Method and apparatus for controlled ultrafiltration during hemodialysis

• US 4,747,950 A
• Filed: 06/06/1986
• Issued: 05/31/1988
• Est. Priority Date: 12/16/1983
• Status: Expired due to Fees

• Current Assignee: CD Medical Incorporated
• Original Assignee: CD Medical Incorporated
• Inventors: Guinn, Perry W.
• Primary Examiner(s): Spear, Frank
• Application Number:
  US06/873,264
• Time in Patent Office: 725 Days
• Field of Search: 210/86, 210/96.2, 210/321.3, 210/257.2, 210/929, 210/646, 210/321.76
• US Class Current: 210/646
• CPC Class Codes: A61M 1/16 with membranes
• CPC Class Codes: A61M 1/1605 Physical characteristics of the dialysate fluid
• CPC Class Codes: A61M 1/1635 with volume chamber balancing devices between used and fresh dialysis fluid
• CPC Class Codes: A61M 1/1641 linked by pistons
• CPC Class Codes: A61M 1/341 by measuring the filtrate rate or volume
• CPC Class Codes: A61M 1/3427 back through the membrane, e.g. by inverted trans-membrane pressure [TMP]
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/3334 Measuring or controlling the flow rate
• CPC Class Codes: A61M 2205/3389 Continuous level detection A61M2205/3393 takes precedence
• CPC Class Codes: A61M 2205/50 with microprocessors or computers

Abstract

A method of hemodialytic ultrafiltration in a device utilizing a dialysate flow path, a hemodialyzer, a first receptacle and a second receptacle comprises supplying fresh dialysate to the first receptacle. Spent dialysate is withdrawn from the second receptacle at substantially the same rate fresh dialysate is supplied to the first receptacle. This method includes variably withdrawing fresh dialysate from the first receptacle and supplying same to the hemodialyzer, and variable withdrawing spent dialysate from the hemodialyzer and delivering same to the second receptacle. The dialysate levels in the receptacles are maintained at relatively constant, pre-determined levels. Further, this method includes withdrawing a controlled amount of dialysate from the dialysate flow path between and including the receptacles to thereby effect a withdrawal of ultrafiltrate from the patient'"'"'s blood into the flow path to substantially balance the amount of dialysate withdrawn therefrom.

A hemodialysis ultrafiltration apparatus carries out the method substantially as described above.

Claims

1. A method for controlling ultrafiltration during hemodialysis comprising:

supplying blood to and removing blood from a hemodialyzer;

supplying fresh dialysate to a dialysate flow path which includes said hemodialyzer, a dialysate reservoir, a first receptacle and a second receptacle, with fresh dialysate being first supplied to said reservoir;

withdrawing fresh dialysate from said reservoir and delivering same to said first receptacle and then to said hemodialyzer at a controlled flow rate;

sensing the volume of fresh dialysate in the first receptacle and maintaining same at a relatively constant, pre-determined level;

withdrawing spent dialysate, including any ultrafiltrate, from said hemodialyzer and delivering same to said second receptacle and then removing same from said second receptacle and out of said dialysate flow path at said controlled flow rate;

sensing the volume of spent dialysate in the second receptacle and maintaining same at a relatively constant, pre-determined level;

withdrawing a controlled amount of dialysate from either of said receptacles causing a system response to thereby exert a negative pressure in the dialysate section of said hemodialyzer to effect a withdrawal of ultrafiltrate from the patient'"'"'s blood into said flow path to substantially balance the amount of dialysate withdrawn therefrom.

2. The method of claim 1 wherein fresh dialysate is supplied to said first receptacle and spent dialysate is removed from said second receptacle by respectively pumping said fresh and said spent dialysate at substantially equivalent fixed rates of flow.

3. The method of claim 2 which further includes calibrating said rates of pumping to assure that they are substantially equivalent during operation.

