Hemodialysis system having a flow path with a controlled compliant volume

Patent metadata

Field	Value
Publication number	US-10695481-B2
Application number	US-201213565733-A
Country	US
Kind code	B2
Filing date	Aug 2, 2012
Priority date	Aug 2, 2011
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

Abstract

Systems and methods for the performance of kidney replacement therapy having or using a dialyzer, control components, sorbent cartridge and fluid reservoirs configured to be of a weight and size suitable to be worn or carried by an individual requiring treatment are disclosed. The system for performing kidney replacement therapy has a controlled compliance dialysis circuit, where a control pump controls the bi-directional movement of fluid across a dialysis membrane. The dialysis circuit and an extracorporeal circuit for circulating blood are in fluid communication through the dialysis membrane. The flux of fluid moving between the extracorporeal circuit and the dialysis circuit is modified by the rate at which the control pump is operating such that a rate of ultrafiltration and convective clearance can be controlled. The system provides for the monitoring of an inlet and outlet conductivity of the sorbent cartridge to provide a facility to quantify or monitor the removal of urea by the sorbent cartridge.

First claim

What is claimed is:

1. A system for performing kidney replacement treatment comprising:
a hemodialysis system having an extracorporeal circuit, a controlled compliant dialysis circuit, a dialyzer with a dialyzer membrane, one or more controllers, and one or more pumps;
wherein the extracorporeal circuit comprises
a conduit for receiving blood from a subject;
a conduit for returning blood to the subject; and
a blood pump for conveying blood from the subject through the extracorporeal circuit and the dialyzer;

wherein the controlled compliant dialysis circuit comprises
a sorbent cartridge configured to remove at least one impurity or waste species from the dialysate, the sorbent cartridge having a dialysate inlet end and a dialysate outlet end;
a dialysate pump for conveying dialysate from the sorbent cartridge to the dialyzer and back to the sorbent cartridge;
one or more reservoirs configured to store fluid; and
one or more pumps configured to provide bi-directional flow of fluid so as to selectively adjust the volume of the controlled compliant dialysis circuit;

wherein the one or more controllers are configured to control the operation of the blood pump, the dialysate pump and the one or more pumps;
wherein the one or more pumps are configured to provide selective adjustment of the volume of the controlled compliant dialysis circuit by
(A) operating in an influx direction so that fluid moves from the one or more reservoirs to the controlled compliance dialysis circuit; and
(B) operating in an efflux direction so that fluid moves from the controlled compliant dialysis circuit into the one or more reservoirs;

wherein controlled compliance of the controlled compliant dialysis circuit is achieved by actively controlling, via the one or more controllers, the influx and efflux of fluid to and from both the dialysis circuit and the extracorporeal circuit;
wherein a volume of fluid in the dialysis circuit, once the system is in operation, is substantially constant; and
wherein the hemodialysis system provides fluid balancing without the use of scales or balancing chambers.

2. The system of claim 1 , with the proviso that the blood pump and the dialysate pump are not pulsatile pumps.

3. The system of claim 1 , wherein transfer of fluid by the one or more pumps results in substantially the same volume of fluid transferred to the body of the subject by transferring fluid from the one or more reservoirs to the dialysis circuit; and wherein the one or more pumps transfer fluid from the body of the subject to the system for performing kidney replacement treatment by transferring fluid from the dialysis circuit to the one or more reservoirs.

4. The system of claim 1 , wherein the volume of the dialysate within the dialysis circuit is a substantially inflexible volume.

5. The system of claim 1 , wherein a void volume for accommodating the dialysate in the sorbent cartridge, the dialyzer, and conduits comprising the dialysis circuit has a substantially inflexible volume.

6. The system of claim 1 , further comprising a relative blood volume monitor to determine the relative blood volume hydration status (RBVHS) of the blood in the extracorporeal circuit, the relative blood volume monitor configured to send information to the one or more controllers, wherein the relative blood volume monitor determines the level (C 0 ) of one or more solutes in the blood at a first time and determines the level (C t ) of the one or more solutes in the blood at a second time later than the first time, and the relative blood volume hydration status is calculated by the formula RBVHS=C 0 /C t , wherein optionally the relative blood volume monitor is configured to determine the fluid volume of the blood at a position prior to the blood entering the dialyzer.

