Glucose sensor signal stability analysis

• US 10,429,395 B2
• Filed: 07/10/2015
• Issued: 10/01/2019
• Est. Priority Date: 06/23/2010
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Luo, Ying, Gottlieb, Rebecca K., Ramachandran, Meena, Chiu, Chia-Hung, Dangui-Patel, Nandita, Kremliovsky, Michael, Rose, Jefferson
• Primary Examiner(s): Park, Hyun D
• Application Number:
  US14/796,995
• Publication Number:
  US 20150316559A1
• Time in Patent Office: 1,544 Days
• Field of Search: 702179, 702182, 600345, 600347, 600365
• CPC Class Codes: A61B 5/0017 transmitting optical signals transmission by light H04B10/00
• CPC Class Codes: A61B 5/002 Monitoring the patient using a local or closed circuit, e.g. in a room or building A61B5/0017 takes precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: G01N 33/66 involving blood sugars, e.g. galactose

Abstract

Disclosed are methods, apparatuses, etc. for glucose sensor signal stability analysis. In certain example embodiments, a series of samples of at least one sensor signal that is responsive to a blood glucose level of a patient may be obtained. Based at least partly on the series of samples, at least one metric may be determined to assess an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time. A reliability of the at least one sensor signal to respond to the blood glucose level of the patient may be assessed based at least partly on the at least one metric assessing the underlying trend. Other example embodiments are disclosed herein.

Claims

1. A method comprising:

obtaining a series of samples of at least one sensor signal that is responsive to a blood glucose level of a patient wherein the at least one sensor signal is generated by a glucose sensor during a time that the glucose sensor is in contact with the patient;

determining, using the series of samples and using one or more processors, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assessing a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend and using the one or more processors; and

in response to the assessing the reliability of the at least one sensor signal, altering an infusion treatment for the patient, or transmitting notification to the patient or a healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the assessing the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold,

wherein the at least one sensor signal is assessed to not be drifting or the at least one sensor is assessed to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the at least one sensor signal is assessed to be drifting or the at least one sensor is assessed to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the at least one sensor is assessed to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the determining of the at least one metric assessing the underlying trend comprises determining the at least one metric using a slope of a linear regression that is derived at least partly from the series of samples of the at least one sensor signal.

2. A method comprising:

obtaining a series of samples of at least one sensor signal that is responsive to a blood glucose level of a patient wherein the at least one sensor signal is generated by a glucose sensor during a time that the glucose sensor is in contact with the patient;

transforming the series of samples of the at least one sensor signal to derive a monotonic curve;

determining, using the series of samples and using one or more processors, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assessing a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend and using the one or more processors; and

in response to the assessing the reliability of the at least one sensor signal, altering an infusion treatment for the patient, or transmitting notification to the patient or a healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the assessing the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold,

wherein the at least one sensor signal is assessed to not be drifting or the at least one sensor is assessed to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the at least one sensor signal is assessed to be drifting or the at least one sensor is assessed to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the at least one sensor is assessed to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the determining of the at least one metric assessing the underlying trend comprises determining the at least one metric using a slope of a linear regression that is derived at least partly from the monotonic curve.

3. A method comprising:

obtaining a series of samples of at least one sensor signal that is responsive to a blood glucose level of a patient wherein the at least one sensor signal is generated by a glucose sensor during a time that the glucose sensor is in contact with the patient;

determining, using the series of samples and using one or more processors, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assessing a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend and using the one or more processors; and

in response to the assessing the reliability of the at least one sensor signal, altering an infusion treatment for the patient, or transmitting notification to the patient or a healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the assessing the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold,

wherein the at least one sensor signal is assessed to not be drifting or the at least one sensor is assessed to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the at least one sensor signal is assessed to be drifting or the at least one sensor is assessed to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the at least one sensor is assessed to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the determining of the at least one metric assessing the underlying trend comprises determining the at least one metric by iteratively updating a trend estimation at multiple samples of the series of samples of the at least one sensor signal based at least partly on a trend estimation at a previous sample and a growth term.

4. A method comprising:

obtaining a series of samples of at least one sensor signal that is responsive to a blood glucose level of a patient wherein the at least one sensor signal is generated by a glucose sensor during a time that the glucose sensor is in contact with the patient;

determining, using the series of samples and using one or more processors, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assessing a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend and using the one or more processors; and

in response to the assessing the reliability of the at least one sensor signal, altering an infusion treatment for the patient, or transmitting notification to the patient or a healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the assessing the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold,

wherein the at least one sensor signal is assessed to not be drifting or the at least one sensor is assessed to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the at least one sensor signal is assessed to be drifting or the at least one sensor is assessed to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the at least one sensor is assessed to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the determining of the at least one metric assessing the underlying trend comprises determining the at least one metric by;

decomposing the at least one sensor signal as represented by the series of samples using at least one empirical mode decomposition and one or more spline functions to derive a monotonic curve; and

calculating the slope of a linear regression, the linear regression being derived at least partly from the monotonic curve.

5. A method comprising:

obtaining a series of samples of at least one sensor signal that is responsive to a blood glucose level of a patient wherein the at least one sensor signal is generated by a glucose sensor during a time that the glucose sensor is in contact with the patient;

determining, using the series of samples and using one or more processors, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assessing a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend and using the one or more processors; and

in response to the assessing the reliability of the at least one sensor signal, altering an infusion treatment for the patient, or transmitting notification to the patient or a healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the assessing the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold,

wherein the at least one sensor signal is assessed to not be drifting or the at least one sensor is assessed to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the at least one sensor signal is assessed to be drifting or the at least one sensor is assessed to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the at least one sensor is assessed to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the determining of the at least one metric assessing the underlying trend comprises determining the at least one metric by;

decomposing the at least one sensor signal as represented by the series of samples using at least one discrete wavelet transform; and

reconstructing a smoothed signal from one or more approximation coefficients resulting from the at least one discrete wavelet transform.

