Multistage hemodiafiltration/hemofiltration method and apparatus

• US 20040068219A1
• Filed: 06/18/2003
• Published: 04/08/2004
• Est. Priority Date: 12/20/2000
• Status: Active Grant

• Current Assignee: Nephros, Inc.
• Original Assignee: Nephros, Inc.
• Inventors: Summerton, James, Collins, Gregory R., Spence, Edward
• Granted Patent: US 7,074,332 B2
• Time in Patent Office: Days
• US Class Current: 604/5.01
• CPC Class Codes: A61M 1/3401 Cassettes therefor
• CPC Class Codes: A61M 1/3413 Diafiltration
• CPC Class Codes: A61M 1/3417 using distinct filters for dialysis and ultra-filtration
• CPC Class Codes: A61M 1/342 Adding solutions to the blood, e.g. substitution solutions for preventing coagulation A61M1/3672
• 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 1/3441 Substitution rate control as a function of the ultrafiltration rate
• CPC Class Codes: A61M 1/3465 using dialysate as substitution fluid
• CPC Class Codes: B01D 61/145 Ultrafiltration
• CPC Class Codes: B01D 61/243 Dialysis
• CPC Class Codes: B01D 61/244 comprising multiple dialysis steps
• CPC Class Codes: B01D 61/58 Multistep processes
• CPC Class Codes: Y10S 210/929 Hemoultrafiltrate volume measurement or control processes

Abstract

In a blood dialysis system including a source of substitution fluid (10) and a blood dialysis machine, a hemodiafiltration system having a first dialyzer (1) including a first blood compartment (4) having a first blood inlet which receives blood to be cleaned and a first blood outlet which discharges partially diafiltered blood and a first dialysate compartment (5) having a first dialysate inlet and a first dialysate outlet, means (8) for mixing the partially diafiltered blood with substitution fluid from the source to obtain a blood/substitution fluid mixture, and a second hemofilter (2) including a second blood compartment (11) having a second blood inlet which receives the blood/substitution fluid mixture and a second blood outlet which discharges filtered blood and a second permeate compartment (12) having a second permeate outlet.

Claims

1. In a blood dialysis system including a source of substitution fluid and a blood dialysis machine, a hemodiafiltration/hemofiltration system comprising:

a first dialyzer including;

a first semi-permeable membrane partitioning said first dialyzer into;

a first blood compartment having a first blood inlet which receives blood to be cleaned and a first blood outlet which discharges partially diafiltered blood; and

a first dialysate compartment having a first dialysate inlet and a first dialysate outlet;

a mixing chamber for mixing said partially diafiltered blood with substitution fluid from said source to obtain a blood/substitution fluid mixture; and

a second hemofilter including;

a second semi-permeable partitioning said second hemofilter into;

a second blood compartment having a second blood inlet which receives said blood/substitution fluid mixture and a second blood outlet which discharges filtered blood; and

a second permeate compartment having a second permeate outlet.

2. A system according to claim 1, further including:

a control feature for regulating filtration in at least one of said first dialyzer and said second hemofilter.

3. A system according to claim 2, wherein said control feature comprises:

a flow restrictor disposed along a dialysate conduit proximate to said first dialysate outlet for carrying spent dialysate fluid from the first dialysate compartment, and wherein a permeate conduit is connected at one end to said second permeate outlet and at an opposite end to said dialysate conduit downstream of said flow restrictor, said permeate conduit for carrying plasma water from said second hemofilter, said flow restrictor for selectively raising a first fluid pressure of said first dialysate compartment relative to a second fluid pressure of said second permeate compartment.

4. A system according to claim 3, wherein said flow restrictor is a portion of said dialysate conduit that has a reduced inner diameter that defines an opening of reduced diameter along a predetermined length of said dialysate conduit.

5. A system according to claim 2, wherein the control feature comprises:

a fluid throttling valve disposed along a dialysate conduit proximate to said first dialysate outlet for carrying spent dialysate fluid from said first dialysate compartment, and wherein a permeate conduit is connected at one end to said second permeate outlet and at an opposite end to said dialysate conduit downstream of said fluid throttling valve, said permeate conduit for carrying plasma water from said second hemofilter, said fluid throttling valve for selectively raising a first fluid pressure of said first dialysate compartment relative to a second fluid pressure of said second permeate compartment.

6. A system according to claim 2, wherein the control feature comprises:

an outlet flow regulating pump disposed along a dialysate conduit proximate to said first dialysate outlet for carrying spent dialysate fluid from said first dialysate compartment, and wherein a permeate conduit is connected at one end to said second permeate outlet and at an opposite end to said dialysate conduit downstream of said outlet flow regulating pump, said permeate conduit for carrying plasma water from said second hemofilter, said outlet flow regulating pump being positionable in a number of settings for selectively regulating a first fluid pressure of said first dialysate compartment relative to a second fluid pressure of said second permeate compartment.

