In situ calibration system for sensors located in a physiologic line

• US 5,976,085 A
• Filed: 10/07/1997
• Issued: 11/02/1999
• Est. Priority Date: 01/27/1995
• Status: Expired due to Fees

• Current Assignee: Optical Sensors Incorporated
• Original Assignee: Optical Sensors Incorporated
• Inventors: Kimball, Victor E., Pierskalla, Irvin T., Porter, Christopher H., Lynch, Laurie E.
• Primary Examiner(s): GILBERT, SAMUEL G
• Application Number:
  US08/946,597
• Time in Patent Office: 756 Days
• Field of Search: 600/300, 600/301, 600/309, 600/310, 600/345, 600/370
• US Class Current: 600/309
• CPC Class Codes: A61B 5/14557 specially adapted to extracorporeal circuits
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150992 Blood sampling from a fluid line external to a patient, such as a catheter line, combined with an infusion line; blood sampling from indwelling needle sets, e.g. sealable ports, luer couplings, valves tubing connectors and couplings A61M39/00
• CPC Class Codes: A61B 5/155 Devices specially adapted for continuous or multiple sampling, e.g. at predetermined intervals devices loaded with multiple lancets simultaneously A61B5/15146
• CPC Class Codes: A61B 5/157 Devices characterised by integrated means for measuring characteristics of blood

Abstract

A method is provided for calibrating sensors used to analyze characteristics of physiologic fluids such as blood. The method involves the use of a sensor assembly having an analyte-responsive sensor in communication with a passageway which is in divertable fluid communication with a physiologic line and a conduit by which a reference sample may be introduced into the passageway. The method involves exposing the sensor to the reference sample, thereby producing a sensor response. The method also allows performing quality control on the sensors. Also provided is an apparatus with which the claimed method may be practiced.

Claims

1. A method of calibrating a system for analyzing characteristics of a physiologic fluid, wherein said method comprises:

a) providing a sterile sensor assembly located in a sterile physiologic line, said assembly comprising (i) at least one sensor responsive to a characteristic of an analyte in the physiologic fluid and in direct or indirect contact with the analyte, and (ii) at least one sterile passageway detachably affixed to and in divertable fluid communication with the physiologic line and a conduit by which at least one single-use reference sample may be introduced into the passageway without compromising the sterility of the physiologic line, wherein the reference sample is sterile, biocompatible and has a known concentration of the analyte, and wherein the sensor is in communication with the passageway;

b) exposing the sensor in the sensor assembly to the reference sample, thereby producing a sensor response; and

c) correlating the sensor response to the characteristic of the analyte in the reference sample.

2. The method of claim 1, wherein the reference sample comprises an infusion medium or a calibrant.

3. The method of claim 2, wherein the reference sample comprises a calibrant.

4. The method of claim 3, wherein the calibrant is a synthetic calibrant.

5. The method of claim 4, wherein the synthetic calibrant comprises a synthetic buffer.

6. The method of claim 1, wherein exposing the sensor to the reference sample comprises directly contacting the sensor with the reference sample.

7. The method of claim 6, wherein contacting the sensor comprises dynamic contacting.

8. The method of claim 1, wherein the passageway comprises a shunt.

9. The method of claim 8, wherein the shunt comprises first and second passageways in divertable fluid communication one with the other, wherein the first and second passageways respectively comprise the physiologic line and the sensor assembly.

10. The method of claim 9, wherein the first passageway comprises a means to pass the physiologic fluid and the sensor is in direct contact with the second passageway.

11. The method of claim 8, wherein the shunt comprises adjacent first and second passageways and, interposed therebetween, a semipermeable membrane.

12. The method of claim 11, wherein the semipermeable membrane is permeable to the analyte and impermeable to the physiologic fluid and the reference sample.

13. The method of claim 12, wherein the first passageway comprises a means to pass the physiologic fluid and the sensor is in direct contact with the second passageway.

