Insulin on board compensation for a closed-loop insulin infusion system

• US 9,364,609 B2
• Filed: 04/25/2013
• Issued: 06/14/2016
• Est. Priority Date: 08/30/2012
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Keenan, Desmond Barry, Mastrototaro, John J., Grosman, Benyamin, Parikh, Neha J., Roy, Anirban
• Primary Examiner(s): Lubin, Valerie
• Application Number:
  US13/870,902
• Publication Number:
  US 20140066892A1
• Time in Patent Office: 1,146 Days
• Field of Search: 702/19
• US Class Current: 1/1
• CPC Class Codes: A61B 5/14503 invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors A61B5/1459, A61B5/1464, A61B5/1473, A61B5/1482, A61B5/14865 take precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/4839 combined with drug delivery
• CPC Class Codes: A61B 5/746 Alarms related to a physiological condition, e.g. details of setting alarm thresholds or avoiding false alarms alarms per se G08B
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/502 User interfaces, e.g. screens or keyboards
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• CPC Class Codes: A61M 2205/582 by tactile feedback
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• 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 10/40 for data related to laboratory analysis, e.g. patient specimen analysis
• CPC Class Codes: G16H 20/17 delivered via infusion or injection
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

An electronic controller for an insulin infusion device includes a processor architecture and at least one memory element. The memory element stores executable instructions that, when executed by the processor architecture, provide an insulin on board (IOB) compensation module to estimate a current IOB value that indicates an amount of active insulin in the body of the user, calculate an IOB rate based at least in part on the estimated current IOB value, determine an adjusted insulin infusion rate based at least in part on the calculated IOB rate and an uncompensated insulin infusion rate, select a final insulin infusion rate for the device, and provide the selected final insulin infusion rate to regulate delivery of insulin by the device.

Claims

1. An electronic insulin infusion device comprising:

an insulin reservoir for insulin to be delivered from the insulin infusion device to a body of a user;

a processor architecture comprising at least one processor device; and

at least one memory element associated with the processor architecture, the at least one memory element storing processor-executable instructions that, when executed by the processor architecture, perform a method of controlling closed-loop delivery of insulin from the insulin reservoir to the body of the user, the method comprising;

computing a current insulin on board (IOB) value that indicates an amount of active insulin in the body of the user;

calculating an IOB rate based at least in part on the computed IOB value, wherein the IOB rate represents an amount of active insulin accumulated from manual boluses in the body of the user per unit of time;

determining an adjusted insulin infusion rate based at least in part on the calculated IOB rate and an uncompensated insulin infusion rate;

selecting a final insulin infusion rate for the insulin infusion device, wherein the selecting selects either the determined adjusted insulin infusion rate, the uncompensated insulin infusion rate, or a current basal rate as the final insulin infusion rate, wherein selecting the final insulin infusion rate is in accordance with either expression FinalRate(n)=max(Basal;

AdjustedRate(n)) when PIDRate>

Basal, or expression FinalRate(n)=PIDRate(n) when PIDRate Basal, wherein;

FinalRate(n) is the selected final insulin infusion rate;

Basal is the current basal rate;

AdjustedRate(n) is the determined adjusted insulin infusion rate; and

PIDRate(n) is the uncompensated insulin infusion rate; and

operating the insulin infusion device in a closed-loop mode to continuously deliver insulin from the insulin reservoir to the body of the user in accordance with the final insulin infusion rate that is selected, wherein the final insulin infusion rate represents an amount of insulin to be delivered per unit of time.

2. The insulin infusion device of claim 1, wherein the method performed by the processor-executable instructions further comprises:

repeating the computing, the calculating, the determining, the selecting, and the operating in accordance with a predetermined schedule to adjust the final insulin infusion rate in an ongoing manner.

3. The insulin infusion device of claim 1, wherein the current IOB value is calculated based at least in part on historical bolus delivery data for the user.

4. The insulin infusion device of claim 3, wherein the current IOB value is calculated in accordance with a three-compartment insulin pharmacokinetic model.

5. The insulin infusion device of claim 3, wherein determining the adjusted insulin infusion rate comprises:

selecting the adjusted insulin infusion rate in accordance with the expression AdjustedRate(n)=max(0;

PIDRate(n)−

IOBRate(n)), wherein;

AdjustedRate(n) is the selected adjusted insulin infusion rate;

PIDRate(n) is the uncompensated insulin infusion rate; and

IOBRate(n) is the calculated IOB rate.

6. A closed-loop insulin infusion system comprising:

a continuous glucose sensor that generates sensor data indicative of sensor glucose values for a user; and

an insulin infusion device coupled to receive the sensor data generated by the continuous glucose sensor, the insulin infusion device comprising an insulin reservoir for insulin to be delivered from the insulin infusion device to the user, a processor architecture comprising at least one processor device and further comprising at least one memory element associated with the processor architecture, the at least one memory element storing processor-executable instructions that, when executed by the processor architecture, cause the insulin infusion device to perform a method comprising;

initiating a closed-loop operating mode of the insulin infusion device;

in response to initiating the closed-loop operating mode, obtaining a most recent sensor glucose value for the user;

computing a current insulin on board (IOB) value that indicates an amount of active insulin in the body of the user;

calculating an IOB rate based at least in part on the computed IOB value, wherein the IOB rate represents an amount of active insulin accumulated from manual boluses in the body of the user per unit of time;

determining an adjusted insulin infusion rate based at least in part on the calculated IOB rate and an uncompensated insulin infusion rate;

selecting a final insulin infusion rate for the insulin infusion device, wherein the selecting selects either the determined adjusted insulin infusion rate, the uncompensated insulin infusion rate, or a current basal rate as the final insulin infusion rate;

wherein selecting the final insulin infusion rate is in accordance with either expression FinalRate(n)=max(Basal;

AdjustedRate(n)) when PIDRate>

Basal, or expression FinalRate(n)=PIDRate(n) when PIDRate≦

Basal, wherein;

FinalRate(n) is the selected final insulin infusion rate;

Basal is the current basal rate;

AdjustedRate(n) is the determined adjusted insulin infusion rate; and

PIDRate(n) is the uncompensated insulin infusion rate;

and operating the insulin infusion device in the closed-loop operating mode to continuously deliver insulin from the insulin reservoir to the body of the user in accordance with the final insulin infusion rate that is selected, wherein the final insulin infusion rate represents an amount of insulin to be delivered per unit of time.

7. The closed-loop insulin infusion system of claim 6, wherein the current IOB value is calculated based at least in part on historical bolus delivery data for the user.

8. The closed-loop insulin infusion system of claim 7, wherein the current IOB value is calculated in accordance with a three-compartment insulin pharmacokinetic model.

9. The closed-loop insulin infusion system of claim 6, wherein determining the adjusted insulin infusion rate comprises:

selecting the adjusted insulin infusion rate in accordance with the expression

AdjustedRate(n)=max(0;

PIDRate(n)−

IOBRate(n)), wherein;

AdjustedRate(n) is the selected adjusted insulin infusion rate;

PIDRate(n) is the uncompensated insulin infusion rate; and

IOBRate(n) is the calculated IOB rate.

10. The closed-loop insulin infusion system of claim 6, wherein the method performed by the processor-executable instructions further comprises:

repeating the computing, the calculating, the determining, the selecting, and the operating in accordance with a predetermined schedule to adjust the final insulin infusion rate in an ongoing manner.