Systems and methods for replacing signal artifacts in a glucose sensor data stream

• US 9,649,069 B2
• Filed: 06/29/2016
• Issued: 05/16/2017
• Est. Priority Date: 08/22/2003
• Status: Expired due to Term

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Goode, Paul V., Brauker, James H., Kamath, Arpurv U., Thrower, James Patrick, Carr-Brendel, Victoria
• Primary Examiner(s): JANG, CHRISTIAN YONGKYUN
• Application Number:
  US15/197,349
• Publication Number:
  US 20160302731A1
• Time in Patent Office: 321 Days
• 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 processing data from an electrochemical glucose sensor, the method comprising:

applying a voltage to an electrochemical glucose sensor configured to measure a glucose concentration of a biological sample of a host, wherein applying the voltage comprises at least one process selected from the group consisting of switching a voltage applied to the electrochemical glucose sensor, cycling a voltage applied to the electrochemical glucose sensor, and pulsing a voltage applied to the electrochemical glucose sensor;

measuring a signal response of the electrochemical glucose sensor responsive to the at least one process; and

detecting, using a processor, a signal artifact based on the signal response of the electrochemical glucose sensor to the switching, cycling, or pulsing of the applied voltage, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and an interfering species.

2. The method of claim 1, wherein the detecting comprises evaluating a severity of the signal artifact.

3. The method of claim 1, further comprising providing an output based on the detected signal artifact.

4. The method of claim 1, further comprising providing an output indicative of the glucose concentration of the host.

5. The method of claim 1, wherein the electrochemical glucose sensor is a continuous glucose sensor.

6. The method of claim 1, wherein the biological sample is blood.

7. The method of claim 1, wherein the signal response is a current.

8. The method of claim 1, wherein the signal response is a voltage.

9. The method of claim 1, wherein the detecting comprises examining a spectral content of the signal response.

10. A method for processing data from an electrochemical glucose sensor, the method comprising:

applying a voltage to an electrochemical glucose sensor configured to measure a glucose concentration of a biological sample of a host;

switching the voltage applied to the electrochemical glucose sensor to a different setting;

measuring a signal response of the electrochemical glucose sensor responsive to the switching;

detecting, using a processor, a signal artifact based on the signal response of the electrochemical glucose sensor to the switching, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and a biochemical species;

generating, using a processor, an estimated glucose value responsive to detection of the signal artifact, wherein the estimated glucose value accounts for the signal artifact; and

displaying the estimated glucose value on a user interface.

11. The method of claim 10, wherein the detecting comprises evaluating a severity of the signal artifact.

12. The method of claim 11, wherein the generating comprises applying one of a plurality of signal estimation algorithm factors in response to the severity.

13. The method of claim 12, wherein the plurality of signal estimation algorithm factors includes a single algorithm with a plurality of parameters that are selectively applied to the algorithm.

14. The method of claim 10, wherein the electrochemical glucose sensor is a continuous glucose sensor.

15. The method of claim 10, wherein the biological sample is blood.

16. The method of claim 10, wherein the signal response is a current.

17. The method of claim 10, wherein the signal response is a voltage.

18. The method of claim 10, wherein the detecting comprises examining a spectral content of the signal response.

19. A method for processing data from an electrochemical glucose sensor, the method comprising:

applying a voltage to an electrochemical glucose sensor configured to measure a glucose concentration of a biological sample of a host;

switching a voltage applied to the electrochemical glucose sensor to a different setting;

measuring a signal response of the electrochemical glucose sensor responsive to the switching;

detecting, using a processor, a signal artifact based on a signal response of the electrochemical glucose sensor to the switching, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and a biochemical species;

evaluating, using a processor, a severity of the signal artifact;

generating, using a processor, an estimated glucose value responsive to the severity of the signal artifact, wherein the estimated glucose value is generated based at least in part on the severity of the signal artifact; and

displaying the estimated glucose value on a user interface.

