Flow Reversing Valve for Venous Line Leak Detection
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Solution Overview
Problem
Current methods for detecting leaks in extracorporeal blood circuits, particularly in positive pressure return lines, are inadequate, leading to increased risk of blood loss and fatalities due to their inability to reliably detect small leaks or disconnections, especially in two-access systems.
Innovation Solution
A flow reversing valve system that periodically generates negative pressure in the venous line to draw air into the line, which is then detected by sensors, triggering a shutdown and alarm, thereby ensuring leak detection in the return line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If air infiltration detection is used in the venous line during normal forward flow, then leak detection capability is provided, but false alarms increase and patient discomfort occurs due to inability to distinguish air from bubbles
Solution Approach 1:
The patent applies flow reversal to invert the normal flow direction in the venous line. By temporarily reversing flow, the system creates negative pressure that draws air into the line through leaks, allowing differentiation between air (from leaks) and bubbles (from patient). This inversion technique resolves the false alarm problem by changing the detection mechanism from detecting air during forward flow to detecting air infiltration during reverse flow.
Solution Approach 2:
The patent implements periodic flow reversal cycles rather than continuous reversal. The system alternates between forward flow (normal treatment) and reverse flow (leak detection) in periodic intervals. This periodic action allows the system to maintain treatment functionality while periodically checking for leaks, reducing false alarms by only detecting air during reverse flow phases when bubbles would not be present.
2Reliability
If continuous trained supervision is used to detect leaks, then patient safety is improved, but labor requirements and treatment cost increase enormously
Solution Approach 1:
The patent implements a self-monitoring system where the blood processing system automatically detects leaks without requiring continuous human supervision. The flow reversal mechanism and air detection sensors enable the system to self-diagnose leaks in the venous line, allowing unattended operation and home use. This self-service capability eliminates the need for constant trained staff while maintaining patient safety.
3Device complexity
If sensors are located far from the patient, then system complexity is reduced, but response time to leaks increases and detection reliability decreases
Solution Approach 1:
The patent uses flow reversal as an intermediary mechanism to enable remote sensor placement while maintaining high detection reliability. By reversing flow temporarily, the system actively draws air from remote leak locations toward the sensor, compensating for the distance between the sensor and potential leak sites. This intermediary action ensures that even sensors placed farther from the patient can reliably detect leaks through the negative pressure gradient created during reverse flow.
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 significantly reduces the risk of blood loss by providing a more reliable detection method for leaks in return lines, enhancing safety in both clinical and non-clinical settings without the need for constant trained supervision.
Implementation Method 1
periodically generates negative pressure in the venous line to draw air into the line
Implementation Method 2
Air is typically detected using an ultrasonic air detector on the tubing line, which detects air bubbles in the blood
Data Source
AI summary
A blood processing system includes a flow reversing device with at least an air sensor in the venous line located near the patient. During treatment, blood flow is reversed to cause air to infiltrate the blood lines if any disconnections or breaks in the blood line are present. One means for placing the sensor close to the patient is to provide the flow switching device aid sensors in a small lightweight module that can be located close the treatment machine. Another is to provide a module with just the sensors near the access.