Flow Sensor Occlusion Detection in Infusion Systems
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Solution Overview
Problem
Infusion systems face delays and diminished therapeutic effectiveness due to undetected occlusions, particularly at low fluid flowrates, where pressure build-up takes significant time to reach detection thresholds, leading to delayed occlusion detection.
Innovation Solution
Incorporating a flowrate sensor with a noise reduction filter and a processing device that compares the filtered output signal to a threshold value, and optionally using spectral analysis to determine signal strength within specific frequency ranges, to quickly detect occlusions and reduce false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure sensor is used to detect occlusion by monitoring pressure build-up in fluid lines, then occlusion detection is possible, but detection delay increases significantly at low flowrates
Solution Approach 1:
The patent replaces the pressure-based detection system with a flowrate sensor that directly measures fluid flow. This substitution eliminates the indirect pressure measurement approach that caused detection delays at low flowrates, enabling immediate occlusion detection regardless of flowrate magnitude.
Solution Approach 2:
The patent introduces a flowrate sensor as an intermediary device between the fluid pathway and the detection system. This sensor directly monitors flowrate changes and provides real-time data to the processing device, eliminating the time delay associated with pressure build-up and threshold activation.
2Loss of time
If flowrate sensor output is used directly for occlusion detection, then response time is improved, but noise and artifacts cause false alarms
Solution Approach 1:
The patent applies preliminary signal processing actions by filtering the flowrate sensor output through a noise reduction filter before threshold comparison. This pre-processing step removes noise and artifacts in advance, preventing false alarms while preserving the fast response capability of direct flowrate monitoring.
Solution Approach 2:
The patent implements feedback through continuous monitoring of the flowrate sensor output and real-time threshold comparison. The system continuously adjusts and refines its detection based on the incoming signal, allowing immediate occlusion detection while using feedback mechanisms to verify signal validity and reduce false alarms.
3Reliability
If noise reduction filter is applied to flowrate sensor signal, then false alarms are reduced, but signal processing complexity increases
Solution Approach 1:
The patent employs simple, effective noise reduction techniques such as moving average filters or threshold-based filtering that are computationally lightweight. These straightforward filtering methods reduce false alarms without requiring complex processing algorithms, maintaining system simplicity while improving reliability.
Data Source
AI summary
A method of detecting an occlusion for an infusion therapy in one embodiment includes: monitoring an output signal from a flowrate sensor for a pulsatile fluid flow having a frequency range, the pulsatile flow being through a fluid pathway to a patient; acquiring a data set that includes the output signal as a function of time; filtering the data set with a noise rejection filter to produce a filtered data set; performing spectra analysis on the filtered data set to determine a strength of the output signal in a frequency domain; calculating a signal strength for the frequency range using the strength of the output signal in the frequency domain; and comparing the signal strength of the range to at least one threshold level to determine if an occlusion is present during the infusion therapy.