14. The method of claim 1, further comprising, prior to step (a), providing the reference sample in premixed form.

15. The method of claim 14, wherein the reference sample is provided by premixing using tonometry.

16. The method of claim 1, further comprising exposing the sensor to two or more reference samples.

17. The method of claim 16, wherein the sensor is exposed to first and second reference samples having different known analyte concentrations.

18. The method of claim 16, wherein the reference sample comprises an infusion medium or a calibrant.

19. The method of claim 1, further comprising prior to step (b) detaching the passageway from the physiologic line.

20. The method of claim 1 wherein the passageway comprises an in-dwelling intraarterial cannula having an interior barrel and an end situated in an artery and the sensor comprises a tip retractably inserted into the cannula so that the tip extends beyond the end of the cannula into the artery, said method further comprising, prior to step (b), retracting the tip of the sensor to be situated in the barrel of the cannula.

21. The method of claim 1 wherein the passageway comprises an in-dwelling intraarterial cannula having an interior barrel and an end situated in an artery and the sensor comprises a tip retractably inserted into the cannula so that the tip extends beyond the end of the cannula into the artery, said method further comprising, prior to step (b), retracting the tip of the sensor to be situated in the barrel of the cannula.

40. A method of performing quality control for confirming the accuracy of a system for analyzing characteristics of a physiologic fluid, wherein said method comprises:

a) providing a sterile sensor assembly located in a sterile physiologic line, said assembly comprising (i) at least one sensor responsive to a characteristic of an analyte in the physiologic fluid and calibrated according to the method of claim 1, said sensor in direct or indirect contact with the analyte and, (ii) at least one sterile passageway detachably affixed to and in divertable fluid communication with a physiologic line and a conduit by which at least one single-use reference sample may be introduced into the passageway without compromising the sterility of the physiologic line, wherein the reference sample is sterile, biocompatible and has a known concentration of the analyte, and wherein the sensor is in communication with the passageway;

b) exposing the calibrated sensor to the reference sample, thereby producing a sensor response;

c) calculating a composition value for the analyte in the reference sample from the sensor response; and

d) comparing the calculated composition value for the analyte with the known concentration of the analyte in the reference sample.

41. A method of detecting an analyte in a fluid comprising performing quality control according to the method of claim 40, and further comprising exposing the sensor to the fluid and detecting the analyte in the fluid.

22. A method of performing quality control for confirming the accuracy of a system for analyzing characteristics of a physiologic fluid, wherein said method comprises:

a) providing a sterile sensor assembly located in a sterile physiologic line, said assembly comprising (i) at least one calibrated sensor responsive to a characteristic of an analyte in the physiologic fluid and in direct or indirect contact with the analyte and, (ii) at least one sterile passageway detachably affixed to and in divertable fluid communication with the physiologic line and a conduit by which at least one single-use reference sample may be introduced into the passageway without compromising the sterility of the physiologic line, wherein the reference sample is sterile, biocompatible and has a known concentration of the analyte, and wherein the sensor is in communication with the passageway;

b) exposing the calibrated sensor to the reference sample, thereby producing a sensor response;

c) calculating a composition value for the analyte in the reference sample from the sensor response; and

d) comparing the calculated composition value for the analyte with the known concentration of the analyte in the reference sample.

23. The method of claim 22, wherein the reference sample comprises an infusion medium, a quality control medium, or a calibrant.

24. The method of claim 23, wherein the reference sample comprises a quality control medium.

25. The method of claim 24, wherein the quality control medium is comprised of an infusion medium.

26. The method of claim 22, wherein the quality control medium is a synthetic quality control medium.

27. The method of claim 26, wherein the synthetic quality control medium comprises a synthetic buffer.

28. The method of claim 22, wherein exposing the sensor assembly to the reference sample comprises directly contacting the sensor assembly with said reference sample.

29. The method of claim 28, wherein contacting the sensor comprises dynamic contacting.

30. The method of claim 29, wherein the passageway comprises a shunt.

31. The method of claim 30, wherein the shunt comprises first and second passageways in divertable fluid communication one with the other, wherein the first and second passageways respectively comprise the physiologic line and the sensor assembly.

32. The method of claim 31, wherein the first passageway comprises a means to pass the physiologic fluid and the sensor is in direct contact with the interior of the second fluid passageway.

