CA1104507A

CA1104507A - Proportioning dialysis machine for coil and parallel- flow dialyzers

Info

Publication number: CA1104507A
Application number: CA288,782A
Authority: CA
Inventors: Rene G. Lamadrid
Original assignee: Baxter Travenol Laboratories Inc
Current assignee: Baxter International Inc
Priority date: 1976-11-22
Filing date: 1977-10-14
Publication date: 1981-07-07
Also published as: IT1088968B; BR7707711A; JPS5364996A; BE860703A; FR2371218A1; DE2749462A1; GB1587143A; GB1587144A

Abstract

ABSTRACT OF THE DISCLOSURE

A proportioning-type dialysis machine is disclosed for preparing dialysis solution from water and dialysis con-centrate, delivering fresh dialysis solution to a dialyzer and discharging spent dialysis solution. The machine in-cludes inlet means through which water enters the machine from an external source, a reservoir for receiving and holding liquid, outlet means through which spent dialysis solution exits the machine, and a heat exchanger and heater for heating said water to a predetermined physiological temperature. The heat exchanger is positioned downstream of the inlet means and upstream of the reservoir and the heater and is constructed to permit flow therethrough of water flowing from the inlet means to the reservoir and heater. The heat exchanger is also positioned and constructed to permit flow therethrough of warm spent dialysis solution flowing from a dialyzer to said outlet means, and so as to maximize the transfer of heat from the spent dialysis solution to the entering water.

Description

4;~7 BACKGROUNV OF THE INVENTION
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This invention relates to artificial kidney systems; and more particularly, -to a proportioning~type dialysis machine for use in such systems.
Ar-tificial kidney sys-tems include a dialyzer which has a semipermeable membrane. In the dialyzer J
blood which is to be treated flows through the dialyzer on one side of the membrane, and dialysis solution which receives waste products from the blood flows on the other side of the membraneO 5uch dialyzers may be of the coil-type, the parallel-plate type, or the hollow-fiber type.
The parallel-plate and hollow-fiber types are - similar in certain respects, while the coil-type is markedly different. In both the parallel-plate~and hollow-fiber type dialysis, dialysis solution is drawn :': ::
through the dialyzer by a~pump positioned downstream of the dialyzer and fluid flow wlthîn either type of the dialyzer can be characterized as a parallel-flow. Further~
more, in parallel-flow dialyæers the downstream pump causes :
a negative~(below atmosphere) pressure on the dialysis solution side of the semipermeable membrane.

In coil-type dialyzers, the d1alysis solution is pumped into and throu~h the dialyzer under a pos1tive pressure by a pùmp positioned upstream of the dialyzer.
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Coil-type dialyzers are open to atmosphere at the dialysis ~; ~ solution exi~t~, and the dialyzer is positioned in a large ~recirculation reservo1r which receives the solution leaving the dialyzer. A predetermined amount of the dialysis '~

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solution in the reservoir is continuously removed, and fresh solution is continuously mixed with the remaining solution so as to maintain the appropriate dialysis solu-tion composition Eor dialysis and this mixture is circulated through the dialyzer.
There are two types of dialysis mach1nes: One is a batch-type and the other is a proportioning or con-tinuous-feed type. In the batch-type, a. large quantity of dialysis solution is prepared, by mixing water and lQ dialysis concentrate, and stored 1n a Iarge reservoir.
Such machines are generally used with a coil-type dialyzer.
- Proportioning or continuous-feed machines of the type shown in U.S. Patent ~o. 3,878,095 hav~ become popular. In these machines dialysis solution is continuously prepared, by mlxlng~fresh water~and dlalysls~concentrate, and then delivered to the~dialyzer. The proportioning machines have~generally been lntendèd~for~use with~the parallel-flow~dialyzers and thus/ lnclude~a~negative~pres~
sure pump for drawing the dialysis solution through the dialyzer.
It is an object of the present invention to provide an improvement~in~a~proportlonlng-type dialysis machine. ; ;

SUMMARY :OF~ THE ~INVENTION
According~to~the lnvention there is provided a pro~
portioning-type dialysis machine for preparing dialysis ;
solution from water and dialysis concentrate, delivering~fresh~
dlalysis~solution to~a dlalyzer and discharging spent dialyais sol~ution. The machine includes inlet means through which water :::
enters the~machine frorn an external source, a reservoir for

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receiving and holding liquid, outlet means through which spent dialysis solution exits the machine, and a heat e~changer and heater for heating said water to a predetermined physiological temperature. The heat exchanger is positioned downstream of the inlet means and upstream of the reservoir and the heater and is constructed to permit flow therethrough of water Elowing from the inlet means to the reservoir and heater. The heat ex-changer is also positioned and constructed to permit flow there-through of warm spent dialysis solution flowing from a dlalyzer to said outlet means, and so as to maximize the -transfer of heat from the spent dialysis solution to the entering water.

