Generation and application of an insulin limit for a closed-loop operating mode of an insulin infusion system

Patent metadata

Field	Value
Publication number	US-9849239-B2
Application number	US-201313966120-A
Country	US
Kind code	B2
Filing date	Aug 13, 2013
Priority date	Aug 30, 2012
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

A controller for an insulin infusion device includes a processor device and a memory element that cooperate to provide a processor-implemented closed-loop insulin limit module. The insulin limit module is operated to obtain: a fasting blood glucose value of a user; a total daily insulin value of the user; and fasting insulin delivery data that is indicative of insulin delivered to the user during a fasting period. The insulin limit module calculates a maximum insulin infusion rate for the user based on the fasting blood glucose value, the total daily insulin value, and the fasting insulin delivery data. The maximum insulin infusion rate is applicable during a period of closed-loop operation of the insulin infusion device.

First claim

What is claimed is:

1. An insulin infusion device comprising:
an insulin reservoir for insulin to be delivered from the insulin infusion device to 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 user, the method comprising:
calculating a maximum insulin infusion rate for the user based on a fasting blood glucose value associated with the user, a total daily insulin value associated with the user, and fasting insulin delivery data that is indicative of insulin delivered to the user during a fasting period, wherein the maximum insulin infusion rate is applicable during a period of closed-loop operation of the insulin infusion device;
obtaining a first closed-loop insulin infusion rate for the user, wherein the first closed-loop insulin infusion rate is obtained for a current sampling point during the period of closed-loop operation;
providing a second closed-loop insulin infusion rate for the user when the obtained first closed-loop insulin infusion rate is greater than the calculated maximum insulin infusion rate, wherein the second closed-loop insulin infusion rate is less than the first closed-loop insulin infusion rate; and
operating the insulin infusion device in a closed-loop mode to continuously deliver insulin from the insulin reservoir to the user in accordance with either the first closed-loop insulin infusion rate or the second closed-loop insulin infusion rate.

2. The insulin infusion device of claim 1 , wherein the provided second closed-loop insulin infusion rate is equal to the calculated maximum insulin infusion rate.

3. The insulin infusion device of claim 1 , wherein:
the first closed-loop insulin infusion rate is calculated in accordance with a proportional-integral-derivative insulin feedback (PID-IFB) control algorithm; and
the method performed by the processor-executable instructions further comprises the step of inhibiting windup of an integral component of the PID-IFB control algorithm when the obtained first closed-loop insulin infusion rate is greater than the calculated maximum insulin infusion rate.

4. The insulin infusion device of claim 3 , wherein inhibiting windup of the integral component comprises:
freezing the integral component while permitting continued updating of a proportional component of the PID-IFB control algorithm, and while permitting continued updating of a derivative component of the PID-IFB control algorithm.

5. The insulin infusion device of claim 4 , wherein the method performed by the processor-executable instructions further comprises:
unfreezing the integral component when a third closed-loop insulin infusion rate for the user is less than or equal to the calculated maximum insulin infusion rate, wherein the third closed-loop insulin infusion rate is obtained for a subsequent sampling point during the period of closed-loop operation, the subsequent sampling point occurring after the current sampling point.

6. The insulin infusion device of claim 1 , wherein the fasting insulin delivery data is correlated to the fasting blood glucose value.

7. The insulin infusion device of claim 1 , wherein:
the maximum insulin infusion rate is calculated in accordance with the expression

Umax
=

I

basal
,
0

+

BG
LBL

-

FBG
0

KI

;

Umax is the maximum insulin infusion rate, expressed in Units/hour;
I basal,0 is an estimated basal rate that results in the fasting blood glucose value for the user, expressed in Units/hour;
BG LBL is a lower blood glucose limit, expressed in mg/dL, and corresponding to operation of the insulin infusion device at Umax;
FBG 0 is the fasting blood glucose value, expressed in mg/dL; and
KI is an insulin gain value, expressed in

mg
dL

⁢

⁢
per
⁢

⁢

⁢

Units
hour

.

8. The insulin infusion device of claim 7 , wherein:

KI
=

-
IS

*
3
⁢

(

mg
dL

⁢

⁢
per
⁢

⁢

Units
hour

)

;

IS is an insulin sensitivity value for the user, expressed in mg/dL/Units; and
IS is derived from the total daily insulin value obtained for the user.

9. The insulin infusion device of claim 8 , wherein:

IS
=

1800
TDI

;

and
TDI is the total daily insulin value obtained for the user, expressed in Units.

10. The insulin infusion 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.

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

12. The insulin infusion 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.

13. A tangible and non-transitory electronic storage medium having processor-executable instructi

Assignees

• Medtronic Minimed Inc

Inventors

• Grosman Benyamin
• Parikh Neha J
• Roy Anirban
• Keenan Desmond Barry
• Mastrototaro John J

Classifications

• G06F19/3468

  Physics · mapped topic

• A61B5/14503

  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 title

• A61B5/4839

  combined with drug delivery · CPC title

• A61B5/14532

  for measuring glucose, e.g. by tissue impedance measurement · CPC title

• A61M5/1723 Primary

  using feedback of body parameters, e.g. blood-sugar, pressure (measurement of body parameters A61B5/00) · CPC title