Determination and application of glucose sensor reliability indicator and/or metric

• US 8,919,180 B2
• Filed: 10/26/2011
• Issued: 12/30/2014
• Est. Priority Date: 10/28/2010
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Gottlieb, Rebecca K., Luo, Ying, Gautham, Raghavendhar, Liang, Bradley, Roy, Anirban, Cooper, Kenneth W., Shah, Rajiv, Keenan, Barry
• Primary Examiner(s): Larkin, Daniel S
• Assistant Examiner(s): Campbell, Irving A
• Application Number:
  US13/282,128
• Publication Number:
  US 20120125075A1
• Time in Patent Office: 1,161 Days
• Field of Search: 702/104, 702/106, 600/316, 600/319, 600/347, 600/365, 73/10.2
• US Class Current: 73/1.02
• 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 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: A61B 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• CPC Class Codes: A61M 2205/3303 Using a biosensor
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00

Abstract

Disclosed are a system and method for determining a metric and/or indicator of a reliability of a blood glucose sensor in providing glucose measurements. In one aspect, the metric and/or indicator may be computed based, at least in part, on an observed trend associated with signals generated by the blood glucose sensor.

Claims

1. A method of using two or more pairs of sensor elements to monitor a reliability of a blood glucose sensor, the method comprising:

determining a metric and/or indicator of said reliability of said blood glucose sensor in providing blood glucose measurements based, at least in part, on an observed trend associated with said blood glucose sensor, and wherein said metric and/or indicator is further based, at least in part, on a correlation between output signals of said two or more pairs of sensor elements,

wherein said correlation between output signals is based, at least in part, on a correlation value for each pair of sensor elements of said two or more pairs of sensor elements; and

providing a signal to indicate replacement of said blood glucose sensor based, at least in part, on said metric and/or indicator.

2. The method of claim 1, and further comprising displaying information on a display based, at least in part, on said metric and/or indicator.

3. The method of claim 1, wherein said blood glucose sensor is coupled to an insulin pump as part of a system to provide closed-loop continuous insulin infusion to a patient, the method further comprising transitioning said system from closed loop operation to an open loop and/or manual operation based, at least in part, on said metric and/or indicator.

4. The method of claim 1, and further comprising displaying an indicator requesting additional or more frequent metered blood glucose reference samples for calibration of said sensor in response to said metric and/or indicator to thereby extend an operating life of said blood glucose sensor.

5. The method of claim 1, wherein said observed trend comprises detection of a reduced sensitivity of said sensor in responding to a presence of glucose.

6. The method of claim 1, wherein said observed trend further comprises one or more detected non-physiological anomalies.

7. The method of claim 1, wherein said observed trend comprises a sensor drift.

8. The method of claim 1, wherein said observed trend comprises a noise trend.

9. The method of claim 1, wherein said metric and/or indicator is further based, at least in part, on an indicator of a reliability of a calibration of said blood glucose sensor.

10. The method of claim 1, further comprising:

combining measurements obtained from said two or more pairs of sensor elements to provide a single measurement of a blood glucose concentration.

11. The method of claim 1 wherein said signal to indicate replacement of said blood glucose sensor is transmitted to a display.

12. The method of claim 1, further comprising:

determining a linear mapping between output signals of each pair of said two or more pairs of sensor elements, said linear mapping being defined by a slope value and an intercept value; and

determining a correlation metric at a time n for each pair of said two or more pairs of sensor elements based, at least in part, on said linear mapping.

13. The method of claim 12, wherein said slope value is based, at least in part, on a difference between a current signal value of a first sensor element of a pair of said two or more pairs of sensor elements, and a current signal value of a second sensor element of a pair of said two or more pairs of sensor elements, and wherein said intercept value is based, at least in part, on a product of the current signal value of said first sensor element and a slope value.

14. An apparatus comprising:

a blood glucose sensor to generate signals responsive to a concentration of glucose in a fluid, said blood glucose sensor comprising two or more pairs of sensor elements;

a processor programmed with instructions to;

determine a metric and/or indicator of a reliability of said blood glucose sensor in providing blood glucose measurements from said signals based, at least in part, on an observed trend associated with said blood glucose sensor, and on a correlation between output signals of said two or more pairs of sensor elements,

wherein said correlation between output signals is based at least in part on a correlation value for each pair of sensor elements of said two or more pairs of sensor elements; and

generate a signal to indicate replacement of said blood glucose sensor based, at least in part, on said metric and/or indicator.

15. The apparatus of claim 14, wherein said processor is further programmed with instructions to:

combine measurements obtained from said two or more pairs of sensor elements to provide a single measurement of a blood glucose concentration.

16. An article comprising:

a non-transitory storage medium comprising machine-readable instructions stored thereon which are executable by a special purpose computing apparatus to;

determine a metric and/or indicator of a reliability of a blood glucose sensor in providing blood glucose measurements based, at least in part, on an observed trend associated with said blood glucose sensor, and on a correlation between output signals of two or more pairs of sensor elements,

wherein said correlation between output signals is based, at least in part, on a correlation value for each pair of sensor elements of said two or more pairs of sensor elements; and

indicate replacement of said blood glucose sensor based, at least in part, on said metric and/or indicator.

17. The article of claim 16, wherein said observed trend comprises detection of a reduced sensitivity of said sensor in responding to a presence of glucose.

18. The article of claim 16, wherein said observed trend comprises one or more detected non-physiological anomalies.

19. The article of claim 16, wherein said observed trend comprises a sensor drift.

20. The article of claim 16, wherein said observed trend comprises a noise trend.

21. An apparatus comprising:

means for obtaining signals generated by a blood glucose sensor in response to a presence of glucose in a fluid;

means for determining a metric and/or indicator of a reliability of the blood glucose sensor in providing blood glucose measurements based, at least in part, on an observed trend associated with said obtained signals, and on a correlation between output signals of two or more pairs of sensor elements,

wherein said correlation between output signals is based, at least in part, on a correlation value for each pair of sensor elements of said two or more pairs of sensor elements; and

means for indicating replacement of said blood glucose sensor based, at least in part, on said metric and/or indicator.