GENERATION OF TARGET GLUCOSE VALUES FOR A CLOSED-LOOP OPERATING MODE OF AN INSULIN INFUSION SYSTEM

• US 20140066886A1
• Filed: 08/13/2013
• Published: 03/06/2014
• Est. Priority Date: 08/30/2012
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Roy, Anirban, Keenan, Desmond Barry, Mastrototaro, John J., Grosman, Benyamin, Parikh, Neha J.
• Granted Patent: US 9,878,096 B2
• Time in Patent Office: Days
• US Class Current: 604/504
• 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: 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
• CPC Class Codes: G16H 40/40 for the management of medical equipment or devices, e.g. scheduling maintenance or upgrades
• CPC Class Codes: G16H 50/00 ICT specially adapted for medical diagnosis, medical simulation or medical data mining; ICT specially adapted for detecting, monitoring or modelling epidemics or pandemics
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

A controller for an insulin infusion device includes at least one processor device and at least one memory element that cooperate to provide a processor-implemented closed-loop start-up module. The start-up module is operated to initiate a closed-loop mode of the infusion device and to obtain a most recent sensor glucose value for the user. The start-up module also calculates a difference between the most recent sensor glucose value and a target glucose setpoint value. When the difference is less than or equal to a threshold value, the closed-loop insulin infusion rate is adjusted over time, based on a fixed final target glucose value that is derived from the target glucose setpoint value. When the difference is greater than the threshold, the infusion rate is adjusted over time, based on a dynamic final target glucose value that decreases over time toward the target glucose setpoint value.

Claims

1. An electronic device comprising:

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 an insulin infusion device for a user, the 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;

calculating a difference between the most recent sensor glucose value and a target glucose setpoint value;

when the calculated difference is less than or equal to a minimum threshold value, adjusting a closed-loop insulin infusion rate over time, based on a fixed final target glucose value that is derived from the target glucose setpoint value; and

when the calculated difference is greater than the minimum threshold value, adjusting the closed-loop insulin infusion rate over time, based on a dynamic final target glucose value that decreases over time toward the target glucose setpoint value.

2. The electronic device of claim 1, wherein:

the electronic device comprises a monitor device for the insulin infusion device; and

the monitor device and the insulin infusion device are physically distinct hardware devices.

3. The electronic device of claim 1, wherein the electronic device comprises the insulin infusion device.

4. The electronic device of claim 1, wherein:

the electronic device comprises a portable wireless device; and

the portable wireless device and the insulin infusion device are physically distinct hardware devices.

5. The electronic device of claim 1, wherein the fixed final target glucose value is equal to the target glucose setpoint value.

6. The electronic device of claim 1, wherein adjusting the closed-loop insulin infusion rate over time is performed in accordance with a proportional-integral-derivative insulin feedback (PID-IFB) control algorithm.

7. The electronic device of claim 1, wherein the method performed by the processor-executable instructions further comprises:

calculating the dynamic final target glucose value in accordance with the expression FinalTarget(n)=Setpoint+DynSP(n), where

n represents a current sampling point;

FinalTarget(n) is the dynamic final target glucose value at the current sampling point;

Setpoint is the target glucose setpoint value; and

DynSP(n) is a dynamic glucose setpoint value at the current sampling point.

8. The electronic device of claim 7, wherein the method performed by the processor-executable instructions further comprises:

calculating the dynamic glucose setpoint value in accordance with a discretized second order transfer function model.

9. The electronic device of claim 8, wherein the dynamic glucose setpoint value is calculated in accordance with the expression DynSP(n)=cd₁·

DynSP(n−

1)+cd₂·

DynSP(n−

2)+cn₀·

DeltaGlu(n)+cn₁·

DeltaGlu(n−

1), where

DeltaGlu(n) is the difference, at the current sampling point, between the most recent sensor glucose value and the target glucose setpoint value; and

cd₁, cd₂, cn₀, and cn₁ are coefficients of the discretized second order transfer function model.

10. The electronic device of claim 9, wherein each of cd₁, cd₂, and cn₁ is based on two time constants of the discretized second order transfer function model.

11. The electronic device of claim 9, wherein:

DeltaGlu(n) is equal to the calculated difference only for an initial calculation of the dynamic glucose setpoint value; and

DeltaGlu(n) is equal to zero for all subsequent calculations of the dynamic glucose setpoint value following the initial calculation of the dynamic glucose setpoint value.