4. The method of claim 1 which includes maintaining said receptacles at atmospheric pressure during hemodialysis.

5. The method of claim 1 which includes maintaining said receptacles at a pre-selected pressure during hemodialysis.

6. The method of claim 1 wherein said maintaining of fresh dialysate at the pre-determined level and said maintaining of spent dialysate at the pre-determined level are achieved by varying the flow rates at which fresh dialysate is withdrawn from the first receptacle and at which spent dialysate is delivered to said second receptacle in response to changes from said pre-determined levels.

7. The method of claim 1 wherein the volume of spent dialysate in the second receptacle is maintained at a relatively constant, pre-determined level substantially equivalent to said pre-determined level of said fresh dialysate in said first receptacle.

8. A method of hemodialytic ultrafiltration in a device utilizing a continuous loop dialysate flow path having a hemodialyzer, a first receptacle and a second receptacle comprising:

supplying blood to and removing blood from said hemodialyzer;

supplying fresh dialysate to said first receptacle and withdrawing spent dialysate from said second receptacle at substantially equivalent rates;

withdrawing fresh dialysate at variable flow rates from said first receptacle and supplying same to said hemodialyzer;

withdrawing spent dialysate, including any ultrafiltrate, at variable flow rates from said hemodialyzer and delivering same to said second receptacle;

maintaining the dialysate levels in said receptacles at relatively constant, pre-determined levels; and

withdrawing a controlled amount of dialysate from either of said receptacles to thereby effect a withdrawal of ultrafiltrate from the patient'"'"'s blood into said flow path to substantially balance the amount of dialysate withdrawn therefrom.

9. A method of liquid infusion into a patient utilizing an apparatus with a dialysate flow path comprising a fluid-separation device with a liquid permeable membrane therein, a first receptacle and a second receptacle, said method comprising:

supplying blood to and removing blood from said device;

supplying fresh liquid to said first receptacle and withdrawing spent liquid from said second receptacle at substantially equivalent rates;

withdrawing fresh liquid at variable flow rates from said first receptacle and supplying same to said device;

withdrawing spent liquid at variable flow rates from said device and delivering same to said second receptacle;

maintaining the liquid levels in said receptacles at relatively constant, pre-determined levels; and

supplying a controlled amount of infusate to the fresh liquid upstream of said device to thereby effect an infusion of infusate into the patient'"'"'s blood from said flow path.

10. An apparatus for controlling ultrafiltration during hemodialysis comprising a dialysate flow path having a fresh dialysate supply line for connection to a source of fresh dialysate and a spent dialysate removal line for connection to drain means, said flow path including, between said supply line and said removal line:

a hemodialyzer for the dialysis and ultrafiltration of blood including inlet and outlet blood ports, an inlet dialysate port for the entry of fresh dialysate and an outlet dialysate port for the exit of spent dialysate;

a dialysate reservoir connected to said supply line for the delivery of fresh dialysate thereinto;

a first receptacle positioned in the flow path between said reservoir and the inlet dialysate port of said hemodialyzer;

a first controlled flow rate pump for withdrawing fresh dialysate from said reservoir at a controlled rate and delivering same to said first receptacle;

a first variable rate pump for withdrawing fresh dialysate from said first receptacle at a controlled rate and delivering same to said hemodialyzer;

first sensing means for sensing the volume of fresh dialysate in said first receptacle and for controlling the flow rate of said first variable pump to maintain the volume of fresh dialysate therein at a relatively constant, pre-determined level;

a second receptacle positioned in the flow path between said outlet dialysate port of said hemodialyzer and said removal line;

a second variable rate pump for withdrawing spent dialysate, including any ultrafiltrate from said hemodialyzer at said controlled rate and delivering same to said second receptacle;

second sensing means for sensing the volume of spent dialysate in said second receptacle and for controlling the flow rate of said second variable pump to maintain the volume of spent dialysate therein at a relatively constant, pre-determined level;

a second controlled flow rate pump for withdrawing spent dialysate from said second receptacle at said controlled rate and delivering same to said removal line; and

an ultrafiltrate removal pump positioned in the flow path between the output side of said first controlled flow rate pump and the intake side of said second controlled flow rate pump for withdrawing a controlled amount of dialysate from the dialysate flow path between and including of said receptacles to thereby cause said first and second variable rate pumps to respectively change flow rates to seek the equilibrium of said pre-determined levels and exert a zero negative pressure, relative to patient blood pressure, in the dialysate section of said hemodialyzer to effect a withdrawal of ultrafiltrate from the patient'"'"'s blood into said dialysate flow path to substantially balance the amount of dialysate withdrawn therefrom.

