CLOSED-LOOP GLUCOSE AND/OR INSULIN CONTROL SYSTEM

• US 20100324382A1
• Filed: 06/17/2009
• Published: 12/23/2010
• Est. Priority Date: 06/17/2009
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Steil, Garry M., Cantwell, Martin, Clark, H. Bud
• Granted Patent: US 9,687,194 B2
• Time in Patent Office: Days
• US Class Current: 600/316
• CPC Class Codes: A61B 2560/0276 Determining malfunction
• 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: A61M 2005/14208 with a programmable infusion control system, characterised by the infusion program
• CPC Class Codes: A61M 2005/1581 Right-angle needle-type devices
• CPC Class Codes: A61M 2205/3569 sublocal, e.g. between console and disposable
• CPC Class Codes: A61M 2205/3592 using telemetric means, e.g. radio or optical transmission
• CPC Class Codes: A61M 2230/201 Glucose concentration
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/1723 using feedback of body parameters, e.g. blood-sugar, pressure measurement of body parameters A61B5/00

Abstract

Disclosed are a method and/or system for determining a suggested change in a recommended therapy for a patient based, at least in part, on sensor measurements, and generating an alert to an attendant in a hospital environment upon detection of the suggested change. In another embodiment, a method and/or system is directed to automatically determining a maximum interval to alert an attendant following receipt of a measurement at an operator interface. In yet another embodiment, a method and/or system is directed to blood-glucose sensor calibration.

Claims

1. A method comprising:

determining a recommended therapy for a patient derived from signals representative of blood-glucose sensor measurements; and

generating a signal to initiate an alarm to an attendant in response to detection of a suggested change in said recommended therapy based, at least in part, on signals representative of subsequent blood-glucose sensor measurements.

2. The method of claim 1, wherein said recommended therapy comprises infusion of insulin in said patient at a set infusion rate.

3. The method of claim 2, wherein and further comprising:

calculating an insulin infusion rate based, at least in part, on a PID command associated with said subsequent command cycle; and

establishing a new insulin infusion rate for said subsequent command cycle as said calculated infusion rate if a difference between an insulin infusion rate in a current command cycle and said calculated infusion rate exceed a predetermined threshold.

4. The method of claim 1, and further comprising:

forecasting a blood-glucose level in said patient in a subsequent command cycle; and

determining said suggested change commencing in said subsequent command cycle based, at least in part, on said forecasted blood-glucose level.

5. The method of claim 4, and further comprising:

determining a PID command associated with said subsequent command cycle;

determining a rate of insulin infusion for said suggested change in said recommended therapy based, at least in part, on said PID command if said forecasted blood glucose level exceeds a predetermined threshold blood glucose level.

6. The method of claim 1, wherein said recommended therapy comprises an infusion of a bolus of glucose.

7. The method of claim 6, and further comprising determining a size of said bolus based, at least in part, on the magnitude of at least one PID command associated with a command cycle.

8. The method of claim 6, and further comprising:

forecasting a blood-glucose level in said patient in a subsequent command cycle; and

selectively providing a command for infusion of a bolus of glucose based, at least in part, on a PID command associated with said subsequent command cycle if said forecasted blood-glucose level does not exceed a threshold blood glucose level.

9. The method of claim 1, and further comprising:

determining at least one current PID command based, at least in part, on blood-glucose sensor measurements processed in a current command cycle; and

determining at least one subsequent PID commands based, at least in part, on blood-glucose sensor measurements processed in a subsequent command cycle.

10. The method of claim 9, and further comprising detecting said suggested change in said recommended therapy based, at least in part, on said at least one PID command.

11. The method of claim 9, wherein at least one component of said at least one PID command comprises a derivative component, the method further comprising:

determining a blood glucose derivative based, at least in part, on values of blood glucose sensor measurements obtained at times separated by a sample interval; and

limiting said sample value to a predetermined minimum sample value.

12. The method of claim 9, wherein at least one component of said at least one PID command comprises an integral component, the method further comprising:

integrating a difference between an estimated blood glucose and a target blood glucose over an integration interval; and

limiting the integration interval to a predetermined maximum integration interval.

