Dialysate separation method

• US 5,645,734 A
• Filed: 02/23/1995
• Issued: 07/08/1997
• Est. Priority Date: 02/13/1995
• Status: Expired due to Term

• Current Assignee: Baxter Healthcare SA (Baxter International Inc.), Baxter International Inc.
• Original Assignee: Aksys Ltd.
• Inventors: Minns, H. Gordon, Treu, Dennis M., Kenley, Rodney S., Peter, Frederick H. Jr., Matthews, Dawn, Feldsein, Thomas M.
• Primary Examiner(s): KIM, SUN U
• Application Number:
  US08/559,090
• Time in Patent Office: 866 Days
• Field of Search: 210/646, 210/647, 210/774, 210/805, 210/195.2, 210/929, 210/321.65, 210/321.71
• US Class Current: 210/805
• CPC Class Codes: A61L 2/04 Heat A61L2/08 takes precedence
• CPC Class Codes: A61L 2/18 Liquid substances or solutions comprising solids or dissolved gases
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1607 before use, i.e. upstream of dialyser
• CPC Class Codes: A61M 1/1609 after use, i.e. downstream of dialyser
• CPC Class Codes: A61M 1/1649 with pulsatile dialysis fluid flow
• CPC Class Codes: A61M 1/165 with a dialyser bypass on the dialysis fluid line
• CPC Class Codes: A61M 1/1656 Apparatus for preparing dialysates
• CPC Class Codes: A61M 1/1658 Degasification
• CPC Class Codes: A61M 1/166 Heating for sterilisation A61M1/1686
• CPC Class Codes: A61M 1/1662 with heat exchange between fresh and used dialysate
• CPC Class Codes: A61M 1/1666 by dissolving solids
• CPC Class Codes: A61M 1/1668 Details of containers
• CPC Class Codes: A61M 1/1672 using membrane filters, e.g. for sterilising the dialysate
• CPC Class Codes: A61M 1/1682 both machine and membrane module, i.e. also the module blood side
• CPC Class Codes: A61M 1/1684 Checking the module characteristics before reuse
• CPC Class Codes: A61M 1/1686 by heat
• CPC Class Codes: A61M 1/1688 with recirculation of the sterilising fluid
• CPC Class Codes: A61M 1/169 using chemical substances
• CPC Class Codes: A61M 1/1692 Detection of blood traces in dialysate
• CPC Class Codes: A61M 1/1694 : with recirculating dialysing liquid
• CPC Class Codes: A61M 1/288 : Priming priming in extracorporeal blood circuits A61M1/3643
• CPC Class Codes: A61M 1/3434 : with pre-dilution and post-dilution
• CPC Class Codes: A61M 1/3437 : downstream of the filter, e.g. post-dilution with filtrate
• CPC Class Codes: A61M 1/3465 : using dialysate as substitution fluid
• CPC Class Codes: A61M 1/3468 : using treated filtrate as substitution fluid
• CPC Class Codes: A61M 1/3609 : Physical characteristics of the blood, e.g. haematocrit, urea
• CPC Class Codes: A61M 1/3622 : with a cassette forming partially or totally the blood circuit
• CPC Class Codes: A61M 1/36224 : with sensing means or components thereof
• CPC Class Codes: A61M 1/36226 : Constructional details of cassettes, e.g. specific details on material or shape
• CPC Class Codes: A61M 1/362263 : Details of incorporated filters
• CPC Class Codes: A61M 1/3626 : Gas bubble detectors
• CPC Class Codes: A61M 1/3627 : Degassing devices; Buffer reservoirs; Drip chambers; Blood filters
• CPC Class Codes: A61M 1/3629 : degassing by changing pump speed, e.g. during priming
• CPC Class Codes: A61M 1/3639 : Blood pressure control, pressure transducers specially adapted therefor
• CPC Class Codes: A61M 1/3641 : Pressure isolators
• CPC Class Codes: A61M 1/3643 : Priming, rinsing before or after use
• CPC Class Codes: A61M 1/3644 : Mode of operation
• CPC Class Codes: A61M 1/3646 : Expelling the residual body fluid after use, e.g. back to the body
• CPC Class Codes: A61M 1/3647 : with recirculation of the priming solution
• CPC Class Codes: A61M 1/3649 : using dialysate as priming or rinsing liquid
• CPC Class Codes: A61M 1/365 : through membranes, e.g. by inverted trans-membrane pressure [TMP]
• CPC Class Codes: A61M 2205/12 : with interchangeable cassettes forming partially or totally the fluid circuit
• CPC Class Codes: A61M 2205/15 : Detection of leaks
• CPC Class Codes: A61M 2205/17 : with redundant control systems
• CPC Class Codes: A61M 2205/18 : with alarm
• CPC Class Codes: A61M 2205/3317 : Electromagnetic, inductive or dielectric measuring means
• CPC Class Codes: A61M 2205/3324 : PH measuring means
• CPC Class Codes: A61M 2205/3331 : Pressure; Flow
• CPC Class Codes: A61M 2205/3344 : Measuring or controlling pressure at the body treatment site
• CPC Class Codes: A61M 2205/3368 : Temperature
• CPC Class Codes: A61M 2205/3382 : Upper level detectors
• CPC Class Codes: A61M 2205/3386 : Low level detectors
• CPC Class Codes: A61M 2205/502 : User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/505 : Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2205/6072 : Bar codes
• CPC Class Codes: A61M 2205/705 : Testing of filters for leaks blood in dialysate A61M1/1692
• CPC Class Codes: A61M 2205/707 : Testing of filters for clogging
• CPC Class Codes: A61M 2205/7554 : with means for unclogging or regenerating filters
• CPC Class Codes: A61M 2205/7581 : with means for switching over to a fresh filter on clogging or saturation
• CPC Class Codes: A61M 2206/11 : Laminar flow
• CPC Class Codes: A61M 2230/65 : Impedance, e.g. conductivity, capacity
• CPC Class Codes: A61M 39/16 : having provision for disinfection or sterilisation A61M39/143 takes precedence; methods or apparatus for disinfection or sterilisation A61L2/00
• CPC Class Codes: B01D 2311/04 : Specific process operations in the feed stream; Feed pretreatment
• CPC Class Codes: B01D 2311/10 : Temperature control
• CPC Class Codes: B01D 2311/25 : Recirculation, recycling or bypass, e.g. recirculation of concentrate into the feed
• CPC Class Codes: B01D 2311/2626 : Absorption or adsorption
• CPC Class Codes: B01D 2321/04 : Backflushing
• CPC Class Codes: B01D 2321/16 : Use of chemical agents
• CPC Class Codes: B01D 2321/32 : By heating or pyrolysis
• CPC Class Codes: B01D 61/02 : Reverse osmosis; Hyperfiltration ; Nanofiltration
• CPC Class Codes: B01D 61/025 : Reverse osmosis; Hyperfiltration
• CPC Class Codes: B01D 61/04 : Feed pretreatment
• CPC Class Codes: B01D 61/12 : Controlling or regulating
• CPC Class Codes: B01D 61/32 : Controlling or regulating
• CPC Class Codes: B01D 65/022 : Membrane sterilisation
• CPC Class Codes: B01D 65/102 : Detection of leaks in membranes
• CPC Class Codes: B01D 65/104 : Detection of leaks in membrane apparatus or modules
• CPC Class Codes: C02F 1/441 : by reverse osmosis
• CPC Class Codes: F16K 17/0453 : the member being a diaphragm
• CPC Class Codes: Y10S 210/929 : Hemoultrafiltrate volume measurement or control processes
• CPC Class Codes: Y10S 215/03 : Medical
• CPC Class Codes: Y10T 137/7722 : Line condition change responsive valves
• CPC Class Codes: Y10T 137/7794 : With relief valve
• CPC Class Codes: Y10T 137/7796 : Senses inlet pressure
• CPC Class Codes: Y10T 137/7799 : Liquid transfer

