Access Cannula Blocking Device for Dialysis Needle Dislodgement
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Solution Overview
Problem
Current solutions for detecting venous needle dislodgement (VND) during dialysis treatments are not 100% reliable, often result in delayed detection, and can be costly, with existing methods prone to false alarms and requiring additional equipment.
Innovation Solution
An access cannula with a locking device that kinks the indwelling tube when dislodged, using a spring element to balance elastic restoring forces and blood pressure, allowing for immediate detection of blood flow interruption through standard pressure monitoring systems without additional equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure monitoring is used to detect venous needle dislodgement, then detection capability is provided, but detection is delayed and unreliable due to pressure variations and flow resistance
Solution Approach 1:
The spring element is pre-loaded to exert a blocking force on the indwelling tube in the event of dislodgement. This preliminary preparation ensures that when VND occurs, the tube is immediately blocked by the spring force, preventing blood loss and enabling rapid detection without waiting for pressure changes to manifest.
Solution Approach 2:
The locking device with spring element is positioned and pre-configured to automatically engage and block the tube if dislodgement occurs. The spring is pre-compressed between the mounting base and the connection section, ready to instantly restrict tube movement and blood flow upon loss of tensile force from needle dislodgement.
2Measurement precision
If leak sensors are used to detect blood loss, then detection accuracy is improved, but additional expensive equipment and disposable parts are required
Solution Approach 1:
The system uses the existing pressure monitoring equipment already present in dialysis machines to detect blood loss. The spring element creates a mechanical-blockage-based pressure change that the standard pressure sensor can detect, eliminating the need for separate leak sensors or additional detection equipment.
Solution Approach 2:
The spring element serves multiple functions: it provides the blocking mechanism for immediate tube occlusion upon dislodgement, creates a detectable pressure signal for the existing pressure monitor, and eliminates the need for separate leak detection equipment by making the standard pressure sensor sufficient for VND detection.
3Reliability
If alarms are triggered frequently due to false positives, then detection sensitivity is high, but alarm reliability decreases and alarms are ignored
Solution Approach 1:
The spring element is pre-loaded to immediately block the tube upon dislodgement, creating a rapid and significant pressure change that is distinct from normal operational variations. This preliminary blocking action ensures that the pressure signal triggering the alarm is unequivocal and unlikely to be mistaken for normal conditions, reducing false alarms.
Solution Approach 2:
The spring element acts so rapidly upon dislodgement that it rushes through the blocking action before any gradual pressure changes or flow resistance issues can occur. This immediate action creates a sharp, distinct pressure signal that is easily distinguishable from normal operational fluctuations, improving alarm reliability.
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
Enables rapid and reliable detection of VND, preventing significant blood loss and potential complications by blocking blood flow, thus triggering alarms and stopping the blood pump promptly, without the need for extra devices or complex handling.
Implementation Method 1
The locking device has a spring element, the first end of which is located at a first position on the indwelling tube, and the second end of which is connected or connectable to the indwelling tube at a second position... the spring element, in a tensioned position outside the rest position, exerts a force on the dwell tube
Data Source
Figure 1~3
Figure 4~6
AI summary
The present invention relates to an access cannula (Z), in particular an indwelling venous cannula, with an indwelling tube (3) which is configured to serve as an access point during a treatment, in particular a dialysis treatment, wherein a locking device (1) is provided to keep the indwelling tube (3) kinked in a resting position.