Conjunctival monitor

• US 20040111018A1
• Filed: 12/09/2002
• Published: 06/10/2004
• Est. Priority Date: 12/09/2002
• Status: Active Grant

• Current Assignee: Los Angeles Biomedical Research Institute At Harbor-Ucla Medical Center (University of California)
• Original Assignee: Research and Education Institute Incorporated
• Inventors: Isenberg, Sherwin J., Weiss, Irwin
• Granted Patent: US 6,973,338 B2
• Time in Patent Office: Days
• US Class Current: 600/364
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/6821 Eye

Abstract

A method for monitoring blood/tissue gases, blood pH, and other elements of blood and tissue chemistry is described that uses a sensor tip that is placed adjacent to the conjunctiva of a patient to be monitored. Monitors and sensor using optical fiber sensors for performing the monitoring are also described.

Claims

1. A method for monitoring blood and tissue gas or pH of a patient, comprising

placing an optical blood and tissue gas monitor sensor tip adjacent the conjunctiva of said patient, wherein said sensor tip comprises at least one optical sensor fiber for detecting at least one blood and tissue gas or blood and tissue pH and said sensor tip is connected with analysis and display components of a blood monitor system;

determining patient blood and tissue gas or pH values or both with said monitor system; and

recording or displaying said patient blood and tissue gas or pH values or both.

2. The method of claim 1, wherein said sensor tip has a detection length of 2 cm or less.

3. The method of claim 1, wherein said sensor tip comprises an exterior biocompatible, microporous membrane containing at least two of a pH optical sensor fiber, a PCO₂ optical sensor fiber, and a PO₂ optical sensor fiber, wherein fluid flow through said microporous membrane is inhibited.

4. The method of claim 1, wherein said monitoring is conducted during treatment of said patient.

5. The method of claim 4, wherein said treatment comprises surgery.

6. The method of claim 5, wherein said surgery comprises heart surgery.

7. The method of claim 5, wherein said surgery comprises lung surgery.

8. The method of claim 4, wherein said treatment comprises injection or infusion of a drug.

9. The method of claim 4, wherein said monitoring is performed for a period of at least one hour.

10. The method of claim 3, wherein said sensor tip further comprises at least one distal terminal mirror that returns light through one or more of said optical sensor fibers.

11. The method of claim 10, wherein said sensor tip is 1.5 cm or less in length.

12. The method of claim 10, wherein said sensor tip is 1.0 cm or less in length.

13. The method of claim 1, wherein said sensor tip comprises a pH optical sensor fiber, a PCO₂ optical sensor fiber, and a PO₂ optical sensor fiber.

14. The method of claim 13, wherein said sensor tip further comprises a temperature sensor.

15. The method of claim 3, wherein said fluid flow is inhibited by a gel.

16. The method of claim 15, wherein said gel comprises polyacrylamide gel.

17. The method of claim 3, wherein said sensor tip is coated with heparin.

18. The method of claim 3, wherein said optical sensor fibers comprises acrylic optical fibers.

19. The method of claim 13, wherein said pH optical sensor fiber comprises phenol red in polyacrylamide gel, and said fiber is perforated.

20. The method of claim 13, wherein said PCO₂ optical sensor fiber comprises phenol red in bicarbonate solution, and said fiber is perforated.

21. The method of claim 13, wherein said PO₂ optical sensor fiber comprises ruthenium dye in a silicone matrix, and said fiber is perforated.

22. The method of claim 13, wherein said pH optical sensor comprises phenol red in polyacrylamide gel, said PCO₂ optical sensor fiber comprises phenol red in bicarbonate solution, and said PO₂ optical sensor fiber comprises ruthenium dye in a silicone matrix, and said fibers are perforated.

23. The method of claim 22, wherein said monitor a light source and photodetectors.

24. The method of claim 23, wherein green light pulses are used for detection and red light pulses are used for reference in said pH and PCO₂ optical sensor fibers, and blue light is used for detection and green light is used for reference in said PO₂ optical sensor fiber.

25. The method of claim 14, wherein said temperature sensor comprises a thermocouple.

26. The method of claim 25, wherein temperature readings from said temperature sensor are used to normalize readings for one or more of pH, CO₂, and O₂.