BRIEF DESCRIPTION OF THE DRAWINGS
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FIGVRE 1 shows a proportioning dialysis machine, a coil dialyzer modulel and a parallel-plate type dialyzer is shown adjacent the coil dialyzer module;
FIGURE 2 is a flow diagram representing the flow of fluid through the dialysis machine;
FIGURE 3 is a diagrarnmatic representation of a control system for`directing flow in the two diEferent modesi and FIGURE 4 is a cross-sectional view of a venturi-like xestriction used in the machine~

DESCRIPTION OF THE PREFERRED EMBOVIMENT
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General Referrlng now to FIGURE 1, there is shown a pro-portioning dialysis machine 5, which is similar to the pro-portioning machine disclosed in U.S. Patent No. 3,878,095.

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~3~5~7 The machine 5 can be used with a coil dialyzer module 6 of the type sold by Baxter Travenol Laborato~ies, Inc., under the trademark ~SP ~ Clear Cannister Module ~Cat. No. 5M1141). The module includes both a coil dia-lyzer 6A and a reservoir 6B~ The coil dialy~er module 6 is position~d above the machine 5 so as to obtain yravity return of dialysis solution to the machine. The machine 5 can also be used with a parallel-plate dialyzer 7 of the type sold by ~axter ~ravenol Laboratories, Inc., under the trademark Para-Flo O parallel-plate dialyzex ~Cat.
No. SM1170).
Referring now to FIGURE 2, it will be seen that the proportioning dialysis machine 5 includes several cooperating sections~ There is provided a connection section 10, a water preparation sectlon 12, a concentrate supply and dialysis solution mixing section 14, and a fluid delivery section 16.
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The Connection Section ~he connection section 10 is at the rear of the machine and includes: a water inlet 18; a dialysis concentrate inlet 20; a fresh dialysis solution outlet 22, from which freshly prepared dialysis solution flows Erom the machine to a dialyzer; and a spent or used dia-lysis solution inlet 24 for receiving flow of used dialysis solution from the dialyzer. A blood leak detector 26 is mounted to the section 10 for detecting the presence of blood in the spent dialysis solution, and an internal line connects the blood leak detector 26 to a drain con-nection 28 from which the spent dialysis solution exits the machine for disposal.
Water entering the dialysis machine through the inlet 18 flows along line 30 to a heat exchanger 32 through which spent dialysis solution also flows. The cold incom-ing water in line 30 receives some heat from the warmer ~pent dialysis solution. Water exiting the heat exchanger 32 flows along line 34 into the water preparation section 12.
In the preparatiorl section 12 the water enters an atmospheric-pressure water reservoir or holding tank 36c The water level in the tank 36 is controlled by a float valve 38. Water is drawn from the tank through line 40, through~a heater 42, and~through a venturi-llke~restric tion 94 by a positive displacement degassing pump~46. ~ ~ -As the fluid is drawn~through the restriction 44,~entrained :
and~dissolved air ssparates from ths water for;subsequent removal.
The restrlction 44 is shown in greater detail in FIGURE~4, and it is seen that the restriction includes a~large inlet throat 44a whlch~terminates at the inlet to~a~small dlameter throat;44b. The outlet end of throat 44~ opens into the full-diamstsr of the llne 45 connsotlng the restriction 44 with the pump 46. The abrupt change in diametsr between the throat 44b~and the line 45, coupled ;~
with~the change in speed of ths liquid exiting the throat~
results in turbulent flow and pressure differences which oause ths entrained and dissolved air, or other gases, to separate from the water.
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~ ~3!45~7 The water and separated air, flow from the pump 46 along the line 48 to a degassing tank 50. The tank 50 is vented throuyh pressure rel:ief valve S2 and any overflow returns through line 54 to the holding tank 3G~ The valve 52 opens when the pressure in the tank exceeds 5 psi. Degassed water flows from the bottom of the degas-sing tank 50 along line 56 to a flow mvdule at which the water flow rate is measured. Water ~eaving the module 58 flows along line 60 to the mixing section 14.

