USABILITY FEATURES FOR INTEGRATED INSULIN DELIVERY SYSTEM

• US 20100295686A1
• Filed: 05/21/2010
• Published: 11/25/2010
• Est. Priority Date: 05/22/2009
• Status: Active Grant

• Current Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Original Assignee: Abbott Diabetes Care Incorporated (Abbott Laboratories Incorporated)
• Inventors: Sloan, Mark, Hayter, Gary A., Wei, Charles, Taub, Marc B., Harper, Wesley Scott, Budiman, Erwin S.
• Granted Patent: US 8,597,274 B2
• Time in Patent Office: Days
• US Class Current: 340/573.1
• 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 5/746 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 5/142 Pressure infusion, e.g. using pumps
• 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: G08B 21/0453 worn on the body to detect health condition by physiological monitoring, e.g. electrocardiogram, temperature, breathing detecting, measuring or recording for diagnostic purposes A61B5/00
• CPC Class Codes: G08B 21/182 Level alarms, e.g. alarms responsive to variables exceeding a threshold
• CPC Class Codes: G16H 20/17 delivered via infusion or injection
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders

Abstract

Various systems and methods for improving the usability of continuous glucose monitors and drug delivery pumps are described.

Claims

1. A method for determining a bolus volume to be administered to make up for a cessation of basal delivery of insulin, comprising:

determining an amount of insulin remaining in a user'"'"'s body such that

insulin remaining=amount of insulin delivered before cessation×

(user'"'"'s insulin action time minus the time since insulin was last delivered)/(user'"'"'s insulin action time); and

calculating a bolus delivery to equal the amount of basal delivery lost.

2. The method of claim 1, wherein determining an amount of insulin remaining includes using a model to estimate the amount of insulin remaining.

3. A method of determining an insulin delivery rate when a closed loop insulin delivery system terminates unexpectedly, comprising:

a) providing a glucose level and predicting a future glucose level in order to determine the appropriate insulin bolus for the latest control action, and assuming that this commanded is immediately followed by open loop control where the pre-programmed basal delivery amount will be in effect thereafter;

b) analyzing the future glucose level using this latest bolus value plus a future basal rate to determine if the future glucose level is acceptable, and if so, waiting for a selected period of time and repeating step a);

c) if the glucose level of step b) is not acceptable, computing an alternate maximum temporary basal delivery amount that is lower than the previously assumed basal rate, such that the predicted future glucose level is acceptable, and if so, providing a temporary basal command at the computed basal rate and duration, and predicting a future glucose level; and

if so, waiting for a selected period of time and repeating step a);

d) if the predicted future glucose level is unacceptable, projecting a future glucose level using the lowest temporary basal delivery rate computable in step c) and a maximum duration that is shorter than the maximum delivery duration, and, if the future glucose level is acceptable, providing a temporary basal command including the rate and duration of along with a nominal bolus command and then wait for a selected period of time and repeat step a); and

f) reducing the bolus command by minimum bolus resolution and repeat step a) such that the combination of the reduced bolus and a suitable temporary basal rate results in an acceptable predicted glucose profile if calculating a lower alternate temporary basal rate or a lower and shorter temporary basal rate does not result in an acceptable future glucose level.

4. The method of claim 3, further comprising alerting the user to take action to counter the effect of excessive insulin if an acceptable glucose profile cannot be obtained in step f) above.

5. A method for predicting insulin needs at a future time to avoid unwanted out of range alarms and adjusting current insulin delivery;

comprising;

providing a current glucose level;

providing a future time when a predicted glucose level is required;

determining the predicted level at the future time based upon the current glucose level, a value for insulin on board, current bolus parameters and current parameters defining an acceptable range of glucose levels; and

adjusting insulin delivery to maintain the glucose level in a target range.

