METHODS AND SYSTEMS FOR ANALYTE MEASUREMENT

• US 20110184683A1
• Filed: 01/21/2011
• Published: 07/28/2011
• Est. Priority Date: 01/22/2010
• Status: Active Grant

• Current Assignee: Zoll Medical Corporation (Asahi Kasei Corporation), University Of Massachusetts
• Original Assignee: Sotera Wireless Incorporated (Foxconn Technology Co., Ltd.), Sotera Research, Inc.
• Inventors: Peshlov, Boyan, Zou, Fengmei, Yang, Ye, Ross, Randy, Soller, Babs R.
• Granted Patent: US 9,057,689 B2
• Time in Patent Office: Days
• US Class Current: 702/85
• CPC Class Codes: G01N 21/3577 for analysing liquids, e.g. polluted water
• CPC Class Codes: G01N 33/4925 measuring blood gas content, e.g. O2, CO2 , HCO3

Abstract

Methods are disclosed for determining a value associated with an analyte in a sample. The methods include: determining a set of spectra from a model for light attenuation in the sample, where the model includes contributions from at least two different sources of light attenuation in the sample; determining a set of spectral correction factors associated with the analyte in the sample based on the set of spectra; and using the set of spectral correction factors to determine the value associated with the analyte of interest.

Claims

1. A method for determining a value associated with an analyte in a sample, the method comprising:

determining a set of spectra from a model for light attenuation in the sample, wherein the model comprises contributions from at least two different sources of light attenuation in the sample;

determining a set of spectral correction factors associated with the analyte in the sample based on the set of spectra; and

using the set of spectral correction factors to determine the value associated with the analyte.

2. The method of claim 1, wherein the at least two different sources of light attenuation comprise light scattering and absorption.

3. The method of claim 1, wherein the analyte comprises at least one member selected from the group consisting of pH, temperature, oxygen tension, oxygen saturation, carbon dioxide partial pressure, hemoglobin concentration, water concentration, and hematocrit.

4. The method of claim 1, wherein determining the set of spectral correction factors comprises determining mean-centered spectra from the set of spectra.

5. The method of claim 4, wherein determining the set of spectral correction factors comprises determining orthogonalized spectra based on the mean-centered spectra.

6. The method of claim 1, wherein determining the value associated with the analyte comprises using the set of spectral correction factors to correct at least one member of the set of spectra, and using the corrected at least one member of the set of spectra as input to a calibration equation for the analyte.

7. The method of claim 6, wherein determining the value associated with the analyte comprises obtaining measured spectral information for the sample, and determining a member of the set of spectra that is closest to the measured spectral information.

8. The method of claim 7, further comprising determining the member of the set of spectra that is closest to the measured spectral information based on maximum and minimum differences between the measured spectral information and at least some of the members of the set of spectra.

9. The method of claim 7, wherein determining the value associated with the analyte comprises using the member of the set of spectra that is closest to the measured spectral information as input to the calibration equation, and determining the value associated with the analyte from the calibration equation.

10. The method of claim 2, wherein the light scattering comprises contributions from light scattering by one or more fat layers and light scattering by muscle tissue.

11. The method of claim 2, wherein the absorption comprises contributions from light absorption by at least two different analytes.

12. The method of claim 6, wherein determining the value associated with the analyte comprises:

simulating spectral information for the sample using the model for light attenuation in the sample;

using the simulated spectral information as input to the calibration equation; and

determining the value associated with the analyte from the calibration equation.

13. A method for determining a value associated with an analyte in a sample, the method comprising:

determining a set of spectra from a model for light attenuation in a sample;

obtaining spectral information corresponding to the sample and identifying a member of the set of spectra that corresponds to the spectral information; and

determining the value associated with the analyte in the sample based on the identified member of the set of spectra.

14. The method of claim 13, wherein identifying a member of the set of spectra comprises determining maximum and minimum differences between the spectral information and at least some members of the set of spectra, and identifying the member of the set of spectra that corresponds to the spectral information based on the maximum and minimum differences.

15. The method of claim 13, wherein determining the value associated with the analyte comprises using the identified member of the set of spectra as input to a calibration equation that relates spectral information to values of the analyte.

16. The method of claim 15, wherein determining the value associated with the analyte comprises determining spectral correction factors associated with the analyte from the set of spectra, applying the spectral correction factors to the identified member of the set of spectra to correct the identified member, and using the corrected identified member as input to the calibration equation.

17. The method of claim 13, wherein the analyte comprises at least one member selected from the group consisting of pH, temperature, oxygen tension, oxygen saturation, carbon dioxide partial pressure, hemoglobin concentration, water concentration, and hematocrit.

18. The method of claim 13, wherein the model for light attenuation comprises contributions from light scattering and from light absorption by at least two different analytes in the sample, and wherein the at least two different analytes comprise at least one of oxygenated hemoglobin, de-oxygenated hemoglobin, and myoglobin.

19. A system for determining a value associated with an analyte in a sample, the system comprising:

a radiation source configured to direct radiation to be incident on the sample;

a detector configured to detect radiation from the sample; and

an electronic processor configured to;

obtain measured spectral information about the sample based on the detected radiation;

compare the measured spectral information to a set of spectra determined from a model for light attenuation in the sample to identify a member of the set of spectra that corresponds to the measured spectral information;

correct the identified member of the set of spectra using a set of spectral correction factors determined from the set of spectra; and

use the corrected identified member of the set of spectra as input to a calibration equation to determine the value associated with the analyte.

20. The system of claim 19, wherein the electronic processor is configured to determine values associated with two or more analytes, and wherein the two or more analytes are selected from the group consisting of pH, temperature, oxygen tension, oxygen saturation, carbon dioxide partial pressure, hemoglobin concentration, water concentration, and hematocrit.