Infusion Pump Air-in-Line Detection Using Bolus Flow
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Solution Overview
Problem
Existing medical infusion pumps often trigger false air-in-line alarms due to micro-bubbles formed when nutritional liquids are vigorously shaken, leading to potential disruptions in fluid delivery.
Innovation Solution
The infusion pump system includes a microprocessor and memory module that detect air-in-line conditions and respond by delivering a bolus volume of fluid at a higher flow rate to clear micro-bubbles, followed by compensation to maintain the therapy flow rate, without altering the pump or sensor hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an air-in-line sensor is used to detect air bubbles in the fluid delivery line, then patient safety is improved by detecting real air-in-line conditions, but false alarms are generated when micro-bubbles from shaken nutritional liquids accumulate at the sensor
Solution Approach 1:
The system performs preliminary analysis of air detection patterns by tracking the duration and frequency of air-in-line sensor activations. When micro-bubbles are detected (short-duration activations), the system preemptively delivers a bolus volume of fluid at a higher flow rate to clear the bubbles before they can accumulate and trigger a false alarm, while maintaining accurate detection of genuine air-in-line conditions through continuous monitoring
2Use of energy by moving object
If the pump delivers fluid in discrete time segments with the motor on and off, then energy consumption is reduced, but micro-bubbles have time to float upstream and gather at the air-in-line sensor causing false alarms
Solution Approach 1:
The system uses feedback from the air-in-line sensor to monitor fluid flow conditions in real-time. When micro-bubbles are detected during the motor-off periods, the system responds by delivering a bolus volume at a higher flow rate to clear the bubbles, then compensates by reducing the flow rate in subsequent segments to maintain the prescribed therapy flow rate, thus eliminating false alarms while preserving energy-efficient discrete segment operation
Solution Approach 2:
The system dynamically changes flow rate parameters in response to detected micro-bubbles. When micro-bubbles are detected, the flow rate is temporarily increased to a bolus flow rate to clear the bubbles, then adjusted downward to compensate for the excess volume delivered, maintaining the prescribed therapy flow rate over time while preventing false alarm conditions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces false alarms and ensures consistent fluid delivery by addressing micro-bubble accumulation at the air-in-line sensor, thereby preventing unnecessary interruptions in treatment.
Implementation Method 1
the air-in-line sensor may include an ultrasonic transmitter arranged to direct ultrasound through the tubing and a receiver on an opposite side of the tubing from the transmitter for receiving the ultrasound waves after passage through the tubing and the fluid carried thereby
Implementation Method 2
The peristaltic pump has a pumping mechanism for progressively squeezing successive portions of the tubing to cause fluid to flow through the tubing in a flow direction toward the patient
Implementation Method 3
Due to gravity, air micro-bubbles caused by shaking may float upstream and gather at the air-in-line sensor, potentially causing detection of an air- in-line condition which will trigger a 'false' alarm
Data Source
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AI summary
In an infusion pump operable to deliver fluid to a patient at a programmed therapy flow rate, air-in-line sensing is improved by commanding the pumping mechanism to deliver a bolus volume of fluid at a flow rate higher than the therapy flow rate when an uninterrupted volume of air is detected that exceeds a first threshold. In many cases, the bolus will be effective to clear microbubbles from an observation zone of the air-in-line sensor to avoid an air-in-line alarm condition. If the uninterrupted volume of air continues to grow beyond a second threshold in spite of the bolus, then an alarm may be triggered. The invention reduces false alarms.