Measuring chemical properties of a sample fluid in dialysis systems

• US 9,599,599 B2
• Filed: 01/30/2015
• Issued: 03/21/2017
• Est. Priority Date: 04/06/2011
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Original Assignee: Fresenius Medical Care Holdings Incorporated (Fresenius Medical Care AG)
• Inventors: Ash, Stephen R., Sullivan, Thomas A., Carr, David, Beiriger, Michael James
• Primary Examiner(s): Soderquist, Arlen
• Application Number:
  US14/609,989
• Publication Number:
  US 20150204831A1
• Time in Patent Office: 781 Days
• Field of Search: 436/52, 436/108, 436/113, 436/133, 436/163
• US Class Current: 1/1
• CPC Class Codes: A61M 1/1607 before use, i.e. upstream of dialyser
• CPC Class Codes: A61M 1/1609 after use, i.e. downstream of dialyser
• CPC Class Codes: A61M 1/1656 Apparatus for preparing dialysates
• CPC Class Codes: A61M 1/1658 Degasification
• CPC Class Codes: A61M 1/166 Heating for sterilisation A61M1/1686
• CPC Class Codes: A61M 1/1666 by dissolving solids
• CPC Class Codes: A61M 1/1668 Details of containers
• CPC Class Codes: A61M 1/1696 with dialysate regeneration
• CPC Class Codes: A61M 1/305 Control of inversion point between collection and re-infusion phase
• CPC Class Codes: A61M 1/3612 after treatment
• CPC Class Codes: A61M 2205/3306 Optical measuring means
• CPC Class Codes: A61M 2205/3324 PH measuring means
• CPC Class Codes: A61M 2230/202 partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)
• CPC Class Codes: A61M 2230/208 pH-value
• CPC Class Codes: G01N 2033/0068 using a computer specifically programmed
• CPC Class Codes: G01N 21/3504 for analysing gases, e.g. multi-gas analysis
• CPC Class Codes: G01N 33/0067 by measuring the rate of variation of the concentration
• CPC Class Codes: G01N 33/4925 measuring blood gas content, e.g. O2, CO2 , HCO3
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/171538 Urea or blood urea nitrogen
• CPC Class Codes: Y10T 436/175383 : Ammonia
• CPC Class Codes: Y10T 436/204998 : Inorganic carbon compounds

Abstract

In one aspect of the invention, a method includes determining an amount of carbon dioxide (CO₂) in dialysate flowing through a dialysis system using a CO₂ sensor associated with the dialysis system, determining, using a pH sensor associated with the dialysis system, a pH level of the dialysate, and calculating a level of bicarbonate in the dialysate based at least in part on the determined amount of CO₂ measured in the gas and the determined pH level of the dialysate.

Claims

1. A method comprising:

causing dialysate to flow into a chamber having a gas-permeable membrane and a material that is configured to alter an appearance of the material based at least in part on a pH level of the dialysate, wherein the chamber is removably attached to a hemodialysis machine having;

a CO₂ sensor,

a pH sensor, and

a dialyzer,

determining an amount of carbon dioxide in the dialysate using the CO₂ sensor

determining a pH level of the dialysate using the pH sensor;

calculating a level of bicarbonate in the dialysate based at least in part on the determined amount of CO₂ in the dialysate and the determined pH level of the dialysate; and

causing bicarbonate to flow into the dialysate based at least in part on the calculated level of bicarbonate.

2. The method of claim 1 further comprising causing the dialysate to flow through the dialyzer after exiting the chamber.

3. The method of claim 2 further comprising

determining an infusion amount of replacement substance based at least in part on the on the calculated level of bicarbonate.

4. The method of claim 1 further comprising causing the dialysate to flow from the dialyzer to the chamber.

5. The method of claim 1 wherein the membrane is configured to prevent liquid from passing through the membrane.

6. The method of claim 1 wherein the CO₂ sensor comprises an infrared sensor.

7. The method of claim 1 further comprising causing the dialysate to contact the material.

8. The method of claim 1 wherein the material is configured to alter a color of the material based at least in part on the pH level of the dialysate.

