Positive Displacement Flush Syringe with Collapsible Stopper
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Solution Overview
Problem
Traditional syringe assemblies fail to prevent reflux of blood into catheters during flush procedures, leading to occlusions, as they rely on user technique and do not automatically compensate for syringe stopper-induced reflux, which can occur even when recommended flush procedures are not followed.
Innovation Solution
A syringe assembly with a plunger stopper that collapses under liquid pressure during the flush procedure and returns to its original shape to force additional flush solution into the catheter, ensuring positive displacement and minimizing reflux, even if user technique is not precise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional syringe assemblies are used with elastomeric stoppers, then the syringe can deliver medications accurately, but the compressed stopper expands back to its normal size after flushing, drawing fluid back into the catheter and causing reflux
Solution Approach 1:
The patent modifies the physical parameters of the stopper by creating a compliance chamber that changes the stopper's compressibility characteristics. The chamber allows the stopper to be compressed during flushing while preventing expansion that would cause reflux, thereby changing the stopper's mechanical behavior to eliminate the harmful effect while preserving medication delivery accuracy
Solution Approach 2:
The compliance chamber acts as an intermediary element between the stopper and the fluid system. It mediates the compression and expansion forces, allowing the stopper to be compressed during flushing while the chamber absorbs the expansion, preventing fluid from being drawn back into the catheter
2Reliability
If users maintain positive pressure on the syringe plunger while clamping the I.V. line at the end of flush solution delivery, then reflux can be prevented, but this technique requires precise user execution and does not compensate for stopper-induced reflux
Solution Approach 1:
The compliance chamber enables the syringe system to self-regulate pressure automatically. During flushing, the chamber compresses to allow fluid delivery, and after flushing, it expands to maintain positive pressure in the catheter, preventing reflux without requiring the user to maintain manual pressure or execute complex techniques
Solution Approach 2:
The compliance chamber is pre-configured to automatically respond to pressure changes. It is designed to compress during flushing and expand after flushing to maintain positive pressure, performing the reflux prevention action automatically based on the flushing cycle rather than requiring real-time user intervention
3Productivity
If the distal wall of the stopper is made flexible to collapse under liquid pressure, then additional flush solution can be delivered after plunger motion stops, but the stopper structure becomes more complex
Solution Approach 1:
The patent applies a flexible membrane or thin film to the distal wall of the stopper, allowing it to collapse under liquid pressure during flushing and expand afterward to deliver additional flush solution. This flexible element is integrated into the stopper structure, adding minimal complexity while enabling the additional fluid delivery function
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
The syringe assembly effectively reduces or eliminates reflux, enhancing the reliability of flush procedures and reducing the risk of catheter occlusions by automatically delivering additional fluid after the flush solution has been delivered, thus maintaining catheter patency.
Implementation Method 1
the stopper having a distal end with a distal wall and a cavity therein defining an inside surface, and a proximal end. The distal wall of the stopper is flexible enough to collapse at least partially into the cavity under the liquid pressure of a flush procedure and to move back toward its original shape at the completion of the flush procedure to force additional fluid into the passageway
Data Source
AI summary
A flush syringe assembly comprises a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including an elongate tip extending distally therefrom having a passageway in fluid communication with the chamber. A plunger including an elongate body portion has a stopper at its distal end. The stopper is slidably positioned in fluid-tight engagement with the inside surface of the barrel for driving fluid out of the chamber. The distal end of the stopper is configured to collapse while fluid is being driven though the passageway through motion of a plunger and to continue to drive fluid through the passageway after motion of the plunger has stopped.