Analyte sensor

• US 8,886,273 B2
• Filed: 11/07/2008
• Issued: 11/11/2014
• Est. Priority Date: 08/01/2003
• Status: Active Grant

• Current Assignee: DexCom Incorporated
• Original Assignee: DexCom Incorporated
• Inventors: Li, Ying, Kamath, Apurv Ullas, Yang, Richard C.
• Primary Examiner(s): D'ANGELO, MICHAEL J
• Application Number:
  US12/267,542
• Publication Number:
  US 20090143659A1
• Time in Patent Office: 2,195 Days
• Field of Search: 600345-347, 600/365, 435/4, 435/14, 422/50, 422420-429, 20440301-40315, 702/23, 604 64- 66
• US Class Current: 600/345
• CPC Class Codes: A61B 2560/0223 of calibration, e.g. protocols for calibrating sensors
• CPC Class Codes: A61B 2560/04 Constructional details of apparatus
• CPC Class Codes: A61B 2562/085 combined with means for recording calibration data
• 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 5/14546 for measuring analytes not otherwise provided for, e.g. ions, cytochromes
• 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 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6848 Needles
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• 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 2005/14296 Pharmacokinetic models
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/14 Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
• CPC Class Codes: A61M 5/16804 Flow controllers
• CPC Class Codes: A61M 5/1723 : using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00
• CPC Class Codes: C12Q 1/001 : Enzyme electrodes
• CPC Class Codes: C12Q 1/006 : for glucose
• CPC Class Codes: G16H 10/40 : for data related to laboratory analysis, e.g. patient specimen analysis
• CPC Class Codes: G16H 20/17 : delivered via infusion or injection
• CPC Class Codes: G16H 40/40 : for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: Y02A 90/10 : Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

Systems and methods of use for continuous analyte measurement of a host'"'"'s vascular system are provided. In some embodiments, a continuous glucose measurement system includes a vascular access device, a sensor and sensor electronics, the system being configured for insertion into communication with a host'"'"'s circulatory system.

Claims

1. A system for measuring an analyte in a sample of a host and for infusion into the host comprising:

an analyte sensor configured to measure an analyte concentration in a biological sample of a circulatory system of a host, wherein the analyte sensor is located in at least one of a fluid coupler lumen or a lumen of a vascular access device;

a fluid control device configured to both intermittently draw the biological sample from the host to the analyte sensor and to intermittently expose the sensor to a reference solution via the fluid coupler lumen or the lumen of a vascular access device; and

a computer system, wherein the computer system comprises;

an input module configured to receive sensor analyte data and reference analyte data, wherein the sensor data comprises one or more sensor analyte values measured in the biological sample from the circulatory system of the host and wherein the reference data comprises one or more reference analyte values measured in the reference solution introduced into the circulatory system of the host; and

a processor module configured to intermittently calculate a sensitivity of the analyte sensor before the sensor is stabilized and during a break-in period of the sensor based at least in part on the reference analyte data and to evaluate a change in sensitivity by evaluating a plurality of time-spaced sensitivity calculations over a predetermined time period.

2. The system of claim 1, wherein the predetermined time period is less than or equal to about 30 minutes.

3. The system of claim 2, wherein the predetermined time period is less than or equal to about 20 minutes.

4. The system of claim 3, wherein the predetermined time period is less than or equal to about 10 minutes.

5. The system of claim 2, wherein the processor module is configured to evaluate the change in sensitivity at least in part by evaluating at least two sensitivity measurements during the predetermined time period.

6. The system of claim 5, wherein the processor module is further configured to average and/or filter the at least two sensitivity measurements prior to evaluating the at least two sensitivity measurements.

7. The system of claim 2, wherein the processor module is further configured to compare the change in sensitivity with one or more criteria.

8. The system of claim 7, wherein the processor module is further configured to use a most recent sensitivity calculation evaluated to calibrate the analyte sensor when the change in sensitivity meets one or more criteria.

9. The system of claim 7, wherein the processor module is further configured to not use a most recent sensitivity calculation evaluated to calibrate the analyte sensor when the change in sensitivity does not meet one or more criteria.

