in that portion of the
dialysate transporting means which carries dialysate solution from
the canister to the dialyzer element, and wherein said second pump
means is coupled into that portion of the dialysate transporting
means which carries solution from the dialyzer element to the
canister.
10. A hemodialyzer comprising
a dialyzer element through which blood of a patient and dialysate
solution are circulated to enable transfer of waste and water from
the blood to the solution,
blood transporting means for transporting blood from the patient to
the dialyzer element and from the dialzer element back to the
patient,
first pump means coupled into said blood transporting means, said
pump means including a flexible casing which, when alternately
compressed and released, causes blood to flow in said blood
transporting means,
a dialysate source and a dialysate sink,
dialysate transporting means for transporting dialysate solution
from the dialysate source to the dialyzer element and from the
dialyzer element to the dialysate sink,
second pump means coupled into said dialysate transporting means,
said second pump means including a flexible casing which, when
alternately compressed and released, causes dialysate solution to
flow in the dialysate transporting means,
means for compressing and releasing the casings of said first and
second pump means to produce a pumping action in the blood
transporting means and the dialysate transporting means, and
a vacuum regulator means coupled in said dialysate transporting
means, said regulator means including a reservoir having an orifice
through which dialysate solution flows, and plug means positionable
in fron of said orifice at adjustable distances therefrom to
control the rate of flow of solution through the orifice.
11. A hemodialyzer as defined in claim 10 wherein said vacuum
regulator means is interposed in that portion of the dialysate
transporting means which carries solution from the dialysate source
to the dialyzer element.
12. A hemodialyzer comprising
a dialyzer element through which blood of a patient and dialysate
solution are circulated to enable transfer of waste and water from
the blood to the solution,
blood transporting means for tranporting blood from the patient to
the dialyzer element and from the dialyzer element back to the
patient,
first pump means coupled into said blood transporting means, said
pump means including a flexible casing which, when alternately
compressed and released, causes blood to flow in said blood
transporting means,
a dialysate source and a dialysate sink,
dialysate transporting means for transporting dialysate solution
from the dialysate source to the dialyzer element and from the
dialyzer element to the dialysate sink,
second pump means coupled into said dialysate transporting means,
said second pump means including a flexible casing which, when
alternately compressed and released, causes dialysate solution to
flow in the dialysate transporting means,
means for compressing and releasing the casing of said first and
second pump means to produce a pumping action in the blood
transporting means and the dialysate transporting means, and
wherein the flexible casing of each of said pump means includes an
inlet and an outlet by which the casing is coupled into the
respective transporting means, an inlet check valve for allowing
fluid to flow therethrough into the casing, and an outlet check
valve for allowing fluid to flow therethrough from the casing.
13. A hemodialyzer as defined in claim 12 wherein said casings are
constructed of rubber having a wall thickness of substantially
one-eighth of an inch.
14. A hemodialyzer as defined in claim 12 wherein said each casing
is elongated, with the inlet valve located at one end of the casing
and the outlet and outlet valve located at the other end.
15. A hemodialyzer as defined in claim 12 wherein said casings are
positioned side by side, and wherein said pump operating means
includes a compression element disposed between the casings and
moveable alternately to a first position to compress the casing of
said first pump means and to a second position to compress the
casing of said second pump means thereby to alternately operate the
first and second pump means.
16. A hemodialyzer as defined in claim 15 further comprising
a first retaining plate, one surface of which is shaped to comform
to one side of the casing of said first pump means, said plate
being positioned so that said one surface contacts said one side of
the casing to prevent deformation of the one side when the casing
is compressed, and
a second retaining plate, one surface of which is shaped to conform
to one side of the casing of said second pump means, said second
plate being positioned so that said one surface thereof contacts
said one side of the casing of the second pump means to prevent
deformation thereof when the casing of the second pump means is
compressed.
17. A hemodialyzer as defined in claim 12 wherein said casings are
positioned together, and wherein said pump operating means includes
a compression element movable between a first position in which
both casing are compressed by the element, and a second position,
in which the casings are released by the element.
