Method for determining blood constituents

• US 6,480,729 B2
• Filed: 03/26/2001
• Issued: 11/12/2002
• Est. Priority Date: 04/28/2000
• Status: Expired due to Fees

• Current Assignee: Woolsthorpe Technologies Corporation
• Original Assignee: Alexander K. Mills
• Inventors: Stone, Robert T.
• Primary Examiner(s): Winakur, Eric F.
• Assistant Examiner(s): KREMER, MATTHEW J
• Application Number:
  US09/817,667
• Publication Number:
  US 20010037058A1
• Time in Patent Office: 596 Days
• Field of Search: 600/309-311, 600/316, 600/330, 600/322-324, 600/334-336, 356/39-41
• US Class Current: 600/323
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/6826 Finger
• CPC Class Codes: A61B 5/6838 Clamps or clips

Abstract

A method for determining the blood constituents of a patient comprising coupling an oximeter sensor arrangement to a tissue region of the patient; passing first and second lights through the patient'"'"'s tissue region for a first period of time while the venous blood in the tissue region has a first volume and for a second period of time while the venous blood in the tissue region has a second volume, the first light being substantially in a red light range and the second light being substantially in an infrared light range; detecting a red light signal and an infrared light signal, the red and infrared signals having at least first and second frequencies; computing a first ratio of the red and infrared signals at the first frequency; computing a second ratio of the red and infrared signals at the second frequency; comparing the first and second ratios to determine a first blood constituent.

Claims

1. A method for determining blood constituents of a patient, said patient having a tissue region, said tissue region including venous and arterial blood, comprising;

coupling an oximeter sensor arrangement to said tissue region of said patient;

passing first and second lights through said patient'"'"'s tissue region while said venous blood in said tissue region has a first volume for a first period of time and said venous blood in said tissue region has a second volume for a second period of time, said first light being substantially in a red light range and said second light being substantially in an infrared light range;

detecting light absorbed by said tissue region and providing a first signal corresponding to said absorbed light;

processing said first signal to provide a second signal corresponding to a red light signal component and a third signal corresponding to an infrared light signal component, each of said second and third signals having at least first and second frequencies, wherein said first frequency comprises approximately the reciprocal of the sum of said first and second periods;

computing a first ratio of said second and third signals at said first frequency;

computing a second ratio of said second and third signals at said second frequency;

comparing said first and second ratios to determine a first blood constituent.

2. The method of claim 1, wherein said first light is in the range of approximately 650-670 nm.

3. The method of claim 1, wherein said second light is in the range of approximately 800-1000 nm.

4. The method of claim 1, wherein said first volume of said venous blood is substantially less than said second volume of said venous blood.

5. The method of claim 1, wherein said first and second periods of time are in the range of approximately 4-6 sec.

6. The method of claim 5, wherein said first and second periods of time are substantially equal.

7. The method of claim 1, wherein said first frequency is in the range of approximately 0.08-0.12 Hz.

8. The method of claim 1, wherein said second frequency is in the range of approximately 0.8-1.2 Hz.

9. The method of claim 1, wherein said first blood constituent comprises a venous blood component.

10. A method for determining blood constituents of a patient, comprising;

passing first and second lights through said patient'"'"'s tissue while said tissue is in a first position for a first period of time and in a second period for a second period of time, said first position being above the patient'"'"'s heart level and said second position being below said patient'"'"'s heart region, said first light being substantially in a red light range and said second light being substantially in an infrared light range;

detecting light absorbed by said tissue and providing a first signal corresponding to said absorbed light;

processing said first signal to provide a second signal corresponding to a red light signal component and a third signal corresponding to an infrared light signal component, each of said second and third signals having at least first and second frequencies, wherein said first frequency comprises approximately the reciprocal of the sum of said first and second periods;

computing a first ratio of said second and third signals at said first frequency;

computing a second ratio of said second and third signals at said second frequency;

comparing said first and second ratios to determine a first blood constituent.

11. The method of claim 10, wherein said first light is in the range of approximately 650-670 nm.

12. The method of claim 10, wherein said second light is in the range of approximately 800-1000 nm.

13. The method of claim 10, wherein said first period of time is in the range of approximately 4-6 sec.

14. The method of claim 10, wherein said second period of time is in the range of approximately 4-6 sec.

15. The method of claim 14, wherein said first and second periods of time are substantially equal.

16. The method of claim 10, wherein said first frequency is in the range of approximately 0.08-0.12 Hz.

17. The method of claim 10, wherein said second frequency is in the range of approximately 0.8-1.2 Hz.

18. The method of claim 10, wherein said first blood constituent comprises a venous blood component.

19. A method for determining blood constituents of a patient, comprising;

passing first and second lights through said patient'"'"'s tissue while said tissue is in a first position for a first period of time and in a second position for a second period of time, said first position being above the patient'"'"'s heart level and said second position being below said patient'"'"'s heart region, said first light being substantially in a red light range and said second light being substantially in an infrared light;

detecting a red light signal and an infrared light signal, said red and infrared signals having at least first and second frequencies, wherein said first frequency comprises approximately the reciprocal of the sum of said first and second periods;

computing a first ratio of said red and infrared signals at said first frequency;

computing a second ratio of said red and infrared signals at said second frequency;

comparing said first and second ratios to determine a first blood constituent.

20. The method of claim 19, wherein said first light is in the range of approximately 650-670 nm.

21. The method of claim 19, wherein said second light is in the range of approximately 800-100 nm.

22. The method of claim 19, wherein said first period of time is in the range of approximately 4-6 sec.

23. The method of claim 19, wherein said second period of time is in the range of approximately 4-6 sec.

24. The method of claim 23, wherein said first and second periods of time are substantially equal.

25. The method of claim 19, wherein said first frequency is in the range of approximately 0.08-0.12 Hz.

26. The method of claim 19, wherein said second frequency is in the range of approximately 0.8-1.2 Hz.

27. The method of claim 19, wherein said first blood constituent comprises a venous blood component.