Apparatus and method for automatically controlling hemodialysis at a pre-selected ultrafiltration rate

• US 4,209,391 A
• Filed: 11/06/1978
• Issued: 06/24/1980
• Est. Priority Date: 11/06/1978
• Status: Expired due to Term

• Current Assignee: Cordis Dow Corp.
• Original Assignee: Cordis Dow Corp.
• Inventors: Lipps, Bennie J., Landau, Julian I.
• Primary Examiner(s): Wyse, Thomas G.
• Assistant Examiner(s): Cross, E. Rollins
• Application Number:
  US05/958,329
• Time in Patent Office: 596 Days
• Field of Search: 210/321 B, 210/97, 210/88, 210/188, 210/196.1, 210/143, 210/22 C, 417/25, 417/99, 417/251, 137/99
• US Class Current: 210/647
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1611 Weight of the patient
• CPC Class Codes: A61M 1/1639 linked by membranes
• CPC Class Codes: A61M 1/1641 linked by pistons
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3358 Measuring barometric pressure, e.g. for compensation
• CPC Class Codes: A61M 2205/3393 by weighing the reservoir
• CPC Class Codes: A61M 2205/50 with microprocessors or computers
• CPC Class Codes: Y10S 210/929 Hemoultrafiltrate volume measurement or control processes
• CPC Class Codes: Y10T 137/2516 Interconnected flow displacement elements

Abstract

Apparatus for and method of automatically controlling the quantity and rate of liquid removed from blood during hemodialysis. The apparatus supplies dialysate in a single pass system in a closed, controlled volume circuit which includes an above atmospheric pressure portion and a below atmospheric pressure portion. The above atmospheric pressure portion includes a pair of chambers for alternate supply to and removal of the dialysate from the below atmospheric pressure portion which contains an artificial kidney and a third means for removing fresh dialysate from the above atmospheric pressure portion; the below atmospheric pressure portion includes means which isolates the kidney containing portion and restores pressure to spent dialysate to a pressure at least equal to or higher than the pressure of the dialysate fed into said closed circuit; the above atmospheric circuit also includes means for removing gas from the spent dialysate prior to filling the spent dialysate removal chamber before discard.

Claims

1. An improved closed dialysate circuit for use in hemodialysis comprising an above atmospheric pressure portion comprising dialysate supply and removal means and ultrafiltrate removal means and below atmospheric pressure portion comprising a hemodialyzer,

said above atmospheric pressure portion including a dialysate supply line and a dialysate drain line,

a portion of a kidney fresh dialysate supply line and

a portion of a kidney spent dialysate removal line, first and second cylinder units having means for separating each said cylinders(s) into two chambers as said means moves between the ends of said cylinder, said first and second units each having valves and interconnected switching means effective to cause concurrently one of said units to fill with fresh dialysate as spent dialysate is discarded while the other said unit fills with spent dialysate as fresh dialysate is supplied to said kidney and to alternate functions after said valves are switched at the same time, and ultrafiltrate removal means connected between one of said dialysate lines and said dialysate drain line effective to withdraw dialysate from said line and transfer same to said dialysate drain line, and means for actuating said ultrafiltrate removal means independently of the means actuating said first and said second cylinder units and remotely located control means for controlling said ultrafiltrate removal means, and a degassifier located in the spent dialysate delivery line adjacent to the chamber of said cylinder unit to be filled therewith,

said below atmospheric pressure portion including a portion of a kidney spent dialysate removal line,

an artificial kidney having a membrane capable of permitting simultaneous dialysis and ultrafiltration of blood and a pair of inlet and outlet blood ports and a pair of inlet and outlet dialysate ports,

pressure reducing means in the fresh dialysate supply line to said artificial kidney adjacent to said dialysate inlet port thereof, and pressure increasing means in the spent dialysate removal line from said kidney adjacent to said dialysate outlet port thereof.

2. An improved dialysate circuit in accordance with claim 1 wherein each said first and second cylinder is separated into two chambers by a double-acting piston attached to a common driving means for reciprocating said pistons.

3. An improved dialysate circuit in accordance with claim 2 wherein said (fresh dialysate) ultrafiltrate removal means is a double-acting piston and cylinder unit having valves and interconnected switching means effective to withdraw fresh dialysate from said fresh dialysate supply line and (trasnfer) transfer same to said dialysate drain line and said actuating means is controllable to vary the quantity transferred.

4. An improved dialysate circuit in accordance with claim 1 wherein each said first and second cylinder is separated into two chambers by a diaphragm.

5. An improved dialysate circuit in accordance with claim 1 wherein means is provided to connect said fresh dialysate supply line directly to the spent dialysate line at a location between said pressure reducing means and the fresh dialysate inlet port of said kidney.

6. An improved dialysis circuit in accordance with claim 1 wherein said pressure reducing means is a back pressure regulator.

7. An improved dialysate circuit in accordance with claim 1 wherein said pressure increasing means is pump means.

12. An improved dialysate circuit in accordance with claim 1 wherein said ultrafiltrate removal means is connected into said fresh dialysate supply line.

8. A method for automatically controlling ultrafiltration during hemodialysis in a single pass system which comprises the steps of

(1) providing a closed circuit having an artificial kidney below atmospheric pressure portion thereof and means for supplying fresh and removing spent dialysate from said kidney and for removing fresh dialysate from said circuit in an above atmospheric pressure portion of said circuit,

(2) supplying blood to and from said kidney,

(3) supplying fresh dialysate from means in said above atmospheric pressure portion of said circuit to said kidney,

(4) withdrawing degassed dialysate from said closed circuit at a location in said above atmospheric pressure portion of said circuit at a rate pre-selected for removal of water from said blood,

(5) returning spent dialysate from said kidney to said spent dialysate removal means, and

(6) raising the pressure on said spent dialysate to a pressure higher than the pressure on said spent dialysate at the kidney exit port and to a pressure at least as high as the pressure on said fresh dialysate in said fresh dialysate supply means at a location intermediate said kidney and said spent dialysate removal means, and

(7) removing gas bubbles from the pressurized spent dialysate solution produced in step 6 prior to returning the resultant gas-free spent dialysate to said spent dialysate removal means, and

(8) controlling the rate of water removal from said blood in said kidney by controlling the rate of withdrawal of dialysate in the said above atmospheric pressure portion of said circuit.

9. A method in accordance with claim 8 wherein the pressure in said above atmospheric pressure portion of said closed circuit is maintained in the range of about 1 to about 20 psi above atmospheric pressure.

10. A method in accordance with claim 9 wherein the pressure on said supply dialysate in said dialysate supply means is maintained in the range of about 2 to about 7 psi above atmospheric pressure, and the pressure on spent dialysate resulting from step 6 is maintained in the range of about 2 to about 10 psi greater than the pressure on said supply dialysate.

11. A method in accordance with claim 8 wherein the pressure in said below atmospheric pressure portion of said circuit is in the range of about 260 to about 720 mm of mercury below atmospheric pressure.

13. A method in accordance with claim 8 wherein said dialysate is withdrawn from a portion of said fresh dialysate supply line that is located within said above atmospheric pressure portion of said circuit.