Method and apparatus for detecting occlusions in an ambulatory infusion pump

• US 9,364,608 B2
• Filed: 01/31/2014
• Issued: 06/14/2016
• 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): Lieu, Julie
• Application Number:
  US14/169,563
• Publication Number:
  US 20140148785A1
• Time in Patent Office: 865 Days
• Field of Search: None
• 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. A method of detecting an occlusion in an infusion pump having a drive mechanism that includes a motor and one or more drive train components coupled to a reservoir for delivering fluid from the reservoir through a fluid path into a body of a user, the method comprising:

taking a series of measurements of a parameter associated with the motor or one of the drive train components;

after each measurement in the series of measurements is taken, performing a comparison between the measurement taken and a calculated threshold value before taking the next measurement in the series of measurements; and

if the comparison indicates that the measurement taken is less than the calculated threshold value, determining that there is no occlusion, and delivering said fluid to the user'"'"'s body; and

wherein, if the comparison indicates that the measurement taken is greater than the calculated threshold value, then an additional measurement of said parameter is taken, up to a predetermined total number of measurements, and wherein, if the additional measurement is greater than the calculated threshold value and the predetermined total number of measurements has been reached, the method further includes;

(a) calculating a weighted average of the total number of measurements, (b) comparing the weighted average to a comparison value, and (c) determining whether an occlusion has occurred in the fluid path of the infusion pump by determining whether the weighted average is greater than the comparison value.

2. The method of claim 1, wherein the calculated threshold value is equal to N multiplied by a calculated conversion value, wherein N is less than 1.0.

3. The method of claim 1, further including activating an alarm if a determination is made that the weighted average is greater than the comparison value.

4. The method of claim 1, wherein said weighted average is calculated by applying a weighting factor to each measurement in the total number of measurements to determine a weighted value corresponding to each said measurement and calculating the average of the weighted values.

5. The method of claim 4, further including removing the highest weighted value and the lowest weighted value prior to calculating the average of the weighted values.

6. The method of claim 4, wherein the total number of measurements includes at least three measurements, and wherein the total number of measurements is filtered to remove at least two measurements before calculating the weighted values.

7. The method of claim 6, wherein the total number of measurements includes at least five measurements, and further including removing the highest weighted value and the lowest weighted value prior to calculating the average of the weighted values.

8. The method of claim 4, wherein each measurement after the first measurement in the total number of measurements is taken a predetermined time after the previous measurement.

9. The method of claim 4, wherein a different weighting factor is applied to each measurement in the total number of measurements to determine the weighted value corresponding to each said measurement.

10. The method of claim 1, further including determining a drive count value based on the motor drive count and calculating the comparison value based on the drive count value.

11. The method of claim 10, wherein the comparison value is calculated by multiplying the drive count value by a calculated conversion value.

12. The method of claim 11, wherein the calculated 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.

13. The method of claim 1, wherein the infusion pump includes a sensor to measure force.

14. The method of claim 1, wherein said parameter is motor drive count, and the infusion pump includes an encoder to measure the motor drive count.