Method and device for predicting physiological values

• US 6,653,091 B1
• Filed: 07/23/2001
• Issued: 11/25/2003
• Est. Priority Date: 09/30/1998
• Status: Expired due to Term

• Current Assignee: LifeScan IP Holdings, LLC
• Original Assignee: Cyngnus Incorporated
• Inventors: Jayalakshmi, Yalia, Waterhouse, Steven Richard, Oliver, Jonathan James, Dunn, Timothy C., Kurnik, Ronald T., Potts, Russell O., Tamada, Janet A., Lesho, Matthew J., Wei, Charles W.
• Primary Examiner(s): Chin, Christopher L.
• Application Number:
  US09/911,341
• Publication Number:
  US 20020019022A1
• Time in Patent Office: 855 Days
• Field of Search: 422/82.01, 422/82.02, 204/400, 204/403, 435/14, 435/25, 435/176, 435/287.1, 435/817, 436/149, 436/150, 436/151, 436/518, 436/525, 436/806
• US Class Current: 435/14
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/441 Skin evaluation, e.g. for skin disorder diagnosis
• CPC Class Codes: Y10S 435/808 Optical sensing apparatus
• CPC Class Codes: Y10S 435/817 Enzyme or microbe electrode
• CPC Class Codes: Y10S 436/805 Optical property
• CPC Class Codes: Y10S 436/806 Electrical property or magnetic property
• CPC Class Codes: Y10S 436/815 Test for named compound or class of compounds
• CPC Class Codes: Y10T 436/115831 Condition or time responsive

Abstract

The invention relates generally to methods, systems, and devices for measuring the concentration of target analytes present in a biological system using a series of measurements obtained from a monitoring system and a Mixtures of Experts (MOE) algorithm. In one embodiment, the present invention describes a method for measuring blood glucose in a subject.

Claims

1. A method for measuring glucose present in a biological system, said method comprising:

transdermally extracting a sample comprising glucose from the biological system using a sampling system that is in operative contact with a skin or mucosal surface of said biological system;

obtaining a raw signal from the extracted glucose, wherein said raw signal is specifically related to glucose amount or concentration in the biological system;

performing a calibration which correlates the raw signal with a measurement value indicative of the amount or concentration of glucose present in the biological system at the time of extraction;

repeating said transdermal extracting and said obtaining a raw signal to obtain a series of two or more measurement values at selected time intervals; and

predicting a measurement value based on the series of measurement values using a Mixtures of Experts algorithm comprising the following

 

BG=w₁BG₁+w₂BG₂+w₃BG₃ 

 

(15)

 

wherein (BG) is blood glucose, BG_i is the blood glucose predicted by Expert i;

w_i is a weighting value, and the individual Experts BG_i are further defined by the expression shown as Equations 16, 17, and 18

2. The method of claim 1, wherein the sample is extracted from the biological system into a collection reservoir to obtain an amount or concentration of the glucose in said reservoir.

3. The method of claim 2, wherein the collection reservoir is in contact with the skin or mucosal surface of the biological system and the sample is extracted using an iontophoretic current applied to said skin or mucosal surface.

4. The method of claim 3, wherein the collection reservoir comprises an enzyme that reacts with the extracted glucose to produce an electrochemically detectable signal.

5. The method of claim 4, wherein the enzyme is glucose oxidase.

6. The method of claim 1, which includes further parameters for measurement values, said parameters selected from the group consisting of temperature, ionophoretic voltage, and skin conductivity.

7. A method for measuring glucose in a subject, said method comprising:

obtaining a raw signal from a sensing apparatus, wherein said raw signal is specifically related to an amount or concentration of glucose in the subject;

performing a calibration which correlates the raw signal with a measurement value indicative of the glucose amount or concentration in the subject;

repeating said obtaining of raw signal to obtain a series of measurement values at selected time intervals; and

predicting a measurement value using a Mixtures of Experts algorithm comprising the following,

 

BG=w₁BG₁+w₂BG₂+w₃BG₃ 

 

(15)

 

wherein (BG) is blood glucose, BG_i is the blood glucose predicted by Expert i;

w_i is a weighting value, and the individual Experts BG_i are further defined by the expression shown as Equations 16, 17, and 18

8. The method of claim 7, wherein the sensing apparatus is a near-IR spectrometer.

9. The method of claim 7, wherein the sensing apparatus comprises a biosensor having an electrochemical sensing element.

10. The method of claim 7, wherein before said obtaining of a raw signal, a sample comprising glucose is extracted from the subject into a collection reservoir to obtain an amount or concentration of the glucose in said reservoir.

11. The method of claim 10, wherein the collection reservoir is in contact with the skin or mucosal surface of the biological system and the sample is transdermally extracted.

12. The method of claim 11, wherein said sample is extracted using an iontophoretic current applied to said skin or mucosal surface.

13. The method of claim 12, wherein the collection reservoir comprises an enzyme that reacts with the extracted glucose to produce an electrochemically detectable signal.

14. The method of claim 13, wherein the enzyme is glucose oxidase.

15. A monitoring system for measuring glucose present in a biological system, said monitoring system comprising, in operative combination:

a sampling device for extracting a sample comprising glucose from the biological system, wherein said sampling device extracts the sample across a skin or mucosal surface of said biological system;

a sensing device in operative contact with the sample extracted by the sampling device, wherein said sensing device obtains a raw signal from the extracted glucose and said raw signal is specifically related to an amount or concentration of glucose present in the biological system; and

one or more microprocessors in operative communication with the sampling device and the sensing device, wherein said microprocessors (i) control the sampling device and the sensing device to obtain a series of raw signals at selected time intervals during a measurement period, (ii) correlate the raw signals with measurement values indicative of the amount or concentration of glucose present in the biological system, and (iii) predict a measurement value using a Mixtures of Experts algorithm comprising the following,

 

BG=w₁BG₁+w₂BG₂+w₃BG₃ 

 

(15)

 

wherein (BG) is blood glucose, BG_i is the blood glucose predicted by Expert i;

w_i is a weighting value, and the individual Experts BG_i are further defined by the expression shown as Equations 16, 17, and 18

16. The monitoring system of claim 15, wherein the sampling device includes one or more collection reservoirs for containing the extracted sample.

17. The monitoring system of claim 16, wherein the sampling device uses an iontophoretic current to extract the sample from the biological system.

18. The monitoring system of claim 17, wherein the collection reservoir comprises an enzyme that reacts with the extracted glucose to produce an electrochemically detectable signal.

19. The monitoring system of claim 18, wherein the enzyme is glucose oxidase.

20. A monitoring system for measuring glucose in a subject, said system comprising, in operative combination:

a sensing device in operative contact with a sample extracted from the subject, said sample comprising glucose, wherein said sensing device obtains a raw signal specifically related to an amount or concentration of glucose in the subject; and

one or more microprocessors in operative communication with the sensing device, wherein said microprocessors (i) control the sensing device to obtain a series of raw signals at selected time intervals, (ii) correlate the raw signals with measurement values indicative of the amount or concentration of glucose present in the subject, and (iii) predict a measurement value using a Mixtures of Experts algorithm comprising the following,

21. The monitoring system of claim 20, which includes further parameters for raw signals, said parameters selected from the group consisting of temperature, ionophoretic voltage, and skin conductivity.

22. The monitoring system of claim 20, wherein the sensing device comprises a biosensor having an electrochemical sensing element.

23. The monitoring system of claim 20, wherein the sensing device comprises a near-IR spectrometer.