9. The method of claim 1 wherein the material comprises a pH strip.

10. The method of claim 1 wherein the material comprises a sol-gel.

11. The method of claim 1 further comprising using the pH sensor to detect the alteration in the appearance of the material.

12. The method of claim 11 further comprising causing one or more artificial light sources to direct light toward the material such that the material reflects at least a portion of the directed light.

13. The method of claim 12, further comprising using the pH sensor to detect at least a portion of light reflected by the material.

14. The method of claim 1, wherein an amount of CO₂ is emitted from the dialysate, and wherein determining the amount of CO₂ in the dialysate comprises measuring the amount of CO₂ emitted from the dialysate.

15. The method of claim 1, wherein an amount of CO₂ is emitted from the dialysate, and wherein determining the amount of CO₂ in the dialysate comprises determining a partial pressure of CO₂ associated with a gas emitted by the dialysate.

16. A method comprising

causing dialysate to flow into a chamber having a gas-permeable membrane and a material that is configured to alter an appearance of the material based at least in part on a pH level of the dialysate, wherein the chamber is removably attached to a hemodialysis machine having:

a CO₂ sensor,

a pH sensor, and

a dialyzer, the chamber being positioned upstream of the dialyzer;

determining an amount of carbon dioxide in the dialysate using the CO₂ sensor

determining a pH level of the dialysate using the pH sensor;

calculating a level of bicarbonate in the dialysate based at least in part on the determined amount of CO₂ in the dialysate and the determined pH level of the dialysate; and

determining a toxin removal efficiency based at least in part on the calculated bicarbonate level.

17. The method of claim 16 further comprising

determining an infusion amount of replacement substance based at least in part on the toxin removal efficiency;

and

causing the replacement substance to flow into the dialysate.

18. The method of claim 17 wherein the replacement substance is bicarbonate.

19. The method of claim 16 wherein the membrane is configured to prevent liquid from passing through the membrane.

20. The method of claim 16 further comprising using the pH sensor to detect the alteration in the appearance of the material.

21. A method comprising:

causing dialysate to flow into a first chamber positioned upstream from a dialyzer of a hemodialysis machine, the hemodialysis machine also having a CO₂ sensor and a pH sensor, the chamber having a gas-permeable membrane and a material that is configured to alter an appearance of the material based at least in part on a pH level of the dialysate, wherein the first chamber is removably attached to the hemodialysis machine;

determining a first amount of carbon dioxide in the dialysate using the CO₂ sensor

determining a first pH level of the dialysate using the pH sensor;

calculating a first level of bicarbonate in the dialysate based at least in part on the determined amount of CO₂ in the dialysate and the determined pH level of the dialysate;

causing dialysate to flow into a second chamber having a gas-permeable membrane and a material that is configured to alter an appearance of the material based at least in part on the pH level of the dialysate, wherein the second chamber is removably attached to the hemodialysis machine downstream from the dialyzer;

determining an second amount of carbon dioxide in the dialysate using the CO₂ sensor;

determining a second pH level of the dialysate using the pH sensor; and

calculating a second level of bicarbonate in the dialysate based at least in part on the determined amount of CO₂ in the dialysate and the determined pH level of the dialysate.

22. The method of claim 21 further comprising determining a patient disturbance of the bicarbonate levels of the dialysate based at least in part on comparing the first bicarbonate level to the second bicarbonate.

23. The method of claim 22 further comprising causing bicarbonate to flow into the dialysate based at least in part on the patient disturbance.

24. The method of claim 21 wherein the gas-permeable membranes are configured to prevent liquid from passing through the membrane.

25. The method of claim 21 further comprising using the pH sensor to detect the alteration in the appearance of the material.