Infusion Pump Air Detection Using Plunger Force Profiles
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Solution Overview
Problem
Existing infusion systems face issues with inaccurate detection of air in the line due to the use of univariate sensors, leading to false negatives or false alarms, as they fail to account for the complexity of the problem with multiple dimensions.
Innovation Solution
A method involving a plunger actuated by an actuator device to detect force changes on a chamber, using a sensor to measure and communicate force to a processor, which determines the presence of air based on threshold exceedance and differential analysis of force profiles, and potentially combining with existing ultrasonic sensors for improved reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If ultrasonic sensors with univariate signals are used to detect air in the line, then the detection system is simple, but the accuracy is poor leading to false negatives or false alarms
Solution Approach 1:
The patent transitions from univariate ultrasonic sensing to multivariate sensing by incorporating both ultrasonic signals and force measurements from the plunger. This dimensional expansion allows the system to capture multiple aspects of air presence simultaneously, resolving the contradiction between system simplicity and detection accuracy.
Solution Approach 2:
The patent merges ultrasonic detection with force measurement capabilities into a unified air detection system. By combining these two different measurement approaches, the system achieves higher accuracy while maintaining reasonable complexity through integrated processing.
2Device complexity
If a single sensor with univariate signal is used, then the device complexity is low, but the reliability is reduced due to false positives and negatives
Solution Approach 1:
The system adds another dimension of measurement by incorporating force data from the plunger movement. This multivariate approach provides cross-validation between different sensing modalities, significantly improving reliability while keeping the added complexity manageable through integrated analysis.
Solution Approach 2:
The system uses feedback from both ultrasonic sensors and force measurements to continuously monitor and adjust air detection decisions. This feedback mechanism allows the system to correct false positives and negatives by cross-referencing multiple data streams.
3Measurement precision
If multiple sensors and dimensional analysis are implemented, then the air detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The plunger force measurement system serves multiple functions: it drives the pump, provides mechanical feedback, and enables air detection. This multi-functionality reduces the need for separate dedicated sensors, thereby limiting the increase in overall system complexity while achieving high detection accuracy.
Solution Approach 2:
The patent combines the pump actuation mechanism with the air detection function by using the same plunger force measurements for both purposes. This merging approach achieves accurate air detection without proportionally increasing device complexity.
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
The method provides accurate detection of air in infusion systems, reducing false positives and negatives, and enhances the reliability of air detection without requiring additional hardware modifications.
Implementation Method 1
a force acting on the plunger, as it moves against the chamber, is detected with a sensor
Implementation Method 2
a plunger is moved against a chamber containing fluid with an actuator device
Data Source
AI summary
Various systems and methods for detecting air in a chamber of an infusion system are disclosed. In one embodiment, a determination is made that air is contained in the chamber on the basis of a change in the average force exerted against the plunger utilizing a derivative spike for event detection and a systematic reduction in the average force to confirm the nature of the change. In another embodiment, a determination is made that the chamber contains air when a difference between the current force profile and a baseline force profile crosses a threshold. In an additional embodiment, a force profile is classified as being an air force profile or a liquid force profile based on extracted features of the force profile.