Infusion Line Occlusion Detection Using Dynamic Friction Modeling
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Solution Overview
Problem
Existing methods for detecting occlusions in infusion lines are unreliable due to the assumption of a constant frictional force, which can lead to false alarms or missed detections, especially in neonate and pediatric care where accuracy is critical.
Innovation Solution
A method that determines the frictional force using a mathematical model accounting for the position and velocity of the piston, and specific characteristics of the syringe, such as size, brand, and liquid type, to accurately calculate pressure and detect occlusions, combined with a slope-based approach to verify frictional force changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant frictional force value is used for pressure calculation, then the calculation method is simple, but the detection accuracy deteriorates due to false alarms or missed detections
Solution Approach 1:
The patent applies the dynamics principle by transitioning from a static constant frictional force value to a dynamic frictional force model that varies with piston position. The frictional force is calculated as a function of the piston's position within the syringe barrel, allowing the system to adapt to changing friction conditions during the infusion process. This resolves the contradiction by maintaining calculation simplicity through a systematic model while improving detection accuracy by accounting for position-dependent friction variations.
Solution Approach 2:
The patent implements parameter changes by making the frictional force value variable rather than constant. Specifically, the frictional force is expressed as a function of piston position, and this position-dependent frictional force is used in the pressure calculation. This parameter change allows the system to accurately reflect the actual physical conditions during infusion, thereby improving occlusion detection accuracy without significantly complicating the calculation process.
2Measurement precision
If a position-dependent frictional force model is used, then the occlusion detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent applies the feedback principle by continuously monitoring the piston position and using this information to adjust the frictional force calculation in real-time. The system measures or determines the piston position, feeds this information back into the frictional force model, and uses the updated frictional force value for pressure calculation. This feedback mechanism enables accurate occlusion detection while keeping the system relatively simple by using readily available position information.
Solution Approach 2:
The patent implements self-service by utilizing the existing piston position information that is already available during the infusion process. Rather than requiring additional sensors or complex measurements, the system uses the position data that is inherently generated by the infusion mechanism itself. This self-service approach improves detection accuracy by incorporating position-dependent friction without significantly increasing device complexity.
3Ease of manufacture
If the frictional force variation is not accounted for, then the calculation method remains simple, but false alarms occur due to overpressure detection
Solution Approach 1:
The patent applies the preliminary action principle by pre-establishing a frictional force model that accounts for position-dependent friction variations before the infusion process begins. This model is prepared in advance and can be directly applied during the infusion without requiring complex real-time adjustments. By preparing the frictional force characteristics beforehand, the system prevents false alarms caused by unaccounted friction variations while maintaining calculation simplicity during the actual infusion process.
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 method provides a reliable and accurate detection of occlusions by accounting for variable frictional forces, reducing false alarms and ensuring timely intervention, particularly in sensitive care scenarios.
Implementation Method 1
measuring a force applied to a piston by a pusher device of an infusion device for moving the piston along a movement direction into a cylindrical tube in order to deliver a medical fluid from the cylindrical tube towards an infusion line connected to the cylindrical tube
Implementation Method 2
for calculating said value indicative of said pressure a frictional force value indicative of a friction of the piston relative to the cylindrical tube is taken into account
Data Source
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AI summary
A method for detecting an occlusion in an infusion line (3) connected to an infusion device (1) comprises: measuring a force (F) applied to a piston (21) by a pusher device (12) of an infusion device (1) for moving the piston (21) along a movement direction (X) into a cylindrical tube (20) in order to deliver a medical fluid from the cylindrical tube (21) towards an infusion line (3) connected to the cylindrical tube (20); calculating, from the measured force (F), a value indicative of a pressure (P) in the cylindrical tube (20), wherein for calculating said value indicative of said pressure (P) a frictional force value (F0) indicative of a friction of the piston (21) relative to the cylindrical tube (20) is taken into account; and comparing said value indicative of said pressure (P) to a threshold value to determine whether an occlusion is present in the infusion line (3). Herein, the frictional force value (F0) is determined using a mathematical model modelling the friction of the piston (21) relative to the cylindrical tube (20) in dependence on the position of the piston (21) relative to the cylindrical tube (20) along the movement direction (X) and in dependence on the velocity by which the piston (21) is moved relative to the cylindrical tube (3). In this way a method for reliably detecting an occlusion in an infusion line during an infusion process is provided.