GB1587144A - Proportioning apparatus for use in a dialysis machine - Google Patents

Description

PATENT SPECIFICATION ( 11) 1 587 144

( 21) Application No 2642/80 ( 22) Filed 27 Oct1977 ( 19) ( 62) Divided out of No 1587143 ( 31) Convention Application No 743892 ( 32) Filed 22 Nov 1976 in,.

( 33) United States of America (US) tn ( 44) Complete Specification Published 1 Apr 1981 ( 51) INT CL 3 A 61 M 1/03 B 01 D 13/00 ( 52) Index at Acceptance Bl X 6 A 1 6 B 1 6 B 3 6 B 4 6 F 6 6 H 1 6 HX ( 54) PROPORTIONING APPARATUS FOR USE IN A DIALYSIS MACHINE ( 71) We, BAXTER TRAVENOL LABORATORIES INC, a Corporation organised and existing under the Laws of the State of Delaware, United States of America, of One Baxter Parkway, Deerfield, Illinois 60015, United States of America, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: 5

This invention relates to proportioning apparatus for use in a proportioning-type dialysis machine, e g for use in an artificial kidney system.

Artificial kidney systems include a dialyzer which has a semipermeable membrane In the dialyzer, 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 10 the membrane Such 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 15 fluid flow within either type of the dialyzer can be characterized as a parallel-flow Furthermore, in parallel-flow dialyzers the downstream pump causes a negative (below atmosphere) pressure on the dialysis solution side of the semipermeable membrane.

In coil-type dialyzers, the dialysis solution is pumped into and through the dialyzer under a positive pressure by a pump positioned upstream of the dialyzer Coil-type dialyzers are open 20 to atmosphere at the dialysis solution exit, and the dialyzer is positioned in a large recirculation reservoir which receives the solution leaving the dialyzer A predetermined amount of the dialysis solution in the reservoir is continuously removed, and fresh solution is continusously mixed with the remaining solution so as to maintain the appropriate dialysis solution composition for dialysis and this mixture is circulated through the dialyzer 25 There are two types of dialysis machines: one is a batch-type and the other is proportioning or continuous-feed type In the batch-type, a large quantity of dialysis solution is prepared, by mixing water and dialysis concentrate, and stored in a large reservoir.

Proportioning or continuous-feed machines of the type shown in U S Patent No.

3,878095 have become popular These machines include apparatus in which dialysis solution 30 is continuously prepared, by mixing fresh water and dialysis concentrate, and then delivered to the dialyzer.

The present invention provides proportioning apparatus for use in a dialysis machine for preparing dialysis solution from water and dialysis concentrate, said apparatus including:

inlet means through which water enters said apparatus from an external source, a reservoir 35 for receiving and holding the water; and a heat exchanger and heater for heating said water to a predetermined physiological temperature, said heat exchanger being positioned downstream of said inlet means and upstream of said reservoir and said heater, said heat exchanger being positioned and constructed to permit flow therethrough of spent dialysis solution and to effect the transfer of heat from said spent dialysis solution to said entering water 40 Reference is made to the accompanying drawings, wherein:

Figure 1 shows proportioning apparatus, together with a coil dialyzer module and a parallel-plate type dialyzer; Figure 2 is a flow diagram representing the flow of fluid through the apparatus; Figure 3 is a diagrammatic representation of a control system for directing flow in the two 45 2 1587144 2 different modes; and Figure 4 is a cross-sectional view of a venturi-like restriction used in the apparatus.

Referring now to Figure 1, there is shown a proportioning apparatus 5, which is similar to the proportioning apparatus disclosed in U S Patent No 3,878,095.

The apparatus 5 can be used with a coil dialyzer 6 A and a reservoir 6 B The coil dialyzer 5 module 6 of the type sold by Baxter Travenol Laboratories, Inc, under the trademark RSP Clear Cannister Module (Cat No 5 M 1141) The module includes both a coil dialyzer module 6 is positioned above the apparatus 5 so as to obtain gravity return of dialysis solution to the apparatus The apparatus 5 can also be used with a parallel-plate dialyzer 7 of the type sold by Baxter Travenol Laboratories, Inc, under the trademark Para-Flo parallel-plate 10 dialyzer(Cat No 5 M 1170).