lbThe Mixing Section Water flowing along line 60 flows to a mixing site or chamber 62. Dialysis solution concentrate is drawn from the concentrate inlet 20 through lines 64 and 66 by an adjustable concentrate pump 68. The concentrate then flows along llne 70 to the ~mixlng site 62.~ A
pressure relief valve 72 bridges the pump and is posi- :
tioned between the concentrate line 70 and the~concen-trate inlet line 66. This valve prevents a pressure build-up in the concentrate line so as to prevent rupture of the line 70 due to excessive concentrate pressure.
At the mixing site 62, the water and concen-trate mix to form dialysis solution which flows along line 74 to a dialysis solut1on conductivity meter 76 at which the conductivity of the solution is monitored.
A feedback control loop (not shown) is provided whereby operation of the concentrate pump 68 is controlled by the conductivity meter so as to control the quantity of 5~

concentrate delivered to the mixing site and thus, the composition of the dialysis solution. The dialysis solution leaves the conductivity met~r 76 and flows along line 78 -to the dialysis solution pressure monitor 80.
From the pressure monitor 80, the dialysis solution flows along line 82 to the fluid delivery section 16.

The Fluid Delivery Sectlon The fluid delivery section 16 includes a fresh dialysis solution flow line 84 which connects to the line 82. The fresh ~ialysls solution flows through a fresh dialysis solution oulet valve 86 and line 88 to the fresh dialysis solution outlet 22 and then to the dialyzer.
Used or spent dialysis solution from the dialyzer re-enters the machine through the i~let 24 and flows in to `
the fluid delivery section~via line 90,~through the spent dia~lysis~solution inlet vslve 92, and through~ the spent dialysis solution line 94,~ The spsnt dialysis solution then flows, depending upon whether the machine is in the parallel-flow or coil mode, in one~or two directions.
In the coil mode, the used dialysis solution flows from line 94, through the branch 96a of line 96, through the drain line access valve 98 and line lO0 to a drain line 102 which connects to the inlet of the blood leak detector 26. In thé parallel-flow mode, used dialysis ~solution flows from line 94, through the branch 96b of line 96, away ~rom valve 98 to branch 82a of line 82. Branch ::: :
82a carries the dialysis solution through the heat sxchsnger 32, thrvugh line 104 to the negative prsssur~

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or effluent p~p 106. The solution then exits pump 106 and flows to drain through line 102. In the parallel-flow mode~ the negative pressure pump 106 draws the dia-ly~is solution from the mixing site 62 through the dialy~er to the pump and then pumps the so.lution to the drain 28.
A bypass valve 108 is arranged for connecting line 82 and branch 82a for use during sterilization and bypass operation~ ' Operation .

10The machine is operable in the coil mode, the parallel-flow mode, and a sterilization mode. The parallel-flow and coil mode each includes an operational and,bypass variation. The machine includes a mode con~
trol~ll0 for operating:the~machine in the selected mode : : ~:
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or variation by se~lectively, and in some.cases sequen~
~: tially,operating the valves 86, 92, 98 and 102~as well :~
as the pump 106. The re1ationship of tha~control ~110, ~ :
:
: : the flow valves and the pump are shown in FIGURE 3.

The basic modes of operation are as follows: :
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1 Parallel-flow A. Operation ' B. Bypass . : : 2. Coil ~: A. Operation : : , : B. Bypass 3. St rilize :

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S~ 7 Parallel-Flow Opera-ti,onal Mocle. In -the parallel~
~ _ ____ flow operational mode, the dialysis solution enters the fluicl d~livery section 16 and the control 110 cooperates with the valves and pump so that: the valve 86 is open;
the bypass valve 108 is closed; the valve g2 is open;
the valve 98 is closed; and the pump 106 is active or operative. In that arrangement dialysis solution is drawn rom line 82 through line 84, va~ve 86, line 88 and into the parallel-plate dialyzer 7. The dialyzer 7 is connected to both the ~resh dialysis solution outlet 22 and the inlet 24. The spent dialysis solution is drawn through the dialyzer and back into the machine throuyh the inlet 24 and through valve 92.
Since the valve 98 is in a closed position,~
the negative pressure pump 106 draws the spent dlalysis aolution from the valve 92 through line 94, branch 96b and then to the pump 106 via lines 82a and 104. From the pump 106 the dialysis solution then flows to drain.
Parallel-Flow Bypass Mode. In the even~ cer-ta,in predetermined failure or alarm conditions occur, the control 110 cooperates with the valves to bypass the dialyzer. In the parallel-flow bypass mode, the valves 86, 92 and 98 are closed, the valve 108 is opened~ and the pump 106 is operative. The dialysis solution flows from line 82 through the valve 108, through the branch g2a and from there through the pump 106 to drain.
Coil Operational Mode~ In *he coil operational mode, dialysis solution is prepared as in the parallei-. .

