SYSTEMS AND METHODS FOR REPLACING SIGNAL ARTIFACTS IN A GLUCOSE SENSOR DATA STREAM

• US 20100179407A1
• Filed: 03/25/2010
• Published: 07/15/2010
• Est. Priority Date: 08/22/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Brauker, James H., Carr-Brendel, Victoria, Thrower, James Patrick, Kamath, Apurv U., Goode, Paul V. JR.
• Granted Patent: US 8,167,801 B2
• Time in Patent Office: Days
• US Class Current: 600/365
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2562/0247 Pressure sensors
• CPC Class Codes: A61B 2562/0271 Thermal or temperature sensors
• CPC Class Codes: A61B 2562/08 Sensors provided with means for identification, e.g. barcodes or memory chips
• CPC Class Codes: A61B 5/0004 characterised by the type of physiological signal transmitted
• CPC Class Codes: A61B 5/0031 Implanted circuitry
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• 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: A61B 5/7225 Details of analog processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation A61B5/30, A61B5/316 take precedence; transformers for specific applications H01F38/00; amplifiers H03F
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A61B 5/726 using Wavelet transforms
• CPC Class Codes: A61B 5/7278 Artificial waveform generation or derivation, e.g. synthesising signals from measured signals A61B5/327 takes precedence
• CPC Class Codes: A61B 5/742 using visual displays A61B5/339 takes precedence
• CPC Class Codes: A61B 5/7475 User input or interface means, e.g. keyboard, pointing device, joystick

Abstract

Systems and methods for minimizing or eliminating transient non-glucose related signal noise due to non-glucose rate limiting phenomenon such as ischemia, pH changes, temperatures changes, and the like. The system monitors a data stream from a glucose sensor and detects signal artifacts that have higher amplitude than electronic or diffusion-related system noise. The system replaces some or the entire data stream continually or intermittently including signal estimation methods that particularly address transient signal artifacts. The system is also capable of detecting the severity of the signal artifacts and selectively applying one or more signal estimation algorithm factors responsive to the severity of the signal artifacts, which includes selectively applying distinct sets of parameters to a signal estimation algorithm or selectively applying distinct signal estimation algorithms.

Claims

1. A method for analyzing data from a continuous analyte sensor, the method comprising:

receiving data from an analyte sensor;

detecting an occurrence of a signal artifact event; and

processing the received data, wherein the processing is based at least in part upon whether the signal artifact event occurs.

2. The method of claim 1, wherein detecting an occurrence of a signal artifact event comprises determining an amplitude of sensor data and determining an amplitude of a signal artifact.

3. The method of claim 2, wherein detecting an occurrence of a signal artifact event comprises detecting a start of a signal artifact event when an amplitude of a signal artifact meets a first predetermined condition.

4. The method of claim 3, wherein detecting an occurrence of a signal artifact even comprises detecting an end of a signal artifact event when an amplitude of a signal artifact meets a second predetermined condition.

5. The method of claim 4, further comprising filtering the received data to generate filtered data, wherein detecting an occurrence of a signal artifact event comprises comparing received data with filtered data to obtain at least one residual.

6. The method of claim 5, wherein one of the first predetermined condition and the second predetermined condition includes a residual amplitude of a sensor data amplitude.

7. The method of claim 5, wherein detecting an occurrence of a signal artifact event comprises determining a differential between a first residual at a first time point and a second residual at a second time point.

8. The method of claim 7, wherein one of the first predetermined condition or the second predetermined condition includes a differential amplitude of a sensor data amplitude.

9. The method of claim 4, wherein the first predetermined condition is different from the second predetermined condition.

10. The method of claim 1, further comprising filtering the received data to generate filtered data, wherein processing the received data comprises displaying a graphical representation of the filtered data responsive to a determination of a start of a signal artifact event.

11. The method of claim 1, wherein the received data comprises an unfiltered signal, and wherein processing the received data comprises displaying a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

12. The method of claim 1, wherein the received data comprises an unfiltered signal, and wherein processing the received data comprises displaying a graphical representation of the unfiltered data except when a signal artifact event occurs.

13. A device comprising a computer readable memory, the computer readable memory containing code for analyzing data from a continuous analyte sensor, wherein the code comprises:

instructions for receiving data from an analyte sensor, the data comprising at least one sensor data point;

instructions for detecting an occurrence of a signal artifact event; and

instructions for processing the received data, wherein the processing is based at least in part upon whether a signal artifact event has occurred.

14. The device of claim 13, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for determining an amplitude of the sensor data and instructions for determining an amplitude of a signal artifact.

15. The device of claim 14, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for detecting a start of a signal artifact event when an amplitude of a signal artifact meets a first predetermined condition.

16. The device of claim 14, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for detecting an end of a signal artifact event when an amplitude of a signal artifact meets a second predetermined condition.

17. The device of claim 16, wherein the code further comprises instructions for filtering the received data to generate filtered data, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for comparing the received data with filtered data to obtain at least one residual.

