OCCLUSION DETECTION FOR A FLUID INFUSION DEVICE

• US 20120160033A1
• Filed: 09/02/2011
• Published: 06/28/2012
• Est. Priority Date: 12/22/2010
• Status: Active Grant

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: KOW, Hsiao-Yu S., BAZARGAN, Afshin, VAZQUEZ, Pablo, HANSON, Ian B., ALDERETE, Juan M. Jr., MONIRABBASI, Salman
• Granted Patent: US 8,469,942 B2
• Time in Patent Office: Days
• US Class Current: 73/861.71
• CPC Class Codes: A61M 2005/16863 Occlusion detection
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 5/14 Infusion devices, e.g. infusing by gravity; Blood infusion; Accessories therefor
• CPC Class Codes: A61M 5/142 Pressure infusion, e.g. using pumps
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: A61M 5/16831 Monitoring, detecting, signalling or eliminating infusion flow anomalies low-level float-valves causing cut-off A61M5/40; indicating or recording presence, absence or direction of flow in general G01P13/0066
• CPC Class Codes: A61M 5/172 electrical or electronic A61M5/16804, A61M5/16831 take precedence
• CPC Class Codes: A61M 5/5086 for indicating if defective, used, tampered with or unsterile
• CPC Class Codes: G01F 13/00 Apparatus for measuring by volume and delivering fluids or fluent solid materials, not provided for in the preceding groups
• CPC Class Codes: G01L 1/26 Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload

Abstract

A device for delivering fluid to a user includes a housing, a drive motor assembly in the housing, a force sensor, and an electronics module. The drive motor assembly regulates delivery of fluid by actuating a piston of a fluid reservoir, and the force sensor generates output levels in response to force imparted thereto during, for example, fluid delivery operations. The electronics module processes the output levels of the force sensor to assess the operating health of the force sensor, to check for occlusions in the fluid delivery path, and to monitor the seating status of the fluid reservoir.

Claims

1. In a fluid infusion device comprising a drive motor assembly and a force sensor associated with the drive motor assembly, a method of detecting occlusions in a fluid path of the fluid infusion device, the method comprising:

determining a plurality of force measurements for a fluid delivery action of the drive motor assembly, the plurality of force measurements indicating measures of actuation force imparted to the force sensor for the fluid delivery action;

determining a plurality of quantity measurements for the fluid delivery action, each of the plurality of quantity measurements being determined relative to a reference quantity measurement;

indicating an occlusion when a first slope of force-versus-quantity for a large sample of the plurality of quantity measurements is greater than or equal to a first threshold slope value; and

indicating an occlusion when both;

(a) a second slope of force-versus-quantity for a small sample of the plurality of quantity measurements is greater than or equal to a second threshold slope value; and

(b) a current one of the plurality of force measurements is greater than or equal to a threshold force value.

2. The method of claim 1, wherein each of the plurality of quantity measurements corresponds to a respective one of the plurality of force measurements.

3. The method of claim 1, wherein the first threshold slope is greater than the second threshold slope.

4. The method of claim 1, further comprising the step of initiating corrective action for the fluid infusion device when an occlusion is indicated.

5. The method of claim 4, wherein initiating corrective action comprises generating a user alert at the fluid infusion device.

6. The method of claim 1, further comprising the steps of:

initiating the fluid delivery action;

determining an initial force measurement that indicates an initial measure of actuation force imparted to the force sensor; and

indicating an occlusion when the initial force measurement is greater than an initial force limit, wherein the initial force limit is greater than the threshold force value.

7. The method of claim 1, wherein each of the plurality of force measurements is determined by averaging a number of actuation force measures sampled while the drive motor assembly is stationary.

8. The method of claim 1, wherein:

each of the plurality of quantity measurements indicates a volume of fluid dispensed from a fluid reservoir of the fluid infusion device;

the large sample corresponds to a predefined large volume reference; and

the small sample corresponds to a predefined small volume reference.

9. The method of claim 1, further comprising the step of calculating the first slope based upon:

the current one of the plurality of force measurements;

a current one of the plurality of quantity measurements, corresponding to the current one of the plurality of force measurements;

a previous one of the plurality of force measurements; and

a previous one of the plurality of quantity measurements, corresponding to the previous one of the plurality of force measurements.

10. The method of claim 9, further comprising the step of calculating the second slope based upon:

the current one of the plurality of force measurements;

the current one of the plurality of quantity measurements;

an intervening one of the plurality of force measurements; and

an intervening one of the plurality of quantity measurements, corresponding to the intervening one of the plurality of force measurements, wherein the intervening one of the plurality of force measurements is determined after determining the previous one of the plurality of force measurements, and wherein the intervening one of the plurality of quantity measurements is determined after determining the previous one of the plurality of quantity measurements.

11. The method of claim 1, wherein size of the large sample of the plurality of quantity measurements varies as a function of the current one of the plurality of force measurements.

12. The method of claim 1, wherein size of the small sample of the plurality of quantity measurements varies as a function of the current one of the plurality of force measurements.

