Closed loop system for controlling insulin infusion

• US 6,558,351 B1
• Filed: 06/01/2000
• Issued: 05/06/2003
• Est. Priority Date: 06/03/1999
• Status: Expired due to Term

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Goode, Paul V. Jr., Shin, John J., Rebrin, Kerstin, Steil, Garry M., Talbot, Cary D., Van Antwerp, William P., Mastrototaro, John J., Purvis, Richard E.
• Primary Examiner(s): Walberg, Teresa
• Assistant Examiner(s): ROBINSON, DANIEL LEON
• Application Number:
  US09/586,175
• Time in Patent Office: 1,069 Days
• Field of Search: 604/131, 604/31, 604/522, 604/500, 604/30, 604/93.01
• US Class Current: 604/131
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14539 for measuring pH
• 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 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: A61B 5/7242 using integration
• CPC Class Codes: A61M 2005/1581 Right-angle needle-type devices
• CPC Class Codes: A61M 2005/1726 the body parameters being measured at, or proximate to, the infusion site
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/158 Needles for infusions; Accessories therefor, e.g. for inserting infusion needles, or for holding them on the body
• CPC Class Codes: A61M 5/1582 Double lumen needles
• 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: G16H 20/17 delivered via infusion or injection

Abstract

A closed loop infusion system controls the rate that fluid is infused into the body of a user. The closed loop infusion system includes a sensor system, a controller, and a delivery system. The sensor system includes a sensor for monitoring a condition of the user. The sensor produces a sensor signal, which is representative of the condition of the user. The sensor signal is used to generate a controller input. The controller uses the controller input to generate commands to operate the delivery system. The delivery system infuses a liquid into the user at a rate dictated by the commands from the controller. Preferably, the sensor system monitors the glucose concentration in the body of the user, and the liquid infused by the delivery system into the body of the user includes insulin. The sensor system uses the sensor signal to generate a message that is sent to the delivery system. The message includes the information used to generate the controller input. The sensor may be a subcutaneous sensor in contact with interstitial fluid. Also, two or more sensors may be used by the sensor system.

Claims

1. A closed loop infusion system for infusing a fluid into a user, the system comprising:

a sensor system that includes a sensor for monitoring glucose concentration of the user, and produces a sensor signal, which is representative of the glucose concentration of the user, and wherein the sensor signal is used to generate a controller input;

a proportional plus, integral plus, derivative (PID) controller that uses the controller input to generate commands; and

a delivery system that infuses a liquid, which includes insulin, into the user, wherein the operation of the delivery system is affected by the commands.

2. A closed loop infusion system according to claim 1, wherein the controller is influenced by one or more manual inputs from the user.

3. A closed loop infusion system according to claim 1, wherein the one or more manual inputs from the user includes at least one of the group consisting of the start of a meal, the number of carbohydrates in a meal, the beginning of exercise for the body of the user, the duration of the exercise for the body of the user, the start of sleep for the user, and the duration of sleep for the user.

4. A closed loop infusion system according to claim 1, wherein one or more controller gains are selected such that the commands generated by the controller cause the delivery system to infuse insulin into the body of the user in response to a glucose concentration at a rate similar to the rate that beta cells would release insulin in an individual with a healthy normally functioning pancreas.

5. A closed loop infusion system according to claim 4, wherein one or more controller gains are selected by a method that includes the step of measuring an insulin response of at least one individual with a healthy normally functioning pancreas and calculating the controller gains that cause the commands to generally match the insulin response of at least one individual.

6. A closed loop infusion system according to claim 1, wherein the controller is influenced by inputs of more than one measured body characteristic.

7. A closed loop infusion system according to claim 6, wherein the more than one measured body characteristic includes one or more measured body characteristics from a group including one or more amino acid concentrations, one or more gastrointestinal hormone concentrations, one or more other hormone concentrations, blood pH, interstitial fluid (ISF) pH, one or more blood glucose concentrations, and one or more interstitial fluid (ISF) glucose concentrations.

8. A closed loop infusion system according to claim 1, wherein the sensor is a multi-sensor that measures both glucose concentration and pH.

9. A closed loop infusion system according to claim 1, wherein the sensor system produces a diagnostic signal in addition to the sensor signal, and wherein the diagnostic signal is used to indicate when the sensor signal accuracy has diminished.

10. A closed loop infusion system according to claim 1, wherein one or more controller gains are selected such that the commands generated by the controller cause the delivery system to infuse insulin into the body of the user in response to a glucose concentration at a rate such that the insulin concentration profile in the user'"'"'s blood stream is similar to the insulin concentration profile that would be generated by the release of insulin beta cells in an individual with a healthy normally functioning pancreas.

11. A closed loop infusion system according to claim 1, wherein the derivative gain K_D is calculated using the first phase insulin response (φ

1) measured from a normal glucose tolerant (NGT) individual.

12. A closed loop infusion system according to claim 1, wherein one or more controller gains are calculated from a ratio of one or more controller gains.

13. A closed loop infusion system according to claim 1, wherein a post-controller lead/lag compensator is used to modify the commands generated by the controller to cause the delivery system to infuse insulin into the body of the user in response to a glucose concentration at a rate such that the insulin concentration profile in the user'"'"'s blood stream is similar to the insulin concentration profile that would be generated by the release of insulin beta cells in an individual with a healthy normally functioning pancreas.

14. A closed loop infusion system according to claim 1, wherein a post-controller lead/lag compensator is used to modify the commands generated by the controller to compensate for an insulin delivery delay due to infusing insulin into a user'"'"' tissue rather than directly into the user'"'"'s blood stream.