Abstract

A method for maintaining separation of old and new dialysate in a dialysate preparation tank is disclosed. The new dialysate is stored in the tank at a first temperature and withdrawn from the bottom of the tank. The dialysate is circulated through a dialyzer, and then returned to the tank at the top of the tank at a higher temperature in a substantially non-turbulent manner. The temperature differential between old and new dialysate and the manner of withdrawing and reintroducing the dialysate to the tank cooperate to form discrete zones of old and new dialysate without substantial mixing of the dialysate in the two zones.

Claims

1. A method for maintaining separation of old and new dialysate in a batch dialysate preparation tank, comprising the steps of:

storing said new dialysate in said tank at a first temperature;

withdrawing said new dialysate from the bottom of said tank;

returning old dialysate to said tank at the top of said tank at a second temperature warmer than said first temperature in a manner so as to substantially prevent turbulence of said old dialysate during the return of said old dialysate to said tank;

the temperature differential between the first and second temperatures of dialysate and the manner of returning said old dialysate causing old and new dialysate to be maintained in substantially discrete zones with said old dialysate in a first zone above the new dialysate in a second zone with a boundary therebetween, said boundary lowering as dialysis of the patient proceeds.

2. The method of claim 1, wherein said temperature differential between said old and said new dialysate is normally greater than 3 degrees C.

3. The method of claim 2, wherein said first temperature of said new dialysate in said tank is approximately 28 to 30 degrees C. and said second temperature of said old dialysate returned to said tank is normally approximately 37 degrees C.

4. The method as claimed in claim 1, wherein said step of returning old dialysate to said tank further comprises the step providing a dialysate inlet at the top of said tank and passing said old dialysate through said dialysate inlet into said tank, said dialysate inlet constructed so as to gently introduce said old dialysate into the top of said tank.

5. The method as claimed in claim 1, wherein said tank comprises a closed and substantially noncompliant vessel.

6. A method for maintaining separation of old and new dialysate in a batch dialysate preparation tank, comprising the steps of:

storing said new dialysate in said tank at a first temperature;

withdrawing said new dialysate from the bottom of said tank;

returning old dialysate to said tank at the top of said tank at a second temperature warmer than said first temperature in a manner so as to substantially prevent turbulence of said old dialysate during the return of said old dialysate to said tank;

the temperature differential between the first and second temperatures of dialysate and the manner of returning said old dialysate causing old and new dialysate to be maintained in substantially discrete zones with said old dialysate in a first zone above the new dialysate in a second zone with a boundary therebetween, said boundary lowering as dialysis of the patient proceeds;

the method further comprising the step of introducing warmer dialysate into said top of said tank at a temperature greater than said first temperature prior to the return of said old dialysate to said tank, thereby establishing a temperature gradient of dialysate in said tank with said warmer introduced dialysate forming said first zone at the top of said tank, said old dialysate being returned to said tank and mixing with said warmer introduced dialysate in said first zone.

7. The method of claim 6, wherein said step of introducing comprises the step of heating up to two liters of new dialysate to said second temperature and returning said heated up to two liters of new dialysate to said top of said tank in a non-turbulent manner.