pH buffer measurement system for hemodialysis systems

Patent metadata

Field	Value
Publication number	US-9827361-B2
Application number	US-201313837287-A
Country	US
Kind code	B2
Filing date	Mar 15, 2013
Priority date	Feb 2, 2013
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

A pH-buffer measurement system that has at least one source for modifying the pH of a fluid entering the system, the source selected from an acid source and a base source. The acid source adds an acid equivalent to provide an acid reacted fluid and the base source adds a base equivalent to provide a base reacted fluid. The source is in fluid communication with a flow path and a component for determining a fluid characteristic of the acid reacted fluid or the base reacted fluid. The fluid characteristic that is measured is any one of a gas phase pressure, an electrical conductivity, or thermal conductivity.

First claim

What is claimed is:

1. A pH-buffer measurement system for a dialysis system, comprising:
at least one source for modifying the pH of a fluid entering the pH-buffer measurement system, wherein at least one source for modifying the pH is selected from an acid source and a base source, and wherein the acid source adds an acid equivalent to provide an acid reacted fluid and the base source adds a base equivalent to provide a base reacted fluid, and wherein the at least one source is in fluid communication with a dialysate flow path; and
a component, positioned downstream of the at least one source for modifying the pH of the fluid entering the pH-buffer measurement system, for determining a fluid characteristic of the acid reacted fluid or the base reacted fluid; wherein the fluid characteristic that is measured is any one of a gas phase pressure, an electrical conductivity, or thermal conductivity,
a sorbent system in the dialysate flow path;
wherein the acid reacted fluid comprises at least a portion of the acid equivalent reacted with buffer in the fluid entering the pH-buffer measurement system, and the base reacted fluid comprises at least a portion of the base equivalent reacted with buffer in the fluid entering the pH-buffer measurement system.

2. The system of claim 1 , wherein the component determines a fluid characteristic of an unreacted fluid.

3. The system of claim 1 , further comprising a static mixer downstream from the at least one source for modifying the pH of the fluid entering the pH-buffer measurement system.

4. The system of claim 1 , further comprising one or more pumps for pumping fluid into and out of the pH-buffer measurement system.

5. The system of claim 1 , wherein the pH-buffer measurement system is configured to determine pH, buffer content, or both of the fluid by taking a difference between a first value of the fluid characteristic of the fluid entering the pH-buffer measurement system and a second value of the fluid characteristic of the acid reacted fluid or the base reacted fluid.

6. The system of claim 1 , wherein the pH-buffer measurement system determines a pH, buffer content or both of the fluid by taking a difference between a first value of the fluid characteristic of the fluid entering the pH-buffer measurement system and a second value of the fluid characteristic of an unreacted fluid.

7. The system of claim 1 , wherein the component measures a gas phase pressure in an area over the fluid entering the pH-buffer measurement system.

8. The system of claim 1 , wherein the component measures a gas phase pressure in an area over the acid reacted fluid or the base reacted fluid.

9. The system of claim 1 , wherein the component measures a gas phase thermal conductivity of the fluid entering the pH-buffer measurement system.

10. The system of claim 1 , wherein the component measures a gas phase thermal conductivity of the acid reacted fluid or the base reacted fluid.

11. The system of claim 9 or 10 , wherein the component measuring the thermal conductivity is configured to be flushed with a purge gas wherein the gas to be measured diffuses from the fluid entering the pH-buffer measurement system, the acid reacted fluid, or the base reacted fluid through a membrane changing the thermal conductivity of a gas surrounding an electrode.

12. The system of claim 11 , wherein a rate of change of the thermal conductivity is used to calculate a concentration of a gas.

13. The system of claim 1 , wherein the component is configured to measure an electrical conductivity of the acid reacted fluid or the base reacted fluid.

14. The system of claim 1 , wherein the component is configured to measure an electrical conductivity of the fluid entering the pH-buffer measurement system.

15. The system of claim 1 , wherein the fluid entering the pH-buffer measurement system is dialysate.

16. The system of claim 1 , wherein the fluid characteristic comprises a buffer content to be measured, and wherein the buffer content to be measured is bicarbonate content of the fluid.

17. The system of claim 1 , wherein the acid source adds acid in a predetermined amount to ensure complete conversion of bicarbonate in the fluid entering the pH-buffer measurement system.

18. The system of claim 1 , wherein the acid source adds at least one of acetic acid, citric acid, hydrochloric acid, and phosphoric acid.

19. The system of claim 1 , wherein the component has a first measurement chamber to measure a gas phase pressure of the acid reacted fluid or the base reacted fluid, and a second measurement chamber to measure a gas phase pressure of the fluid entering the pH-buffer measurement system.

20. The system of claim 19 , further comprising a differential pressure sensor in fluid communication with the first and second measurement chambers.

21. The system of claim 19 , wherein the first or second measurement chamber has an air-gap above a gas permeable membrane in fluid communication with a pressure transducer and a vent valve to allow gas to escape from the first or second measurement chamber wherein the pressure transducer measures a pressure of the gas phase above any one of the acid reacted fluid, the base reacted fluid, or the fluid entering the pH-buffer measurement system.

22. The system of claim 1 , further comprising a control system to perform calculations necessary for determining the fluid characteristic based on any one of the acid reacted fluid, the base reacted fluid, or the fluid entering the pH-buffer measurement system.

23. A fluid therapy system, comprising:
a dialyzer and a sorbent system in fluid communication with a pH-buffer measurement system to form a dialysate flow path; wherein the pH-buffer measurement system comprises:
at least one source for modifying the pH of a fluid entering the pH-buffer measurement system, the at least one source selected from an acid source and a base source wherein the acid source adds an acid equivalent to provide an acid reacted fluid and the base source adds a base equivalent to provide a base reacted fluid wherein the at least one source is in fluid communication with the dialysate flow path; and
a component positioned downstream of the source for modifying the pH of the fluid entering the pH-buffer measurement system, for determining a fluid characteristic of the acid reacted fluid or the base reacted fluid; wherein the fluid characteristic that is measured is any one of a gas phase pressure, an electrical conductivity, or thermal conductivity; and
a reconstitution system positioned downstream of the pH-buffer measurement system for providing a controlled amount of a buffer to be added to a dialysate to form a second dialysate with a predetermined concentration of the buffer prior to use in the dialyzer,
wherein the pH-buffer measurement system determines the pH, buffer concentration or both of any one of the acid reacted fluid, the base reacted fluid, or the fluid entering the pH-buffer measurement system.

24. The system of claim 23 , wherein the buffer is bicarbonate.

25. The system of claim 23 , wherein the pH-buffer measurement system is positioned downstream from the sorbent system and a degasser.

26. The system of claim 23 , wherein the reconstitution system adjusts the pH and bicarbonate concentration to desired levels.

27. The system of claim 23 , further comprising a conductivity sensor connected anywhere along the dialys

Assignees

• Medtronic Inc

Inventors

• Pudil Bryant J
• Meyer Thomas E
• Lura David B
• Gerber Martin T

Classifications

• A61M2205/7518

  bacterial · CPC title

• A61M2205/3317

  Electromagnetic, inductive or dielectric measuring means · CPC title

• A61M1/1605

  Physical characteristics of the dialysate fluid · CPC title

• A61M1/1668

  Details of containers · CPC title

• A61M1/287

  Dialysates therefor · CPC title