Closed loop control with improved alarm functions

• US 8,734,422 B2
• Filed: 08/31/2008
• Issued: 05/27/2014
• Est. Priority Date: 08/31/2008
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Hayter, Gary
• Primary Examiner(s): Sirmons, Kevin
• Assistant Examiner(s): CARPENTER, WILLIAM R
• Application Number:
  US12/202,305
• Publication Number:
  US 20100057042A1
• Time in Patent Office: 2,095 Days
• Field of Search: 604/131, 604/65, 604/66, 604503-504, 600/365, 702/19, 702/181
• US Class Current: 604/504
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1486 using enzyme electrodes, e.g. with immobilised oxidase
• 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 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7275 Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor
• CPC Class Codes: A61B 5/7282 Event detection, e.g. detecting unique waveforms indicative of a medical condition A61B5/4094, A61B5/4818, A61B5/349, A61B5/0823 take precedence
• 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 2230/201 Glucose concentration
• 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

Abstract

Methods, system and devices for monitoring control parameters in a closed loop control operation including continuously monitoring glucose level and automatic administration of a medication, detecting a condition associated with hypoglycemia, determining whether a probability of the detected condition associated with hypoglycemia exceeding a threshold level, and outputting a notification based upon the determination are provided.

Claims

1. A method, comprising:

monitoring control parameters in a closed loop control operation including monitoring a glucose level and administration of a medication;

determining a predictive glucose response based on a predictive modeling analysis, the predictive modeling analysis based on prior monitored sensor data and one or more exogenous factors including insulin delivery information, meal intake and exercise events;

comparing the predictive glucose response with corresponding monitored sensor data;

detecting sensor anomalies based on the comparison of the predictive glucose response with the corresponding monitored sensor data;

detecting a condition associated with hypoglycemia including determining a level of uncertainty in the monitored glucose level based on a predicted or anticipated glucose level;

when the condition associated with hypoglycemia is detected, determining a probability that the detected condition associated with hypoglycemia corresponds to a hypoglycemic condition, wherein determining the probability that the detected condition associated with hypoglycemia corresponds to the hypoglycemic condition includes receiving additional sensor data and analyzing the received additional sensor data to determine whether the analyzed sensor data indicates a persistent low glucose level;

comparing the determined probability that the detected condition associated with hypoglycemia corresponds to the hypoglycemic condition, to a probability threshold level to confirm a presence of the hypoglycemic condition;

outputting a notification when the determined probability exceeds the probability threshold level and after the presence of the hypoglycemic condition is confirmed;

determining periodically at a first medication delivery rate adjustment frequency whether to adjust a medication delivery rate;

monitoring the glucose level at a predetermined frequency;

determining a variation in a plurality of monitored glucose levels;

modifying the first medication delivery rate adjustment frequency to a second medication delivery rate adjustment frequency based on the determined variation in the plurality of monitored glucose levels; and

determining periodically at the second medication delivery rate adjustment frequency whether to adjust the medication delivery rate.

2. The method of claim 1, further comprising updating the closed loop control operation to modify the administration of the medication.

3. The method of claim 1, wherein the medication includes insulin, glucagon, or a combination thereof.

4. The method of claim 1, wherein outputting the notification after the presence of the hypoglycemic condition is confirmed reduces outputting false low glucose alarms based on a presence of glucose sensor signal dropout or a glucose sensor early signal attenuation condition.

5. The method of claim 1, wherein outputting the notification when the determined probability exceeds the probability threshold level includes outputting an alarm notification.

6. The method of claim 1, wherein outputting the notification includes outputting the notification only after the presence of the hypoglycemic condition is confirmed.

7. The method of claim 1, wherein when the determined probability exceeds the probability threshold level, the hypoglycemic condition is confirmed.

8. The method of claim 1, further comprising reverting to a pre-programmed medication delivery rate when the determined probability exceeds the probability threshold level, wherein the pre-programmed medication delivery rate is less than a delivery rate of the administration of the medication of the closed loop control operation.

9. The method of claim 1, wherein the detected condition associated with hypoglycemia is derived from the monitored sensor data.

10. The method of claim 1, further comprising delaying outputting of the notification for a predetermined period of time.

11. The method of claim 10, wherein the predetermined period of time is based, at least in part, on a time required to determine whether the probability of the detected condition associated with hypoglycemia exceeds the probability threshold level.

12. The method of claim 1, further comprising outputting an alert notification upon detecting the condition associated with hypoglycemia.

13. The method of claim 12, wherein the alert notification includes one or more of a visual notification, an audible notification, a vibratory notification, or one or more combinations thereof.

14. The method of claim 1, wherein determining the level of uncertainty in the monitored glucose level includes determining a confidence level of an accuracy of the monitored glucose level, wherein the confidence level is based, at least in part, on at least one of an amount of insulin delivered, insulin on board information, and rate of change information.