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flow mode. In this mode the con~rol 110 deactivates the pump 106, opens valves 86, 92 and 98, and closes valve 108. The dialysis solution thus flows through the valve 86 to th~ coil dialyzer module 6. The coil dialyzer 6A
is physically positioned in ~he recirculation reservoir 6s which is above the dialysis machine so that there is gravity-induced return flow of spent dialysis solution through the inl2t 24 In the coil mode, the valve 98 is open, and since the pump 106 is deactivated, the spent dialysls solution ~lows through valve 92, line 94 and branch 96a, through valve 98, ~d to drain.
In the coil mode, the pump 106 is deactivated for two reasons. First, in the coil mode the pump is not used to draw dialysis solution through the dialyzer or to deliver spent dialysis solution to the~drain. Secondly, the pump would not receive any fluid flow untll the dialyzer :
recirculation reservoir was~filled and thus could be~
damaged by rllnnlng dry until the reservoir was~filled.
Coil Bypass Mode. In the event of an alarm condition, the dialysis machine is placed in the bypass mode. In the coil mode, bypass is accomplished by the control 110 cooperating in closing valves 86 and 92; and openlng valves lOB and 98. In this configuration, the effluent pump 106 is deactivated. In this manner dialysis solution is bypassed around the dialyæer by flowlng from line 82, through valve 108, up branch 96b, through valve 98, and to the drain 28.
Sterilize, The dialysis machine can bs sterilized by externally interconnecting the outlet 22 to the inlet 24 :, . :, ~
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and appropriately heating the water flowing from the tank through the heater 42. In order to sterilize the dialysis machine r ~he control 110 operate6 the machine through several o~ its modes o~ operation in order to assure complete sterilLzation. The machine is first operated in the parallel-flow bypass mo~de in which onl~
valve 108 is open and the effluent pump 106 is operating;
next, the machine is operated through the normal paral-lel-flow mode in which valves ~6 and 92 are open, valves 98 and 108 are closed, and the effluent pump 106 i5 operating; and the final step is the normal coil mode in which only the bypass valve 108 is closed and the pump 106 is inactive.
For the sake of convenience, the following table is provlded which s ts out~the valve and pump con-figuration depending upon the mode of operatlon. IThe symbols used in the table are~defined in the footnote.) Valves ~ Pump Mode 86 ~92 98 108 106 :
Parallel flow -- : :
Operation O O C C A

Bypass C C C O A
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Coil flow Operation O O O C ~ D
Bypass ~ C~ ~ ~C ~ ~0 O ~ ; D
Sterilize Step l C C C O A
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Step 2 ~ O O C C A

; Step 3 O O O C D
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Footnote: O means the valve is open C means the valve is closed; A means the pump is activated; and D means . . .
the pump is deactivated.

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It should be no-ted that whether the machine is operated in the coil mode or parallel-flow mode that the restriction 44 permits water to flow to the degassing pump ~6 as the pump begins to draw agairlst the restric-tion. Furthermore, in the parallel-flow mode, fluid flows to the negative pressure pump 106 upon flow of fluid through the degassing pump 46. Wikh thi.s arrangement the degassing pump 46 and negative pressure pump 106 are primed quickly and unprimed operation is thus minimized.
It will be appreciated that numerous changes can be made to the embodiment disclosed herein without departing from the spirit and scope of this invention.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A proportioning-type dialysis machine for pre-paring dialysis solution from water and dialysis concen-trate, delivering fresh dialysis solution to a dialyzer and discharging spent dialysis solution, said machine including: inlet means through which water enters said machine from an external source; a reservoir for re-ceiving and holding liquid; outlet means through which spent dialysis solution exits said machine; and a heat exchanger and heater for heating said water to a pre-determined physiological temperature, wherein the improvement comprises said heat exchanger (a) being positioned downstream of said inlet means and upstream of said reservoir and said heater and constructed to permit flow therethrough of water flowing from said inlet means to said reservoir and heater and also (b) being positioned and constructed to permit flow therethrough of warm spent dialysis solution flowing from a dialyzer to said outlet means (c) so as to maximize the transfer of heat from said spent dialysis solution to said entering water.

2. A proportioning dialysis machine as in claim 1, wherein said heater is positioned downstream of said reservoir for heating water from the reservoir.