11. The apparatus of claim 10 wherein said ultrafiltrate removal pump is positioned to withdraw a controlled amount of fresh dialysate from said first receptacle.

12. The apparatus of claim 10 wherein said first and second sensing means each includes operative means to further open or restrict the dialysate flow out of said first receptacle and into said second receptacle, respectively, to maintain said pre-determined levels.

13. The apparatus of claim 10 which further includes means for balancing the output of said first controlled flow rate pump with the intake of said second controlled flow rate pump.

14. The apparatus of claim 13 wherein said balancing means includes a shunt line providing a direct fluid flow communication between the output of said first controlled flow rate pump and the intake of said second controlled flow rate pump for calibrating the output of said first controlled flow rate pump with the intake of said second controlled flow rate pump.

15. The apparatus of claim 14 wherein said balancing means further includes a calibration bleed-off line extending between the output side of said first controlled flow rate pump and said reservoir to remove excess dialysate when said first controlled flow rate pump operates at a higher flow rate than said second controlled flow rate pump.

16. The apparatus of claim 13 wherein said balancing means includes restriction means on the output side of said first controlled flow rate pump to restrict the flow of spent dialysate flow therefrom when said first controlled flow rate pump operates at a higher flow rate than said second controlled flow rate pump.

17. The apparatus of claim 10 wherein the first and second receptacles each includes vent means therein so that said receptacles are operable at atmospheric pressure.

18. The apparatus of claim 10 wherein the first and second receptacles are sealed from the atmosphere so that said receptacles are operable at a pre-selected pressure, and said first and said second sensing means sense the pressures, instead of volumes, inside said respective receptacles for controlling said pre-determined levels.

19. The apparatus of claim 10 wherein said reservoir includes an overflow line connected to said removal line, and wherein an air vent is included in said overflow line and in said removal line near the output side of said second controlled flow rate pump to control the pressures influencing the operation of said controlled flow rate pumps.

20. Hemodialysis ultrafiltration apparatus comprising a dialysate flow path including:

a hemodialyzer;

means for supplying blood to and removing blood from said hemodialyzer;

a first receptacle;

a second receptacle;

first means for supplying fresh dialysate to said first receptacle and for withdrawing spent dialysate from said second receptacle at substantially equivalent and fixed rates;

second means for variably withdrawing fresh dialysate from said first receptacle and supplying same to said hemodialyzer and for variably withdrawing spent dialysate, including any ultrafiltrate, from said hemodialyzer and delivering same to said second receptacle;

control means associated with said receptacles and said first and said second means for maintaining the dialysate levels in said receptacles at relatively constant, pre-determined levels; and

ultrafiltrate removal means for withdrawing a controlled amount of dialysate from the dialysate flow path between and including said receptacles to thereby effect a withdrawal of ultrafiltrate from the patient'"'"'s blood into said flow path to substantially balance the amount of dialysate withdrawn therefrom.

21. Liquid infusion apparatus comprising a liquid flow path including:

a flow-separation device with a liquid permeable membrane therein;

means for supplying blood to and removing blood from said device;

a first receptacle;

a second receptacle;

first means for supplying fresh liquid to said first receptacle and for withdrawing spent liquid from said second receptacle at substantially equivalent and fixed rates;

second means for variably withdrawing fresh liquid from said first receptacle and supplying same to said device and for variably withdrawing spent liquid from said device and delivering same to said second receptacle;

control means associated with said receptacles and said first and said second means for maintaining the liquid levels in said receptacles at relatively constant, pre-determined levels; and

infusate delivery means for supplying a controlled amount of infusate to the fresh liquid upstream of said device to thereby effect an infusion of infusate into the patient'"'"'s blood from said flow path.