MEANS AND METHOD FOR DETECTING FREE FLOW IN AN INFUSION LINE

• US 20140074030A1
• Filed: 09/06/2013
• Published: 03/13/2014
• Est. Priority Date: 09/08/2012
• Status: Active Grant

• Current Assignee: ICU Medical Incorporated
• Original Assignee: ICU Medical Incorporated
• Inventors: Hung, David Tseng Ho, Pih, David, Patil, Purushottam Amarnath, Wyatt, John Michael, DeFrank, Vincent James
• Granted Patent: US 9,468,718 B2
• Time in Patent Office: Days
• US Class Current: 604/152
• CPC Class Codes: A61M 2205/18 with alarm
• CPC Class Codes: A61M 2205/332 Force measuring means
• CPC Class Codes: A61M 2205/3365 Rotational speed
• 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

Abstract

A pump system and method of detecting/alerting for a possible unintended free flow condition in an administration set includes the steps of a) sampling force signals from a force sensor of the pump at a predetermined frequency; b) storing each of the sampled forces signal in a N-point circular buffer, where N is an integer greater than two; c) calculating a derivative dF/dt based on the two most recent samples; d) repeating step c) and when the most recently calculated derivative dF/dt exceeds a first predetermined threshold, then calculating a N-point moving average of the derivatives dF/dt; and f) when the N-point moving average exceeds a second predetermined threshold, generating a user perceptible alarm to alert the user that a flow stop open condition may have occurred.

Claims

1. An infusion pump comprising:

a pump chassis;

a pump mechanism controller supported by the pump chassis and including a processor and a memory;

a pump mechanism mounted on the pump chassis and including a plunger controlled by the pump mechanism controller;

a loader assembly including a carriage movably mounted to the pump chassis, the carriage having an opening formed thereon for receiving an administration set removably installable in the opening by a user, the administration set including a flexible membrane covering a portion of the administration set and a normally closed pivotable flow stop adjacent to the membrane covered portion, the carriage of the loader assembly being movable from

     1) a fully open position wherein the user can remove the administration set with clearance between the flow stop and the plunger, and

     2) a fully closed position wherein the membrane is engaged by the plunger to pump fluid through the administration set and the plunger is free from contact with the flow stop;

a plunger force sensor connected to the plunger for sending plunger force signals to the pump mechanism controller;

the memory including program code stored therein, the program code being executed by the processor to;

a) sample force signals from the plunger force sensor at a predetermined frequency;

b) store each of the sampled forces signal in a N-point circular buffer, where N is an integer greater than two;

c) calculate a derivative dF/dt based on the two most recent samples;

d) repeat step c) and when the most recently calculated derivative dF/dt exceeds a first predetermined threshold, then calculate a N-point moving average of the derivatives dF/dt;

e) when the N-point moving average exceeds a second predetermined threshold, generate a user perceptible alarm to alert the user that a plunger hit/flow stop open condition may have occurred.

2. The infusion pump of claim 1 wherein the user perceptible alarm is generated on a display screen on the pump.

3. A method of detecting and alerting for a possible unintended free flow condition in an administration set for intravenous medical fluids while the administration set is being removed from an infusion pump, the method comprising the steps of:

a. sampling force signals from a force sensor of the pump at a predetermined frequency;

b. storing each of the sampled forces signal in a N-point circular buffer, where N is an integer greater than two;

c. calculating a derivative dF/dt based on the two most recent samples;

d. repeating step c) and when the most recently calculated derivative dF/dt exceeds a first predetermined threshold, then calculating a N-point moving average of the derivatives dF/dt;

e. when the N-point moving average exceeds a second predetermined threshold, generating a user perceptible alarm to alert the user that a flow stop open condition may have occurred.