33. The method of claim 30, wherein the passageway comprises adjacent first and second fluid passageways and, interposed therebetween, a semipermeable membrane.

34. The method of claim 33, wherein the semipermeable membrane is permeable to the analyte and impermeable to the physiologic fluid and the reference sample.

35. The method of claim 34, wherein the first passageway comprises a means to pass the physiologic fluid and the calibrated sensor is in direct contact with the interior of the second passageway.

36. The method of claim 22, further comprising, prior to step (a), providing the quality control medium in premixed form.

37. The method of claim 36, wherein the quality control medium is provided by premixing by tonometry.

38. The method of claim 22, further comprising prior to step (b) detaching the passageway from the physiologic line.

39. A method of detecting an analyte in a fluid comprising performing quality control according to the method of claim 22, and further comprising exposing the sensor to the fluid and detecting the analyte in the fluid.

42. An apparatus for calibrating a system for analyzing a characteristic of a physiologic fluid containing or suspected of containing an analyte, comprising a sterile sensor assembly located in a sterile physiologic line, said assembly comprising (a) at least one sensor responsive to the characteristic and in direct or indirect contact with the analyte and (b) at least one sterile passageway detachably affixed to and in divertable fluid communication with the physiologic line and a conduit by which at least one single-use reference sample may be introduced into the passageway without compromising the sterility of the physiologic line, wherein the reference sample is sterile, biocompatible and has a known concentration of the analyte, and wherein the sensor is in communication with the passageway.

43. The apparatus of claim 42, wherein the passageway comprises a means to pass the physiologic fluid or the reference sample through the passageway.

44. The apparatus of claim 43, wherein the passageway comprises a shunt.

45. The apparatus of claim 44, wherein the shunt comprises first and second passageways in divertable fluid communication one with the other, wherein the first and second passageways respectively comprise the physiologic line and the sensor assembly.

46. The apparatus of claim 45, wherein the first passageway comprises a means to pass the physiologic fluid and the sensor is in direct contact with the interior of the second passageway.

47. The apparatus of claim 44, wherein the shunt comprises adjacent first and second passageways and, interposed therebetween, a semipermeable membrane.

48. The apparatus of claim 47, wherein the semipermeable membrane is permeable to the analyte and impermeable to the physiologic fluid and the reference sample.

49. The apparatus of claim 48, wherein the first passageway comprises a means to pass the physiologic fluid and the sensor is in direct contact with the interior of the second fluid passageway.

50. The apparatus of claim 48, wherein the second passageway comprises a means to pass the physiologic fluid and the sensor is in direct contact with the interior of the second fluid passageway.

51. The apparatus of claim 44, wherein the passageway includes a means to pass the reference sample.

52. The apparatus of claim 51, wherein the means to pass the reference sample comprises a storage means for storing the reference sample, a motive means for delivering the reference sample from the storage means to the passageway, an introduction means for introducing the reference sample into the passageway, a drain means for removing the reference sample from the passageway and a reservoir means to contain the removed reference sample.

53. The apparatus of claim 42 wherein the passageway comprises an in-dwelling intraarterial cannula having an interior barrel and an end situated in an artery and the sensor comprises a tip retractably inserted into the cannula so that the tip extends beyond the end of the cannula into the artery.

54. A method of detecting an analyte in a physiologic fluid comprising:

a) providing a sterile sensor assembly located in a sterile physiologic line, said assembly comprising (i) at least one sensor responsive to a characteristic of the analyte and in direct or indirect contact with the physiologic fluid, and (ii) at least one sterile passageway detachably affixed to and in divertable fluid communication with the physiologic line and a conduit by which at least one single-use reference sample may be introduced into the passageway without compromising the sterility of the physiologic line, wherein the reference sample is sterile and biocompatible, and wherein the sensor is in communication with the passageway;

b) exposing the sensor in the sensor assembly to the reference sample, thereby producing a sensor response if the analyte is present in the physiologic fluid; and

c) correlating the sensor response to the characteristic of the detected analyte in the reference sample.