Referring now to FIGURE 2, it will be seen that the proportioning apparatus 5 includes several cooperating sections There is provided a connection section 10, a water preparation section 12, a concentrate supply and dialysis solution mixing section 14, and a fluid delivery section 16 15 The Connection Section The connection section 10 is at the rear of the apparatus and includes: a water inlet 18; a dialysis concentrate inlet 20; a fresh dialysis solution outlet 22, from which freshly prepared dialysis solution flows from the machine to dialyzer; and a spent or used dialysis solution inlet 20 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 connection 28 from which the spent dialysis solution exits the apparatus for disposal.

Water entering the dialysis apparatus through the inlet 18 flows along line 30 to a heat 25 exchanger 32 through which spent dialysis solution also flows The cold incoming water in line 30 receives some heat from the warmer spent dialysis solution Water exiting the heat exchanger 32 flows along line 34 into the water preparation section 12.

In the preparation section 12 the water enters an atmospheric-pressure water reservoir or holding tank 36 The water level in the tank 36 is controlled by a float valve 38 Water is 30 drawn from the tank through line 40, through a heater 42, and through a venturi-like restriction 44 by a positive displacement degassing pump 46 As the fluid is drawn through the restriction 44 entrained and dissolved air separates from the water for subsequent removal.

The restriction 44 is shown in greater detail in FIGURE 4, and it is seen that the restriction 35 includes a large inlet throat 44 a which terminates at the inlet to a small diameter throat 44 b.

The outlet end of throat 44 b opens into the full diameter of the line 45 connecting the restriction 44 with the pump 46 The abrupt change in diameter between the throat 44 b and the line 45, coupled with the change in speed of the liquid exiting the throat results in turbulent flow and pressure differences which cause the entrained and dissolved air, or other 40 gases, to separate from the water.

The water and separated air, flow from the pump 46 along the line 48 to a degassing tank The tank 50 is vented through pressure relief valve 52 and any overflow returns through line 54 to the holding tank 36 The valve 52 opens when the pressure in the tank exceeds 5 psi.

Degassed water flows from the bottom of the degassing tank 50 along line 56 to a flow module 45 at which the water flow rate is measured Water leaving the module 58 flows along line 60 to the mixing section 14.

The Mixing Section Water flowing along line 60 flows to a mixing site or chamber 62 Dialysis solution 50 concentrate is drawn from the concentrate inlet 20 through lines 64 and 66 by an adjustable concentrate pump 68 The concentrate then flows along line 70 to the mixing site 62 A pressure relief valve 72 bridges the pump and is positioned between the concentrate line 70 and the concentrate 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 55 At the mixing site 62 the water and concentrate mix to form dialysis solution which flows along line 74 to a dialysis solution 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 concentrate delivered to the mixing site and thus, the composition of the dialysis solution 60 The dialysis solution leaves the conductivity meter 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.

1 587, 144 1,587,144 The Fluid Delivery Section The fluid delivery section 16 includes a fresh dialysis solution flow line 84 which connects to the line 82 The fresh dialysis solution flows through a fresh dialysis solution outlet valve 86 and line 88 to the fresh dialysis solution outlet 22 and then to the dialyzer Used or spent 5 dialysis solution from the dialyzer re-enters the apparatus through the inlet 24 and flows in to the fluid delivery section via line 90, through the spend dialysis solution inlet valve 92, and through the spent dialysis solution line 94 The spent 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 96 a of 10 line 96, through the drain line access valve 98 and line 100 to a drain line 102 which connects to the inlet of the blood leak detector 26 In the parallel-flow mode, used dialysis solution flows from line 94, through the branch 96 b of line 96, away from valve 98 to bracnh 82 a of line 82 Branch 82 a carries the dialysis solution through the heat exchanger 32, through line 104 to the negative pressure or effluent pump 106 The solution then exits pump 106 and 15 flows to drain through line 102 In the parallel-flow mode, the negative pressure pump 106 draws the dialysis solution from the mixing site 62 through the dialyzer to the pump and then pumps the solution to the drain 28.

A bypass valve 108 is arranged for connecting line 82 and branch 82 a for use during sterilization and bypass operation 20 Operation The apparatus 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 apparatus includes a mode control 110 for operating the apparatus in the selected mode 25 or variation by selectively, and in some cases sequentially, operating the valves 86, 92, 98 and 102 as well as the pump 106 The relationship of the control 110, the flow valves and the pump are shown in FIGURE 3.