7. A system according to claim 6, wherein said pump is positioned in a setting that causes the first fluid pressure to increase relative to the second fluid pressure.

8. A system according to claim 6, further comprising:

a control unit in communication with said pump for controlling the operation of said pump and positioning said pump within one of said settings based on an input selected from the group consisting of (1) at least one of a dialysate flow rate, a blood flow rate, and a substitution fluid flow; and

(2) a transmembrane pressure of at least one of said first dialyzer and said second hemofilter.

9. A system according to claim 2, wherein said control feature comprises:

an inlet flow regulating pump disposed along a dialysate conduit proximate to said first dialysate inlet for carrying fresh dialysate fluid to said first dialysate compartment, and wherein a permeate conduit is connected at one end to said second permeate outlet and at an opposite end to said dialysate conduit upstream of said inlet flow regulating pump, said permeate conduit for carrying plasma water from said second hemofilter, said inlet flow regulating pump for selectively regulating a first fluid pressure of said first dialysate compartment relative to a second fluid pressure of said second permeate compartment.

10. A system according to claim 2, wherein the control feature comprises:

a permeate pump disposed along a permeate conduit that is connected at a first end to said second permeate outlet and at a second end to a dialysate conduit that is connected to said first dialysate inlet for delivering dialysate fluid thereto, said permeate conduit for carrying plasma water from and being in communication with said dialysate conduit at a location downstream of said permeate pump, said permeate pump for selectively regulating a first fluid pressure of said second permeate compartment relative to a second fluid pressure of said first dialysate compartment.

11. A system according to claim 2, wherein the control feature comprises:

a permeate pump disposed along a permeate conduit that is connected at a first end to said second permeate outlet and at a second end to a dialysate conduit that is connected to said first dialysate outlet for carrying dialysate fluid from said first dialysate compartment, said permeate conduit for carrying plasma water from said second hemofilterand being in communication with said dialysate conduit at a location downstream of said permeate pump, said permeate pump for selectively regulating a first fluid pressure of said second permeate compartment relative to a second fluid pressure of said first dialysate compartment.

12. A system according to claim 2, wherein the control feature comprises:

an inter-stage blood pump disposed along a blood conduit connected between said first blood outlet and said second blood intlet, said inter-stage blood pump for selectively regulating a first fluid pressure of said first blood compartment relative to a second fluid pressure of said second blood compartment.

13. A system according to claim 5, further comprising:

a control unit in communication with said fluid throttling valve for controlling the operation of said throttling valve based on at least one input selected from the group consisting of a dialysate flow rate at said first dialysate outlet;

a transmembrane pressure of at least one of said first dialyzer and second hemofilter; and

a hematocrit level of the partially diafiltered blood.

14. A system according to claim 5, further comprising:

a flow meter disposed along said dialysate conduit between said first dialysate outlet and a location wherein said permeate conduit connects to said dialysate conduit;

a control unit in communication with said flow meter and said fluid throttling valve for controlling the operation of said fluid throttling valve in response to input received from said flow meter.

15. A system according to claim 5, further comprising:

a blood hematocrit sensor disposed in a blood path between said first dialyzer and said second hemofilter;

said blood hematocrit sensor for monitoring the blood hematocrit level;

a control unit in communication with said blood hematocrit sensor and said fluid throttling valve for controlling the operation of said fluid throttling valve in response to input received from said blood hematocrit sensor.

16. A system according to claim 9, further comprising:

a check valve positioned in parallel to said inlet flow regulating pump.

17. In a blood dialysis system including a source of substitution fluid and a blood dialysis machine, a hemodiafiltration/hemofiltration system comprising:

a first dialyzer including;

a first semi-permeable membrane partitioning said first dialyzer into;

a first blood compartment having a first blood inlet which receives blood to be cleaned and a first blood outlet which discharges blood having a first concentration of toxins; and

a first dialysate compartment having a first dialysate inlet and a first dialysate outlet;

a mixing chamber for mixing said discharged blood from said first dialyzer with substitution fluid from said source to obtain a blood/substitution fluid mixture; and

a second hemofilter including;

a second semi-permeable membrane partitioning said second hemofilter into;

a second blood compartment having a second blood inlet which receives said blood/substitution fluid mixture and a second blood outlet which discharges blood having a second concentration of toxins, the first concentration being greater than the second concentration; and

a second permeate compartment having a second permeate outlet; and

a controller for regulating filtration rates in said first dialyzer and said second hemofilter based upon predetermined input.

