Expandable Ureteral Access Sheath for Slim Insertion, Larger Lumen
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Solution Overview
Problem
Conventional ureteral access sheaths require pre-selection of size based on patient anatomy and physician preference, leading to potential trauma and limitations in accommodating larger scopes or stones, and lack flexibility in cross-sectional area.
Innovation Solution
A ureteral access sheath with a flexible NITINOL core and expandable foil member that allows for a slim profile insertion and automatic expansion to a larger lumen upon instrument passage, facilitated by a shape memory alloy and a dilator mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional ureteral access sheath with fixed size is used, then the insertion process is simple, but the sheath causes trauma and cannot accommodate larger scopes or stones
Solution Approach 1:
The sheath transitions from a compressed low-profile state during insertion to an expanded high-lumen state after deployment. The expandable member (balloon or self-expanding structure) is deployed distal to the insertion site, causing the sheath to expand radially and increase its internal diameter, allowing accommodation of larger instruments and stones while minimizing trauma during insertion.
Solution Approach 2:
The expandable member is nested within the sheath during insertion, allowing the entire assembly to pass through the urethra in a compressed state. After the sheath is positioned correctly, the expandable member is deployed from within the sheath structure, transforming the sheath from a small insertion profile to a large working profile.
2Area of stationary object
If a larger fixed-size sheath is used to accommodate larger instruments, then the lumen is sufficiently large, but the insertion becomes more traumatic and difficult
Solution Approach 1:
The sheath dynamically changes its cross-sectional area from small during insertion to large during use. The expandable member provides the mechanism for this transformation, allowing the sheath to present a small profile during passage through the urethra and then expand to provide a large lumen for instrument passage and stone removal.
Solution Approach 2:
The sheath is designed to be inserted in a compressed state first, and the expansion action is performed subsequently after proper positioning. This preliminary insertion followed by expansion allows the small insertion profile to pass through the urethra without trauma, followed by the creation of a large lumen for the intended procedure.
3Adaptability or versatility
If a fixed-size sheath is selected based on pre-operative assessment, then the device is simple to use, but it lacks flexibility to adapt to varying patient anatomy and procedural needs
Solution Approach 1:
The sheath incorporates an expandable member that can be deployed to change the sheath's dimensions. This dynamic capability allows a single sheath design to adapt to varying patient anatomy and procedural requirements, eliminating the need for multiple fixed-size sheaths and the complexity of selecting the appropriate size beforehand.
Solution Approach 2:
The expandable sheath design provides universal applicability across different patient sizes and procedural needs. A single sheath type can be used for all patients, with the expansion capability allowing adaptation to specific anatomical variations and procedural requirements, making the device multi-functional rather than requiring multiple specialized devices.
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 trauma-free insertion and accommodation of larger instruments and stones by dynamically adjusting the cross-sectional area, enhancing procedural efficiency and comfort.
Implementation Method 1
A ureteral access sheath with a flexible NITINOL core and expandable foil member that allows for a slim profile insertion and automatic expansion to a larger lumen upon instrument passage, facilitated by a shape memory alloy
Data Source
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AI summary
A medical access sheath (10) includes a first member (16) and a second member (18). The first member comprises a gap (27) through a wall of the first member. The second member is connected to the first member. The first and second members form a tube. The wall of the first member forms a first wall portion of the tube. The second member extends across the gap such that the second member forms a second wall portion of the tube at the gap.