20. The method of claim 19, wherein the generating comprises applying one of a plurality of signal estimation algorithm factors responsive to the severity.

21. The method of claim 20, wherein the plurality of signal estimation algorithm factors includes a single algorithm with a plurality of parameters that are selectively applied to the algorithm.

22. The method of claim 19, wherein the electrochemical glucose sensor is a continuous glucose sensor.

23. The method of claim 19, wherein the biological sample is blood.

24. The method of claim 19, wherein the signal response is a current.

25. The method of claim 19, wherein the signal response is a voltage.

26. The method of claim 19, wherein the detecting comprises examining a spectral content of the signal response.

27. A method for processing data from an electrochemical glucose sensor, the method comprising:

applying a voltage to an electrochemical glucose sensor configured to measure a glucose concentration of a biological sample of a host;

switching a voltage applied to the electrochemical glucose sensor to a different setting;

measuring a signal response of the electrochemical glucose sensor responsive to the switching;

detecting, using a processor, a signal artifact based on a signal response of the electrochemical glucose sensor to the switching, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and a biochemical species;

evaluating, using a processor, a severity of the signal artifact; and

discarding, using a processor, a glucose measurement when the severity of the signal artifact is outside of a predetermined threshold.

28. The method of claim 27, wherein the electrochemical glucose sensor is a continuous glucose sensor.

29. The method of claim 27, wherein the biological sample is blood.

30. The method of claim 27, wherein the signal response is a current.

31. The method of claim 27, wherein the signal response is a voltage.

32. The method of claim 27, wherein the detecting comprises examining a spectral content of the signal response.

33. A method for processing data from an electrochemical glucose sensor, the method comprising:

applying a voltage to an electrochemical glucose sensor configured to measure a glucose concentration of a biological sample of a host;

switching the voltage applied to the electrochemical glucose sensor to a different setting;

measuring a signal response of the electrochemical glucose sensor responsive to the switching;

detecting, using a processor, a signal artifact based on the signal response of the electrochemical glucose sensor to the switching, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and a biochemical species;

displaying, using a display, a first screen presenting generated glucose concentration data over a first time period;

displaying, using the display, a second screen presenting generated glucose concentration data over a second time period, wherein the second time period is different in length from the first time period;

displaying, using the display, a third screen presenting a single generated real-time estimated glucose value;

receiving an input from a user to toggle between the first screen, the second screen, and the third screen of the display; and

generating an alert responsive to a detection of a hyperglycemic condition or a hypoglycemic condition.

34. The method of claim 33, further comprising:

evaluating, using a processor, a severity of the signal artifact; and

generating, using a processor, the single generated real-time estimated glucose value responsive to detection of the signal artifact, wherein the single generated real-time estimated glucose value is generated based at least in part on the severity of the signal artifact.

35. The method of claim 34, wherein the generating comprises applying one of a plurality of signal estimation algorithm factors in response to the severity.

36. The method of claim 35, wherein the plurality of signal estimation algorithm factors includes a single algorithm with a plurality of parameters that are selectively applied to the algorithm.

37. The method of claim 33, wherein the electrochemical glucose sensor is a continuous glucose sensor.

38. The method of claim 33, wherein the biological sample is blood.

39. The method of claim 33, wherein the signal response is a current.

40. The method of claim 33, wherein the signal response is a voltage.

41. The method of claim 33, wherein the detecting comprises examining a spectral content of the signal response.

42. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with a biological fluid to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film; and

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to an electrochemical glucose sensor configured to measure glucose concentration of a biological sample of a host, wherein applying a voltage comprises at least one process selected from the group consisting of switching a voltage applied to the electrochemical glucose sensor, cycling a voltage applied to the electrochemical glucose sensor, and pulsing a voltage applied to the electrochemical glucose sensor;

measure a signal response of the electrochemical glucose sensor responsive to the at least one process; and

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switching, cycling, or pulsing of the applied voltage, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and an interfering species.

43. The system of claim 42, wherein the sensor electronics are configured to detect the signal artifact by evaluating a severity of the signal artifact.

