Method and apparatus for determining an analyte concentration in a sample having interferents

• US 7,388,202 B2
• Filed: 10/21/2005
• Issued: 06/17/2008
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: OptiScan Biomedical Corporation
• Original Assignee: OptiScan Biomedical Corporation
• Inventors: Zheng, Peng, Sterling, Bernhard B., Wechsler, Mark, Keenan, Richard, Hall, W. Dale, Witte, Kenneth G.
• Primary Examiner(s): Porta; David P.
• Assistant Examiner(s): BRYANT, MICHAEL C
• Application Number:
  US11/256,656
• Publication Number:
  US 20060197015A1
• Time in Patent Office: 970 Days
• Field of Search: 250/361.R, 250/339.07, 250/339.08, 356/39, 356/300, 422/67, 702/25
• US Class Current: 250/339.07
• 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 5/14535 for measuring haematocrit
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61M 2230/20 Blood composition characteristics
• CPC Class Codes: A61M 5/14212 Pumping with an aspiration and an expulsion action
• CPC Class Codes: G01N 21/274 Calibration, base line adjustment, drift correction
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 2201/1215 for interfering gases
• CPC Class Codes: G01N 2201/127 Calibration; base line adjustment; drift compensation
• CPC Class Codes: G01N 35/00693 Calibration
• CPC Class Codes: G01N 35/00712 Automatic status testing, e.g. at start-up or periodic

Abstract

A method and apparatus are described that permit an analyte concentration to be estimated from a measurement in the presence of compounds that interfere with the measurement. The method reduces the error in the analyte concentration in the presence of interferents. The method includes the use of a set of measurements obtained for a large population having a range of known analyte and interfering compound concentrations. From a sample measurement, which may or may not be one of the population, likely present interferents are identified, and a calibration vector is calculated.

Claims

1. A method for estimating the concentration of an analyte in a sample from a single measurement of the sample, said method comprising:

providing a sample containing an analyte;

providing reference population data stored in computer memory, the reference population data derived from a source other than the source of the sample;

providing a library of potential interferent data stored in computer memory;

measuring a spectrum of the sample and recording the measurement in computer memory;

using a computer processor to analyze the spectrum and identify in the sample, based on said measurement and said library of potential interferent data, one or more possible interferents to a measurement of the analyte;

using the reference population data and the potential interferent data to calculate a calibration that is specific to the measurement and reduces error attributable to said one or more possible interferents;

applying the calibration to the measurement of the sample; and

estimating, based on the calibrated measurement, the analyte concentration in the sample; and

recording the estimated analyte concentration in computer memory.

2. The method of claim 1, wherein said using the reference population data and the potential interferent data to calculate a calibration is done without information on the concentration in said sample of any of said one or more interferents.

3. The method of claim 1, wherein said using the reference population data and the potential interferent data to calculate a calibration is done without need for information on the concentration in said sample of any of said one or more interferents.

4. The method of claim 1, wherein said measurement is a measurement from a person, wherein said reference population data has been modified to include concentrations of said one or more possible interferents, and where said reference population does not necessarily include said person.

5. The method of claim 1, where said sample includes at least one component of blood, and said analyte is glucose.

6. The method of claim 1, where said spectrum is an infrared spectrum.

7. The method of claim 1, wherein said sample is a bodily fluid and at least one of said one or more interferents comprises an exogenous interferent.

8. The method of claim 1, wherein said sample is a bodily fluid and at least one of said one or more interferents is possibly but not necessarily present in said bodily fluid.

9. A carrier medium carrying one or more computer readable code segments to instruct a processor to implement a method for estimating the amount of an analyte in a sample from a measurement of the sample, said method comprising the method of claim 1.

10. The method of claim 1, wherein using the reference population data and the potential interferent data to calculate a calibration comprises calculating a vector that is not required to be perpendicular to the spectra of any stored potential interferent.

11. A method of for estimating the concentration of an analyte in a sample from a measurement of the sample, said method comprising:

identifying in the sample, based on said measurement, one or more possible interferents to a measurement of the analyte;

calculating a calibration which reduces error attributable to said one or more possible interferents;

applying the calibration to the measurement of the sample; and

estimating, based on the calibrated measurement, the analyte concentration in the sample;

wherein said calibration is a vector that is not required to be perpendicular to the spectra of the identified possible interferents.

12. An analyte detection system comprising:

a sensor configured to provide information relating to a measurement of an analyte in a sample;

a memory configured to store reference population data and a library of potential interferent data;

a processor; and

stored program instructions executable by said processor such that said system;

(a) identifies in the sample, based on said measurement, one or more possible interferents to the measurement of the analyte in the sample;

(b) calculates, using the reference population data and the potential interferent data, a calibration which reduces error attributable to said one or more possible interferents;

(c) applies the calibration to the measurement; and

(d) estimates, based on the calibrated measurement, the analyte concentration in the sample.

13. The analyte detection system of claim 12, wherein said system calculates said calibration without information on the concentration in said sample of any of said one or more interferents.

14. The analyte detection system of claim 12, wherein said system calculates said calibration without need for information on the concentration in said sample of any of said one or more interferents.

