Analyte sensor

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.

What is claimed is: 
     
         1 . A method for evaluating a change in a sensitivity of an implanted analyte sensor over a predetermined time period, comprising:
 receiving sensor data from an analyte sensor implanted in a host, wherein the implanted sensor is configured to generate sensor data, 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; 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 using a priori sensitivity information throughout a sensor session, wherein the plurality of time spaced sensitivity calculations are not based on a blood-glucose measurement.   
     
     
         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 1 , wherein the predetermined time period is less than or equal to about 20 minutes. 
     
     
         4 . The method of  claim 1 , wherein the predetermined time period is less than or equal to about 10 minutes. 
     
     
         5 . The method of  claim 1 , 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 1 , 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 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 one or more criteria. 
     
     
         10 . The method of  claim 1 , wherein evaluating a change in sensitivity is iteratively performed on the plurality of time-spaced sensitivity calculations over the predetermined time period. 
     
     
         11 . The method of  claim 1 , wherein the predetermined time period is at least about 30 minutes. 
     
     
         12 . The method of  claim 1 , wherein the predetermined time period is at least about 60 minutes. 
     
     
         13 . The method of  claim 1 , wherein the predetermined time period is at least about 120 minutes. 
     
     
         14 . The method of  claim 1 , wherein evaluating a change in sensitivity is iteratively performed on the plurality of time-spaced sensitivity calculations over the predetermined time period. 
     
     
         15 . The method of  claim 1 , wherein evaluating a change in sensitivity comprises evaluating all sensitivity calculations over a sensor session. 
     
     
         16 . The method of  claim 1 , wherein the a priori sensitivity information defines a range of acceptable change in sensitivity. 
     
     
         17 . A method for evaluating a change in a sensitivity of an implanted analyte sensor over a predetermined time period, comprising:
 receiving sensor data from an analyte sensor implanted in a host, wherein the implanted sensor is configured to generate sensor data, wherein the sensor data comprises one or more sensor analyte values measured in a biological sample of a host;   intermittently, using an electronic device, calculating a sensitivity of the analyte sensor;   measuring a change in sensitivity by evaluating a parameter indicative of a change in solute transport of a membrane of the analyte sensor; and   auto-calibrating the analyte sensor responsive to measurement of the change in sensitivity.   
     
     
         18 . 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;   filtering at least two sensitivity values, whereby filtered sensitivity values are obtained; and   evaluating, using an electronic device, a change in sensitivity by evaluating the filtered sensitivity values over a predetermined time period, wherein evaluating a change in sensitivity is based at least in part on using a priori sensitivity information throughout a sensor session.