Means and method for detecting free flow in an infusion line
First Claim
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 force signals in a four point circular buffer;
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 four point moving average of the derivatives dF/dt;
e) when the four 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; and
wherein the program code is executed by the processor while the carriage of the loader assembly is moving between the fully closed position and the fully open position.
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Accused Products
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.
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Citations
3 Claims
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1. An infusion pump, comprising:
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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 force signals in a four point circular buffer; 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 four point moving average of the derivatives dF/dt; e) when the four 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; and wherein the program code is executed by the processor while the carriage of the loader assembly is moving between the fully closed position and the fully open position. - View Dependent Claims (2)
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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:
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a. sampling force signals from a force sensor of the pump at a predetermined frequency; b. storing each of the sampled force signals in a four point circular buffer; 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 four point moving average of the derivatives dF/dt; e. when the four 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; wherein the steps start after an administration set receiving carriage of an automated loader assembly of the infusion pump begins to move away from a fully closed position and are completed before arrival of the carriage of the automated loader assembly at a fully open position.
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Specification