15. The method of claim 1, wherein the sensor anomalies include a sensor signal dropout or an early signal attenuation.

16. The method of claim 1, further comprising:

determining whether the detected sensor anomalies exceed a preset safety level; and

when the detected sensor anomalies exceed the preset safety level, administering the medication according to a pre-programmed delivery rate that is within the safety level.

17. The method of claim 1, further comprising notifying a user of a presence of the detected sensor anomalies and obtaining confirmation from the user of the presence of the detected sensor anomalies.

18. The method of claim 17, further comprising disabling the closed loop control operation when the user fails to confirm the presence of the detected sensor anomalies within a predetermined time period.

19. The method of claim 17, further comprising administering medication according to a predetermined basal profile while maintaining the close loop control operation when sensor anomalies are detected.

20. The method of claim 1, wherein the glucose level is monitored using a glucose sensor including a plurality of electrodes including a working electrode, wherein the working electrode comprises a glucose-responsive enzyme and a mediator, wherein at least one of the glucose-responsive enzyme and the mediator is chemically bonded to a polymer disposed on the working electrode, and wherein at least one of the glucose-responsive enzyme and the mediator is crosslinked with the polymer.

21. A device, comprising:

one or more processors; and

a memory operatively coupled to the one or more processors, the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to monitor control parameters in a closed loop control operation including monitoring a glucose level and administration of a medication, to determine a predictive glucose response based on a predictive modeling analysis, the predictive modeling analysis based on prior monitored sensor data and one or more exogenous factors including insulin delivery information, meal intake and exercise events, to compare the predictive glucose response with corresponding monitored sensor data, to detect sensor anomalies based on the comparison of the predictive glucose response with the corresponding monitored sensor data, to detect a condition associated with hypoglycemia including determining a level of uncertainty in the monitored glucose level based on a predicted or anticipated glucose level by analyzing additional sensor data to determine whether the analyzed sensor data indicates a persistent low glucose level, to determine, when the condition associated with hypoglycemia is detected, a probability that the detected condition associated with hypoglycemia corresponds to a hypoglycemic condition, to compare the determined probability that the detected condition associated with hypoglycemia corresponds to the hypoglycemic condition, to a probability threshold level to confirm a presence of the hypoglycemic condition, to output a notification when the determined probability exceeds the probability threshold level and after the presence of the hypoglycemic condition is confirmed, to determine periodically at a first medication delivery rate adjustment frequency whether to adjust a medication delivery rate, to monitor the glucose level at a predetermined frequency, to determine a variation in a plurality of monitored glucose levels, to modify the first medication delivery rate adjustment frequency to a second medication delivery rate adjustment frequency based on the determined variation in the plurality of monitored glucose levels, and to determine periodically at the second medication delivery rate adjustment frequency whether to adjust the medication delivery rate.

22. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to update the closed loop control operation to modify the administration of the medication.

23. The device of claim 21, wherein the medication includes insulin, glucagon, or a combination thereof.

24. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to output the notification after the presence of the hypoglycemic condition is confirmed to reduce outputting false low glucose alarms based on a presence of a glucose sensor signal dropout or a glucose sensor early signal attenuation condition.

25. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to output an alarm notification when the determined probability exceeds the probability threshold level.

26. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to output the notification only after the presence of the hypoglycemic condition is confirmed.

27. The device of claim 21, wherein when the determined probability exceeds the probability threshold level, the hypoglycemic condition is confirmed.

28. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to revert to a pre-programmed medication delivery rate when the determined probability exceeds the probability threshold level, wherein the pre-programmed medication delivery rate is less than a delivery rate of the administration of the medication of the closed loop control operation.

29. The device of claim 21, wherein the detected condition associated with hypoglycemia is derived from the monitored sensor data.

30. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to delay the output of the notification for a predetermined period of time.

31. The device of claim 30, wherein the predetermined period of time is based, at least in part, on a time required to determine whether the probability of the detected condition associated with hypoglycemia exceeds the probability threshold level.

32. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to output an alert notification upon detecting the condition associated with hypoglycemia.

33. The device of claim 32, wherein the alert notification includes one or more of a visual notification, an audible notification, a vibratory notification, or one or more combinations thereof.

34. The device of claim 21, wherein the memory for storing instructions which, when executed by the one or more processors, causes the one or more processors to determine a confidence level of an accuracy of the monitored glucose level when determining the level of uncertainty, wherein the confidence level is based, at least in part, on at least one of an amount of insulin delivered, insulin on board information, and rate of change information.

35. The device of claim 21, further comprising a glucose sensor including a plurality of electrodes including a working electrode, wherein the working electrode comprises a glucose-responsive enzyme and a mediator, wherein at least one of the glucose-responsive enzyme and the mediator is chemically bonded to a polymer disposed on the working electrode, and wherein at least one of the glucose-responsive enzyme and the mediator is crosslinked with the polymer.