Method and apparatus for improving the accuracy of alternative site analyte concentration measurements

• US 20030175806A1
• Filed: 11/21/2002
• Published: 09/18/2003
• Est. Priority Date: 11/21/2001
• Status: Abandoned Application

• Current Assignee: OptiScan Biomedical Corporation
• Original Assignee: Hercules Technology Growth Capital, Inc.
• Inventors: Hartstein, Phillip C., Braig, James R., Rule, Peter, Smith, Heidi S., Klonoff, David C.
• Application Number:
  US10/302,071
• Publication Number:
  US 20030175806A1
• Time in Patent Office: Days
• US Class Current: 435/7.1
• CPC Class Codes: A61B 2562/0295 Strip shaped analyte sensors for apparatus classified in A61B5/145 or A61B5/157 disposable multilayered or laminated electrodes G01N27/307; details of handling chemical test elements G01N33/4875
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters
• CPC Class Codes: A61B 5/1491 Heated applicators
• CPC Class Codes: A61B 5/150022 for capillary blood or interstitial fluid
• CPC Class Codes: A61B 5/150213 Venting means
• CPC Class Codes: A61B 5/150358 Strips for collecting blood, e.g. absorbent optical reagent test strips G01N21/8483; chemical reagent test strips G01N33/4875, G01N33/52
• CPC Class Codes: A61B 5/150412 Pointed piercing elements, e.g. needles, lancets for piercing the skin blade-like piercing elements A61B5/150442
• CPC Class Codes: A61B 5/150503 Single-ended needles hollow piercing element tip design A61B5/150396, needle sets for catheters A61M25/06, needles for bringing media into the body A61M5/32
• CPC Class Codes: A61B 5/15087 short range, e.g. between console and disposable using implanted devices A61B5/150877
• CPC Class Codes: A61B 5/15107 Piercing being assisted by a triggering mechanism
• CPC Class Codes: A61B 5/15136 by use of radiation, e.g. laser
• CPC Class Codes: A61B 5/1514 by use of gaseous agents, e.g. using suction aspiration or pressurized gas
• CPC Class Codes: A61B 5/15186 Devices loaded with a single lancet, i.e. a single lancet with or without a casing is loaded into a reusable drive device and then discarded after use; drive devices reloadable for multiple use
• CPC Class Codes: A61B 5/157 Devices characterised by integrated means for measuring characteristics of blood
• CPC Class Codes: A61B 5/4839 combined with drug delivery

Abstract

Methods and apparatuses for improving the accuracy of analyte concentration measurements at alternative sites and information provided to the user. The present invention advantageously utilizes information relating to the rate of change of analyte concentrations to adjust analyte concentrations measurements and/or information provided to the user. Therefore, the present invention provides new and improved methods and apparatuses for obtaining analyte concentration information at physiological sites other than the fingertips while ensuring that the analyte concentration information accurately reflects systemic analyte concentration values.

Claims

1. A method for improving the accuracy of analyte concentration measurements, the method comprising:

determining a rate of change of analyte concentration;

measuring an analyte concentration at an alternative site; and

adjusting the measured analyte concentration based on said rate of change to generate an adjusted analyte concentration value which is a more accurate estimate of the systemic analyte concentration value.

2. The method of claim 1, further comprising:

determining the clinical significance of an error in the measured analyte concentration.

3. The method of claim 1, wherein adjusting the measured analyte concentration comprises:

determining a time lag between analyte concentrations measured on-site and at an alternative site;

determining a correction factor based on the time lag and said rate of change of analyte concentration; and

adjusting the measured analyte concentration value by said correction factor.

4. The method of claim 1, further comprising:

correcting the measured analyte concentration based on the rate of change of the analyte concentration, further comprising;

determining the time lag between analyte concentrations measured onsite and at an alternative site;

taking a follow-up analyte concentration measurement at a time that falls between the time of previous analyte concentration measurement and the sum of the time lag and the time of the previous analyte concentration measurement;

determining the rate of analyte concentration change during the time period between the previous analyte concentration measurement and the follow-up analyte concentration measurement; and

extrapolating the analyte concentration value to a time after the sum of the time lag and the time of the previous analyte concentration measurement by using the rate of analyte concentration change in between the previous analyte concentration measurement and the follow-up analyte concentration measurement.

5. The method of claim 1, further comprising:

screening measured analyte concentration values to remove outlier concentration values and/or rate of concentration change values based on statistical analysis, data history, and/or data forecasts or trends.

6. A method for improving the accuracy of information provided to a user by an analyte detection system, said method comprising:

determining a rate of change of analyte concentration; and

adjusting said information provided to said user based on said rate of change.

7. The method of claim 6, wherein determining said rate of change comprises estimating that the absolute value of said rate of change is relatively high.

8. The method of claim 6, wherein determining said rate of change comprises estimating that the absolute value of said rate of change will remain relatively high for about 1-2 hours.

9. The method of claim 6, wherein determining said rate of change comprises receiving data input from the user and estimating, based on said data, that the absolute value of said rate of change is relatively high.

10. The method of claim 9, wherein said data comprises at least one of (i) that the user is about to eat or has just eaten a meal and (ii) that the user is about to engage in or has just engaged in physical exercise.

