Analyte sensing and response system

• US 20080027301A1
• Filed: 11/01/2006
• Published: 01/31/2008
• Est. Priority Date: 07/28/2006
• Status: Active Grant

• Current Assignee: Legacy Emanuel Hospital and Health Center
• Original Assignee: Legacy Emanuel Hospital and Health Center
• Inventors: Duman, Heather M., Nair, Bala, Wood, Michael D., Ward, W. Kenneth
• Granted Patent: US 8,114,023 B2
• Time in Patent Office: Days
• US Class Current: 600/347
• 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 5/14865 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives

Abstract

Electrochemical systems for measuring an analyte concentration, and correcting any surplus or deficiency in the measured concentration. More specifically, systems for measuring an analyte level in a fluid with an implantable sensor, processing the measurements with an algorithm, and determining an appropriate fluid infusion rate in response to the measurements.

Claims

1. An infusion system for infusing a fluid into a user, comprising:

a sensor configured to monitor concentration of an analyte in the user and to generate a sensor output signal based on the monitored concentration, wherein the sensor output signal is used to generate a processor input signal;

a fading memory proportional derivative processor configured to process the processor input signal and to generate a processor output signal; and

a fluid delivery system configured to infuse fluid into the user in a manner based at least partially on the processor output signal.

2. The infusion system of claim 1, wherein the analyte is glucose.

3. The infusion system of claim 1, wherein the fluid contains insulin.

4. The infusion system of claim 1, wherein the sensor includes a disc-shaped body having two opposing sides, each opposing side having a cathode and a plurality of anodes.

5. The infusion system of claim 1, wherein the sensor includes a disc-shaped body having two opposing sides, a cathode and a plurality of anodes positioned on one of the sides.

6. The infusion system of claim 1, further comprising a membrane semi-permeable to the analyte covering at least a portion of the sensor.

7. The infusion system of claim 6, further comprising an enzyme layer disposed between the sensor and the membrane.

8. The infusion system of claim 1, further comprising a transmitter electrically coupled to the sensor, wherein the transmitter is configured to receive the sensor output signal, to convert the sensor output signal into the processor input signal, and to transmit the processor input signal to the processor.

9. A method of determining a fluid infusion rate for infusing a fluid into a user, comprising:

monitoring concentration of an analyte in the user and generating a sensor output signal based on the monitored concentration;

using the sensor output signal to generate a processor input signal;

processing the processor input signal using a fading memory proportional derivative algorithm to generate a processor output signal; and

determining the fluid infusion rate based at least partially on the processor output signal.

10. The method of claim 9, further comprising

infusing the fluid into the user at the determined fluid infusion rate.

11. The method of claim 9, wherein the analyte is glucose.

12. The method of claim 11, wherein the fluid contains insulin.

13. The method of claim 12, further comprising

delivering the fluid containing insulin into the user.

14. The method of claim 13, further comprising

delivering a glucose-increasing substance to the user when the user'"'"'s glucose concentration is falling at a rate above a pre-determined threshold, and the user'"'"'s glucose concentration has fallen below a pre-determined threshold level.

15. The method of claim 14, wherein the glucose-increasing substance is selected from the following:

(a) glucagon, (b) glucagon-like agent, (c) glucose, and (d) dextrose, and mixtures thereof.

16. The method of claim 9, further comprising receiving the sensor output signal at a transmitter electrically coupled to the sensor, converting the sensor output signal to the processor input signal with the transmitter, and transmitting the processor input signal to the processor with the transmitter.

17. The method of claim 9, wherein determining the fluid infusion rate also is based on at least one of the following traits of the user:

insulin sensitivity, age, body weight, usual total daily insulin dose, or physical adiposity.

18. The method of claim 9, wherein determining the fluid infusion rate also is based on at least one of the following traits of the user:

diet, or physical activity level.

19. A method of controlling concentration of an analyte in a mammal, comprising:

repeatedly measuring concentration of an analyte in a mammal with a sensor implanted in the mammal;

using an algorithm to compute a fluid delivery rate based on the measured analyte concentration; and

delivering fluid to the mammal at the computed fluid delivery rate;

wherein the algorithm computes the fluid delivery rate based on;

a current analyte proportional error;

prior analyte proportional errors, wherein more recent prior analyte proportional errors are weighted more heavily than more remote prior analyte proportional errors;

a current analyte derivative error; and

prior analyte derivative errors, wherein more recent prior analyte derivative errors are weighted more heavily than more remote prior analyte derivative errors.

20. The method of claim 19, wherein the algorithm uses a linear weighting system.

21. The method of claim 19, wherein the algorithm uses a nonlinear weighting system.

22. The method of claim 19, wherein the analyte is glucose and the fluid contains insulin.

23. The method of claim 22, wherein delivering fluid to the mammal includes delivering insulin to the mammal with an insulin delivery device located outside the body of the mammal.

24. The method of claim 22, wherein delivering fluid to the mammal includes delivering insulin to the mammal with an insulin delivery device implanted inside the body of the mammal.