Method and apparatus for detecting occlusions in an ambulatory infusion pump

• US 9,327,073 B2
• Filed: 03/16/2015
• Issued: 05/03/2016
• Est. Priority Date: 10/29/1998
• Status: Expired due to Fees

• Current Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Original Assignee: Medtronic Minimed Incorporated (Medtronic Plc)
• Inventors: Moberg, Sheldon B., Hanson, Ian B., Talbot, Cary D.
• Primary Examiner(s): LANDRY II, GERALD ERNEST
• Application Number:
  US14/659,411
• Publication Number:
  US 20150190573A1
• Time in Patent Office: 414 Days
• Field of Search: 604 65- 67, 604131-155, 604/890.1, 604/891.1
• US Class Current: 1/1
• CPC Class Codes: A61M 2005/14208 with a programmable infusion control system, characterised by the infusion program
• CPC Class Codes: A61M 2005/14264 with means for compensating influence from the environment
• CPC Class Codes: A61M 2005/16863 Occlusion detection
• CPC Class Codes: A61M 2005/31518 designed to reduce the overall size of an injection device, e.g. using flexible or pivotally connected chain-like rod members
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 2205/3331 Pressure; Flow
• CPC Class Codes: A61M 2205/70 with testing or calibration facilities
• CPC Class Codes: A61M 5/14216 Reciprocating piston type
• CPC Class Codes: A61M 5/14244 adapted to be carried by the patient, e.g. portable on the body
• CPC Class Codes: A61M 5/145 using pressurised reservoirs, e.g. pressurised by means of pistons
• CPC Class Codes: A61M 5/1452 pressurised by means of pistons
• CPC Class Codes: A61M 5/14566 with a replaceable reservoir for receiving a piston rod of the pump
• CPC Class Codes: A61M 5/1458 Means for capture of the plunger flange
• 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 5/16854 by monitoring line pressure
• 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

Abstract

An improved pump, reservoir and reservoir piston are provided for controlled delivery of fluids. A motor is operably coupled to a drive member, such as a drive screw, which is adapted to advance a plunger slide in response to operation of the motor. The plunger slide is removably coupled to the piston. A method, system, and an article of manufacture for automatically detecting an occlusion in a medication infusion pump is provided. The electrical current to an infusion pump is measured. Based on a series of measurements of one or more variables, the infusion pump detects whether there is an occlusion in the system.

Claims

1. An infusion pump for infusing fluid from a reservoir into a body of a user, the infusion pump comprising:

a housing;

a drive mechanism including a motor and one or more drive components contained within the housing and operatively coupled to the reservoir to deliver fluid from the reservoir through a fluid path into the body of the user;

one or more electronic components to take a series of measurements of a parameter associated with the motor or one of the drive train components; and

a controller contained within the housing, wherein the controller filters the series of measurements to remove at least one measurement from the series of measurements, calculates a weighted average of the remaining measurements in the series of measurements by applying a weighting factor to each remaining measurement in the series of measurements to determine a weighted value corresponding to each said remaining measurement and calculating the average of the weighted values, the weighting factor applied to each said remaining measurement after the first remaining measurement being larger than the weighting factor for the immediately preceding remaining measurement, compares the weighted average to a maximum threshold value, and determines whether an occlusion has occurred in the fluid path of the infusion pump by determining whether the weighted average is greater than the maximum threshold value.

2. The infusion pump of claim 1, wherein said at least one measurement is the highest measure in said series of measurements.

3. The infusion pump of claim 1, wherein said at least one measurement is the lowest measurement in said series of measurements.

4. The infusion pump of claim 1, wherein each measurement after the first measurement in the series of measurements is taken a predetermined time after the previous measurement.

5. The infusion pump of claim 1, further including an alarm configured to activate if a determination is made that the weighted average is greater than the maximum threshold value.

6. The infusion pump of claim 1, wherein the parameter associated with the motor is independently selected from the group consisting of pressure, delivery volume, force, drive current, drive voltage, motor drive time, motor coast time, delivery pulse energy, motor drive count, motor coast count, and delta encoder count.

7. The infusion pump of claim 1, wherein the parameter is force.

8. The infusion pump of claim 1, wherein the electronic components include a sensor to measure force.

9. The infusion pump of claim 1, wherein the electronic components include an encoder to measure motor drive count.

10. The infusion pump of claim 1, wherein the controller determines the drive count of the motor, determines a drive count value based on the drive count of the motor, and calculates the maximum threshold value based on the drive count value.

11. The infusion pump of claim 10, wherein the drive count value is X when the drive count of the motor is within a first range of drive counts, wherein the drive count value is Y when the drive count of the motor is within a second range of drive counts, wherein the drive counts within the first range are less than the drive counts within the second range, and wherein Y is less than X.

12. The infusion pump of claim 10, wherein the controller calculates the maximum threshold value by multiplying the drive count value by a predetermined conversion value.

13. The infusion pump of claim 12, wherein the predetermined conversion value is calculated from a formula including at least one factor selected from the group consisting of current, time of powering the motor, drive count, coast count, and standard deviation of force readings.

14. The infusion pump of claim 10, wherein the parameter is force, and wherein the infusion pump further includes an alarm configured to activate if a determination is made that the weighted average is greater than the maximum threshold value.

15. The infusion pump of claim 1, wherein after each measurement in the series of measurements is taken, the controller compares the measurement to a predetermined lower threshold value before the next measurement in the series of measurements is taken, and wherein if the comparison indicates that the measurement taken is less than the predetermined lower threshold value, the controller determines that there is no occlusion.

16. The infusion pump of claim 15, wherein the predetermined lower threshold value is equal to N multiplied by a predetermined conversion value, wherein N is less than 1.0.

17. The infusion pump of claim 1, wherein the one or more electronic components take said series of measurements prior to delivery of infusion fluid.

18. The infusion pump of claim 1, wherein the one or more electronic components take said series of measurements during delivery of infusion fluid.

19. The infusion pump of claim 1, wherein the one or more electronic components take said series of measurements after delivery of infusion fluid.

20. The infusion pump of claim 1, wherein the series of measurements includes at least three measurements.