Systems and methods for processing analyte sensor data

• US 9,700,253 B2
• Filed: 03/12/2013
• Issued: 07/11/2017
• Est. Priority Date: 03/16/2012
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Estes, Michael J., Peyser, Thomas A., Kamath, Apurv Ullas, Mahalingam, Aarthi, Vanslyke, Stephen J., Bohnett, Lucas, Simpson, Peter C., Bohm, Sebastian, Garcia, Arturo, Rack-Gomer, Anna Leigh
• Primary Examiner(s): Teixeira Moffat, Jonathan C
• Assistant Examiner(s): Dinh, Lynda
• Application Number:
  US13/796,642
• Publication Number:
  US 20130245981A1
• Time in Patent Office: 1,582 Days
• Field of Search: 702 87, 702 85, 702 89
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/02 Details of sensors specially adapted for in-vivo measurements
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14503 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors A61B5/1459, A61B5/1464, A61B5/1473, A61B5/1482, A61B5/14865 take precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/7203 for noise prevention, reduction or removal
• CPC Class Codes: G01D 3/022 having an ideal characteristic, map or correction data stored in a digital memory
• CPC Class Codes: G16H 20/17 delivered via infusion or injection
• CPC Class Codes: G16H 40/67 for remote operation

Abstract

Systems and methods for applying time-dependent algorithmic compensation functions to data output from a continuous analyte sensor. Some embodiments determine a time since sensor implantation and/or whether a newly initialized sensor has been used previously.

Claims

1. A method for processing sensor data of a continuous analyte sensor implanted within a body, wherein the continuous analyte sensor measures glucose levels, and the measurements are processed via sensor electronics, comprising:

initializing the sensor, the sensor in electrical communication with the sensor electronics configured to receive and process sensor data by the sensor;

acquiring sensor data, using the sensor, to measure an analyte level in a body fluid over a first interval based on a first elapsed time since the sensor was implanted;

adjusting the acquired sensor data by applying, using the sensor electronics, a first set of time-dependent algorithmic functions to the sensor data associated with the first interval, wherein the first set of time-dependent algorithmic functions comprise a first boundary of acceptability, wherein the first boundary comprises a first drift rate of the sensitivity over time, wherein the first boundary comprises a first drift of the baseline over time;

acquiring further sensor data, using the sensor, to measure the analyte level in the body fluid over a second interval based on a second elapsed time since the sensor was implanted and after the first interval;

adjusting the acquired further sensor data by applying, by the sensor electronics, a second set of time-dependent algorithmic functions to the sensor data associated with the second interval, wherein the second set of time-dependent algorithmic functions comprise a second boundary of acceptability, wherein the second boundary comprises a second drift rate of the sensitivity over time, wherein the second boundary comprises a second drift of the baseline over time, thereby adapting the system to compensate for sensor drift of the sensor.

2. The method of claim 1, wherein initializing the sensor comprises engaging the sensor electronics with a housing coupled with the sensor.

3. The method of claim 2, wherein engagement of the sensor electronics with the housing is detected and initialization commences automatically upon detection of the engagement.

4. The method of claim 1, further comprising determining whether the sensor has been previously used.

5. The method of claim 4, wherein determining whether the sensor has been previously used comprises comparing a conversion function of the sensor with a conversion function of a previously removed sensor.

6. The method of claim 4, wherein determining whether the sensor has been previously used comprises reading a raw signal of the sensor.

7. The method of claim 4, wherein determining whether the sensor has been previously used comprises comparing a sensitivity and/or baseline of the sensor with a sensitivity and/or baseline of a previously removed sensor.

8. The method of claim 4, wherein determining whether the sensor has been previously used comprises comparing a trend in a signal from the sensor with a trend in a signal from a previously removed sensor.

9. The method of claim 4, wherein determining whether the sensor has been previously used comprises performing two or more independent tests and then determining a probability that the sensor has been previously used based upon results of the tests.

10. The method of claim 1, wherein the first boundary comprises a first sensitivity value and the second boundary comprises a second sensitivity value.

11. The method of claim 1, wherein the first boundary comprises a first baseline value and the second boundary comprises a second baseline value.

12. The method of claim 1, wherein the first boundary delineates acceptable slopes and baselines of a conversion function and the second boundary delineates acceptable slopes and baselines of the conversion function.

13. The method of claim 1, wherein the first and second set of time-dependent algorithmic functions comprise first and second parameters associated with a conversion function.

14. The method of claim 1, wherein the first and second set of time-dependent algorithmic functions comprise first and second drift compensation functions.

15. The method of claim 14, wherein the first and second drift compensation functions differ in the amount of drift compensation that they apply.

16. The method of claim 1, wherein the first interval is predetermined prior to sensor insertion, and wherein applying the second set of time-dependent algorithmic functions is triggered in response to elapsing of the predetermined first interval.

17. The method of claim 1, wherein the first and second sets of time-dependent algorithmic functions comprise different conversion functions used to convert the sensor data into calibrated sensor data.

