Expandable Medical Sheath for Safe Percutaneous Nephroscopy
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Solution Overview
Problem
The existing medical sheaths used in percutaneous nephroscopy face challenges in establishing a working channel safely, as the inner diameter of the sheath must match the inflated balloon's outer diameter to avoid damage to the body and ensure effective channel formation, which is difficult to control and can lead to secondary tissue damage during insertion.
Innovation Solution
A sheath with a ring-shaped inner layer, a ring-shaped outer layer, and a frame structure that radially expands with balloon inflation, allowing the sheath to adapt its inner channel size from a smaller, non-inflated dimension to a larger, inflated dimension, facilitating smooth insertion and expansion without relying solely on balloon inflation control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer diameter of the balloon is reduced to allow sheath insertion, then the sheath can enter smoothly, but a gap forms between the sheath and balloon causing damage to internal organs
Solution Approach 1:
The sheath employs a dynamic structure with radially expandable frame that transitions from a compressed insertion state to an expanded working state. The frame includes deformable sections that allow radial expansion after insertion, enabling the sheath to adapt its inner diameter to match the balloon's outer diameter and eliminate gaps that could cause organ damage.
Solution Approach 2:
The sheath's inner diameter parameter is changed from a small insertion diameter to a large working diameter through radial expansion. The frame structure allows the sheath to transform its dimensional parameters in situ, ensuring optimal fit with the balloon while maintaining safe distance from surrounding organs.
2Object-affected harmful factors
If the outer diameter of the balloon is increased to ensure proper fit with sheath, then organ damage is prevented, but the sheath cannot enter smoothly
Solution Approach 1:
The sheath is divided into functional segments including the frame structure with deformable sections and the outer layer. This segmentation allows the insertion portion to be small and flexible for smooth entry, while the expandable frame can later be deployed to provide the necessary structural support and appropriate inner diameter for organ protection.
Solution Approach 2:
The balloon is nested within the sheath during insertion, with both devices having coordinated dimensions for smooth delivery. After reaching the target position, the sheath expands radially to provide the larger working diameter needed for proper balloon fit and organ protection, while the balloon remains nested within the expanded sheath.
3Ease of repair
If the sheath is inserted again after balloon deflation to remove it, then the balloon can be removed, but secondary damage to tissue may occur
Solution Approach 1:
The removal function is merged into the same sheath that performed insertion. The sheath is designed to accommodate the deflated balloon for simultaneous withdrawal, eliminating the need for a separate insertion/removal cycle. This combined approach reduces the number of tissue penetrations from two to one, preventing secondary damage.
Solution Approach 2:
The sheath is designed in advance to facilitate balloon removal by maintaining appropriate dimensions and structural properties after balloon deflation. The frame structure and outer layer are configured to allow easy withdrawal of the deflated balloon-sheath assembly as a unit, preventing the need for additional insertion procedures.
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
This adaptive sheath design ensures safe and effective channel establishment by allowing the sheath to expand in situ, reducing the risk of secondary tissue damage and simplifying the insertion process, as it can enter the body in a compact state and expand with the balloon, thereby maintaining channel stability and safety.
Implementation Method 1
the frame structure includes at least one ring-shaped frame body, the frame body includes at least one deformable section... when the frame body is radially expanded, the bending degree or curing degree of the deformable section becomes lower, and a length of the deformable section along the circumferential direction of the frame body becomes longer
Data Source
AI summary
A sheath includes: a ring-shaped inner layer structure, a ring-shaped outer layer structure and a frame structure, which can be radially expanded with the inflation of a balloon inside the inner layer structure. When the inner layer structure, the frame structure and the outer layer structure are not radially expanded, a radial dimension of an inner channel of the inner layer structure is at a first radial dimension, and the first radial dimension is greater than or equal to a radial dimension of the balloon that is not inflated. After the inner layer structure, the frame structure, and the outer layer structure are radially expanded, and the balloon is removed or deflated, the radial dimension of the inner channel of the inner layer structure is at a second radial dimension, and the second radial dimension is greater than the first radial dimension.