Split Septum Intravenous Injection Site with Pressure Valve
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Solution Overview
Problem
Existing infusion devices experience blood reflux due to negative pressures generated during cannula removal, leading to clotting and occlusion, which requires frequent device replacement and can be traumatic for patients.
Innovation Solution
An intravenous injection site with a resilient split septum unit and a pressure-actuated flow control valve that precompresses the septum upon cannula insertion, preventing significant distal displacement and thus eliminating negative pressures and blood reflux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a split septum is used to allow cannula insertion and removal, then the injection site can be reused, but negative pressures are generated during cannula removal causing blood reflux
Solution Approach 1:
A check valve is introduced as an intermediary component between the septum and the fluid path. This valve allows fluid to flow in the forward direction (into the patient) but automatically closes to prevent blood from flowing backward into the device during cannula removal, thus eliminating the harmful reflux effect while preserving septum reusability
Solution Approach 2:
The check valve is positioned and configured to anticipate and counteract the negative pressure effect before blood reflux can occur. When the cannula is pulled back, the valve proactively closes in response to pressure changes, preventing the harmful action of blood being drawn into the device
2Ease of operation
If the septum is allowed to move distally during cannula insertion, then the cannula can be inserted, but negative pressures are generated causing clotting and occlusion
Solution Approach 1:
The septum is pre-compressed against the check valve seat before cannula insertion begins. This preliminary action ensures that when the cannula is inserted and the septum moves distally, the check valve remains sealed against the seat, maintaining positive pressure and preventing the formation of negative pressures that would cause clotting and occlusion
Solution Approach 2:
The check valve replicates the one-way flow control function seen in natural biological systems (such as heart valves), using a similar geometric principle where a flexible element closes against a seat to prevent backflow while allowing forward flow
3Object-generated harmful factors
If a check valve is added to prevent blood reflux, then blood reflux is eliminated, but the device complexity increases
Solution Approach 1:
The check valve is constructed from a single piece of flexible elastomeric material that forms both the valve body and the sealing surface. This thin-film flexible structure achieves complex one-way flow control functionality with minimal material and simple geometry, adding little to the overall device complexity while effectively preventing blood reflux
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 solution effectively prevents blood reflux and reduces the risk of clotting and occlusion, enhancing the safety and efficiency of fluid administration by maintaining a stable pressure environment during cannula insertion and removal.
Implementation Method 1
a resilient septum body. The injection site also includes a support body supporting the split septum unit and including an annular septum-engaging surface that presents a flow-through passageway. The septum-engaging surface contacts the distal face of the septum body and thereby restricts distal displacement of the septum body when the cannula is inserted therein
Implementation Method 2
a pressure-actuated flow control valve spaced distally from the septum body and operable to selectively prevent fluid flow in a proximal direction
Data Source
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AI summary
An improved injection site (12) for infusion of parenteral fluids and the like is provided, having a pressure-actuated valve (20) and a novel split septum unit (24), which effectively prevent reflux of blood into the assembly (10). The septum unit (24) includes a resilient split septum body (64) which is precompressed so that the septum body (64) is caused to protrude proximally (78) upon insertion of a cannula (16). Consequently, upon removal of the cannula (16), there is essentially no "drumming" or creation of friction-induced negative pressures sufficient to generate blood reflux. The preloaded septum body (64) also has its proximal surface (74) essentially flush and coplanar with the adjacent proximal end (66b) of the tubular septum holder (66) to enhance the cleanliness of the unit (24). The specialized well (46) and septum unit (24) afford a resilient seal between the periphery of the septum body (64) and the surface (50), and a separate hard-surface seal between the outer margin of the surface (50) and the septum holder (66).