6. A method for reducing false hypoglycemic alarms in a system under closed loop control;

comprising;

a) providing a current glucose level;

b) determining if the first level is below a threshold level and if so, providing a further glucose level at the expiration of a selected period of time;

c) determining if the glucose level taken after the expiration of the selected period of time is below the threshold level, and if so, alerting the user of a low glucose condition if the time between providing the two glucose levels is greater than a selected duration of time, and if not, repeating step c) until either the time since the current glucose level and the last further glucose level exceeds the selected duration of time or the last further glucose level is above the threshold level.

7. A method of adjusting glucose level alarm thresholds and alarm enunciation delay times in a system using CGM and insulin delivery system information, comprising:

using a model based state estimation, determining a predicted future glucose level and alert a user only if the predicted future glucose level falls outside of a predetermined acceptable range.

8. The method of claim 7, wherein the model based state estimation is a Kalman filter.

9. The method of claim 7, wherein the model based state estimation assesses the likelihood that a CGM measurement that exceeds a high or low threshold is due to a true event.

10. The method of claim 7, wherein the model based state estimation assesses the likelihood that a CGM measurement that exceeds a high or low threshold is due to a sensor artifact.

11. The method of claim 9, wherein the likelihood is determined by comparing the difference between the latest CGM measurement and interstitial glucose computed by the model prior to the latest CGM measurement.

12. The method of claim 11, further comprising adjusting the glucose alarm enunciation by adjusting the threshold level and duration in which the CGM measurement exceeds a given threshold before an alarm is enunciated.

13. The method of claim 12, wherein a decreasing CGM signal close to a low threshold alarm value that is not accompanied by a corresponding amount of insulin history will result in a low threshold alarm being made less sensitive by lowering the threshold value and/or increasing the duration of delay before the CGM signal results in enunciation of a low threshold alarm.

14. The method of claim 12, wherein a decreasing CGM signal close to a low threshold alarm value that is accompanied by an insulin history that should have generated a much lower CGM value than is measured results in a low threshold alarm being made more sensitive by increasing the threshold value and/or decreasing the duration of delay before the CGM signal results in the enunciation of a low threshold alarm.

15. The method of claim 12, wherein an increasing CGM signal close to a high threshold alarm value that is not accompanied by an appreciable amount of insulin history results in a high threshold alarm being made more sensitive by lowering the threshold value and/or decreasing the duration of delay before the CGM signal results in the enunciation of a high threshold alarm.

16. The method of claim 12, wherein an increasing CGM signal close to a high threshold alarm value that is accompanied by an appreciable amount of insulin history results in a high threshold alarm being made less sensitive by increasing the threshold value and/or increasing the duration of delay before the CGM signal results in the enunciation of a high threshold alarm.

17. A method of determining a latest insulin delivery amount and a temporary insulin delivery rate to be delivered when a closed loop insulin delivery system terminates unexpectedly, comprising:

a) providing a glucose level and predicting a future glucose level in order to determine the appropriate insulin amount for the latest control action, and assuming that this commanded is immediately followed by open loop control where the pre-programmed temporary basal rate will be in effect thereafter;

b) analyzing the future glucose level using this latest insulin amount plus a future temporary basal rate to determine if the future glucose level is acceptable, and if so, waiting for a selected period of time and repeating step a);

c) if the glucose level of step b) is not acceptable, computing an alternate maximum temporary basal delivery amount that is lower than the previously assumed basal rate, such that the predicted future glucose level is acceptable, and if so, providing a temporary basal command at the computed basal rate and duration, and predicting a future glucose level; and

if so, waiting for a selected period of time and repeating step a);

d) if the predicted future glucose level is unacceptable, projecting a future glucose level using the lowest temporary basal delivery rate computable in step c) and a maximum duration that is shorter than the maximum delivery duration, and, if the future glucose level is acceptable, providing a temporary basal command including the rate and duration of along with a nominal latest insulin delivery command and then wait for a selected period of time and repeat step a); and

f) reducing the latest insulin delivery command by a predetermined minimum insulin delivery resolution and repeat step a) such that the combination of the reduced latest insulin delivery amount and a suitable temporary basal rate results in an acceptable predicted glucose profile if calculating a lower alternate temporary basal rate or a lower and shorter temporary basal rate does not result in an acceptable future glucose level.