7. The system of claim 1 , wherein the one or more controllers control operation of the one or more pumps to intermittently switch between an efflux direction to move fluid across the dialysis membrane from the extracorporeal circuit to the dialysis circuit and a second influx direction to move fluid across the dialysis membrane from the dialysis circuit to the extracorporeal circuit.

8. The system of claim 1 , wherein the one or more controllers control the blood pump and the dialysate pump to pump blood and dialysate at a ratio of flow rates of about 1:1.5 to about 3:1.

9. The system of claim 1 , further comprising a second reservoir and a second reservoir pump.

10. The system of claim 1 , further comprising a first conductivity meter for measuring the conductivity of the dialysate at a position between the dialyzer and a dialysate inlet end of the sorbent cartridge;
a second conductivity meter for measuring the conductivity of the dialysate at a position between the dialyzer and a dialysate outlet end of the sorbent cartridge; and
one or more controllers for comparing the conductivity measured by the first conductivity meter and the second conductivity meter and calculating the amount of urea absorbed by the sorbent cartridge.

11. The system of claim 10 , wherein the one or more controllers calculates the amount of urea absorbed by the sorbent cartridge by:
calculating a starting conductivity by subtracting a conductivity attributed to a substantially constant concentration of Ca 2+ , Mg 2+ , and K + ions in the dialysate from a conductivity measured by the first conductivity meter;
calculating a corrected outlet conductivity by subtracting an increase in conductivity attributed to an exchange of Ca 2+ , Mg 2+ , and K + ions for Na + ions by the sorbent cartridge from a conductivity measured by the second conductivity meter; and
calculating a conductivity increase from the exchange of NH 4 + for Na + ions by the sorbent cartridge by subtracting the starting conductivity from the corrected outlet conductivity.

12. The system of claim 1 , further comprising a second reservoir and a second reservoir pump wherein the second reservoir holds a fluid that can be added to the dialysis circuit by operation of the second reservoir pump, wherein addition of the fluid by the second reservoir pump causes the movement of fluid from the dialysis circuit to the extracorporeal circuit, wherein the one or more controllers control a rate of the second reservoir pump.

13. A method for performing convective clearance using the system of claim 1 , comprising:
attaching the vasculature of a subject to the extracorporeal circuit such that a first end of the extracorporeal circuit draws blood from the subject and a second end of the extracorporeal circuit returns blood to the subject;
conveying blood from the subject through the extracorporeal circuit and the dialyzer and returning the blood to the subject;
conveying a dialysate through the controlled compliance dialysis circuit such that the dialysate moves from the sorbent cartridge, to the dialyzer and back to the sorbent cartridge, where at least one waste species diffuses from the blood to the dialysate through the dialysis membrane and the sorbent cartridge substantially removes at least one impurity or the at least one waste species from the dialysate; and
operating the one or more pumps such that fluid from the one or more reservoirs is added to the dialysis circuit in an influx direction or such that fluid is removed from the dialysis circuit in an efflux direction, and intermittently switching the one or more pumps between:
(1) the efflux direction, to move fluid across the dialysis membrane from the extracorporeal circuit to the dialysis circuit, and
(2) the influx direction, to move fluid across the dialysis membrane from the dialysis circuit to the extracorporeal

Assignees

• Kelly Thomas D
• Lyu Suping
• Pudil Bryant J
• Meyer Thomas E
• Medtronic Inc

Inventors

• Kelly Thomas D
• Lyu Suping
• Pudil Bryant J
• Meyer Thomas E

Classifications

• A61M1/1696 Primary

  with dialysate regeneration · CPC title

• A61M2202/0021

  removed from and reintroduced into the body, e.g. after treatment · CPC title

• A61M2202/0413

  Blood · CPC title

• A61M1/3482 Primary

  by filtrating the filtrate using another cross-flow filter, e.g. a membrane filter · CPC title