13. The method of claim 1, wherein the first threshold slope value varies as a function of the current one of the plurality of force measurements.

14. The method of claim 1, wherein the second threshold slope value varies as a function of the current one of the plurality of force measurements.

15. A method of detecting occlusions in a fluid path of a fluid infusion device having a drive motor assembly that actuates a piston of a fluid reservoir to deliver fluid from the fluid reservoir, the method comprising:

initiating a fluid delivery action to deliver an amount of fluid from the fluid reservoir;

determining, for each of a plurality of measurement points associated with the fluid delivery action, a respective measurement of a quantity that is indicative of pressure in the fluid path, along with a respective delivered volume measurement relative to a reference volume measurement;

calculating a first slope based upon a current measurement of the quantity, a previous measurement of the quantity, a current delivered volume measurement corresponding to the current measurement of the quantity, and a previous delivered volume measurement corresponding to the previous measurement of the quantity;

calculating a second slope based upon the current measurement of the quantity, an intervening measurement of the quantity that is determined after determining the previous measurement of the quantity, the current delivered volume measurement, and an intervening delivered volume measurement corresponding to the intervening measurement of the quantity; and

indicating whether an occlusion has occurred by using the first slope and the second slope.

16. The method of claim 15, wherein the indicating step determines that the occlusion has occurred when the first slope is greater than or equal to a first threshold slope value.

17. The method of claim 16, wherein the indicating step determines that the occlusion has occurred when both:

(a) the second slope is greater than or equal to a second threshold slope value; and

(b) the current measurement of the quantity is greater than or equal to a threshold value of the quantity.

18. The method of claim 17, wherein the first threshold slope is greater than the second threshold slope.

19. The method of claim 15, further comprising the step of initiating corrective action for the fluid infusion device when the indicating step determines that the occlusion has occurred.

20. The method of claim 15, wherein:

the quantity is associated with an actuation force of the piston; and

the determining step determines a respective force measurement for each of the plurality of measurement points.

21. A method of detecting occlusions in a fluid path of a fluid infusion device having a drive motor assembly that actuates a fluid reservoir by applying actuation force to a piston of the fluid reservoir, the method comprising:

initiating a fluid delivery action intended to deliver an amount of fluid from the fluid reservoir;

determining measures of fluid pressure in the fluid path for the fluid delivery action;

indicating an occlusion when a first rate of change of the measures of fluid pressure is greater than or equal to first threshold value, the first rate of change based upon a first measurement window; and

indicating an occlusion when both;

(a) a second rate of change of the measures of fluid pressure is greater than or equal to a second threshold value, the second rate of change based upon a second measurement window; and

(b) a current measure of fluid pressure is greater than or equal to a threshold force value.

22. The method of claim 21, wherein:

the first measurement window represents a first delivered volume, relative to a reference volume; and

the second measurement window represents a second delivered volume, relative to the reference volume.

23. The method of claim 22, wherein the first delivered volume is greater than the second delivered volume.

24. The method of claim 21, wherein:

the first measurement window represents a first delivery time, relative to a reference time;

the second measurement window represents a second delivery time, relative to the reference time; and

the first delivery time is longer than the second delivery time.

25. The method of claim 21, wherein the first threshold value is greater than the second threshold value.

26. The method of claim 21, further comprising the step of initiating corrective action for the fluid infusion device when an occlusion is indicated.

27. A device for delivering fluid to a user, the device comprising:

a housing;

a reservoir cavity within the housing to accommodate fluid reservoirs;

a drive motor assembly in the housing to regulate delivery of fluid by actuating a piston of a fluid reservoir;

a force sensor associated with the drive motor assembly to generate output levels in response to force imparted thereto; and

an electronics module coupled to the force sensor to process the output levels to detect occlusions in a fluid path of the device for a fluid delivery action by;

indicating an occlusion when a first rate of change of the output levels is greater than or equal to a first threshold value, the first rate of change based upon a first measurement window; and

indicating an occlusion when both;

(a) a second rate of change of the output levels is greater than or equal to a second threshold value, the second rate of change based upon a second measurement window; and

(b) a current output level is greater than or equal to a threshold output level.

28. The device of claim 27, wherein each of the output levels represents a measure of actuation force imparted to the force sensor during the fluid delivery action.

29. The device of claim 27, wherein:

the electronics module determines, for each of a plurality of measurement points during the fluid delivery action, a respective output level, along with a respective delivered volume measurement relative to a reference volume measurement;

the electronics module calculates the first rate of change of the output levels based upon the current output level, a previous output level, a current delivered volume measurement corresponding to the current output level, and a previous delivered volume measurement corresponding to the previous output level; and

the electronics module calculates the second rate of change based upon the current output level, an intervening output level that is determined after determining the previous output level, the current delivered volume measurement, and an intervening delivered volume measurement corresponding to the intervening output level.

30. The device of claim 27, wherein the first threshold value is greater than the second threshold value.

31. The device of claim 27, wherein the electronics module initiates corrective action for the fluid infusion device when an occlusion is detected.