Closed loop/semi-closed loop therapy modification system

• US 7,785,313 B2
• Filed: 07/16/2008
• Issued: 08/31/2010
• Est. Priority Date: 04/25/2007
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Mastrototaro, John J.
• Primary Examiner(s): Sirmons; Kevin C
• Assistant Examiner(s): OSINSKI, BRADLEY JAMES
• Application Number:
  US12/174,552
• Publication Number:
  US 20080275384A1
• Time in Patent Office: 776 Days
• Field of Search: 604/890.1, 604/503, 604/504, 604 65- 67
• US Class Current: 604/503
• 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 5/1495 Calibrating or testing of in-vivo probes
• CPC Class Codes: A61B 5/6849 in combination with a needle set
• CPC Class Codes: A61M 2005/1581 Right-angle needle-type devices
• CPC Class Codes: A61M 2205/3561 local, e.g. within room or hospital
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable 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

Abstract

A closed loop/semi-closed loop infusion system provides therapy modification and safeguards against the over-delivery or under-delivery of insulin. A glucose sensor system is configured to obtain a measured blood glucose value. A controller is operationally connected with the glucose sensor system and configured to trigger an alarm based on a measured blood glucose value or amount of insulin delivered, selectively perform calibration of the glucose sensor system when the alarm is triggered, and adjust a therapy delivery parameter when the alarm is triggered, wherein the adjusted therapy delivery parameter is limited to be within a boundary. Thereafter, a delivery system delivers therapy at the adjusted therapy delivery parameter.

Claims

1. A method for providing therapy modification in an infusion system, the method comprising:

continuously delivering insulin according to a therapy delivery parameter based on a measured blood glucose value;

triggering an alarm based on the measured blood glucose value or an amount of insulin delivered;

automatically adjusting the therapy delivery parameter when the alarm is triggered such that the adjusted therapy delivery parameter is limited to be within a boundary;

comparing an expected insulin on board (IOB) value to an actual IOB value; and

determining that insulin action is delayed if the actual IOB value is within a predetermined range of the expected IOB value,

wherein the alarm is not triggered if it is determined that insulin action is delayed even if the measured blood glucose value is not consistent with a target blood glucose value, or the amount of insulin delivered is not consistent with an expected amount of delivered insulin.

2. The method of claim 1, further comprising selectively performing calibration of a glucose sensor system when the alarm is triggered.

3. The method of claim 1, wherein the predetermined range comprises a predetermined percentage above or below the expected IOB value.

4. The method of claim 1, wherein the alarm is not triggered if the actual IOB value is within a predetermined range of the expected IOB value.

5. The method of claim 1, wherein the alarm is triggered if the actual IOB value is not within a predetermined range of the expected IOB value.

6. The method of claim 1, wherein automatic delivery of more insulin due to an elevated glucose level is not performed if the actual IOB value is within a predetermined range of the expected IOB value.

7. The method of claim 1, wherein the therapy delivery parameter is adjusted according to a default basal pattern.

8. The method of claim 7, wherein adjusting the therapy delivery parameter comprises:

suspending closed-loop therapy delivery; and

reverting to open-loop therapy delivery using the default basal pattern.

9. The method of claim 8, further comprising:

resuming closed-loop therapy delivery if a condition triggering the alarm is corrected; and

continuing open-loop therapy delivery if the condition triggering the alarm is not corrected.

10. The method of claim 1, further comprising comparing the measured blood glucose value to a model predicted blood glucose value.

11. The method of claim 10, wherein the alarm is triggered if the measured blood glucose value is not within a predetermined range of the model predicted blood glucose value.

12. The method of claim 10, wherein the model predicted blood glucose value is calculated based on at least one of:

a past history of meals; and

a past history of insulin delivery and values.

13. An infusion system for providing therapy modification, the system comprising:

a glucose sensor system; and

a controller operationally connected with the glucose sensor system, wherein the controller controls a delivery system that continuously delivers insulin according to a therapy delivery parameter based on a measured blood glucose value, triggers an alarm based on the measured blood glucose value or an amount of insulin delivered, automatically adjusts the therapy delivery parameter when the alarm is triggered such that the adjusted therapy delivery parameter is limited to be within a boundary, compares an expected insulin on board (IOB) value to an actual IOB value, determines that insulin action is delayed if the actual IOB value is within a predetermined ranged of the expected IOB value so that the alarm is not triggered if it is determined that insulin action is delayed even if the measured blood glucose value is not consistent with a target blood glucose value, or the amount of insulin delivered is not consistent with an expected amount of delivered insulin.

14. The system of claim 13, wherein the controller selectively performs calibration of the glucose sensor system when the alarm is triggered.

15. The system of claim 13, wherein the predetermined range comprises a predetermined percentage above or below the expected IOB value.

16. The system of claim 13, wherein the alarm is not triggered if the actual IOB value is within a predetermined range of the expected IOB value.

17. The system of claim 13, wherein the alarm is triggered if the actual IOB value is not within a predetermined range of the expected IOB value.

18. The system of claim 13, wherein the controller does not perform automatic delivery of more insulin due to an elevated glucose level if the actual IOB value is within a predetermined range of the expected IOB value.

19. The system of claim 13, wherein the therapy delivery parameter is adjusted according to a default basal pattern.

20. The system of claim 19, wherein the controller adjusts the therapy delivery parameter by:

suspending closed-loop therapy delivery; and

reverting to open-loop therapy delivery using the default basal pattern.

21. The system of claim 20, wherein the controller:

resumes closed-loop therapy delivery if a condition triggering the alarm is corrected; and

continues open-loop therapy delivery if the condition triggering the alarm is not corrected.

22. The system of claim 13, wherein the controller compares the measured blood glucose value to a model predicted blood glucose value.

23. The system of claim 22, wherein the alarm is triggered if the measured blood glucose value is not within a predetermined range of the model predicted blood glucose value.

24. The system of claim 22, wherein the model predicted blood glucose value is calculated based on at least one of:

a past history of meals; and

a past history of insulin delivery and values.