18. A system according to claim 17, further including:

a dialysate conduit connected to one end to said first dialysate outlet for carrying spend dialysate fluid from said first dialysate compartment;

a permeate conduit connected at one end to said second permeate outlet and being in communication, at an opposite end, with said dialysate conduit; and

wherein said permeate conduit carries plasma water that has been filtered across said second semi-permeable membrane to said dialysate conduit, whereby said plasma water bypasses said first dialyzer.

19. A method of hemodiafiltration/hemofiltration comprising the steps of:

receiving a blood inflow;

diafiltering said blood inflow in a first stage to provide a partially diafiltered blood outflow;

mixing said partially diafiltered blood outflow with a substitution fluid to provide a blood/substitution fluid mixture; and

hemofiltering said blood/substitution fluid mixture in a second stage.

20. A method according to claim 19, further comprising the step of:

regulating a hemodiafiltration rate of the first stage and a hemofiltration rate of the second stage with a controller based upon predetermined input received by said controller.

21. A method according to claim 19, further including the steps of:

disposing a flow restrictor in a dialysate conduit that carries spent dialysate fluid from the first stage,

connecting a permeate conduit that carries plasma water derived from the second stage to said dialysate conduit at a location downstream of said flow restrictor; and

operating said flow restrictor so that a hemodiafiltration rate of the first stage

and a hemofiltration rate of the second stage are varied with respect to one another.

22. A method according to claim 19, further including the steps of:

disposing a throttling valve in a dialysate conduit that carries spent dialysate fluid from the first stage,

connecting a permeate conduit that carries plasma water derived from the second stage to said dialysate conduit at a location downstream of said throttling valve; and

operating said throttling valve so that a hemodiafiltration rate of the first stage

and a hemofiltration rate of the second stage are varied with respect to one another.

23. A method according to claim 22, wherein the step of operating said throttling valve comprises the steps of:

providing a control unit in communication with said throttling valve;

disposing a flow meter within said dialysate conduit for detecting a flow rate of said spent dialysate fluid;

said flow meter in communication with said control unit; and

operating said throttling valve in response to input received by said control unit from said flow meter.

24. A method according to claim 22, wherein the step of operating said throttling valve comprises the steps of:

providing a control unit in communication with said throttling valve;

disposing a blood hematocrit sensor within a blood conduit for carrying said partially diafiltered blood outflow, said blood hematocrit sensor being located in said blood conduit prior to a location where said substitution fluid is mixed with said partially diafiltered blood outflow;

said blood hematocrit sensor in communication with said control unit; and

operating said throttling valve in response to input received by said control unit from said blood hematocrit sensor.

25. A method according to claim 19, further including the steps of:

disposing an inlet flow regulating pump in a dialysate conduit that delivers fresh dialysate fluid to the first stage,

connecting a permeate conduit that carries plasma water derived from the hemofiltering step to said dialysate conduit at a location upstream of said inlet flow regulating pump; and

operating said inlet flow regulating pump so that a hemodiafiltration rate of the first stage and a hemofiltration rate of the second stage are varied with respect to one another.

26. A method according to claim 19, further including the steps of:

disposing an outlet flow regulating pump in a dialysate conduit that carries spent dialysate fluid from the first stage,

connecting a permeate conduit that carries plasma water derived from the hemofiltering step to said dialysate conduit at a location downstream of said outlet flow regulating pump, whereby said plasma water bypasses said first stage; and

operating said outlet flow regulating pump so that a hemodiafiltration rate of the first stage and a hemofiltration rate of the second stage are varied with respect to one another.

27. A method according to claim 19, further including the steps of:

disposing a permeate pump in a permeate conduit that carries plasma water derived from the hemofiltering step from said second stage,

connecting said permeate conduit at one end to a dialysate conduit that delivers fresh dialysate, thereby forming a mixture of plasma water and dialysate fluid that is delivered to the first stage; and

operating said permeate pump so that a hemodiafiltration rate of the first stage and a hemofiltration rate of the second stage are varied with respect to one another.

28. A method according to claim 19, further including the steps of:

disposing a permeate pump in a permeate conduit that carries plasma water derived from the hemofiltering step from said second stage,

connecting said permeate conduit at one end to a dialysate conduit that carries spent dialysate derived from said hemodiafiltration step; and

operating said permeate pump so that a hemodiafiltration rate of the first stage and a hemofiltration rate of the second stage are varied with respect to one another.

29. A method according to claim 19, further including the steps of:

disposing an inter-stage blood pump in a blood conduit that carries said partially diafiltered blood, said inter-stage blood pump being located in said blood conduit prior to a location where said partially diafiltered blood is mixed with said substitution fluid; and

operating said inter-stage blood pump so that a hemodiafiltration rate of the first stage and a hemofiltration rate of the second stage are varied with respect to one another.