Method for determining sodium clearance of dialyzer

• US 5,716,531 A
• Filed: 07/15/1997
• Issued: 02/10/1998
• 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: Kenley, Rodney S., Bell, Eric, Peter, Frederick H. Jr., Matthews, Dawn, Feldsein, Thomas M.
• Primary Examiner(s): KIM, SUN U
• Application Number:
  US08/893,125
• Time in Patent Office: 210 Days
• Field of Search: 210/645, 210/646, 210/647, 210/739, 210/746
• US Class Current: 210/746
• 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
• 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 is described for determining the sodium clearance of a dialyzer. Dialysate containing sodium ions is circulated through the dialysate side of the dialyzer. Water is continuously circulated through the blood side of the dialyzer, the water being single passed through the blood side of the dialyzer. Measurements of the conductivity of the dialysate are made prior to the dialysate entering the dialyzer, and measurements of the conductivity of the dialysate are made after the dialysate has passed through the dialyzer. The clearance of the sodium ions by the dialyzer is calculated from the measurements of conductivity. The measurements of conductivity of the dialysate after passing through the dialyzer becomes substantially constant as the dialysate and water are circulated through the dialyzer. The sodium clearance corresponds to urea clearance of the dialyzer, since the two molecules are approximately the same size.

Claims

1. In a dialysis machine, a method of conducting a clearance test of a dialyzer and determining the need for replacement of said dialyzer, the dialyzer having a blood side and a dialysate side, comprising the steps of:

approximating the urea clearance of a dialyzer in a new condition by circulating reverse osmosis water on through said blood side of said dialyzer and circulating a dialysate solution through said dialysate side of said dialyzer, measuring conductivity of said dialysate solution before and after said dialysate solution has circulated through said dialysate side of said dialyzer, and determining a clearance coefficient K_init of the dialyzer from said measurements of conductivity;

storing in a memory for said dialysis machine the value of K_init ;

repeating the step of approximating the urea clearance of said dialyzer after a dialysis session has been conducted by said dialysis machine with said dialyzer by circulating reverse osmosis water through said blood side of said dialyzer and circulating a second dialysate solution through said dialysate side of said dialyzer, measuring conductivity of said second dialysate solution before and after said second dialysate solution has circulated through said dialysate side of said dialyzer, and determining a new clearance coefficient K_i of the dialyzer from said measurements of conductivity;

storing in said memory of said dialysis machine the value of K_i ;

comparing K_init with K_i ; and

responsively prompting a user of said dialysis machine to replace said dialyzer if K_i <

K_init by a predetermined threshold amount.

2. The method of claim 1, wherein said reverse osmosis water is circulated in a single pass through said blood side of said dialyzer.