Shape Memory Polymer Access Tube for Hemodialysis
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Solution Overview
Problem
Current percutaneous intravascular access methods, particularly for hemodialysis, often result in chronic repetitive injury and unwanted penetration of blood vessels due to the use of large diameter needles, leading to complications like venous stenosis, patient discomfort, and increased infection risk.
Innovation Solution
A system and method utilizing a small diameter, flexibly conformable intravascular access tube with a terminal segment made of shape memory polymer that expands radially to facilitate insertion and then returns to its original configuration for fluid flow, minimizing vessel injury and access site size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a large diameter needle is used to establish requisite volumetric flow rate, then fluid flow capability is improved, but risk of unwanted penetration and injury to blood vessel wall increases
Solution Approach 1:
The access tube is divided into a proximal body portion and a distal terminal segment with different functions. The terminal segment is made of shape memory polymer that can transform between compressed and expanded states, allowing the needle to be small during insertion while providing large flow capability after deployment
Solution Approach 2:
The terminal segment of the access tube is designed to dynamically change its configuration from a compressed state during insertion to an expanded state after placement. This dynamic transformation allows the system to adapt to different operational requirements - small size for insertion, large size for fluid flow
2Productivity
If a large diameter needle is used for percutaneous access, then fluid flow capability is improved, but size of access opening and patient discomfort increase
Solution Approach 1:
The access tube dynamically changes size - small during insertion to minimize patient discomfort and access opening size, then expands to large size to provide adequate volumetric flow rate for hemodialysis
Solution Approach 2:
The tube is segmented into a proximal body and distal terminal segment, with only the terminal segment expanding. This allows the majority of the tube to remain small for comfortable insertion while the terminal segment provides the necessary flow capability
3Productivity
If a large diameter needle is used to achieve requisite flow rate, then fluid flow capability is improved, but risk of infection and healing time increase
Solution Approach 1:
The access tube is small during insertion to minimize the access opening size, thereby reducing infection risk and accelerating healing. After insertion, it expands to provide the necessary large volumetric flow rate for hemodialysis treatment
4Object-affected harmful factors
If shape memory polymer terminal segment is used, then unwanted penetration is prevented, but device complexity increases
Solution Approach 1:
Only the distal terminal segment of the access tube is made of shape memory polymer, while the proximal body portion remains simple and rigid. This localized application of complex material minimizes overall device complexity while providing the necessary functionality at the critical insertion point
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 minimally invasive access with reduced risk of injury and infection, improved patient comfort, and enhanced healing, while maintaining a desired volumetric flow rate and accuracy of placement, thereby reducing the need for surgical revisions and blood loss.
Implementation Method 1
the terminal segment being transformable in response to an external condition to return from the modified configuration to the native configuration
Implementation Method 2
the internal passage increases radially outwardly along the terminal segment toward the terminal end to provide the internal passage with a gradually expanded configuration
Data Source
AI summary
A system and method facilitate percutaneous intravascular access while militating against unwanted penetration of the accessed blood vessel. A small diameter access tube includes a terminal segment comprised of a shape memory polymer and configured to flare outwardly toward a larger diameter orifice. The configuration of the terminal segment is modified to taper toward the insertion point of an internal insertion needle for facilitating insertion of the access tube into a blood vessel. Subsequent to insertion, the access tube is advanced relative to the insertion needle which then is retracted, and the terminal segment is allowed to return to the flared configuration so that fluid flow through the access tube is facilitated.