6. An apparatus for use with a healthcare provider and with at least one sensor configured to generate at least one sensor signal that is responsive to a blood glucose level of a patient, the apparatus comprising:

a controller to obtain a series of samples of the at least one sensor signal, the controller comprising one or more processors to;

determine, using the series of samples, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assess a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend, wherein the assessing of the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold; and

in response to the assessing the reliability of the at least one sensor signal, alter an infusion treatment for the patient, or transmit notification to the patient or the healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the one or more processors are further to assess the at least one sensor signal to not be drifting or to assess the at least one sensor to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the one or more processors are further to assess the at least one sensor signal to be drifting or to assess the at least one sensor to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the one or more processors are further to assess the at least one sensor to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the one or more processors are further to determine the at least one metric assessing the underlying trend by using a slope of a linear regression that is derived at least partly from the series of samples of the at least one sensor signal.

7. An apparatus for use with a healthcare provider and with at least one sensor configured to generate at least one sensor signal that is responsive to a blood glucose level of a patient, the apparatus comprising:

a controller to obtain a series of samples of the at least one sensor signal, the controller comprising one or more processors to;

transform the series of samples of the at least one sensor signal to derive a monotonic curve;

determine, using the series of samples, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assess a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend, wherein the assessing of the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold; and

in response to the assessing the reliability of the at least one sensor signal, alter an infusion treatment for the patient, or transmit notification to the patient or the healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the one or more processors are further to assess the at least one sensor signal to not be drifting or to assess the at least one sensor to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the one or more processors are further to assess the at least one sensor signal to be drifting or to assess the at least one sensor to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the one or more processors are further to assess the at least one sensor to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the one or more processors are further to determine the at least one metric assessing the underlying trend by using a slope of a linear regression that is derived at least partly from the monotonic curve.

8. An apparatus for use with a healthcare provider and with at least one sensor configured to generate at least one sensor signal that is responsive to a blood glucose level of a patient, the apparatus comprising:

a controller to obtain a series of samples of the at least one sensor signal, the controller comprising one or more processors to;

determine, using the series of samples, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assess a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend, wherein the assessing of the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold; and

in response to the assessing the reliability of the at least one sensor signal, alter an infusion treatment for the patient, or transmit notification to the patient or the healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the one or more processors are further to assess the at least one sensor signal to not be drifting or to assess the at least one sensor to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the one or more processors are further to assess the at least one sensor signal to be drifting or to assess the at least one sensor to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the one or more processors are further to assess the at least one sensor to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the one or more processors are further to determine the at least one metric assessing the underlying trend by iteratively updating a trend estimation at multiple samples of the series of samples of the at least one sensor signal based at least partly on a trend estimation at a previous sample and a growth term.

9. An apparatus for use with a healthcare provider and with at least one sensor configured to generate at least one sensor signal that is responsive to a blood glucose level of a patient, the apparatus comprising:

a controller to obtain a series of samples of the at least one sensor signal, the controller comprising one or more processors to;

determine, using the series of samples, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assess a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend, wherein the assessing of the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold; and

in response to the assessing the reliability of the at least one sensor signal, alter an infusion treatment for the patient, or transmit notification to the patient or the healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the one or more processors are further to assess the at least one sensor signal to not be drifting or to assess the at least one sensor to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the one or more processors are further to assess the at least one sensor signal to be drifting or to assess the at least one sensor to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the one or more processors are further to assess the at least one sensor to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the one or more processors are further to determine the at least one metric assessing the underlying trend by;

decomposing the at least one sensor signal as represented by the series of samples using at least one empirical mode decomposition and one or more spline functions to derive a monotonic curve; and

calculating the slope of a linear regression, the linear regression being derived at least partly from the monotonic curve.

10. An apparatus for use with a healthcare provider and with at least one sensor configured to generate at least one sensor signal that is responsive to a blood glucose level of a patient, the apparatus comprising:

a controller to obtain a series of samples of the at least one sensor signal, the controller comprising one or more processors to;

determine, using the series of samples, at least one metric assessing an underlying trend of a change in responsiveness of the at least one sensor signal to the blood glucose level of the patient over time;

assess a reliability of the at least one sensor signal to respond to the blood glucose level of the patient using the at least one metric assessing the underlying trend, wherein the assessing of the reliability of the at least one sensor signal comprises comparing the at least one metric with at least a first predetermined threshold and a second predetermined threshold; and

in response to the assessing the reliability of the at least one sensor signal, alter an infusion treatment for the patient, or transmit notification to the patient or the healthcare provider indicative of the reliability of the at least one sensor signal,

wherein the one or more processors are further to assess the at least one sensor signal to not be drifting or to assess the at least one sensor to be stable, or both, if an absolute value of the underlying trend is less than the first predetermined threshold,

wherein the one or more processors are further to assess the at least one sensor signal to be drifting or to assess the at least one sensor to be unstable, or both, if the absolute value of the underlying trend is between the first and second predetermined thresholds,

wherein the one or more processors are further to assess the at least one sensor to be dying, if the absolute value of the underlying trend is greater than the second predetermined threshold, and

wherein the one or more processors are further to determine the at least one metric assessing the underlying trend by;

decomposing the at least one sensor signal as represented by the series of samples using at least one discrete wavelet transform; and

reconstructing a smoothed signal from one or more approximation coefficients resulting from the at least one discrete wavelet transform.