Infusion Device Occlusion Detection Threshold
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Solution Overview
Problem
Infusion devices face challenges in quickly detecting occlusions in delivery lines, leading to delayed alarm triggering, which can be hazardous, and setting a low threshold value increases the risk of false alarms due to varying frictional behaviors among different syringes.
Innovation Solution
The infusion device computes a threshold value based on a desired time for occlusion detection and a force error estimate to balance fast detection with minimizing false alarms, using a processor to determine the optimal threshold value from two criteria: a first candidate based on desired time and a second candidate based on frictional force deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a low threshold value is set for occlusion detection, then occlusion detection speed is improved, but false alarm rate increases
Solution Approach 1:
The system performs preliminary characterization of each syringe's frictional behavior during an initial phase before infusion. This preliminary action captures the specific frictional profile of the syringe-piston combination, which is then used to establish an occlusion threshold tailored to that specific syringe. By preparing this baseline information in advance, the system can quickly detect occlusions without false alarms caused by normal friction variations.
Solution Approach 2:
The system changes the threshold parameter dynamically based on the specific syringe being used. Instead of using a fixed universal threshold, the occlusion detection threshold is adjusted according to the measured frictional characteristics of each individual syringe. This parameter adaptation allows the system to maintain high detection sensitivity while avoiding false alarms from normal friction variations specific to each syringe model.
2Device complexity
If a fixed threshold value is used for occlusion detection, then device complexity is reduced, but adaptability to different syringes deteriorates
Solution Approach 1:
The system performs self-characterization by automatically measuring the frictional behavior of each syringe during an initial phase. The syringe effectively 'teaches' the system its own frictional profile, and the system uses this information to set an appropriate occlusion threshold. This self-service approach eliminates the need for manual threshold configuration while ensuring optimal adaptability to each specific syringe type.
Solution Approach 2:
The system performs preliminary characterization of each syringe's frictional properties before the actual infusion begins. This preliminary measurement phase captures the specific frictional profile of the syringe-piston combination, which is then stored and used for occlusion detection. By doing this preparation in advance, the system achieves high adaptability without adding complexity to the main infusion operation.
3Manufacturing precision
If manual threshold programming is required, then manufacturing precision is improved, but ease of operation deteriorates
Solution Approach 1:
The system automatically performs the threshold calibration by measuring the frictional behavior of each syringe during an initial characterization phase. Instead of requiring the user to manually program threshold values, the system self-determines the appropriate threshold based on actual measurements. This maintains manufacturing precision through accurate measurement-based calibration while dramatically improving ease of operation by eliminating manual configuration steps.
Solution Approach 2:
The system replaces the manual mechanical process of threshold programming with an automated measurement and calculation process. The processor automatically measures frictional forces, analyzes the data, and computes the appropriate occlusion threshold without user intervention. This substitution maintains calibration accuracy through precise measurement while improving operational simplicity by removing the manual programming burden.
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 allows for timely occlusion detection while reducing the likelihood of false alarms by accounting for the unique frictional characteristics of different syringes, enhancing user confidence and safety in infusion processes.
Implementation Method 1
a sensor device measures a force acting in between the pusher device and the piston of the syringe
Implementation Method 2
a processor device derives, from the force measured by the sensor device, a pressure value indicative of the pressure in the tube
Data Source
Figure 1
Figure 2
Figure 3A~4D
AI summary
An Infusion device (1) for administering a medical fluid to a patient (P), comprises: a receptacle (12) for receiving a syringe (2) having a tube (20) containing a medical fluid and a piston (21) movable with respect to the tube (20); a pusher device (11) for acting onto the piston (21) for pumping the medical fluid from the tube (20) towards a patient (P) at a set flow rate; a sensor device (14) for measuring a force acting in between the pusher device (11) and the piston (21) of the syringe (2); and a processor device (15) for deriving, from the force measured by the sensor device (14), a pressure value indicative of the pressure in the delivery line (3), wherein the processor device (15) is constituted to compare the pressure value to a threshold value (Pthres) for determining whether an occlusion (O) in the delivery line (3) is present. Herein, the processor device (15) is constituted to determine the threshold value (Pthres) from a first threshold value candidate computed based on a desired time between the time (t0) of an occurrence of an occlusion (O) in the delivery line (3) and the time (t1) at which the pressure value exceeds the threshold value (Pthres), and a second threshold value candidate based on a force error estimate of a possible deviation between an expected frictional force and a true frictional force occurring when moving the piston (21) relative to the tube (20).