Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
GANAD~
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PORTABLE ARTIFICIAL XIDNEY SYSTEM
This invention relates to an artificial kidn~y
system 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blood is withdrawn from a patient and applied to a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
; 15 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 hemo-
dialyzers in current use are effective, they cause blooddamage, 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
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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.
The present invention provides a compact, portable
artificial kidney system, which includes a novel light-
weight pumping and hydraulic apparatus.
In the artificial kidney system of the inven-
tion, the pumping and suction pressure for moving blood
and dialysate solution can be predetermined and control-
led, and the dialysate source and sink may be combined
in a single filter and chemical treatment element to
provide a closed dialysate circulation system.
A specific illustrati~e embodiment 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 transpor-
ting blood from the patient to the dialyzer element and
~ from the dialy~er element back to the patient, a dia-
lysate transporting system for transporting dialysate
solution to and from the dialyzer element, and first
and second pumps coupled into the blood transporting
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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.
One aspect of the invention is concerned with
pumps which include a flexible casing which, when alter-
nately compressed and released, develop the pressureand suction necessary to cause the blood and dialysate
solution to flow in their respective transporting system.
In accordance witin tr~e invention, there is
provided a hemodialyzer, which comprises a dialyzer
element through which blood of a patient and dialysate
solution may be circulated to enable transfer of waste
and water from the blood to the solution, blood trans-
porting means for transporting blood from the patient
to the dialyzer element and from the diaiyzer element
back to the patient, first pump means coupled into said
blood transporting means, said first pump means inclu-
ding a flexible casing which, when alternately compressed
and released, causes blood to flow in said blood trans-
portin~ means, a dialysate source and a dialysate sink,
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dialysate transporting means for transporting dialysate
solution from the dialysate source to the dialyzer ele-
ment and from the dialyzer element to the dialysate sink,
second pump means coupled into said dialysate transpor-
ting-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 pump operating means for com-
pressing 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. ' :
The dialysate source and sink may include a
canister coupled in the dialysate transporting means
and through which dialysate ~301ution flows, and filter
means disposed in the canister for collecting waste
from the dialysate solution when the solut.ion flows
through the canister,
The dialysate transportation means may comprise
~0 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 transportation means.
The jacket may ~e a flexible jacket. The dialysate trans-
portation may comprise a collector means, which collector
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means may include a collapsible bladder, coupled into
said dialysate transporting means for receiving excess
dialysate solution.
Further features of the hemodialyser of the
invention have already been described or will be des-
cribed below.
The invention further provides an artificial
kidney system comprising a hemodialyser as described
above, including also accumulator means and collector
means, as already described. Further particulars of this
artlficial kidney have already been described or will
be described below.
The invention further provides pulsatile pump
and also a full cycle pump, which are suitable for use
in the hemodialyser or artificial kidney system described.
The invention will now be described with reference
to the accompanying drawings showing, by way of example,
one embodiment of the invention.
In the drawings:
~o FIG. 1 is an overall diagrammatic drawing of
an embodiment of the invention;
FIG. 2 is a cross-sectional view of a pump of the
t~pe shown in FIG.l;
FIG.3 shows a cross-sectional view of the vacuum
regulator of FIG. l;
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FIGS. 4A-4C show top views of the blood and dia-
lysate solution pumps together with the pump actuator
and retaining plates;
FIGS. 5A-5C show end views of the blood and dia-
5 lysate solution pumps with the pump actuator and re-
taining 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.
A diagrammatic view of the artificial kidney
system or hemodialyzer of the present invention is
shown in FIG. l. The system generally includes a blood
transporting system 2 through which blood of a patient
i5 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
o~ dif~usion. Blood is carried through the dialyzer "
- element 38 by a bundle of hollow fiber strands (or
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other suitable membrane structure), represented 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 per-
formed by artificial kidney systems for a number of `
years. The construction of dialyzer elements is also
- 10 known in the art.
The blood transporting system 2 includes tubing 4,
a pump 14, and a single-needle cannula 18 of known
construction. Of course, the blood transporting system 2
could also be used with conventional double-needle
lS cannulas as well as the single-needle cannula. With the
sin~le-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 pro-
vide the necessary pressure and suction for forcing the
hlood to circulate in the blood transporting system 2.
As shown in greater detail in FIG. 2, the pump 14 in-
cludes 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 206 coupled ~;
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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
~ause 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.
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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 atmos-
pheric pressure causing the valve 26 to open and allow
blood to flow from the tubing in the dialyzer element 38,
through the valve 26 and the needle 22 back to the
patient. When the pump casing is released, it creates
a negative pressure in the cannula 18 which is less
than atmospheric pressure so that the valve 26 is caused
~o 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.