13. The method of claim 1, wherein said determining and said generating are performed by one or more processors programmed with instructions to perform said determining and said generating.

14. The method of claim 1, wherein said recommended therapy comprises a continuous infusion of glucose.

15. An apparatus comprising:

means for determining a recommended therapy for a patient derived from signals representative of blood-glucose sensor measurements; and

means for generating a signal to initiate an alarm to an attendant in response to detection of a suggested change in said recommended therapy based, at least in part, on signals representative of subsequent blood-glucose sensor measurements.

16. The apparatus of claim 15, wherein said recommended therapy comprises infusion of insulin in said patient at a set infusion rate.

17. The apparatus of claim 16, wherein and further comprising:

means for calculating an insulin infusion rate based, at least in part, on a PID command associated with said subsequent command cycle; and

means for establishing a new insulin infusion rate for said subsequent command cycle as said calculated infusion rate if a difference between an insulin infusion rate in a current command cycle and said calculated infusion rate exceed a predetermined threshold.

18. The apparatus of claim 15, and further comprising:

means for forecasting a blood-glucose level in said patient in a subsequent command cycle; and

means for determining said suggested change commencing in said subsequent command cycle based, at least in part, on said forecasted blood-glucose level.

19. The apparatus of claim 18, and further comprising:

means for determining a PID command associated with said subsequent command cycle;

means for determining a rate of insulin infusion for said suggested change in said recommended therapy based, at least in part, on said PID command if said forecasted blood glucose level exceeds a predetermined threshold blood glucose level.

20. The apparatus of claim 15, wherein said recommended therapy comprises an infusion of a bolus of glucose.

21. The apparatus of claim 20, and further comprising means for determining a size of said bolus based, at least in part, on the magnitude of at least one PID command associated with a command cycle.

22. The apparatus of claim 20, and further comprising:

means for forecasting a blood-glucose level in said patient in a subsequent command cycle; and

means for selectively providing a command for infusion of a bolus of glucose based, at least in part, on a PID command associated with said subsequent command cycle if said forecasted blood-glucose level does not exceed a threshold blood glucose level.

23. The apparatus of claim 15, and further comprising:

means for determining at least one current PID command based, at least in part, on blood-glucose sensor measurements processed in a current command cycle; and

means for determining at least one subsequent PID commands based, at least in part, on blood-glucose sensor measurements processed in a subsequent command cycle.

24. The apparatus of claim 23, and further comprising means for detecting said suggested change in said recommended therapy based, at least in part, on said least one PID command.

25. The apparatus of claim 23, wherein at least one component of said at least one PID command comprises a derivative component, the apparatus further comprising:

means for determining a blood glucose derivative based, at least in part, on values of blood glucose sensor measurements obtained at times separated by a sample interval; and

means for limiting said sample value to a predetermined minimum sample value.

26. The apparatus of claim 23, wherein at least one component of said at least one PID command comprises an integral component, the apparatus further comprising:

means for integrating a difference between an estimated blood glucose and a target blood glucose over an integration interval; and

means for limiting the integration interval to a predetermined maximum integration interval.

27. The apparatus of claim 15, wherein said recommended therapy comprises a continuous infusion of glucose.

28. An apparatus comprising:

one or more blood-glucose sensors adapted to be coupled to a patient to obtain blood-glucose sensor measurements; and

a controller coupled to said one or more blood-glucose sensors to receive one or more signals representative of said blood-glucose sensor measurements, said controller being adapted to;

determine a recommended therapy for a patient derived from blood-glucose sensor measurements; and

initiate an alarm to an attendant in response to detection of a suggested change in said recommended therapy based, at least in part, on subsequent blood-glucose sensor measurements obtained from said blood-glucose sensor.

29. An article comprising:

a storage medium comprising machine-readable instructions stored thereon which, if executed by a special purpose processor, are adapted to direct said special purpose processor to;

determine a recommended therapy for a patient derived from signals representative of blood-glucose sensor measurements; and

generate a signal to initiate an alarm to an attendant in response to detection of a suggested change in said recommended therapy based, at least in part, on signals representative of subsequent blood-glucose sensor measurements.