The basic modes of operation are as follows:

1 Parallel-flow 30 A Operation B Bypass 2 Coil A Operation B Bypass 35 3 Sterilize Parallel-Flow Operational Mode In the parallel-flow operational mode, the dialysis solution enters the fluid delivery 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 92 is open; the valve 98 is closed; and the pump 106 is active or operative In that arrangement dialysis 40 solution is drawn from line 82 through line 84, valve 86, line 88 and into the parallel-plate dialyzer 7 The dialyzer 7 is connected to both the fresh dialysis solution outlet 22 and the inlet 24 The spent dialysis solution is drawn through the dialyzer and back into the apparatus through the inlet 24 and through valve 92.

Since the valve 98 is in a closed position, the negative pressure pump 106 draws the spent 45 dialysis solution from the valve 92 through line 94, branch 96 b and then to the pump 106 via lines 82 a and 104 From the pump 106 the dialysis solution then flows to drain.

Parallel-Flow Bypass Mode In the event certain 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 50 is operative The dialysis solution flows from line 82 through the valve 108, through the branch 82 a and from there through the pump 106 to drain.

Coil Operational Mode In the coil operational mode, dialysis solution is prepared as in the parallel-flow mode In this mode the control 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 the 55 coil dialyzer module 6 The coil dialyzer 6 A is physically positioned in the recirculation reservoir 6 B which is above the dialysis machine so that there is gravity-induced return flow of spent dialysis solution through the inlet 24 In the coil mode, the valve 98 is open, and since the pump 106 is deactivated, the spent dialysis solution flows through valve 92, line 94 and branch 96 a, through valve 98, and to drain 60 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 until the dialyzer recirculation rese'voir was filled and thus could be damaged by running dry until the reservoir was filled 65 4 1 587 1444 Coil Bypass Mode In the event of an alarm condition, the dialysis apparatus 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 opening valves 108 and 98 In this configuration, the effluent pump 106 is deactivated In this manner dialysis solution is bypassed around the dialyzer by flowing from line 82, through valve 108, up branch 96 b, through valve 98, and to the drain 28 5 Sterilize The dialysis apparatus can be sterilized by externally interconnecting the outlet 22 to the inlet 24 and appropriately heating the water flowing from the tank through the heater 42 In order to sterlize the dialysis apparatus, te e control 110 operates the apparatus through several of its modes of operation in order to assure complete sterilization The apparatus is first operated in the parallel-flow bypass mode in which only valve 108 is open and the 10 effluent pump 106 is operating; next, the apparatus is operated through the normal parallelflow mode in which valves 86 and 92 are open, valves 98 and 108 are closed, and the effluent pump 106 is 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 provided which sets out the valve and 15 pump configuration depending upon the mode of operation (The symbols used in the table are defined in the footnote) Valves Pump Mode 86 92 98 108 106 20 Parallel flow Operation O O C C A Bypass C C C O A Coilflow 25 Operation O O O C D Bypass C C O O D Sterilize Step I C C C O A 30 Step 2 O O C C A Step 3 O O O C D 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.

It should be noted that whether the machine is operated in the coil mode or parallel-flow 35 mode that the restriction 44 permits water to flow to the degassing pump 46 as the pump begins to draw against the restriction Furthermore, in the parallel-flow mode, fluid flows to the negative pressure pu Lmp 106 upon flow of fluid through the degassing pump 46 With this arrangement the degassing pump 46 and negative pressure pump 106 are primed quickly and unprimed operation is thus minimized 40 Reference is made to patent specification no (application no 44683/77) Serial No.

1587143, which describes the same dialysis machine proportioning apparatus as described above and includes claims directed to such apparatus.

Claims (1)

1. WHAT WE CLAIM IS:-

   1 Proportioning apparatus for use in a dialysis machine for preparing dialysis solution 45 from water and dialysis concentrate, said apparatus including: inlet means through which water enters said apparatus from an external source; a reservoir for receiving and holding the water; and a heat exchanger and heater for heating said water to a predetermined physiological temperature said heat exchanger being positioned downstream of said inlet means and upstream of said reservoir and said heater, said heat exchanger being positioned and con 50 structed to permit flow therethrough of spent dialysis solution and to effect the transfer of heat from said spent dialysis solution to said entering water.

   2 A proportioning apparatus as in Claim 1 wherein said heater is positioned downstream of said reservoir for heating water flowing from said reservoir.

   ERIC POTTER& CLARKSON 55 Chartered Patent Agents, 14 Oxford Street.

   Nottingham.

   Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon, Surrey 1981.

   Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

   1.587 144