Catheter Port Stem Geometry for Flow and Coupling
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Solution Overview
Problem
Coupling catheters with rigid stems in confined, wetted environments like subcutaneous placements is challenging due to size mismatches, leading to kinking or fluid flow restrictions, especially with thinner catheters.
Innovation Solution
A stem with an optimized geometry featuring a distal tip structure with radially extending fingers and slots that taper in diameter, facilitating an interference fit while maximizing fluid flow and preventing kinking, and a circumferential ridge for enhanced engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the stem tip outer diameter is increased to improve coupling security, then the coupling strength is improved, but the fluid flow rate through the stem lumen is restricted
Solution Approach 1:
The stem tip is segmented into multiple fingers (typically 3-6) that extend radially inward, creating multiple smaller flow passages instead of a single large opening. This segmentation allows the stem to maintain a larger outer diameter for secure coupling while preserving fluid flow capacity through the distributed finger structures.
Solution Approach 2:
The stem geometry is optimized with different characteristics at different locations: the distal tip features tapered fingers with varying wall thicknesses (thinner at the tip, thicker at the base) to locally maximize both coupling engagement and fluid flow. The proximal portion maintains uniform thickness for structural integrity.
2Ease of operation
If the stem tip outer diameter is decreased to facilitate catheter insertion, then the ease of coupling is improved, but the coupling security and interference fit are compromised
Solution Approach 1:
The stem fingers are designed with tapered geometries that dynamically adapt during insertion. The tapered surfaces guide the catheter into proper alignment while the elastic deformation of the catheter wall creates an interference fit. The dynamic engagement ensures secure coupling is achieved through controlled elastic deformation rather than requiring a larger static diameter.
3Length of moving object
If the catheter wall thickness is decreased to reduce bulk, then the catheter flexibility is improved, but the susceptibility to kinking and collapse increases
Solution Approach 1:
The stem fingers act as intermediary support structures within the catheter lumen during insertion and operation. These fingers provide internal reinforcement that prevents kinking and collapse of the thin-walled catheter, while still allowing the catheter to maintain its flexibility and compliant nature for proper insertion and positioning.
4Productivity
If the stem lumen inner diameter is increased to maximize fluid flow, then the fluid flow rate is improved, but the coupling engagement with the catheter is reduced
Solution Approach 1:
The stem transitions from a simple cylindrical lumen to a multi-dimensional finger structure at the distal tip. The fingers extend radially inward, creating a three-dimensional engagement surface that increases coupling area without significantly reducing the effective flow cross-sectional area. This dimensional transformation allows simultaneous optimization of both flow and engagement.
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 optimized stem geometry ensures secure coupling with a range of catheter sizes, minimizing kinking and fluid flow restrictions while maintaining high fluid flow rates, thus improving the versatility and reliability of catheter-stem connections.
Implementation Method 1
the compliant catheter elastically deforms to engage the stem in an interference fit
Data Source
AI summary
Embodiments disclosed herein are directed to a stem including optimized geometry configured to maximize fluid flow while facilitating engagement with a lumen of a catheter. The stem can define a lumen having a distal opening defining a first diameter. The tip structure can define a tip structure lumen having a second diameter that is less than the first diameter. The tip structure can include one or more fingers extending longitudinally distally and defining one or more slots. The tip structure can fit within the catheter lumen, facilitating engagement therewith, while the one or more slots can improve fluid flow, providing little or no reduction in fluid flow relative to the distal opening.