30. A method comprising:

receiving a signal representative of a measurement value entered at an operator interface; and

executing instructions on a special purpose computing apparatus to determine a maximum interval to alert an operator following said receipt of signal representative of said measurement value.

31. The method of claim 30, wherein said maximum interval is based, at least in part, on said measurement value.

32. The method of claim 30, and further comprising executing said instructions on said special purpose computing apparatus to determine said maximum interval based, at least in part, on a signal representative of measured rate of change in blood glucose of a patient.

33. The method of claim 30, and further comprising:

receiving signals representative of blood glucose sensor measurements from a patient subsequent to receipt of said signal representative of said measurement value; and

further executing said instructions on said special purpose computing apparatus to;

determine one or more PID commands based, at least in part, on said blood glucose sensor measurements; and

determine said maximum interval based, at least in part, on said one or more PID commands.

34. The method of claim 30, and further comprising executing said instructions on said special purpose computing apparatus to:

determine said maximum interval based, at least in part, on whether a glucose bolus was infused to a patient contemporaneously with receipt of said signal representative of said measurement.

35. The method of claim 30, and further comprising further executing said instructions on said special purpose computing apparatus to determine said maximum interval based, at least in part, on one or more signals representative of a measured rate of change in blood glucose of a patient.

36. The method of claim 30, wherein said entered measurement value comprises a blood glucose sample measurement value.

37. An apparatus comprising:

means for receiving an operator entered measurement value; and

means for determining a maximum interval to alert said operator following said receipt of said measurement.

38. An apparatus comprising:

an operator interface to receive an operator entered measurement value; and

a controller to determine a maximum interval to alert said operator following said receipt of said measurement value.

39. An article comprising:

a storage medium comprising machine-readable instructions stored thereon which, if executed by a special purpose computing apparatus, are adapted to direct said special purpose computing apparatus to;

obtain signal representative of a measurement value entered to an operator interface; and

determine a maximum interval to alert said operator following said receipt of said signal representative of said measurement value.

40. A method comprising:

determining a function for estimating a blood-glucose concentration based, at least in part, on one or more signals representative of a plurality of blood-glucose reference measurements, said function to determine estimates of said blood-glucose concentration based on sensor signal values; and

selectively determining a y-intercept offset of said function as either a predetermined constant or a calculated value, said calculated value being determined based, at least in part, on a relationship between at least one blood-glucose reference measurement and one or more signals representative of at least one sensor measurement value.

41. The method of claim 40, and further comprising selectively determining said y-intercept as either said predetermined constant or calculated value based, at least in part, on a number of blood-glucose reference measurements obtained over a set time period.

42. The method of claim 40, and further comprising selecting said calculated value as said y-intercept offset if at least one of the following conditions are present:

at least one of said blood-glucose reference measurements is in a range of about 80.0 to 150.0 mg/dl;

a correlation of blood-glucose reference measurements is at least 0.9;

or

the difference between maximum and minimum blood-glucose reference samples is at least 50 ml/dl and at least 50% of said minimum blood-glucose reference samples.

43. An apparatus comprising:

means for determining a function for estimating a blood-glucose concentration based, at least in part, on a plurality of blood-glucose reference measurements, said function to determine estimates of said blood-glucose concentration based on sensor signal values; and

means for selectively determining a y-intercept offset of said function as either a predetermined constant or a calculated value, said calculated value being determined based, at least in part, on a relationship between at least one blood-glucose reference measurement and at least one sensor signal value.

44. An apparatus comprising:

one or more blood-glucose sensors coupled to a patient to obtain blood-glucose sensor measurements; and

a controller coupled to said one or more blood-glucose sensors to receive signals representative of said blood-glucose sensor measurements, said controller being adapted to;

determine a function for estimating a blood-glucose concentration in said patient based, at least in part, on a plurality of blood-glucose reference measurements, said function to determine estimates of said blood-glucose concentration based on said received signals, said received signals comprising sensor signal values; and

selectively determine a y-intercept offset of said function as either a predetermined constant or a calculated value, said calculated value being determined based, at least in part, on a relationship between at least one blood-glucose reference measurement and at least one sensor signal value.