ANALYTE SENSOR

• US 20080086044A1
• Filed: 03/26/2007
• Published: 04/10/2008
• Est. Priority Date: 10/04/2006
• Status: Active Grant

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 measuring a concentration of an analyte in of a host, the method comprising:

a) providing an analyte measuring system comprising a vascular access device, an analyte sensor configured measure an analyte concentration, and electronics operatively connected to the sensor and configured to generate a signal associated with the analyte concentration;

wherein the analyte sensor is configured to reside within the vascular access device;

b) placing the vascular access device and sensor in fluid communication with the circulatory system;

c) passing a reference solution past the analyte sensor and measuring a signal associated with an analyte concentration of the reference solution; and

d) drawing back a sample from the circulatory system and measuring a signal associated with the analyte concentration of the sample.

2. The method of claim 1, wherein the step of passing a reference solution comprises passing the reference solution at a first flow rate of from about 0.001 ml/min to about 2 ml/min.

3. The method of claim 2, wherein the step of passing a reference solution comprises passing the reference solution at a first flow rate of from about 0.02 ml/min to about 0.35 ml/min.

4. The method of claim 2, wherein the step of passing a reference solution comprises allowing a temperature of the reference solution to equilibrate with a temperature of the host.

5. The method of claim 1, wherein the step of drawing back a sample comprises drawing back a sample at a second flow rate of from about 0.001 ml/min to about 2 ml/min.

6. The method of claim 5, wherein the step of drawing back a sample comprises drawing back a sample at a second flow rate of from about 0.02 ml/min to about 0.35 ml/min.

7. The method of claim 5, wherein the step of drawing back a sample comprises substantially blocking mixing of the reference solution and the sample.

8. The method of claim 5, wherein the second flow rate is substantially equal to the first flow rate.

9. The method of claim 1, wherein the vascular access device is in fluid communication with a vein, the method further comprising a step of keeping the vein open by passing the reference solution past the sensor at a third flow rate.

10. The method of claim 9, wherein the third flow rate is less than the first flow rate.

11. The method of claim 10, wherein the third flow rate is from about 1.0 μ

l/min to about 1.0 ml/min.

12. The method of claim 11, wherein the third flow rate is from about 0.02 ml/min to about 0.2 ml/min.

13. The method of claim 1, wherein the analyte measuring system further comprises a flow control device, wherein the flow control device is configured to meter flow during steps c) and d).

14. The method of claim 13, wherein the flow control device comprises a valve comprising a first discreet position and a second discreet position.

15. The method of claim 14, wherein the step of passing a reference solution comprises moving the valve from the first position to the second position.

16. The method of claim 15, wherein the step of passing a reference solution comprises passing a solution volume of about 500 microliters or less during movement of the valve from the first position to the second position.

17. The method of claim 14, wherein the step of drawing back a sample comprises moving the valve from the second position to the first position.

18. The method of claim 17, wherein the step of drawing back a sample comprises drawing back a sample volume of about 500 microliters or less during movement of the valve from the second position to the first position.

19. The method of claim 12, wherein the step of drawing back a sample comprises drawing back a sample volume of about 50 microliters or less during movement of the valve from the second position to the first position.

20. The method of claim 14, wherein the vascular access device is in fluid communication with a vein, the method further comprising a step of keeping the vein open by metering flow of the reference solution through the vascular access device at a predetermined rate.

21. The method of claim 20, wherein the step of metering the flow is controlled at least in part by a timing for the valve to move between the first position and the second position.

22. The method of claim 1, wherein the step of drawing back the sample from the circulatory system comprises drawing back the sample substantially no farther than the vascular access device.

23. The method of claim 22, wherein the step of drawing back the sample from the circulatory system comprises drawing back the sample into the vascular access device substantially no farther than a plane defined by the skin of the host.

24. The method of claim 1, wherein the analyte is glucose, and wherein the step of measuring the concentration of the analyte comprises measuring a glucose concentration.

25. The method of claim 1, wherein the flow control device comprises a valve.

26. The method of claim 1, wherein the flow control device comprises a pump.

27. The method of claim 1, further comprising repeating steps c) through d).

28. A method for measuring a concentration of an analyte in a circulatory system of a host, the method comprising:

a) providing an analyte measuring system comprising a vascular access device, an analyte sensor, a flow control device, a fluids bag, an IV tubing, and a processor, wherein the processor is operatively connected to the flow control device and analyte sensor;

b) inserting the vascular access device and the analyte sensor into fluid communication with the host'"'"'s circulatory system;

c) injecting a first reference solution into the IV tubing;

d) coupling the fluids bag to the IV tubing, the fluids bag comprising a second reference solution; and

e) initiating the analyte measuring system,

wherein the processor is configured to auto-calibrate the analyte sensor without additional user interaction with the system.

29. The method of claim 28, wherein the first reference solution has a first known analyte concentration and wherein the second reference solution comprises a second known reference solution.

30. The method of claim 28, wherein the system is configured to auto-calibrate the analyte sensor using the first reference solution and the second reference solution.

31. The method of claim 28, wherein the system provides calibrated sensor data for at least about 24 hours prior to injection of another reference solution into the IV tubing.