15. The analyte detection system of claim 12, further comprising a source of electromagnetic radiation, wherein said sensor comprises a detector configured to detect radiation emitted by said source and transmitted through said sample.

16. The analyte detection system of claim 12, wherein said sensor comprises a spectroscopic sensor.

17. The analyte detection system of claim 12, further comprising a sampling system configured to draw said sample from a patient periodically and conduct said sample into operative engagement with said sensor.

18. The analyte detection system of claim 12, wherein each of said one or more interferents comprises a sample component the presence of which tends to reduce the accuracy of a measurement of a concentration of an analyte of interest.

19. The analyte detection system of claim 12, wherein at least one of said one or more interferents comprises a medicament.

20. The analyte detection system of claim 12, wherein said sample is a bodily fluid and at least one of said one or more interferents comprises an exogenous interferent.

21. The analyte detection system of claim 12, wherein said sample is a bodily fluid and at least one of said one or more interferents is possibly but not necessarily present in said bodily fluid.

22. The analyte detection system of claim 12, wherein said sample includes at least one component of blood, and said analyte is glucose.

23. The analyte detection system of claim 12, wherein said stored program instructions are executable by said processor such that said system identifies said one or more possible interferents by analyzing combinations of sample spectra and interferent spectra corresponding to varying concentrations of a selected interferent, and identifying the selected interferent as a possible interferent if any of said combinations are within predetermined bounds.

24. The analyte detection system of claim 12, wherein said stored program instructions are executable by said processor such that said system identifies said one or more possible interferents by performing a statistical test for the presence of said one or more interferents.

25. An analyte detection system comprising:

a sensor configured to provide information relating to a measurement of an analyte in a sample;

a processor; and

stored program instructions executable by said processor such that said system;

(a) identifies, based on said measurement, one or more possible interferents to the measurement of the analyte in the sample;

(b) calculates a calibration which reduces error attributable to said one or more possible interferents;

(c) applies the calibration to the measurement; and

(d) estimates, based on the calibrated measurement, the analyte concentration in the sample;

wherein said stored program instructions are executable by said processor such that said system identifies said one or more possible interferents by analyzing combinations of sample spectra and interferent spectra corresponding to varying concentrations of a selected interferent, and identifying the selected interferent as a possible interferent if any of said combinations are within predetermined bounds.

26. An analyte detection system comprising:

a sensor configured to provide information relating to a measurement of an analyte in a sample;

a processor; and

stored program instructions executable by said processor such that said system;

(a) identifies, based on said measurement, one or more possible interferents to the measurement of the analyte in the sample;

(b) calculates a calibration which reduces error attributable to said one or more possible interferents;

(c) applies the calibration to the measurement; and

(d) estimates, based on the calibrated measurement, the analyte concentration in the sample;

wherein said stored program instructions are executable by said processor such that said system identifies said one or more possible interferents by performing a statistical test for the presence of said one or more interferents.

27. An analyte detection system comprising:

a sensor configured to provide information relating to a measurement of an analyte in a sample;

a processor; and

stored program instructions executable by said processor such that said system;

(a) identifies, based on said measurement, one or more possible interferents to the measurement of the analyte in the sample;

(b) calculates a calibration which reduces error attributable to said one or more possible interferents;

(c) applies the calibration to the measurement; and

(d) estimates, based on the calibrated measurement, the analyte concentration in the sample;

wherein said stored program instructions are executable by said processor such that said system calculates said calibration based on sample population data and library interferent data.

28. An analyte detection system configured to determine a concentration of an analyte in a sample, said system comprising:

a sensor configured to collect information useful for making a measurement of an analyte in a sample;

a processor; and

software executable by said processor such that said system;

determines the presence in the sample of possible interferents to the measurement by analyzing combinations of sample spectra and interferent spectra corresponding to varying concentrations of a selected interferent, and identifying the selected interferent as a possible interferent if any of said combinations are within predetermined bounds; and

determines a calibration that reduces errors in the measurement due to the presence of the determined possible interferents.

29. An analyte detection system configured to determine a concentration of an analyte in a sample, said system comprising:

a sensor configured to collect information useful for making a measurement of an analyte in a sample;

a processor; and

software executable by said processor such that said system;

determines the presence in the sample of possible interferents to the measurement by performing a statistical test for the presence of said possible interferents; and

determines a calibration that reduces errors in the measurement due to the presence of the determined possible interferents.

30. An analyte detection system configured to determine a concentration of an analyte in a sample, said system comprising:

a sensor configured to collect information useful for making a measurement of an analyte in a sample;

a processor; and

software executable by said processor such that said system;

determines the presence in the sample of possible interferents to the measurement; and

determines a calibration that reduces errors in the measurement due to the presence of the determined possible interferents;

wherein said software is executable by said processor such that said system determines said calibration based on sample population data and library interferent data.

31. The analyte detection system of claim 30, wherein at least one of said possible interferents comprises a medicament.

32. The analyte detection system of claim 30, wherein said sample includes at least one component of blood, and said analyte is glucose.

33. The analyte detection system of claim 30, wherein said sample is a bodily fluid and at least one of said possible interferents comprises an exogenous interferent.

34. The analyte detection system of claim 30, wherein said sample is a bodily fluid and at least one of said possible interferents is possibly but not necessarily present in said bodily fluid.