27. The method of claim 1, wherein said monitoring is performed on a patient in an emergency room.

28. The method of claim 1, wherein said monitoring is performed in an intensive care unit.

29. The method of claim 1, wherein said monitoring is performed in an emergency transport vehicle.

30. A conjunctival monitor, comprising

a sensor comprising a sensor tip with a detection length of 2 cm or less adapted to fit adjacent the conjunctiva of a patient'"'"'s eye, comprising at least one optical sensor fiber.

31. The conjunctival monitor of claim 30, wherein said sensor tip further comprises an exterior biocompatible, microporous membrane containing at least two of a pH optical sensor fiber, a PCO₂ optical sensor fiber, and a PO₂ optical sensor fiber, wherein fluid flow through said microporous membrane is inhibited.

32. The conjunctival monitor of claim 30, wherein said sensor tip further comprises at least one distal terminal mirror that returns light through one or more of said optical sensor fibers.

33. The conjunctival monitor of claim 30, wherein said detection length is 1.5 cm or less.

34. The conjunctival monitor of claim 30, wherein said detection length is 1.0 cm or less.

35. The conjunctival monitor of claim 30, comprising a pH optical sensor fiber, a PCO₂ optical sensor fiber, and a PO₂ optical sensor fiber.

36. The conjunctival monitor of claim 30, wherein said sensor tip further comprises a temperature sensor.

37. The conjunctival monitor of claim 31, wherein said fluid flow is inhibited by a gel.

38. The conjunctival monitor of claim 37, wherein said gel comprises polyacrylamide gel.

39. The conjunctival monitor of claim 31, wherein said sensor tip is coated with heparin.

40. The conjunctival monitor of claim 31, wherein said optical sensor fibers comprises acrylic optical fibers.

41. The conjunctival monitor of claim 31, wherein said pH optical sensor fiber comprises phenol red in polyacrylamide gel, and said fiber is perforated.

42. The conjunctival monitor of claim 31, wherein said PCO₂ optical sensor fiber comprises phenol red in bicarbonate solution, and said fiber is perforated.

43. The conjunctival monitor of claim 31, wherein said PO₂ optical sensor fiber comprises ruthenium dye in a silicone matrix, and said fiber is perforated.

44. The conjunctival monitor of claim 31, wherein said pH optical sensor comprises phenol red in polyacrylamide gel, said PCO₂ optical sensor fiber comprises phenol red in bicarbonate solution, and said PO₂ optical sensor fiber comprises ruthenium dye in a silicone matrix, and said fibers are perforated.

45. The conjunctival monitor of claim 30, further comprising a light source and photodetectors.

46. The conjunctival monitor of claim 44, wherein green light pulses are used for detection and red light pulses are used for reference in said pH and PCO₂ optical sensor fibers, and blue light is used for detection and green light is used for reference in said PO₂ optical sensor fiber.

47. The conjunctival monitor of claim 36, wherein said temperature sensor comprises a thermocouple.

48. The conjunctival monitor of claim 47, wherein temperature readings from said temperature sensor are used to normalize readings for one or more of pH, CO₂, and O₂.

49. The conjunctival monitor of claim 30, further comprising an analysis unit that processes signals from said sensor tip and converts said signals into output representative of blood gas or blood pH values or both.

50. The conjunctival monitor of claim 49, further comprising a display unit for displaying output for blood gas or blood pH values or both.

51. The conjunctival monitor of claim 30, further comprising a written indication that said monitor or said sensor can be used for conjunctival monitoring.

58. The sensor of claim 49, where said written indication is on said sterile packaging.

52. A disposable sensor for a conjunctival monitor, comprising

a sensor tip comprising at least two of a pH sensor fiber or electrode, a PCO₂ sensor fiber or electrode, and a PO₂ sensor fiber or electrode, wherein said sensor tip has a thickness of 0.5 mm or less;

a sterile packaging enclosing at least the portion of said sensor tip that contacts the conjunctiva of a patient during use; and

a written indication for use of said sensor for conjunctival monitoring.

53. The sensor of claim 52, wherein said sensor tip comprises an exterior biocompatible, microporous membrane containing said sensor fibers or electrodes, wherein fluid flow through said microporous membrane is inhibited.

54. The sensor of claim 53, wherein said sensor tip further comprises an PCO₂ optical sensor fiber, and a PO₂ optical sensor fiber.

55. The sensor of claim 54, wherein said sensor tip further comprises a pH optical sensor fiber and a thermocouple for temperature determination.

56. The sensor of claim 55, wherein said sensor tip has a detection length of 2 cm or less.

57. The sensor of claim 55, wherein said sensor tip has a detection length of 1.5 cm or less.