Non-invasive determination of direction and rate of change of an analyte

• US 20040167382A1
• Filed: 01/08/2004
• Published: 08/26/2004
• Est. Priority Date: 08/09/1995
• Status: Active Grant

• Current Assignee: Inlight Solutions, Inc.
• Original Assignee: Inlight Solutions, Inc.
• Inventors: Gruner, William, Ridder, Trent D., Gardner, Craig M.
• Granted Patent: US 7,016,713 B2
• Time in Patent Office: Days
• US Class Current: 600/310
• CPC Class Codes: A61B 2560/0233 Optical standards
• CPC Class Codes: A61B 2562/146 for optical coupling
• 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 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/1491 Heated applicators

Abstract

The present invention relates generally to a non-invasive method and apparatus for measuring a fluid analyte, particularly relating to glucose or alcohol contained in blood or tissue, utilizing spectroscopic methods. More particularly, the method and apparatus incorporate means for detecting and quantifying changes in the concentration of specific analytes in tissue fluid. Also, the method and apparatus can be used to predict future levels of analyte concentration either in the tissue fluid or in blood in an adjacent vascular system.

Claims

1. A method for non-invasive determination of a characteristic of change in an analyte property in a first tissue compartment, comprising:

a. irradiating the first tissue compartment;

b. measuring a signal from the first tissue compartment to acquire a first output signal;

c. after a first time interval, measuring a signal from the first tissue compartment to acquire a second output signal;

d. determining a characteristic of change of the analyte property in the first tissue compartment from the first and second output signals.

2. The method of claim 1, wherein the property is the analyte'"'"'s concentration.

3. The method of claim 1, wherein the characteristic comprises the rate of change, the direction of change, or a combination thereof.

4. The method of claim 1, further comprising determining a first analyte property in the first tissue compartment, and determining a second analyte property in a second tissue compartment from the first analyte property and the characteristic of change.

5. The method of claim 1, further comprising determining a first value of an analyte property in the first tissue compartment, and determining a second value of the analyte property in the first tissue compartment from the first value and the characteristic of change.

6. The method of claim 1, further comprising determining a first value of an analyte property, which first property comprises at least one of:

an analyte property in the first tissue compartment, and an analyte property in a second tissue compartment, and determining a second value of the analyte property from the first value and the characteristic of change.

7. The method of claim 1, further comprising determining a characteristic of change in an analyte property in a second tissue compartment from the characteristic of change in the first tissue compartment.

8. The method of claim 1, wherein the analyte is glucose.

9. The method of claim 1, wherein the analyte is urea.

10. The method of claim 1, wherein the analyte is alcohol.

11. The method of claim 1, wherein the analyte is a controlled substance.

12. The method of claim 1, wherein determination of a characteristic of change in an analyte property comprises determination of a characteristic of change in more than one analyte.

13. The method of claim 1, wherein the first tissue compartment comprises interstitial fluid.

14. The method of claim 1, wherein the first tissue compartment comprises blood.

15. The method of claim 1, further comprising increasing the change in the analyte property.

16. The method of claim 1, wherein the step of irradiating the tissue comprises providing light incident on a first side of the tissue and the steps of measuring a signal comprise receiving light exiting the tissue on a second side of the tissue.

17. The method of claim 1, wherein the step of irradiating the tissue comprises providing light incident on a first side of the tissue and the steps of measuring a signal comprise receiving light exiting the tissue on the first side of the tissue.

18. The method of claim 1, further comprising after a second time interval, measuring a signal from the tissue to acquire a third output signal, and wherein determining a characteristic of change comprises determining a characteristic of change of the analyte property from the first, second, and third output signals.

19. An apparatus for determining a direction and rate of change in concentration of an analyte in tissue comprising:

a. energy means for providing optical energy;

b. input means coupling the optical energy into a tissue sample;

c. output means for capturing an optical signal from the tissue sample; and

d. analyzing means for analyzing the optical signal and determine the direction and rate of change.

20. The apparatus of claim 19, wherein the output means is adapted to modulate the optical signal to enable the analyzing means to analyze a first sample of the optical signal at a first time and a second sample of the optical signal at a second time.

21. The apparatus of claim 19, wherein the analyzing means includes differentiation means for performing the mathematical function of differentiation upon at least one selected frequency of the optical signal over time.

22. A method of measuring changes in concentration of an analyte disposed in tissue comprising:

a. irradiating the tissue;

b. capturing radiation at a plurality of selected frequencies emanating from the tissue at a first time and a second time;

c. determining the direction or rate of change, or both, of the concentration of the analyte from the captured radiation.

23. The method of claim 22, further including the step of providing means for accelerating changes in concentration of the analyte in the tissue during the interval between the first and second times.

24. The method of claim 22, further including the step of providing means for accelerating equilibration of the concentration of the analyte in a first tissue compartment to a concentration of the analyte in a second tissue compartment.

25. The method of claim 22, further including the step of determining a present concentration of the analyte in a second tissue compartment from the captured radiation.

26. The method of claim 22, further including the steps of:

a. determining a set of acceptable combinations of present analyte concentration, direction of change, and rate of change of analyte concentration;

b. determining whether the present analyte concentration, direction of change, and rate of change are within the set of acceptable combinations,

c. generating a signal indicative of whether the present analyte concentration, direction of change, and rate of change are within the set of acceptable combinations.

27. A method of determining a first analyte property in a first tissue compartment, comprising:

a. Determining a measure that is characteristic of a second analyte property in a second tissue compartment;

b. Determining the first analyte property in the first tissue compartment from the measure.

28. A method as in claim 27, wherein the first analyte property comprises the concentration of the first analyte, the rate of change of the concentration of the first analyte, the direction of change of the concentration of the first analyte, or a combination thereof.

29. A method as in claim 28, wherein the measure comprises a measure of the rate of change of the concentration of the second analyte.

30. A method as in claim 28, wherein the measure comprises a measure of the concentration of the second analyte.

31. A method as in claim 28, wherein the measure comprises a measure of the concentration of the second analyte and a measure of the rate of change of the concentration of the second analyte.

32. A method as in claim 28, wherein determining the first analyte property comprises applying an experimentally-derived model relating the measure to the first analyte property.

33. A method as in claim 28, wherein determining the first analyte property comprises applying a theoretically-derived model relating the measure to the first analyte property.

34. A method as in claim 28, wherein the first analyte is the same as the second analyte.

35. A method as in claim 28, wherein the first analyte is distinct from the second analyte.

36. A method as in claim 28, wherein the first tissue compartment is the same as the second tissue compartment.

37. A method as in claim 28, wherein the first tissue compartment is distinct from the second tissue compartment.

38. A method of determining the direction of change, the rate of change, or both, of an analyte property in tissue that contains the analyte, comprising:

a. Detecting a signal from the tissue;

b. Determining the direction of change, the rate of change, or both, of the analyte property from the signal and a model that relates the signal to the direction of change, the rate of change, or both.