44. The system of claim 42, further comprising:

a user interface configured to provide an output based on the detected signal artifact.

45. The system of claim 44, wherein the output is a glucose concentration of the host.

46. The system of claim 42, wherein the electrochemical glucose sensor is a continuous glucose sensor.

47. The system of claim 42, wherein the biological sample is blood.

48. The system of claim 42, wherein the signal response is a current.

49. The system of claim 42, wherein the signal response is a voltage.

50. The system of claim 42, wherein the sensor electronics are configured to detect the signal artifact by examining a spectral content of the signal response.

51. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with a biological fluid to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film;

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to the electrochemical glucose sensor at a first setting,

switch the voltage applied to the electrochemical sensor to a different setting,

measure a signal response of the electrochemical glucose sensor responsive to the switch,

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switch, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and biochemical species, and

generate an estimated glucose value responsive to detection of the signal artifact, wherein the estimated glucose value accounts for the signal artifact; and

a user interface configured to display the estimated glucose value.

52. The system of claim 51, wherein the sensor electronics are configured to detect the signal artifact by evaluating a severity of the signal artifact.

53. The system of claim 52, wherein the sensor electronics are configured to generate the estimated glucose value by applying one of a plurality of signal estimation algorithm factors in response to the severity.

54. The system of claim 53, wherein the plurality of signal estimation algorithm factors includes a single algorithm with a plurality of parameters that are selectively applied to the algorithm.

55. The system of claim 51, wherein the electrochemical glucose sensor is a continuous glucose sensor.

56. The system of claim 51, wherein the biological sample is blood.

57. The system of claim 51, wherein the signal response is a current.

58. The system of claim 51, wherein the signal response is a voltage.

59. The system of claim 51, wherein the sensor electronics are configured to detect the signal artifact by examining a spectral content of the signal response.

60. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with a biological fluid to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film;

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to the electrochemical glucose sensor at a first setting,

switch the voltage applied to the electrochemical sensor to a different setting,

measure a signal response of the electrochemical glucose sensor responsive to the switch,

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switch, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and a biochemical species,

evaluate a severity of the signal artifact, and

generate an estimated glucose value responsive to severity of the signal artifact, wherein the estimated glucose value is generated based at least in part on the severity of the signal artifact; and

a user interface configured to display the estimated glucose value.

61. The system of claim 60, wherein the sensor electronics are configured to generate the estimated glucose value by applying one of a plurality of signal estimation algorithm factors responsive to the severity.

62. The system of claim 61, wherein the plurality of signal estimation algorithm factors includes a single algorithm with a plurality of parameters that are selectively applied to the algorithm.

63. The system of claim 60, wherein the electrochemical glucose sensor is a continuous glucose sensor.

64. The system of claim 60, wherein the biological sample is blood.

65. The system of claim 60, wherein the signal response is a current.

66. The system of claim 60, wherein the signal response is a voltage.

67. The system of claim 60, wherein the sensor electronics are configured to detect the signal artifact by examining a spectral content of the signal response.

68. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with a biological fluid to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film; and

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to the electrochemical glucose sensor at a first setting,

switch the voltage applied to the electrochemical sensor to a different setting,

measure a signal response of the electrochemical glucose sensor responsive to the switch,

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switch, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and biochemical species,

evaluate a severity of the signal artifact; and

discard a glucose measurement when the severity of the signal artifact is outside of a predetermined threshold.

69. The system of claim 68, wherein the electrochemical glucose sensor is a continuous glucose sensor.

70. The system of claim 68, wherein the biological sample is blood.

71. The system of claim 68, wherein the signal response is a current.

72. The system of claim 68, wherein the signal response is a voltage.

73. The system of claim 68, wherein the sensor electronics are configured to detect the signal artifact by examining a spectral content of the signal response.

74. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with a biological fluid to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film;

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to the electrochemical glucose sensor at a first setting,

switch the voltage applied to the electrochemical sensor to a different setting,

measure a signal response of the electrochemical glucose sensor responsive to the switch, and

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switch, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and biochemical species; and

a user interface configured to;

display a first screen presenting generated glucose concentration data over a first time period,

display a second screen presenting generated glucose concentration data over a second time period, wherein the second time period is different in length from the first time period,

display a third screen presenting a single generated real-time estimated glucose value;

allow a user to toggle between the first screen, the second screen, and the third screen; and

generate an alert responsive to a detection of a hyperglycemic condition or a hypoglycemic condition.

75. The system of claim 74, wherein the sensor electronics are further configured to:

evaluate a severity of the signal artifact; and

generate the single generated real-time estimated glucose value responsive to detection of the signal artifact, wherein the single generated real-time estimated glucose value is generated based at least in part on the severity of the signal artifact.

76. The system of claim 75, wherein the sensor electronics are configured to generate the single generated real-time glucose value by applying one of a plurality of signal estimation algorithm factors in response to the severity.

77. The system of claim 76, wherein the plurality of signal estimation algorithm factors includes a single algorithm with a plurality of parameters that are selectively applied to the algorithm.

78. The system of claim 74, wherein the electrochemical glucose sensor is a continuous glucose sensor.

79. The system of claim 74, wherein the biological sample is blood.

80. The system of claim 74, wherein the signal response is a current.

81. The system of claim 74, wherein the signal response is a voltage.

82. The system of claim 74, wherein the sensor electronics are configured to detect the signal artifact by examining a spectral content of the signal response.

83. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with blood to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film;

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to the electrochemical glucose sensor at a first setting,

switch the voltage applied to the electrochemical sensor to a different setting,

measure a signal response of the electrochemical glucose sensor responsive to the switch, wherein the signal response is a voltage,

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switch, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and biochemical species,

evaluate a severity of the signal artifact, and

generate a single generated real-time estimated glucose value responsive to detection of the signal artifact, wherein the single generated real-time estimated glucose value is generated based at least in part on the severity of the signal artifact; and

a user interface configured to;

display a first screen presenting generated glucose concentration data over a first time period,

display a second screen presenting generated glucose concentration data over a second time period, wherein the second time period is different in length from the first time period,

display a third screen presenting a single generated real-time estimated glucose value;

allow a user to toggle between the first screen, the second screen, and the third screen; and

generate an alert responsive to detection of a hyperglycemic condition or a hypoglycemic condition.

84. A glucose sensor system, the system comprising:

an electrochemical glucose sensor configured to be in contact with blood to obtain a glucose measurement, wherein the electrochemical glucose sensor comprises a first electrode, a second electrode, and an enzyme-containing film; and

sensor electronics comprising a processor for executing computer program code stored in a memory to cause the processor to;

apply a voltage to the electrochemical glucose sensor at a first setting,

switch the voltage applied to the electrochemical sensor to a different setting,

measure a signal response of the electrochemical glucose sensor responsive to the switch, wherein the signal response is a voltage,

detect a signal artifact based on the signal response of the electrochemical glucose sensor to the switch, wherein the signal artifact is associated with at least one condition selected from the group consisting of ischemia, a pH change, a temperature change, a change in available electrode surface area, and biochemical species,

evaluate a severity of the signal artifact,

discard a glucose measurement when the severity of the signal artifact is outside of a predetermined threshold,

generate, when the severity of the signal artifact is within a predetermined threshold, a single generated real-time estimated glucose value responsive to detection of the signal artifact, wherein the single generated real-time estimated glucose value is generated based at least in part on the severity of the signal artifact; and

a user interface configured to;

display a first screen presenting generated glucose concentration data over a first time period,

display a second screen presenting generated glucose concentration data over a second time period, wherein the second time period is different in length from the first time period,

display a third screen presenting a single generated real-time estimated glucose value;

allow a user to toggle between the first screen, the second screen, and the third screen; and

generate an alert responsive to detection of a hyperglycemic condition or a hypoglycemic condition.