10. The system of claim 1, wherein the predetermined time period is at least about 30 minutes.

11. The system of claim 10, wherein the predetermined time period is at least about 60 minutes.

12. The system of claim 11, wherein the predetermined time period is at least about 120 minutes.

13. The system of claim 10, wherein the processor module is configured to iteratively evaluate a sensitivity of the plurality of time-spaced sensitivity calculations over the predetermined time period.

14. The system of claim 10, wherein the processor module is configured to evaluate all sensitivity calculations over a sensor session.

15. The system of claim 10, wherein the processor module is configured to evaluate a sensitivity based at least in part on a priori sensitivity information.

16. The system of claim 15, wherein the a priori sensitivity information is an expected profile.

17. The system of claim 15, wherein the a priori sensitivity information defines a range of acceptable change in sensitivity.

18. The system of claim 1, wherein the analyte sensor data comprises a first signal comprising an analyte component and a baseline component and a second signal comprising a baseline component without an analyte component.

19. The system of claim 18, wherein the processor module is configured to calculate a sensitivity of the analyte sensor based at least in part on the first signal.

20. The system of claim 18, wherein the processor module is configured to calculate a sensitivity of the analyte sensor based at least in part on the second signal.

21. The system of claim 18, wherein the processor module is further configured to calculate a sensitivity of the analyte sensor based at least in part on a subtracted signal, wherein the subtracted signal comprises the second signal subtracted from the first signal.

22. The system of claim 1 wherein the processor module is configured to intermittently calculate a sensitivity of the analyte sensor based at least in part on a signal obtained when the analyte sensor is exposed to the biological sample.

23. The system of claim 1 wherein the processor module is configured to intermittently calculate a sensitivity of the analyte sensor based at least in part on a signal obtained when the analyte sensor is exposed to the reference solution.

24. The system of claim 1 wherein the processor module is configured to intermittently calculate a sensitivity of the analyte sensor based on a signal obtained when the analyte sensor is exposed to the biological sample and a signal obtained when the analyte sensor is exposed to the reference solution.

25. The system of claim 1, wherein the processor module configured to:

calculate rate of changes (ROCs) for initial measurement phases and subsequent measurement phases in a predetermined period of time;

compare each of the ROCs to a threshold; and

assign a flag to each of the ROCs based on the comparison, each flag comprising +1 when the ROC exceeds the threshold, −

0.1 when the ROC falls below the threshold, or 0 when the ROC is within the threshold.

27. The system of claim 25, wherein the processor module configured to:

calculate the sum of all the flags assigned to each of the ROCs multiple times during the predetermine period of time;

determine that the sensor is substantially stable when the sum of the flags is equal to zero at least twice in the predetermined period of time.

26. A system for measuring an analyte in a sample of a host and for infusion into the host comprising:

an analyte sensor configured to measure an analyte concentration in a biological sample of a circulatory system of a host;

a fluid control device configured to both intermittently draw the biological sample from the host to the analyte sensor and to intermittently expose the sensor to a reference solution via the fluid coupler lumen or the lumen of a vascular access device; and

a computer system, wherein the computer system comprises;

an input module configured to receive sensor analyte data and reference analyte data, wherein the sensor data comprises one or more sensor analyte values measured in a biological sample from the vasculature of the host and wherein the reference data comprises one or more reference analyte values measured in the reference solution introduced into the circulatory system of the host; and

a processor module configured to intermittently calculate a sensitivity of the analyte sensor based at least in part on the reference analyte data and to evaluate a change in sensitivity by evaluating a plurality of time-spaced sensitivity calculations over a predetermined time period;

wherein the processor module is configured to intermittently calculate a sensitivity of the analyte sensor before the sensor is stabilized and during a break-in period of the sensor based on a signal obtained when the analyte sensor is exposed to the biological sample within the vasculature system and a signal obtained when the analyte sensor is exposed to the reference solution; and

wherein the analyte sensor data comprises a first signal comprising an analyte component and a baseline component.