18. The method of claim 1, wherein the first and second sets of time-dependent algorithmic functions comprise different parameters applied to a conversion function used to convert the sensor data into calibrated sensor data.

19. The method of claim 1, wherein the first and second set of time-dependent algorithmic functions are determined prior to sensor implantation.

20. The method of claim 1, wherein the applying the second set of time-dependent algorithmic functions to the sensor data associated with the second interval comprises dynamically applying a priori information based on time since sensor implantation.

21. The method of claim 1, wherein the applying the second set of time-dependent algorithmic functions to the sensor data associated with the second interval comprises dynamically adapting a parameter of the second set of time-dependent algorithmic functions based on a prior knowledge of time-based sensor behavior during implantation.

22. A continuous analyte monitoring system for processing sensor data of a continuous analyte sensor implanted within a body, wherein the analyte sensor measures glucose levels, and the measurements are processed via sensor electronics, comprising:

a sensor configured to be implanted within a body and acquire sensor data associated with analyte levels of a body fluid; and

the sensor electronics configured to receive and process the sensor data obtained by the sensor, the sensor electronics including a processor configured to

initialize the sensor,

process the sensor data acquired using the sensor to measure an analyte level in the body fluid over a first interval based on a first elapsed time since the sensor was implanted,

adjust the acquired sensor data by applying a first set of time-dependent algorithmic functions to the sensor data associated with the first interval, wherein the first set of time-dependent algorithmic functions comprise a first boundary of acceptability, wherein the first boundary comprises a first drift rate of the sensitivity over time, wherein the first boundary comprises a first drift of the baseline over time,

process further sensor data acquired using the sensor to measure the analyte level in the body fluid over a second interval based on a second elapsed time since the sensor was implanted and after the first interval,

adjust the acquired further sensor data by applying second set of time-dependent algorithmic functions to the sensor data associated with the second interval, wherein the second set of time-dependent algorithmic functions comprise a second boundary of acceptability, wherein the second boundary comprises a second drift rate of the sensitivity over time, wherein the second boundary comprises a second drift of the baseline over time, thereby adapting the system to compensate for sensor drift of the sensor.

23. The system of claim 22, wherein initialization of the sensor commences automatically when the sensor electronics engages a housing with the sensor.

24. The system of claim 23, wherein engagement of the electronics with the housing is detected and initialization commences automatically upon detection of the engagement.

25. The system of claim 22, wherein the processor is further configured to determine whether the sensor has been previously used.

26. The system of claim 25, wherein determining whether the sensor has been previously used comprises comparing a conversion function of the sensor with a conversion function of a previously removed sensor.

27. The system of claim 25, wherein determining whether the sensor has been previously used comprises reading a raw signal of the sensor.

28. The system of claim 25, wherein determining whether the sensor has been previously used comprises comparing a sensitivity and/or baseline of the sensor with a sensitivity and/or baseline of a previously removed sensor.

29. The system of claim 25, wherein determining whether the sensor has been previously used comprises comparing a trend in a signal from the sensor with a trend in a signal from a previously removed sensor.

30. The system of claim 25, wherein determining whether the sensor has been previously used comprises performing two or more independent tests and then determining a probability that the sensor has been previously used based upon results of the tests.

31. The system of claim 22, wherein the first boundary comprises a first sensitivity value and the second boundary comprises a second sensitivity value.

32. The system of claim 22, wherein the first boundary comprises a first baseline value and the second boundary comprises a second baseline value.

33. The system of claim 22, wherein the first boundary delineates acceptable slopes and baselines of a conversion function and the second boundary delineates acceptable slopes and baselines of the conversion function.

34. The system of claim 22, wherein the first and second set of time-dependent algorithmic functions comprise first and second parameters associated with a conversion function.

35. The system of claim 22, wherein the first and second set of time-dependent algorithmic functions comprise first and second drift compensation functions.

36. The system of claim 35, wherein the first and second drift compensation functions differ in the amount of drift compensation that they apply.

37. The system of claim 22, wherein the first interval is predetermined prior to sensor insertion, and wherein a processor is configured to apply the second set of time-dependent algorithmic functions in response to elapsing of the predetermined first interval.

38. The system of claim 22, wherein the first and second sets of time-dependent algorithmic functions comprise different conversion functions used to convert the sensor data into calibrated sensor data.

39. The system of claim 22, wherein the first and second sets of time-dependent algorithmic functions comprise different parameters applied to a conversion function used to convert the sensor data into calibrated sensor data.

40. The system of claim 22, wherein the first and second set of time-dependent algorithmic functions are determined prior to sensor implantation.

41. The system of claim 22, wherein the processor is configured to apply the second set of time-dependent algorithmic functions to the sensor data associated with the second interval by dynamically applying a priori information based on time since sensor implantation.

42. The system of claim 22, wherein the processor is configured to apply the second set of time-dependent algorithmic functions to the sensor data associated with the second interval by dynamically adapting a parameter of the second set of time-dependent algorithmic functions based on a prior knowledge of time-based sensor behavior during implantation.