18. An artificial kidney system comprising
a dialyzer element through which blood of a patient and dialysate
solution are circulated to enable transfer of waste and water from
the blood to the solution,
blood transporting means for transporting blood from the patient to
the dialyzer element and from the dialyzer element back to the
patient,
first pump means coupled into said blood transporting means for
causing blood to flow from the patient to the dialyzer element and
from the dialyzer element back to the patient,
a dialysate source and sink,
dialysate transporting means for transporting dialysate solution
from the dialysate source to the dialyzer element and from the
dialyzer element to the dialysate sink,
second pump means coupled into that portion of the dialysate
transporting means which transports dialysate solution from the
dialyzer element to the dialysate sink for causing solution to flow
from the dialyzer element to the dialysate sink and from the
dialysate source to the dialyzer element,
said second pump means including a flexible casing which, when
compressed, forces solution from the casing toward the dialysate
sink and which, when released, withdraws solution from the dialyzer
element into the casing,
an accumulator means coupled into the dialysate transporting means
for receiving dialysate solution when said second pump means is
compressed and for discharging dialysate solution when said second
pump means is released, and
a collector means coupled into said dialysate transporting for
receiving excess dialysate solution from the dialysate transporting
means.
19. A system as in claim 18 further comprising a check valve
disposed in said collector means for allowing the flow of solution
from the dialysate transporting means to the collector means and
for preventing the flow of solution from the collector means to the
dialysate transporting means.
20. A system as in claim 18 wherein said collector means includes a
collapsible bladder, and said system further comprises
means for alternately compressing and releasing the casing of said
second pump means,
feeler means positioned so as to be engageable by the bladder when
the bladder fills beyond some predetermined volume, and
means responsive to the engagement of the bladder with the feeler
means for disabling said pump compressing and releasing means.
21. A system as in claim 18 wherein said accumulator means and
collector means are interposed in that portion of the dialysate
transporting means which carries solution from the dialysate source
to the dialyzer element.
22. A system as in claim 21 further including vacuum regulator
means interposed in the dialysate transporting means between the
dialyzer element and the accumulator means and collector means for
regulating the rate of flow of solution into the dialyzer
element.
23. A system as in claim 22 wherein said vacuum regulator means
includes a reservoir having an orifice through which dialysate
solution flows, and plug means having a diameter larger than the
diameter of the orifice and positioned in front of the orifice at
adjustable distances therefrom to control the rate of flow of
solution through the orifice.
Description
BACKGROUND OF THE INVENTION
This invention relates to artificial kidney systems and more
particularly to a compact, portable and lightweight artificial
kidney.
Artificial kidney systems have been in use for some time and have
proven effective as partial replacements for defective human
kidneys. In the use of such systems, blood is withdrawn from a
patient and applied to a dialyzer through which dialysate solution
is circulated. By the process of dialysis, chemical wastes,
electrolytes and water in the blood pass into the dialysate
solution (and in some cases vice versa) through the thin walls of
membrane structure, such as hollow fibers, carrying the blood. The
dialysate solution containing the wastes and water is drawn from
the dialyzer and disposed of and the blood is returned to the
patient. This process of transporting wastes and water from the
blood is referred to as hemodialysis.
Although the artificial kidney systems or hemodialyzers in current
use are effective, they cause blood damage, are large in size,
cumbersome, complicated and generally unsuitable for transport.
Part of the reason for this is that the pumps utilized in such
systems are themselves large and heavy and require considerable
tubing for carrying the blood and dialysate solution. The use of
large volume baths of dialysate solution also contributes to the
lack of portability of the prior art systems.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a compact,
portable artificial kidney system.
It is also an object of the present invention to provide an
artificial kidney system which includes a novel, efficient and
lightweight pumping and hydraulic apparatus.
It is an additional object of the present invention to provide an
artificial system in which the pumping and suction pressure for
moving blood and dialysate solution can be predetermined and
controlled with a high degree of precision and reliability.
It is further object of the present invention, in accordance with
one aspect thereof, to provide an artificial kidney system in which
the dialysate source and sink may be combined in a single filter
and chemical treatment element to provide a closed dialysate
circulation system.
