Method and apparatus for improving performance of noninvasive analyte property estimation

• US 7,698,105 B2
• Filed: 06/27/2005
• Issued: 04/13/2010
• Est. Priority Date: 05/23/2005
• Status: Active Grant

• Current Assignee: GLT Acquisition Corporation
• Original Assignee: Sensys Medical, Inc. (Sensys Medical Limited)
• Inventors: Ruchti, Timothy L., Hockersmith, Linda, Monfre, Stephen L., Hazen, Kevin H.
• Primary Examiner(s): Bui; Bryan
• Application Number:
  US11/168,941
• Publication Number:
  US 20060264718A1
• Time in Patent Office: 1,751 Days
• Field of Search: 702/77, 702/185, 702/189, 600/310, 600/316, 600/322, 600/473, 250/339.11, 250/339.12
• US Class Current: 702/185
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• 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: G01N 21/359 using near infrared light

Abstract

The invention relates to noninvasive analyte property determination. More particularly, the invention relates to a method and apparatus for performing conditional additional acquisition of noninvasive spectra to improve analyzer performance. Conditional additional data acquisition is used to confirm, update, and/or supplement spectral data.

Claims

1. A method for enhancing performance of a noninvasive spectroscopy based analyzer, comprising the steps of:

providing at least one condition, wherein said condition comprises a glucose concentration of less than about ninety milligrams per deciliter;

collecting at least one noninvasive spectrum using said noninvasive spectroscopy based analyzer;

determining a first estimated analyte property using said at least one noninvasive spectrum;

if said at least one condition is met, collecting at least one additional spectrum; and

using said at least one additional spectrum with either of said at least one noninvasive spectrum, or with said first estimated analyte property to enhance precision of said analyzer when said glucose concentration is hypoglycemic.

2. The method of claim 1, wherein said step of using said at least one additional spectrum replaces said at least one noninvasive spectrum.

3. The method of claim 1, wherein said step of using said at least one additional spectrum verifies said estimated analyte property.

4. The method of claim 1, wherein said step of using said at least one additional spectrum supplements said at least one noninvasive spectrum.

5. The method of claim 1, wherein said additional spectrum is collected using a multiplexed spectroscopy based analyzer.

6. The method of claim 1, wherein said at least one condition comprises any of:

an expected value;

an estimated analyte concentration;

an upper threshold;

a lower threshold; and

a threshold range.

7. The method of claim 1, wherein said condition comprises:

a number of replicates.

8. The method of claim 1, wherein said condition comprises:

a specification.

9. The method of claim 8, wherein said specification comprises:

a signal-to-noise ratio.

10. The method of claim 1, wherein said noninvasive spectrum comprises wavelengths in the near-infrared region.

11. The method of claim 10, wherein said near-infrared regions comprises wavelengths at least partially within the region of about 1100 to 1900 nm.

12. The method of claim 1, wherein said condition controls either semi-continuous or continuous analysis of said analyte property.

13. An apparatus for noninvasive analysis of a body part, comprising

a noninvasive analyzer;

an algorithm operating in conjunction with said analyzer; and

at least one condition in said algorithm, wherein said condition comprises a glucose concentration of less than about ninety milligrams per deciliter;

wherein said analyzer operates to collect at least one noninvasive spectrum and wherein said algorithm determines an estimated analyte property of the body part using said noninvasive spectrum; and

wherein if said at least one condition is met, said analyzer collects at least one additional spectrum and said at least one additional spectrum is used with either of said at least one noninvasive spectrum or said estimated analyte property to enhance precision of said analyzer when said glucose concentration is hypoglycemic.

14. The apparatus of claim 13, wherein said analyzer comprises at least:

a near-infrared source emitting light over at least 1100 to 1900 nm; and

a detector array.

15. The apparatus of claim 13, wherein said at least one additional spectrum comprises any of:

at least one replacement spectrum;

at least one verification spectrum; and

at least one supplemental spectrum.

16. The apparatus of claim 13, wherein said enhanced performance comprises:

an improved precision.

17. The apparatus of claim 13, wherein said at least one condition comprises any of:

an expected value; and

a threshold value.

18. The apparatus of claim 17, wherein said enhanced performance comprises any of:

an improved precision above said threshold value;

an improved precision below said threshold value;

an improved precision at a glucose concentration sensitive to integral insulin unit dosage;

an improved precision about a value maintained in a look-up table.

19. The apparatus of claim 13, wherein said algorithm comprises:

an outlier identification routine.

20. The apparatus of claim 19, wherein said outlier identification routine uses said additional spectrum.

21. The apparatus of claim 13, wherein said analyzer comprises at least one of:

a multiplexed optical path; and

a detector array.

22. The apparatus of claim 13, wherein said noninvasive analyzer comprises:

a handheld unit.

23. A method for reducing non invasive analyte property estimation error, comprising the steps of:

providing at least one set of conditions, wherein said condition comprises an expected value generated using successive measurements, wherein said expected value indicates a potential for hypoglycemia in the next about 15 minutes;

collecting a noninvasive spectrum using a noninvasive spectroscopy based analyzer;

estimating an analyte property using said spectrum;

recording said analyte property in a set of estimations;

if said set of conditions is met repeating said steps of collecting, estimating, and recording; and

generating an analyte property estimation using said set of estimations;

wherein said set of estimations comprises at least two estimations of said analyte property.

24. A method for reducing noninvasive analyte property estimation error, comprising the steps of:

providing at least one set of conditions, wherein said set of conditions comprises a number of replicates greater than ten, wherein each of said replicates comprise acquisition within about five hundred milliseconds;

collecting a noninvasive spectrum using a noninvasive spectroscopy based analyzer;

estimating an analyte property using said spectrum;

if said set of conditions is met, recording said analyte property estimation;

repeating said steps of collecting and estimating; and

updating said recorded analyte property estimation using said analyte property estimation and said recorded analyte property estimation.