11. The method of claim 6, wherein determining said rate of change comprises:

measuring a first analyte concentration at a first measurement time;

measuring a second analyte concentration at a second measurement time; and

computing said rate of change based on said first and second analyte concentrations and said first and second measurement times.

12. The method of claim 11, wherein determining said rate of change further comprises continuously computing said rate of change.

13. The method of claim 6, wherein adjusting said information comprises warning the user that the absolute value of said rate of change is relatively high.

14. The method of claim 13, wherein adjusting said information further comprises prompting the user to take an on-site analyte concentration measurement.

15. The method of claim 6, wherein adjusting said information comprises warning the user, when the absolute value of said rate of change is relatively high, that alternative-site measurements are likely to be inaccurate.

16. The method of claim 15, wherein adjusting said information further comprises prompting the user to take an on-site analyte concentration measurement.

17. The method of claim 6, wherein adjusting said information comprises at least one of (i) warning the user that said analyte concentration is increasing and (ii) warning the user that said analyte concentration is decreasing.

18. The method of claim 6, wherein adjusting said information comprises adjusting an analyte concentration measurement based on said rate of change.

19. The method of claim 6, wherein adjusting said information comprises:

measuring a raw analyte concentration;

calculating a corrected analyte concentration based on said rate of change and said raw analyte concentration;

assessing the clinical significance of a measurement error based on said raw analyte concentration and said corrected analyte concentration; and

warning the user to take an on-site analyte concentration measurement based on the clinical significance of said measurement error.

20. The method of claim 19, wherein assessing the clinical significance comprises using an external model.

21. The method of claim 20, wherein the external model comprises a variation of the Clarke error grid.

22. The method of claim 6, wherein determining said rate of change comprises rejecting outlier analyte-concentration measurements.

23. A system for measuring the concentration of an analyte at an alternative site, said system comprising:

a processing circuit; and

a module executable by the processing circuit whereby the processing circuit receives an analyte concentration measurement taken at the alternative site, determines a rate of change of the concentration of said analyte, and provides information to the user based on said rate of change.

24. The system of claim 23, wherein providing information comprises warning the user that the absolute value of the rate of change is high.

25. The system of claim 23, wherein providing information comprises prompting the user to take an on-site analyte concentration measurement.

26. The system of claim 23, wherein providing information comprises warning the user, when the absolute value of said rate of change is relatively high, that alternative-site measurements are likely to be inaccurate.

27. The system of claim 26, wherein providing information further comprises prompting the user to take an on-site analyte concentration measurement.

28. The system of claim 23, wherein providing information comprises at least one of (i) warning the user that the concentration of said analyte is increasing and (ii) warning the user that the concentration of said analyte is decreasing.

29. The system of claim 23, wherein the analyte concentration measurement is a measurement of the concentration of glucose within blood.

30. The system of claim 23, further comprising a timing circuit accessible by said processing circuit.

31. The system of claim 30, wherein the timing circuit comprises a real-time clock.

32. The system of claim 31, wherein the real-time clock is capable of keeping the time of day, the day of week, the day of month, the month, and/or the year.

33. The system of claim 23, further comprising a user-interface whereby the user is able to input data into the analyte detection system, wherein the processing circuit considers said data in adjusting the analyte concentration to generate an adjusted analyte concentration value.

34. The system of claim 33, wherein said data comprises at least one of (i) that the user is about to eat or has just eaten a meal and (ii) that the user is about to engage in or has just engaged in physical exercise.

35. The system of claim 23, wherein the processing circuit assesses the clinical significance of a possible error in said analyte concentration measurement.

36. The system of claim 35, wherein assessing the clinical significance comprises using an external model.

37. The system of claim 36, wherein the external model comprises a variation of the Clarke error grid.

38. The system of claim 23, wherein the processing circuit screens measured analyte concentration values to remove outlier concentration values and/or rate of concentration change values based on statistical analysis, data history, and/or data forecasts or trends.

39. A system for measuring the concentration of an analyte at an alternative site, said system comprising:

a processing circuit; and

a module executable by the processing circuit whereby the processing circuit receives an analyte concentration measurement taken at the alternative site, determines a rate of change of the concentration of said analyte, and adjusts said analyte concentration measurement based on said rate of change.

40. The system of claim 39, wherein the analyte concentration measurement is a measurement of the concentration of glucose within blood.

41. The system of claim 39, further comprising a timing circuit accessible by said processing circuit.

42. The system of claim 41, wherein the timing circuit comprises a real-time clock.

43. The system of claim 42, wherein the real-time clock is capable of keeping the time of day, the day of week, the day of month, the month, and/or the year.

44. The system of claim 39, further comprising a user-interface whereby the user is able to input data into the analyte detection system, wherein the processing circuit considers said data in adjusting the analyte concentration to generate an adjusted analyte concentration value.

45. The system of claim 44, wherein said data comprises at least one of (i) that the user is about to eat or has just eaten a meal and (ii) that the user is about to engage in or has just engaged in physical exercise.

46. The system of claim 39, wherein the processing circuit assesses the clinical significance of a possible error in said analyte concentration measurement.

47. The system of claim 46, wherein assessing the clinical significance comprises using an external model.

48. The system of claim 47, wherein the external model comprises a variation of the Clarke error grid.

49. The system of claim 39, wherein the processing circuit screens measured analyte concentration values to remove outlier concentration values and/or rate of concentration change values based on statistical analysis, data history, and/or data forecasts or trends.