These and other objects of the present invention are realized in a
specific illustrative embodiment which includes a dialyzer element
through which blood of a patient and dialysate solution are
circulated to enable transfer of undesirable chemicals and water
from the blood to the solution, a blood transporting system for
transporting blood from the patient to the dialyzer element and
from the dialyzer element back to the patient, a dialysate
transporting system for transporting dialysate solution to the
dialyzer element and from the dialyzer element, and first and
second pumps coupled into the blood transporting system and
dialysate transporting system for causing the blood and the
dialysate solution to flow in the blood transporting system and
dialysate transporting system respectively. The system also
includes apparatus for operating both the first pump and the second
pump to produce a pulsating pumping action for the blood and
dialysate solution.
In accordance with one aspect of the invention, each of the pumps
includes a flexible casing which, when alternately compressed and
released, develops the pressure and suction necessary to cause the
blood and dialysate solution to flow in their respective
transporting systems.
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of the present invention, together with
other and further objects and features thereof, reference is had to
the following description taken in connection with the accompanying
drawings described as follows:
FIG. 1 is an overall diagrammatic showing of one illustrative
embodiment of the present invention;
FIG. 2 is a cross-sectional view of a pump of the type shown in
FIG. 1;
FIG. 3 shows a cross-sectional view of the vacuum regulator of FIG.
1;
FIGS. 4A-4C show top views of the blood and dialysate solution
pumps together with the pump actuator and retaining plates;
FIGS. 5A-5C show end views of the blood and dialysate solution
pumps also with the pump actuator and retaining plates;
FIGS. 6A and 6B show end views of an alternative embodiment of the
blood and dialysate solution pumps and pump actuator; and
FIG. 7 shows a top view of the embodiment of FIGS. 6A and 6B with
the pump casings compressed.
FIG. 8 shows a full-cycle pump made in accordance with the present
invention.
DETAILED DESCRIPTION
a diagrammatic view of the artificial kidney system or hemodialyzer
of the present invention is shown in FIG. 1. The system generally
includes a blood transporting system 2 through which blood of a
patient is circulated and a dialysate transporting system 6 through
which dialysate solution is circulated. Both the blood and the
dialysate solution are circulated through a dialyzer element 38
where chemical wastes and water are transported from the blood by
the process of diffusion. Blood is carried through the dialyzer
element 38 by a bundle of hollow fiber strands (or other suitable
membrane structure), respresented as a single tube 42 in FIG. 1,
which are immersed in dialysate solution contained in the dialyzer
element. As the blood is carried through the dialyzer element 38,
chemical wastes and water transfer through the thin walls of the
fiber strands into the solution. This process of hemodialysis is
well known in the art and has been performed by artificial kidney
systems for a number of years. The construction of dialyzer
elements is also known in the art.
The blood transporting system 2 includes tubing 4, a pump 14, and a
single-needle cannula 18. The cannula 18 is described more fully in
copending application, Ser. No. 455,180. Of course, the blood
transporting system 2 could also be used with conventional
double-needle cannulas as well as the single-needle cannula. With
the single-needle cannula, the pump 14 causes blood to be
alternately withdrawn from and returned to the patient.
The pump 14 is coupled into the tubing 4 to provide the necessary
pressure and suction for forcing the blood to circulate in the
blood transporting system 2. As shown in greater detail in FIG. 2,
the pump 14 includes a flexible cylindrical-shaped casing 202 open
at either end, an inlet check valve 210 coupled in one end of the
casing, and an outlet check valve 202 coupled in the other end of
the casing. Each valve includes a valve seat (214 and 222) and a
valve head (218 and 226) for controlling the flow of blood into and
out of the pump casing 202. The pump 14 of FIG. 2 is coupled into
the blood circulation system 2 so that blood flows from the cannula
18 through the pump to the dialyzer element 38. It should be
understood that the casing 202 could have shapes other than the
cylindrical shape illustrated so long as the pumping action, to be
described hereafter, is carried out.
