Fluid Connection Disruption Detection via Dynamic Pressure Tracking
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Solution Overview
Problem
Existing techniques for detecting disruptions in fluid connections between extracorporeal blood processing systems and the vascular system are prone to false alarms due to natural variations in fluid pressure, making it challenging to accurately detect venous needle dislodgement without increasing the risk of false positives or negatives.
Innovation Solution
A monitoring system that generates a tracking signal more smoothed over time than the monitoring signal, allowing the detection range to follow changes in the tracking signal, thereby reducing the risk of false alarms by setting a relatively small detection range based on expected signal changes during disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If alarm thresholds are set to avoid false negatives in VND detection, then detection sensitivity is improved, but false alarm rate increases due to natural pressure variations
Solution Approach 1:
The alarm thresholds are made dynamic by continuously updating them based on the tracking signal that follows natural pressure variations. Instead of using fixed thresholds, the system adapts thresholds in real-time to match the patient's physiological state, allowing the detection system to distinguish between normal pressure fluctuations and actual disconnection events.
Solution Approach 2:
A tracking signal is introduced as an intermediary between the raw pressure signal and the alarm threshold setting. This tracking signal smooths out natural pressure variations while preserving the overall trend, serving as a reference to dynamically adjust thresholds and reduce false alarms caused by physiological fluctuations.
2Adaptability or versatility
If a fixed detection range is used, then system complexity is reduced, but the system becomes less adaptable to changing pressure conditions during treatment
Solution Approach 1:
The detection system performs self-adjustment by automatically updating alarm thresholds based on the tracking signal without requiring manual intervention. The system monitors its own operating conditions and adapts thresholds autonomously, reducing the need for complex external control mechanisms while maintaining high adaptability to changing pressure conditions.
3Speed
If alarm thresholds are updated frequently, then response to pressure changes is improved, but false alarms increase due to signal noise
Solution Approach 1:
The tracking signal is generated in advance by smoothing the raw pressure signal over a moving time window before it is used to update thresholds. This preliminary processing removes high-frequency noise and physiological fluctuations, allowing thresholds to be updated frequently without triggering false alarms from signal noise.
Solution Approach 2:
The system uses a dynamic time window approach where the smoothing period adapts to the current operating conditions. During stable periods, longer smoothing windows reduce noise impact, while during rapid changes, shorter windows maintain responsiveness. This dynamic adjustment allows frequent threshold updates without sacrificing noise immunity.
Data Source
AI summary
A monitoring system performs a method for detecting a disruption of a fluid connection between a first fluid containing system and a second fluid containing system. The monitoring system generates a monitoring signal which is representative of a fluid pressure in respect of the first fluid containing system and which is responsive to the disruption of the fluid connection, and a tracking signal which corresponds to and is more smoothed over time than the monitoring signal. The monitoring system further sets a detection range in a given relation to the tracking signal so that the detection range follows changes in the tracking signal, and detects a condition indicative of the disruption by comparing a current pressure value of the monitoring signal to the detection range. The monitoring system may be connected to or part of an apparatus for blood treatment and operable to detect a disconnection of an extracorporeal blood circuit from a vascular system of a patient, e.g. downstream of a blood pump in the extracorporeal blood circuit.