Methods for reducing false hypoglycemia alarm occurrence

Patent metadata

Field	Value
Publication number	US-9579456-B2
Application number	US-78498110-A
Country	US
Kind code	B2
Filing date	May 21, 2010
Priority date	May 22, 2009
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

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.

First claim

We claim:

1. An electronic analyte monitoring system comprising:
an electronic analyte monitor comprising an implantable analyte sensor;
a processor configured to receive a signal from the electronic analyte monitor indicative of an analyte level obtained from the implantable analyte sensor, wherein the signal can indicate the analyte level as falsely low, the processor also adapted to recursively analyze the signal in accordance with one or more software commands, the one or more software commands programming at least a portion of the processor to operate as a state machine with states comprising:
a no hypoglycemia confirm state during which the analyte level is compared to a first threshold, the no hypoglycemia confirm state having a predetermined time delay for activation of an alarm where a duration of the predetermined time delay is dependent on a value of the analyte level, wherein the predetermined time delay is initiated if the analyte level is below the first threshold and, after being initiated, the predetermined time delay is reset if the analyte level rises above the first threshold and the predetermined time delay has not yet expired; and
a confirm hypoglycemia state that is entered if the analyte level is below the first threshold after expiration of the predetermined time delay, the confirm hypoglycemia state causing generation of the alarm; and

wherein the processor is further coupled to a memory on which instructions are stored, wherein the instructions, when executed by the processor, cause the processor to transmit a command to cause adjustment of a medication delivery rate when there is a confirm hypoglycemia state.

2. The system of claim 1 , wherein the duration of the predetermined time delay is a first length when the analyte level is below the first threshold and above a second threshold.

3. The system of claim 2 , wherein the duration of the predetermined time delay is a second length when the analyte level is below the second threshold, the second length being less than the first length.

4. The system of claim 3 , wherein the state machine further comprises:
a confirm severe hypoglycemia state that is entered when the analyte level is below a third threshold that is less than the second threshold and indicative of severe hypoglycemia, the confirm severe hypoglycemia state causing generation of the alarm.

5. The system of claim 2 , wherein the predetermined time delay is a first predetermined time delay and, if the duration of the first predetermined time delay is set to the first length and the analyte level falls below the second threshold, the no hypoglycemia confirm state initiates a second predetermined time delay having a second length that is less than the first length, and
wherein the confirm hypoglycemia state is also entered if the analyte level is below the second threshold after expiration of the second predetermined time delay, the confirm hypoglycemia state causing generation of the alarm.

6. The system of claim 5 , wherein if the confirm hypoglycemia state is entered thereby causing generation of the alarm, all predetermined time delays that have not yet expired are reset.

7. The system of claim 1 , wherein generation of the alarm occurs with display of a first message to the user to perform a blood glucose measurement.

8. The system of claim 7 , wherein the state machine further comprises:
a blood analyte level check state that receives a blood analyte level measurement and determines whether a hypoglycemic condition is present and, if so, displays a second, corresponding message to the user.

9. The system of claim 8 , wherein the second message to the user recommends administration of rescue carbohydrates.

10. A method for determining when to adjust a medication delivery rate and to present a hypoglycemic alarm to a user of an electronic analyte monitoring system comprising an electronic analyte monitor, an implanted analyte sensor of the electronic analyte monitor, and a processor device adapted to recursively analyze a signal from the electronic analyte monitor in accordance with one or more software commands, wherein the signal can indicate an analyte level that is falsely low, and wherein the one or more software commands program at least a portion of the processor device to operate as a state machine with states comprising a no hypoglycemia confirm state and a confirm hypoglycemia state, the method comprising:
sensing an analyte level with the implanted analyte sensor of the electronic analyte monitor;
receiving, by the processor device, the signal from the electronic analyte monitor, wherein the signal is indicative of the analyte level obtained from the implanted analyte sensor;
comparing, by the processor device in the no hypoglycemia confirm state, the analyte level to a first threshold,
initiating, by the processor device in the no hypoglycemia confirm state, a predetermined time delay for activation of an alarm if the analyte level is below the first threshold, wherein a duration of the predetermined time delay is dependent on a value of the analyte level;
resetting, by the processor device in the no hypoglycemia confirm state, the predetermined time delay if the analyte level rises above the first threshold and the predetermined time delay has not yet expired;
causing generation of the hypoglycemic alarm, by the processor device in the confirm hypoglycemia state, if the analyte level is below the first threshold after expiration of the predetermined time delay; and
transmitting a command to cause an adjustment of a medication delivery rate when there is a confirm hypoglycemia state.

11. The method of claim 10 , wherein the state machine further comprises a confirm severe hypoglycemia state and the method further comprises:
causing generation of the alarm, by the processor device in the confirm severe hypoglycemia state, if the analyte level is below a second threshold that is less than the first threshold and indicative of severe hypoglycemia.

12. The method of claim 10 , wherein the duration of the predetermined time delay is a first length when the analyte level is below the first threshold and above a second threshold.

13. The method of claim 12 , wherein the duration of the predetermined time delay is a second length when the analyte level is below the second threshold, the second length being less than the first length.

14. The method of claim 13 , wherein the state machine further comprises a confirm severe hypoglycemia state and the method further comprises:
causing generation of the alarm, by the processor device in the confirm severe hypoglycemia state, if the analyte level is below a third threshold that is less than the second threshold and indicative of severe hypoglycemia.

15. The method of claim 12 , wherein the predetermined time delay is a first predetermined time delay and the method further comprises:
initiating, by the processor device in the no hypoglycemia confirm state, a second predetermined time delay having a second length that is less than the first length, the second predetermined time delay being initiated if the duration of the first predetermined time delay is set to the first length and the analyte level falls below the second threshold; and
causing generation of the alarm, by the processor device in the confirm hypoglycemia state, if the analyte level is below the second threshold after expiration of the second predetermined time delay.

16. The method of claim 15 , comprising:
if the alarm is caused to be generated by the processor device in the confirm hypoglycemia state, then resetting, by the

Assignees

• Budiman Erwin S
• Hayter Gary A
• Taub Marc B
• Hovorka Roman
• Wilinska Malgorzata
• Dunger David
• Abbott Diabetes Care Inc
• Cambridge Entpr Ltd

Inventors

• Budiman Erwin S
• Hayter Gary A
• Taub Marc B
• Hovorka Roman
• Wilinska Malgorzata
• Dunger David

Classifications

• G06F19/345

  Physics · mapped topic

• A61M2005/14296

  Pharmacokinetic models · CPC title

• A61B5/7275

  Determining trends in physiological measurement data; Predicting development of a medical condition based on physiological measurements, e.g. determining a risk factor · CPC title

• A61M5/1723 Primary

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

• G06F19/3468

  Physics · mapped topic