The pump 14 is operated by compressing the pump casing by means of
a compression element 16 and then releasing the casing. A motor 84
is mechanically coupled to the compression element 16 to cause it
to alternately compress and release the casing. As the casing is
compressed, as diagramatically illustrated in FIG. 1, blood in the
pump will force check valve 30 to close and the check valve 34 to
open so that blood will flow from the pump to the dialyzer element
38. When the pump casing is released the resiliency of the casing
will cause it to resume its normal shape thereby creating a vacuum
which forces check valve 34 to close and check valve 30 to open to
thereby draw blood from the patient through the cannula 18 into the
pump.
The valve 26 and pump 14 cooperate in a unique manner to provide a
one-way flow of blood through the blood transporting system 2. When
the pump casing is compressed, the pressure of the blood in the
tubing 4 and thus in the valve 26 increases to a value greater than
the atmospheric pressure causing the valve 26 to open and allow
blood to flow from the tubing in the dialyzer element 38, through
the vlave 26 and the needle 22 back into the patient. When the pump
casing is released, it creates a vacuum or negative pressure in the
cannula 18 which is less then the atmospheric pressure so that the
valve 26 is caused to close and blood is thereby withdrawn from the
patient through the cannula 18 into the pump 14 and not from the
tubing in the dialyzer element 38 through the valve 26 to the pump.
The pump 14 and valve 26 thus cooperate to alternately withdraw
blood from the patient into the pump 14 and then force the blood
from the pump 14 into dialyzer element 38 and from the dialyzer
element 38 back through the valve 26 to the patient. As indicated
earlier, the cannula 18 and valve 26 are described fully in the
aforecited copending application.
The pump 14 provides a non-occulsive pumping action which, unlike
certain other pumps presently used in artificial kidney systems--
such as the roller pump, does very little damage to the blood
during the pumping operation. (With the roller pump, blood caught
between the walls of the tubing being "rolled" by the pump roller
is oftentimes damaged.) Also, very little tubing is needed with the
pump 14 so that the foreign surface area which the blood must
contact during the dialysis process is minimized.
The casing of the pump 14 might illustratively be made of latex
rubber, silicone rubber or other suitably resilient material. A
wall thickness of substantially one-eighth of an inch has been
found suitable for the casing, using either latex rubber or
silicone rubber, to develop the suction necessary to withdraw the
blood from the patient.
The dialysate transporting system 6 of FIG. 1 provides for
transporting dialysate solution from a dialysate source to the
dialyzer element 38 and for transporting dialysate solution from
the dialyzer element 38 to a dialysate sink. In the FIG. 1
embodiment, a chemical removal canister 46 acts as both the
dialysate source and dialysate sink. The canister 46 contains a bed
of activated charcoal particles and other chemical agents 48 for
processing the dialysate solution as it flows through the canister.
The canister 46 is divided into a receiving compartment 50, into
which dialysate solution is pumped from the dialyzer element 38,
and a discharging compartment 54, from which dialysate solution is
taken for transport to the dialyzer element 38. Division of the
canister 46 in this manner forces the dialyzer solution to flow
through the charcoal particles and other chemical agents to thereby
provide maxiumum processing of the dialysate solution. The
dialysate solution is pumped into the dialyzer element 38 to
circulate about the hollow blood-carrying fibers represented by the
tube 42 to facilitate the process of dialysis previously
described.
Although the dialysate source and sink are combined in the canister
46, it should be understood that the FIG. 1 system could be used
with the conventional separate source and sink.
The dialysate transporting system 6 includes a pump 52, of similar
construction as the pump 14 of the blood transporting system 2, for
causing the dialysate solution to circulate through the dialyzer
element 38. The pump 52 is interposed in that portion of the
dialysate transporting system which carries solution from the
dialyzer element 38 to the canister 46. The motor driven
compression element 16 which operates pump 14 also operates pump
52.