12. The electronic device of claim 9, wherein:

DynSP(n−

1) is equal to zero for an initial calculation of the dynamic glucose setpoint value;

DynSP(n−

2) is equal to zero for the initial calculation of the dynamic glucose setpoint value; and

DeltaGlu(n−

1) is equal to zero for the initial calculation of the dynamic glucose setpoint value.

13. A tangible and non-transitory electronic storage medium having processor-executable instructions that, when executed by a processor architecture comprising at least one processor device, perform a method of controlling an insulin infusion device for a user, the 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;

calculating a difference between the most recent sensor glucose value and a target glucose setpoint value;

when the calculated difference is less than or equal to a minimum threshold value, adjusting a closed-loop insulin infusion rate over time, based on a fixed final target glucose value that is derived from the target glucose setpoint value; and

when the calculated difference is greater than the minimum threshold value, adjusting the closed-loop insulin infusion rate over time, based on a dynamic final target glucose value that decreases over time toward the target glucose setpoint value.

14. The electronic storage medium of claim 13, wherein the fixed final target glucose value is equal to the target glucose setpoint value.

15. The electronic storage medium of claim 13, wherein adjusting the closed-loop insulin infusion rate over time is performed in accordance with a proportional-integral-derivative insulin feedback (PID-IFB) control algorithm.

16. The electronic storage medium of claim 13, wherein the method performed by the processor-executable instructions further comprises:

calculating the dynamic final target glucose value in accordance with the expression FinalTarget(n)=Setpoint+DynSP(n), where

n represents a current sampling point;

FinalTarget(n) is the dynamic final target glucose value at the current sampling point;

Setpoint is the target glucose setpoint value; and

DynSP(n) is a dynamic glucose setpoint value at the current sampling point.

17. The electronic storage medium of claim 16, wherein the method performed by the processor-executable instructions further comprises:

calculating the dynamic glucose setpoint value in accordance with a discretized second order transfer function model.

18. The electronic storage medium of claim 17, wherein the dynamic glucose setpoint value is calculated in accordance with the expression DynSP(n)=cd₁·

DynSP(n−

1)+cd₂·

DynSP(n−

2)+cn₀·

DeltaGlu(n)+cn₁·

DeltaGlu(n−

1), where

DeltaGlu(n) is the difference, at the current sampling point, between the most recent sensor glucose value and the target glucose setpoint value; and

cd₁, cd₂, cn₀, and cn₁ are coefficients of the discretized second order transfer function model.

19. The electronic storage medium of claim 18, wherein each of cd₁, cd₂, and cn₁ is based on two time constants of the discretized second order transfer function model.

20. The electronic storage medium of claim 18, wherein:

DeltaGlu(n) is equal to the calculated difference only for an initial calculation of the dynamic glucose setpoint value; and

DeltaGlu(n) is equal to zero for all subsequent calculations of the dynamic glucose setpoint value following the initial calculation of the dynamic glucose setpoint value.

21. The electronic storage medium of claim 18, wherein:

DynSP(n−

1) is equal to zero for an initial calculation of the dynamic glucose setpoint value;

DynSP(n−

2) is equal to zero for the initial calculation of the dynamic glucose setpoint value; and

DeltaGlu(n−

1) is equal to zero for the initial calculation of the dynamic glucose setpoint value.

22. An electronic controller for an insulin infusion device, the electronic controller comprising:

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, provide a closed-loop start-up module configured to;

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

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

calculate a difference between the most recent sensor glucose value and a target glucose setpoint value;

when the calculated difference is less than or equal to a minimum threshold value, adjust a closed-loop insulin infusion rate over time, based on a fixed final target glucose value that is derived from the target glucose setpoint value; and

when the calculated difference is greater than the minimum threshold value, adjust the closed-loop insulin infusion rate over time, based on a dynamic final target glucose value that decreases over time toward the target glucose setpoint value.

23. The electronic controller of claim 22, wherein:

the electronic controller is implemented in a monitor device for the insulin infusion device; and

the monitor device and the insulin infusion device are physically distinct hardware devices.

24. The electronic controller of claim 22, wherein the electronic controller is implemented in the insulin infusion device.

25. The electronic controller of claim 22, wherein:

the electronic controller is implemented in a portable wireless device; and

the portable wireless device and the insulin infusion device are physically distinct hardware devices.