Analyte sensor
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.
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.