The dialysate transporting system 6 also includes an accumulator
66, whose function will be explained momentarily, a collector 70,
whose function will also be explained momentarily, and a vacuum
regulator 74 by which the vacuum of the dialysate solution within
the dialyzer 38 may be controlled. The accumulator 66 is coupled
into the dialysate transporting system 6 to receive dialysate
solution when the pump 42 is compressed and then to discharge
solution back into the system when the pump 42 is released. The
accumulator 66, in effect, accounts for the change in volume of the
dialysate transporting system resulting from operation of the pump
42. (This is necessary because the dialysate transporting system 6
of FIG. 1 is a "closed" system, unlike a transporting system in
which the dislysate source and sink are separate. In such a case,
no accumulator would be needed.) When the volume is decreased due
to compression of the pump, solution is forced into the accumulator
66 and when the volume is increased again as a result of releasing
the pump 42, the solution is drawn from the accumulator 66 back
into the system. The accumulator 66 is a variable-volume container
and could, advantageously, be constructed of a flexible jacket
whose walls expand and contract when dialysate solution is
respectively received into and discharged from the accumulator.
The collector 70 is provided to receive excess solution produced as
a result of the passage of chemicals and water from the blood into
the dialysate solution in dialyzer element 38. The chemicals and
water passing from the blood into the dialysate solution, of
course, increase the volume of the solution giving rise to a need
for some means of accommodating this increase. The collector 70 is
coupled into the dialysate transporting system to receive and
retain this excess fluid. The collector 70 is a variable-volume
container and, advantageously, is comprised of a collapsible
disposable bladder, similar to a common balloon, which is capable
of expanding as the volume of solution in the dialysate
transporting system increases. The bladder is coupled into the
sytem by means of a check valve 72 which, when the pressure in the
system exceeds some threshold level, allows fluid to flow into the
bladder, but prevents fluid from flowing back into the transporting
system. The check valve 72 could be of the same construction as the
valve 210 of FIG. 2, or could be a spring loaded valve similar to
that to be described in conjunction with FIG. 3.
The collector 70 is positioned near a volume detector switch 76 so
that when the bladder of the collector fills with excess solution
and expands to a certain volume, the bladder wall contacts a feeler
arm 80 operating the switch 76 which then generates a signal to
sound an alarm or turn off the motor 84, as desired. In this
manner, the volume of solution in the dialysate transporting system
6 is monitored so that when the volume exceeds some predetermined
value, the volume detector switch 76 is actuated to sound an alarm
or turn off the pump motor 84. The collector 70 could then be
removed for disposal of the excess solution and then replaced in
the dialysate transporting system for further operation of the
kidney system. The switch 76 may be any conventional electrical
switch having a pair of contacts which close when the feeler arm 80
is moved a certain distance to thereby generate the appropriate
signal.
One embodiment of the vacuum regulator 74 of FIG. 1 is shown in
FIG. 3. The regulator includes a reservoir 302 through which the
dialysate solution is passed from the canister 46 to the dialyzer
element 38 (FIG. 1). An element 310 having a threaded bore is
positioned at one end of the reservoir 302 for receiving a
complementarily threaded screw 306. Attached to the end of the
screw is a coil spring 314 which carries a plug or ball 318 on its
free end. As can be seen from FIG. 3, when the screw 306 is screwed
into the element 310, the ball 318 is moved closer to an orifice
322 through which dialysate solution is received, and when the
screw 306 is unscrewed from the element 310 the ball 318 is moved
further from the orifice 322. The ball 318 serves as a partial
obstruction to the flow of fluid through the orifice 322 to thereby
regulate the rate and pressure of such flow. If it is desired to
decrease the rate of flow, then, of course, the ball 318 is moved
closer to the orifice 322 and if it is desired to increase the
flow, the ball 318 is moved further from the opening 322. Numerous
other arrangements could be provided for controlling the rate of
flow of the dialysate solution.
As indicated earlier, the pumps 14 and 52 are operated by a motor
driven compression element 16. The pumps may be arranged so that
the compression element 16 alternately compresses and releases one
pump casing and then compresses and releases the other pump casing
to provide a counter-pulsating pumping action in the blood
transporting system 2 and the dialysate transporting system 6. The
physical arrangement of the pumps 14 and 52 and the compression
element 16 for such a configuration is best seen in composite FIG.
4 and composite FIG, 5 as will next be described.
