Algorithm sensor augmented bolus estimator for semi-closed loop infusion system

• US 8,226,556 B2
• Filed: 05/06/2009
• Issued: 07/24/2012
• Est. Priority Date: 02/01/2005
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Hayes, Andrew C., Mastrototaro, John J., Moberg, Sheldon B., Mueller, John C. Jr., Clark, H. Bud, Tolle, Mike Charles Vallet, Williams, Gary L., Wu, Bihong, Steil, Garry M.
• Primary Examiner(s): Natnithithadha, Navin
• Application Number:
  US12/436,308
• Publication Number:
  US 20090234213A1
• Time in Patent Office: 1,175 Days
• Field of Search: 600/309, 600345-366, 604/65, 604/66
• US Class Current: 600/365
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/7239 using differentiation including higher order derivatives
• CPC Class Codes: A61M 2005/14208 with a programmable infusion control system, characterised by the infusion program
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/35 Communication
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• 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 40/63 for local operation
• CPC Class Codes: G16H 50/50 for simulation or modelling of medical disorders
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

An infusion system is for infusing a fluid into the body of a patient. The infusion system includes at least one sensor for monitoring blood glucose concentration of the patient and an infusion device for delivering fluid to the patient. The sensor produces at least one sensor signal input. The infusion device uses the at least one sensor signal input and a derivative predicted algorithm to determine future blood glucose levels. The infusion device delivers fluid to the patient when future blood glucose levels are in a patient'"'"'s target range. The infusion device is capable of suspending and resuming fluid delivery based on future blood glucose levels and a patient'"'"'s low shutoff threshold. The infusion device suspends fluid delivery when future blood glucose levels falls below the low shutoff threshold. The infusion device resumes fluid delivery when a future blood glucose level is above the low shutoff threshold.

Claims

1. An article of manufacture containing code for predicting blood glucose concentration of a patient, comprising a computer-usable medium including at least one embedded computer program that is capable of causing at least one computer to perform:

receiving at least one sensor signal input representative of current blood glucose concentration from a sensor;

inputting the at least one sensor signal input to a derivative predicted algorithm, wherein the derivative predicted algorithm utilizes at least one of current blood glucose concentration, meal carbohydrate content, sensor current sample at time period n, system calibration factor, and insulin-on-board at time period n;

determining future blood glucose concentration using the derivative predicted algorithm by calculating a first derivative of a sensor current sample from the at least one sensor signal input at time period n, and then calculating a first derivative of a sensor glucose value from the at least one sensor signal input using the first derivative of the sensor current sample; and

commanding an infusion device to perform a fluid delivery function based on the determined future blood glucose concentration.

2. The article of claim 1, wherein the article is the infusion device.

3. The article of claim 1, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

delivering fluid to the patient when the future blood glucose concentration is in a patient'"'"'s predefined target range.

4. The article of claim 3, wherein the fluid is insulin.

5. The article of claim 1, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

suspending and resuming fluid delivery based on the future blood glucose concentration and a patient'"'"'s predefined low shutoff threshold.

6. The article of claim 5, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

suspending fluid delivery when the future blood glucose concentration falls below the predefined low shutoff threshold.

7. The article of claim 5, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

resuming fluid delivery when the future blood glucose concentration is above the predefined low shutoff threshold.

8. The article of claim 5, wherein the predefined low shutoff threshold is always above the infusion device'"'"'s lowest shutoff threshold.

9. The article of claim 1, wherein the infusion device further includes an alarm to provide alerts to the patient.

10. The article of claim 9, wherein the patient selects at least one alarm to activate, wherein the at least one alarm includes an audible alarm for providing audible alerts, a vibration alarm for providing tactile alert, and a visual alarm for providing visual alerts.

11. The article of claim 1, wherein the article is a supplemental device from the infusion device.

12. The article of claim 1, wherein the first derivative of the sensor current sample is calculated from a slope of the sensor current sample versus time using a Savitzky-Golay finite impulse response filter.

13. An article of manufacture containing code for predicting blood glucose concentration of a patient, comprising a computer-usable medium including at least one embedded computer program that is capable of causing at least one computer to perform:

receiving at least one sensor signal input representative of current blood glucose concentration from a sensor;

inputting the at least one sensor signal input to a derivative predicted algorithm;

determining future blood glucose concentration using the derivative predicted algorithm by calculating a first derivative of a sensor current sample from the at least one sensor signal input at time period n, and then calculating a first derivative of a sensor glucose value from the at least one sensor signal input using the first derivative of the sensor current sample, wherein the first derivative of the sensor current sample is calculated from a slope of the sensor current sample versus time using a Savitzky-Golay finite impulse response filter; and

commanding an infusion device to perform a fluid delivery function based on the determined future blood glucose concentration.

14. The article of claim 13, wherein the article is the infusion device.

15. The article of claim 13, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

delivering fluid to the patient when the future blood glucose concentration is in a patient'"'"'s predefined target range.

16. The article of claim 15, wherein the fluid is insulin.

17. The article of claim 13, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

suspending and resuming fluid delivery based on the future blood glucose concentration and a patient'"'"'s predefined low shutoff threshold.

18. The article of claim 17, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

suspending fluid delivery when the future blood glucose concentration falls below the predefined low shutoff threshold.

19. The article of claim 17, wherein the computer-usable medium is capable of causing the at least one computer to further perform:

resuming fluid delivery when the future blood glucose concentration is above the predefined low shutoff threshold.

20. The article of claim 17, wherein the predefined low shutoff threshold is always above the infusion device'"'"'s lowest shutoff threshold.

21. The article of claim 13, wherein the infusion device further includes an alarm to provide alerts to the patient.

22. The article of claim 21, wherein the patient selects at least one alarm to activate, wherein the at least one alarm includes an audible alarm for providing audible alerts, a vibration alarm for providing tactile alert, and a visual alarm for providing visual alerts.

23. The article of claim 13, wherein the article is a supplemental device from the infusion device.

24. The article of claim 13, wherein the derivative predicted algorithm utilizes at least one of current blood glucose concentration, meal carbohydrate content, sensor current sample at time period n, system calibration factor, and insulin-on-board at time period n.