18. The device of claim 17, wherein one of the first predetermined condition or the second predetermined condition includes a residual amplitude a sensor data amplitude.

19. The device of claim 17, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for determining a differential between a first residual at a first time point and a second residual at a second time point.

20. The device of claim 19, wherein one of the first predetermined condition and the second predetermined condition includes a differential amplitude of a sensor data amplitude.

21. The device of claim 16, wherein the first predetermined condition is different from the second predetermined condition.

22. The device of claim 13, wherein the code further comprises instructions for filtering the received data to generate filtered data, wherein the instructions for processing the received data comprise instructions for displaying a graphical representation of filtered data responsive to a determination of a start of a signal artifact event.

23. The device of claim 13, wherein the received data comprises an unfiltered signal, and wherein the instructions for processing the received data comprise instructions for displaying a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

24. The device of claim 13, wherein the received data comprises an unfiltered signal, and wherein the instructions for processing the received data comprise instructions for displaying a graphical representation of the unfiltered data except when a signal artifact even has occurred.

25. A system configured to continuously measure an analyte in a host, the system comprising:

an analyte sensor configured to provide sensor data indicative of an analyte concentration in a host;

electronics operably connected to the sensor and comprising programming configured to detect a signal artifact event, wherein the electronics further comprise programming configured to process the sensor data, wherein the processing is based at least in part upon whether the signal artifact event is detected.

26. The system of claim 25, wherein the programming configured to detect a signal artifact event comprises programming configured to determine an amplitude of the sensor data and programming configured to determine an amplitude of a signal artifact.

27. The system of claim 26, wherein the programming configured to detect a signal artifact even comprises programming configured to detect a start of a signal artifact event when then an amplitude of a signal artifact meets a first predetermined condition.

28. The system of claim 27, wherein the programming configured to detect a signal artifact event comprises programming configured to detect an end of the signal artifact even when an amplitude of a signal artifact meets a second predetermined condition.

29. The system of claim 28, wherein the first predetermined condition is different from the second predetermined condition.

30. The system of claim 25, wherein the electronics further comprise programming configured to filter the sensor data, and wherein the programming configured to process the sensor data comprises programming configured to display a graphical representation of the filtered data responsive to a determination of a start of a signal artifact event.

31. The system of claim 25, wherein the sensor data comprises unfiltered data, and wherein the programming configured to process the sensor data comprises programming configured to display a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

32. The system of claim 25, wherein the sensor data comprises unfiltered data, and wherein the programming configured to process the sensor data comprises programming configured to display a graphical representation of the unfiltered data except when a signal artifact event has occurred.

33. The system of claim 25, wherein the sensor is configured to be transcutaneously implanted or intravascularly implanted.

34. The system of claim 25, wherein the sensor has a variable stiffness.

35. The system of claim 25, wherein the sensor further comprises a membrane configured to block passage therethrough of at least one interferent.

36. The system of claim 35, wherein the interferent comprises at least one substance selected from the group consisting of hydrogen peroxide, reactive oxygen species, and reactive nitrogen species.

37. The system of claim 35, wherein the interferent comprises at least one substance selected from the group consisting of acetaminophen, ascorbic acid, salicylic acid, and uric acid.

38. The system of claim 35, wherein the membrane is configured to substantially block passage therethrough of at least one non-constant noise causing interferent.

39. A method for analyzing data from a continuous analyte sensor, the method comprising:

receiving data from an analyte sensor;

detecting an occurrence of a signal artifact event based at least in part on an amplitude of a signal artifact, including detecting a start and an end of a signal artifact event; and

processing the received data, wherein the processing is based at least in part upon whether the signal artifact event occurs.

40. The method of claim 39, wherein detecting the occurrence of a signal artifact event comprises determining an amplitude of sensor data and determining an amplitude of a signal artifact.

41. The method of claim 40, wherein detecting the occurrence of a signal artifact event comprises detecting a start of a signal artifact event when an amplitude of a signal artifact meets a first predetermined condition.

42. The method of claim 41, wherein detecting the occurrence of a signal artifact event comprises detecting an end of a signal artifact event when an amplitude of a signal artifact meets a second predetermined condition.

43. The method of claim 42, wherein the first predetermined condition is different from the second predetermined condition.

44. The method of claim 39, wherein detecting an occurrence of a signal artifact event comprises comparing received data with filtered data to obtain at least one residual.

45. The method of claim 44, wherein one of the first predetermined condition or the second predetermined condition includes a residual amplitude of a sensor data amplitude.

46. The method of claim 39, wherein detecting an occurrence of a signal artifact event comprises determining a differential between a first residual at a first time point and a second residual at a second time point.

47. The method of claim 46, wherein one of the first predetermined condition or the second predetermined condition includes a differential amplitude of a sensor data amplitude.

48. The method of claim 39, wherein processing the received data comprises displaying a graphical representation of filtered data responsive to a determination of a start of a signal artifact event.

