Expandable Medical Access Sheath With Tapered Fairing
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Solution Overview
Problem
Current percutaneous nephrostomy systems require multiple steps, significant force, and can be time-consuming and traumatic due to the need for angular shearing forces and the use of restraining jackets, which limit the expansion force of expandable sheaths.
Innovation Solution
A medical access system featuring an expandable sheath with a dilator that can expand from a small cross-sectional profile to a larger one without external constraint, using a tapered fairing to shield the distal edge and facilitate tissue diversion, allowing for increased expansion forces and reduced trauma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a restraining jacket is used to maintain small diameter during insertion, then the sheath can be introduced through a small puncture, but the jacket reduces the net expansion force and compromises the sheath function
Solution Approach 1:
The patent removes the restraining jacket entirely from the sheath design. The sheath is introduced without any external constraint and expands freely to its full diameter without the jacket limiting its expansion force or requiring splitting/releasing mechanisms.
2Length of moving object
If angular shearing forces are used to create the tract, then the pathway can be established, but significant force is required and trauma to the tissue increases
Solution Approach 1:
The patent replaces the traditional angular shearing mechanism with a tapered fairing that uses axial force to divert tissue laterally. This substitution reduces the magnitude of force required and eliminates the traumatic shearing action while still achieving tract formation.
3Length of moving object
If multiple sequential sheaths are advanced to establish the tract, then the pathway can be created, but the procedure becomes time-consuming and complex
Solution Approach 1:
The patent combines the functions of multiple sequential sheaths into a single expandable sheath with an integrated dilator. The dilator expands the sheath in-place to the required diameter, eliminating the need for multiple sheath exchanges and reducing procedural time and complexity.
4Ease of operation
If the distal edge of the sheath is exposed during insertion, then the sheath can be advanced, but tissue can impinge on the distal edge causing trauma or malfunction
Solution Approach 1:
The patent introduces a tapered fairing as an intermediary component that covers and protects the distal edge of the sheath during insertion. The fairing diverts tissue laterally and prevents it from impinging on the distal edge, eliminating trauma while allowing smooth advancement.
Data Source
AI summary
An expandable medical sheath is configured to be introduced into a body in a first, low cross-sectional area configuration, and expanded to a second, enlarged cross-sectional configuration. The sheath is maintained in the first, low cross-sectional configuration by structures or elements within the sheath wall that maintain a collapsed shape. Upon expansion with a dilator, the sheath maintains a second, enlarged cross-sectional configuration by elements or structures within the sheath tubing wall that resist re-collapse. The sheath includes a nose cone or tapered fairing to deflect tissue from entering the collapsed distal end of the sheath during introduction. The fairing collapses following expansion and subsequent deflation of the dilator, thus allowing the tapered fairing to be withdrawn proximally through the central lumen of the sheath. In one application, the sheath is utilized to provide access for a diagnostic or therapeutic procedure such as percutaneous nephrostomy or urinary bladder access.