The pump 14 provides a non-occlusive pumping
action which does very little damage to the blood
during the pumping operation. With a roller pump,
blood caught between the walls of the tubing being
"ro-led" by the pump roller can be dam-ged. Also, very
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little tubing is needed with the pump 14 so that the
foreign surface area with which the blood must contact
during the dia~ysis process is minimized.
The casing of the pump 14 may be made of latex
rubber, silicone rubber or other suitably resilient
material. A wall thickness of substantially 1/8 of an
inch has been found particularly 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
lS element 38 to a dialysate sink. In the FIG. 1, 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
agent 47 for processing the dialysate solution as it
flows through the canister. The canister 46 is divided
by divider 48 into a receiving compartment 50, into which
dialysate solution is pumped from the dialyzer element 38 r and
a discharging compartment 5~, from which dialysate solution
is taken for transport to the dialyzer element 38.
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682-6677
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 maximum pro-
cessing 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 des-
cribed.
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 con~truction as the pump 14 of the
blood tran9porting system 2, for causing the dialysate
solution to circulate through the dialyzer element 38.
The pump 52 is interposed in that portlon of the dialy-
sate 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
below, a collector 70, whose function will also be
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explained, and a vacuum regulator 74 b~ 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 52 is compressed and then to
discharge solution back into the system when the pump 52
is released. The accumulator 66, in effect, accounts for
the change in volume of the dialysate transporting
system resulting from operation of the pump 5~. (This
is necessary because the dialysate transportin~g system
6 of FIG. 1 is a "closed" system, unlike a transporting
system in which the dialysate source and sink are
separate. In such a case, no accumulator W0Uld 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 relea-
sing the pump 52, the solution is drawn from the accumu-
lator 66 back into tne system. The accumulator 66 is
a variable-volume container and could,-advantageously,
20 be constructed of a flexible jacket whose walls expand -
and contract when dialysate solution is respectively
recèived into and discharged from the accumulator,
The collector 70 is provided to receive excess
solution produced as a result of the passage of chemicals
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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-, advan-
tageously, is comprised of a collapsible disposable blad-
der, similar to a common balloon, which is capable ofexpanding as the volume of solution in the dialysate
transporting system increases. The bladder is coupled
into the system 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 pre-
vents fluid from flowing back into the transporting
system. The check valve 72 could be of the same construc-
tion as the valve 210 of FIG. 2, or could be a spring
loaded valve similar to that to be described in con-
junction with FIG. 3.
The collector 70 is positioned near a volume detectorswitch 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
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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 trans-
porting 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
~or disposal of the excess solution and then replaced
in the dialysate transporting system for ~urther operation
of the kidney system. The switch 76 may be any conven-
tional 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.l
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 comple-
mentarily threaded screw 306. Attached to the end ofthe screw is a coil spring 314 which carries a plug
or ball 31B 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
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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 pres- ... -.
sure 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 con- ;
trolling 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
1'; 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. S
as will now be described.
As shown in composite FIG. 4, the two pumps 14 and ~`
: 52 are positioned side-by-side, with the compression
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element 16 disposed between the pumps. A retaining
plate 410, having an intexnal 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 corres-
ponding pump casings, the retaining plates prevent de-
formation of the casing surface contacted by the plates
1~ when the casings are compressed by the compression
element 16. Shaping the retaining plate surfaces to co`n-
form to the casing wall surface shapes also serves to
increase the pumping and suction pressures achieveable
with the pumps (compared, for example, to simply compres-
sing the pump casing between two flat plates). Becausethe 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 o~ 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
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pressure and with lesser thickness and resilience giving
rise to lesser pumping and suction pressure. The combin-
ation of retaining plate shape and casing wall thickness
and resilience therefore provides a simple and yet effec-
tive way of controlling pumping and suction pressuresdeveloped by the disclosed artificial kidney s~stem.
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 compres-
sion element 16 is actuated by the motor 84 shown incomposite FIG. 5. The motor, by conventional linkage,
causes the compression element 16 to alternately move
to compress first one pump casin~ and then the other
in a pendulum-like fashion. With the positioning of
the purnp casings as shown, a single compression ele-
ment 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, ~ h the compres-ion element 17 exten~irg up-
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ward between the pumps. The element 17 includes a stem
portion 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 "compressin~;' 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 artificial kidney system of FIG.
1, it is evident that the pumps could be used in a variety
of applications requiring the pumping of fluids.
lS FIG. 8 shows a "full-cycle" pump for use in either
or both the blood transporting ~;ystem 2 (pxovided 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 the compression
element 806. Each casing is constructed similar to the
pump shown in PIG. 2, each including an inlet and outlet
and inlet and outlet valves. The two casings are coupled
in paraliel into a fluid-carrying line 808, with the
lnlets oi each casing coupled to portion 808a of the line
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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
movement of the compression element 806, fluid is passed
to the line portion 808b so that a type of full-cycle
pumping action is developed. This may be contrasted
with so-called half-cycle 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.
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