49. The method of claim 39, wherein the received data comprises unfiltered data, and wherein processing the received data comprises displaying a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

50. The method of claim 39, wherein processing the received data comprises displaying a graphical representation of the unfiltered data except when a signal artifact event occurs.

51. A method for displaying data from a continuous analyte sensor, the method comprising:

receiving data from an analyte sensor, including at least one of unfiltered data and filtered data;

detecting an occurrence of a signal artifact event based at least in part on an amplitude of a signal artifact, including detecting a start and an end of a signal artifact event; and

displaying a graphical representation of filtered data responsive to a determination of a start of a signal artifact event.

52. The method of claim 51, wherein the received data comprises unfiltered data, and wherein processing the received data comprises displaying a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

53. The method of claim 51, wherein processing the received data comprises displaying a graphical representation of the unfiltered data except when a signal artifact event occurs.

54. A device comprising a computer readable memory, the computer readable memory containing code for analyzing data from a continuous analyte sensor, wherein the code comprises:

instructions for receiving data from an analyte sensor, the data comprising at least one sensor data point;

instructions for detecting an occurrence of a signal artifact event based at least in part on an amplitude of a signal artifact; and

instructions for processing the received data, wherein the processing is based at least in part upon whether a signal artifact event has occurred.

55. The device of claim 54, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for determining an amplitude of the sensor data and instructions for determining an amplitude of a signal artifact.

56. The device of claim 55, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for detecting a start of a signal artifact event when an amplitude of a signal artifact meets a first predetermined condition.

57. The device of claim 56, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for detecting an end of a signal artifact event when an amplitude of a signal artifact meets a second predetermined condition.

58. The device of claim 57, wherein the first predetermined condition is different from the second predetermined condition.

59. The device of claim 56, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for comparing the received data with filtered data to obtain at least one residual.

60. The device of claim 58, wherein one of the first predetermined condition and the second predetermined condition includes a residual amplitude of a sensor data amplitude.

61. The device of claim 54, wherein the instructions for detecting an occurrence of a signal artifact event comprise instructions for determining a differential between a first residual at a first time point and a second residual at a second time point.

62. The device of claim 60, wherein one of the first predetermined condition or the second predetermined condition includes a differential amplitude of a sensor data amplitude.

63. A device comprising a computer readable memory, the computer readable memory containing code for displaying data from a continuous analyte sensor, wherein the code comprises:

instructions for receiving data from an analyte sensor, the data comprising at least one unfiltered or filtered sensor data point;

instructions for detecting an occurrence of a signal artifact event based at least in part on an amplitude of a signal artifact event; and

instructions for displaying a graphical representation of filtered data responsive to a determination of a start of a signal artifact event.

64. The device of claim 63, wherein the received data comprises an unfiltered signal, and wherein the instructions for processing the received data comprise instructions for displaying a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

65. The device of claim 63, wherein the received data comprises an unfiltered signal, and wherein the instructions for processing the received data comprise instructions for displaying a graphical representation of the unfiltered data except when a signal artifact event has occurred.

66. A system configured to continuously measure an analyte in a host, the system comprising:

an analyte sensor configured to provide sensor data indicative of an analyte concentration in a host; and

electronics operably connected to the sensor and comprising programming configured to detect a signal artifact event based at least in part on an amplitude of a signal artifact, including detecting a start and an end of a signal artifact event, wherein the electronics further comprise programming configured to process the sensor data, wherein the processing is based at least in part upon whether the signal artifact event is detected.

67. The system of claim 66, wherein the programming configured to detect a signal artifact event comprises programming configured to determine an amplitude of the sensor data and programming configured to determine an amplitude of a signal artifact.

68. The system of claim 67, wherein the programming configured to detect a signal artifact event comprises programming configured to detect a start of a signal artifact event when then an amplitude of a signal artifact meets a first predetermined condition.

69. The system of claim 68, wherein the programming configured to detect a signal artifact event comprises programming configured to detect an end of a signal artifact event when an amplitude of a signal artifact meets a second predetermined condition.

70. A system configured to continuously measure an analyte in a host, the system comprising:

an analyte sensor configured to provide sensor data indicative of an analyte concentration in a host; and

electronics operably connected to the sensor and comprising programming configured to detect a signal artifact event based at least in part on an amplitude of a signal artifact, and wherein the programming configured to process the sensor data comprises programming configured to display a graphical representation of filtered data responsive to a determination of a start of a signal artifact event.

71. The system of claim 70, wherein the sensor data comprises unfiltered data, and wherein the programming configured to process the sensor data comprises programming configured to display a graphical representation of the unfiltered data responsive to a determination of an end of a signal artifact event.

72. The system of claim 70, wherein the sensor data comprises unfiltered data, and wherein the programming configured to process the sensor data comprises programming configured to display a graphical representation of the unfiltered data except when a signal artifact event has occurred.