As shown in composite FIG. 4, the two pumps 14 and 52 are
positioned side-by-side, with the compression element 16 disposed
between the pumps. A retaining plate 410, having an internal
surface which conforms to the exterior surface of the casing of the
pump 14, is positioned to one side of and in contact with the pump
14. A similar retaining plate 414 is positioned to one side of the
pump 52. By shaping the contacting surface of the retaining plates
to conform to the corresponding pump casings, the retaining plates
prevent deformation of the casing surface contacted by the plates
when the casings are compressed by the compression element 16.
Shaping the retaining plate surfaces to conform to the casing wall
surface shapes also serves to increase the pumping and suction
pressures achieveable with the pumps (compared, for example, to
simply compressing the pump casing between two flat plates).
Because the pumping and suction pressure developed by the pumps of
the type disclosed varies with the shape of the retaining plates
used, pumping and suction pressure can, in part, be controlled by
appropriate selection of the shape of the retaining plates. Control
of the pumping and suction pressure can also be obtained by
appropriate selection of casing wall thickness and material
resilience, with the greater thickness and resilience generally
giving rise to greater pumping and suction pressure and with lesser
thickness and resilience giving rise to lesser pumping and suction
pressure. The combination of retaining plate shape and casing wall
thickness and resilience therefore provides a simple and yet
effective way of controlling pumping and suction pressures
developed by the disclosed artificial kidney system.
FIGS. 4B and 4C show pump 52 being compressed by the compression
element 16 and pump 14 being compressed by the compression element
16 respectively. The compression element 16 is actuated by the
motor 84 shown in composite FIG. 5. The motor, by conventional
linkage, causes the compression element 16 to alternately move the
compress first one pump casing and then the other in a
pendulum-like fashion. With the positioning of the pump casings as
shown, a single compression element may be used to operate both
pumps. This provides a simple, effective and compact pump
configuration.
An alternative pump configuration is shown in composite FIG. 6 and
FIG. 7. With this configuration, the casings of the pumps 14 and 52
are compressed simultaneously and then released simultaneously by
compression element 17. As shown in composite FIG. 6 and FIG. 7,
the two pumps 14 and 52 are again positioned together, with the
compression element 17 extending upward between the pumps. The
element 17 includes a stem 17b and a horizontal head portion 17a to
form a structural tee. The motor 84, again by conventional linkage,
causes the compression element 17 to move between a "compressing"
position, in which the casings of the pumps 14 and 52 are both
compressed by the element 17 (FIG. 6B), and a "release" position,
in which the casings of the pumps are released (FIG. 6A). FIG. 7
shows a top view of the pumps with the pump casings being
compressed by the compression element 17.
Although the two pump configurations have been described for use in
the artifical kidney system of FIG. 1, it is evident that the pumps
could be used in a variety of applications requiring the the
pumping of fluids.
FIG. 8 shows a "full-cycle" pump for use in either or both the
blood transporting system 2 (provided a double-needle cannula is
employed) and the dialysate transporting system 6. This pump
includes two casings 802 and 804 positioned on either side of a
compression element 806. Each casing is constructed similar to the
pump shown in FIG. 2, each including an inlet and outlet and inlet
and outlet valves. The two casings are coupled in parallel into a
fluid-carrying line 808, with the inlets of each casing coupled to
portion 808a of the line and the outlets coupled to portion 808b.
The compression element 806 operates to compress and release first
one of the casings and then the other. As one casing is compressed
and the other released, the one casing forces fluid therefrom into
the line portion 808b and the other casing draws fluid thereinto
from the line portion 808a. Thus, with each stroke or half-cycle
movment of the compression element 806, fluid is passed to the line
poriton 808b so that a type of full-cycle pumping action is
developed. This may be contrasted with a so-called half-cylce
pumping action which would be developed if only one casing were
coupled into the line 808. Then, fluid would be passed from the
casing to the line with every other stroke or half-cycle movement
of the compression element 806.
It is to be understood that the above-described embodiments are
only illustrative of the principles of the present invention. Other
embodiments may be described by those skilled in the art without
departing from the spirit and scope of the invention, and the
appended claims are intended to cover such embodiments.
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