METHODS FOR REDUCING FALSE HYPOGLYCEMIA ALARM OCCURRENCE

• US 20100317952A1
• Filed: 05/21/2010
• Published: 12/16/2010
• Est. Priority Date: 05/22/2009
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated), Cambridge Enterprises Limited
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Dunger, David, Wilinska, Malgorzata, Hovorka, Roman, Hayter, Gary A., Taub, Marc B., Budiman, Erwin S.
• Granted Patent: US 9,579,456 B2
• Time in Patent Office: Days
• US Class Current: 600/365
• 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 5/7221 Determining signal validity, reliability or quality A61B5/7207 and A61B5/7217 take precedence
• CPC Class Codes: A61B 5/7264 Classification of physiological signals or data, e.g. using neural networks, statistical classifiers, expert systems or fuzzy systems neural networks per se G06N3/00; expert systems per se G06N5/00
• 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 5/746 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 2005/14296 Pharmacokinetic models
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/3569 sublocal, e.g. between console and disposable
• CPC Class Codes: A61M 2205/52 with memories providing a history of measured variating parameters of apparatus or patient
• 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 15/00 ICT specially adapted for medical reports, e.g. generation or transmission thereof
• CPC Class Codes: G16H 20/17 delivered via infusion or injection
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16H 50/20 for computer-aided diagnosis, e.g. based on medical expert systems
• CPC Class Codes: G16H 50/30 for calculating health indices; for individual health risk assessment
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

A system and method for reducing the number of hypoglycemic alarms presented to a user is presented. The system and methods include use of model based state estimation and variable-delayed threshold values to balance the risk of not presenting an alarm caused by an actual hypoglycemic state with the presentation of alarms caused by artifacts in the signals produced by a continuous glucose monitor.

Claims

1. A system for monitoring the glucose level of a user, comprising:

a continuous glucose monitor;

a processor configured to receive signals from the continuous glucose monitor and also adapted to analyze those signals in accordance with software commands, the software commands including commands to program at least a portion of the processor to operate as a state machine, the state machine having a first state when the signals from the continuous glucose monitor indicate a not hypoglycemic state and a second state when the signals indicate that a glucose value is below a selected threshold value.

2. The system of claim 1, wherein the second state includes starting a timer to delay presentation of an alarm to the user, the delay determined by the glucose value.

3. The system of claim 1, wherein the second state includes presenting an alarm to the user and requesting a confirmation measurement of glucose level when the glucose value is below a second selected threshold value that is lower than the first threshold value.

4. The system of claim 3, wherein the second state includes recommending administration of rescue carbohydrates if the confirmation measurement glucose value is below a selected threshold.

5. The system of claim 2, wherein an alarm is presented to the user at the expiration of the delay if the signal from the continuous glucose monitor indicates that the glucose value is still below the threshold value.

6. A method for determining when to present a hypoglycemic alarm to a user of a continuous glucose monitor, comprising:

providing a controller programmed to operate as a state machine;

providing signals from a continuous glucose monitor as input to the state machine;

wherein the state machine operates in accordance with the programming and the input to determine if an alarm is to be presented to the user indicating that an actual hypoglycemic condition exists.

7. A system for monitoring the glucose level of a user, comprising:

a continuous glucose monitor configured to transmit signals representative of a glucose value;

a processor configured to receive signals from the continuous glucose monitor and also adapted to analyze those signals in accordance with software commands, the software commands including commands to program at least a portion of the processor to operate as an alarm specificity optimizing system, the alarm specificity system having a first subsystem where temporal behavior of the signals from the continuous glucose monitor is used to maximize the specificity of a hypoglycemic event detection and assert a hypoglycemic alarm, and a second subsystem where one or more glucose level measurements is used to ensure whether or not the hypoglycemic event has been resolved.

8. The system of claim 7, wherein optimization of the alarm specificity includes having the first subsystem starting one or more timers to delay presentation of an alarm to the user, wherein the delay for each timer is a function of the level of hypoglycemia indicated by signals received from the continuous glucose monitor.

9. The system of claim 7, wherein the second subsystem includes requesting a confirmation measurement of glucose level when the first subsystem presents an alarm or when a value of a previous glucose level measurement is below a selected threshold value.

10. The system of claim 9, wherein the second subsystem includes recommending administration of rescue carbohydrates if the confirmation measurement glucose value is below a selected threshold.

11. The system of claim 9, wherein the second subsystem utilizes temporal glucose information and other relevant information to aid in minimizing false alarms by determining the appropriate amount of delay since the latest glucose level measurement that confirms a non-hypoglycemic event before the first subsystem can start detecting hypoglycemic events again.

12. The system of claim 8, wherein an alarm is presented to the user at the expiration of the delay if the signal from the continuous glucose monitor indicates that the glucose value is still below the threshold value.

13. The system of claim 12, wherein the delay can be zero if the glucose measurement is below a low glucose threshold value.

14. A method for determining when to present a hypoglycemic alarm to a user of a continuous glucose monitor, comprising:

providing at least one timer to track the amount of time since one or more low glucose value thresholds have been passed;

providing signals from a continuous glucose monitor as an input to a processor controlling the operation of the at least one timer;

presenting a hypoglycemic alarm when the at least one timer has elapsed;

requesting a glucose level measurement to verify a hypoglycemic event;

utilizing glucose level measurements to determine whether the at least one timer should reset and start over;

utilizing continuous glucose measurements, knowledge of a meal, knowledge of insulin delivery, and other physiologically relevant information in order to determine the amount of time before the at least one timer can be reset and start detecting hypoglycemic events again since the last time a glucose level measurement confirms that the patient is no longer in a hypoglycemic state;

utilizing glucose level measurements to suggest corrective action such as taking rescue carbohydrates when the latest glucose level measurement confirms that the patient is in a hypoglycemic state;

wherein the processor operates in accordance with suitable programming and the input to determine if an alarm is to be presented to the user indicating that an actual hypoglycemic condition exists.

15. A method for determining when to present a hypoglycemic alarm to a user of a continuous glucose monitor, comprising:

providing a plurality timers to track the amount of time since one or more low glucose value thresholds have been passed;

providing signals from a continuous glucose monitor as a primary input to the system;

presenting a hypoglycemic alarm when any one of the plurality of timers has elapsed past its corresponding limit;

requesting a glucose level measurement to verify the hypoglycemic event;

utilizing glucose level measurements to confirm the predicted hypoglycemic event;

utilizing continuous glucose measurements, knowledge of a meal, knowledge of insulin delivery, and other physiologically relevant information in order to determine the amount of time before the plurality of timers can reset and start detecting hypoglycemic events again since the last time a glucose level measurement confirms that the patient is no longer in a hypoglycemic state;

wherein the system operates in accordance with suitable programming and the input to determine if an alarm is to be presented to the user indicating that an actual hypoglycemic condition exists.

16. A system for monitoring the glucose level of a user, comprising:

a continuous glucose monitor;

a processor configured to receive signals from the continuous glucose monitor and also adapted to analyze those signals in accordance with software commands, the software commands including commands to program at least a portion of the processor to operate as a state machine, the state machine having a first state when the signals from the continuous glucose monitor are used to predict threshold detection with minimal annunciation of a false alarm with respect to signal artifacts and a second state when the signals confirm the event prediction.

17. The system of claim 16, wherein the second state includes minimizing the false alarm with respect to signal artifacts by starting a timer to delay presentation of an alarm to the user, the delay determined by the glucose value.