Analyte sensor

• US 8,626,257 B2
• Filed: 11/07/2008
• Issued: 01/07/2014
• 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., Brister, Mark C.
• Primary Examiner(s): D'ANGELO, MICHAEL J
• Application Number:
  US12/267,525
• Publication Number:
  US 20090178459A1
• Time in Patent Office: 1,887 Days
• Field of Search: 600309-316, 600345-347, 600/365, 435/4, 435/14, 436/68, 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 5/14535 for measuring haematocrit
• 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 5/14735 comprising an immobilised reagent
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• 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 5/15003 for venous or arterial blood
• CPC Class Codes: A61B 5/150992 Blood sampling from a fluid line external to a patient, such as a catheter line, combined with an infusion line; blood sampling from indwelling needle sets, e.g. sealable ports, luer couplings, valves tubing connectors and couplings A61M39/00
• CPC Class Codes: A61B 5/155 Devices specially adapted for continuous or multiple sampling, e.g. at predetermined intervals devices loaded with multiple lancets simultaneously A61B5/15146
• CPC Class Codes: A61B 5/157 Devices characterised by integrated means for measuring characteristics of blood
• 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: G16H 40/63 : for local operation
• 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 method for evaluating a change in a sensitivity of an analyte sensor over a predetermined time period, the method comprising:

receiving sensor data from an analyte sensor, wherein the sensor data comprises one or more sensor analyte values measured in a biological sample of a host;

intermittently calculating a sensitivity of the analyte sensor based at least in part on reference analyte data; and

evaluating, using an electronic device, a change in sensitivity by evaluating a plurality of time-spaced sensitivity calculations over a predetermined time period, wherein evaluating a change in sensitivity is based at least in part on applying, throughout a sensor session, a priori sensitivity information, wherein the a priori sensitivity information comprises an expected profile that is a function of time.

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

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

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

5. The method of claim 2, wherein evaluating a change in sensitivity comprises evaluating at least two sensitivity measurements during the predetermined time period.

6. The method of claim 5, further comprising averaging and/or filtering the at least two sensitivity measurements prior to evaluating the at least two sensitivity measurements.

7. The method of claim 2, wherein evaluating a change in sensitivity comprises comparing the change in sensitivity with one or more criteria.

8. The method of claim 7, further comprising using a most recent sensitivity calculation evaluated to calibrate the analyte sensor when the change in sensitivity meets the one or more criteria.

9. The method of claim 7, further comprising not using a most recent sensitivity calculation evaluated to calibrate the analyte sensor when the change in sensitivity does not meet the one or more criteria.

10. The method of claim 2, wherein intermittently calculating a sensitivity of the analyte sensor comprises intermittently receiving a reference analyte value.

11. The method of claim 2, wherein intermittently receiving a reference analyte value comprises periodically receiving a measured analyte concentration from a reference analyte solution.

12. The method of claim 2, wherein intermittently receiving a reference analyte value comprises receiving a reference analyte value obtained from an in vitro analyte monitor.

13. The method of claim 2, wherein evaluating a change in sensitivity is iteratively performed on the plurality of time-spaced sensitivity calculations over the predetermined time period.

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

15. The method of claim 14, wherein the predetermined time period is at least about 60 minutes.

16. The method of claim 14, wherein the predetermined time period is at least about 120 minutes.

17. The method of claim 14, wherein evaluating a sensitivity is iteratively performed on the plurality of time-spaced sensitivity calculations over the predetermined time period.

18. The method of claim 14, wherein evaluating a sensitivity comprises evaluating all sensitivity calculations over a sensor session.

19. The method of claim 1, wherein the a priori sensitivity information defines a range of acceptable change in sensitivity.

20. The method of claim 1, wherein the analyte sensor comprises a first working electrode and a second working electrode, wherein the first working electrode is configured to provide a first signal comprising an analyte component and a baseline component and wherein the second working electrode is configured to provide a second signal comprising a baseline component without an analyte component.

21. The method of claim 20, wherein intermittently calculating a sensitivity of the analyte sensor is based at least in part on the first signal.

22. The method of claim 20, wherein intermittently calculating a sensitivity of the analyte sensor is based at least in part on the second signal.

23. The method of claim 20, further comprising subtracting the second signal from the first signal to obtain a subtracted signal, wherein intermittently calculating a sensitivity of the analyte sensor is based at least in part on the subtracted signal.

24. The method of claim 1, wherein the analyte sensor is intermittently exposed to a biological sample and to a reference solution.

25. The method of claim 24, wherein intermittently calculating a sensitivity of the analyte sensor is based at least in part on a signal obtained when the analyte sensor is exposed to a biological sample.

26. The method of claim 24, wherein intermittently calculating a sensitivity of the analyte sensor is based at least in part on a signal obtained when the analyte sensor is exposed to a reference solution.

27. The method of claim 24, wherein intermittently calculating a sensitivity of the analyte sensor is based at least in part on a signal obtained when the analyte sensor is exposed to a biological sample and a signal obtained when the analyte sensor is exposed to a reference solution.

28. The method of claim 1, further comprising drawing blood to the analyte sensor by using a flow control device.