Segmented Dilator with Variable Taper Angles
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Solution Overview
Problem
The existing dilators used in the Seldinger method for expanding the diameter of introduction holes in the body result in significant resistance for operators, as the diameter expansion resistance is not effectively reduced, leading to difficult insertion during the procedure.
Innovation Solution
A dilator design featuring sections with varying diameters and angles, where the angles of the outer periphery surface change in a stepwise manner from smaller to larger and back to smaller increases, allowing for a gradual increase in diameter expansion resistance, and a distal end with a parabolic convex shape to decrease puncture resistance, facilitating smooth insertion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a dilator with a single tapered outer periphery surface is used to expand the introduction hole diameter, then the dilator can perform diameter expansion function, but the operator senses great resistance during insertion
Solution Approach 1:
The dilator is divided into multiple sections (first, second, third, and fourth sections) along the axial direction, each with different diameters and angle characteristics. This segmentation allows the dilator to expand the introduction hole diameter in a stepwise manner, reducing the operator-sensed resistance during insertion while maintaining effective diameter expansion capability.
Solution Approach 2:
Different sections of the dilator are designed with different local geometric properties, specifically different angles formed by outer periphery surfaces with respect to the axial direction. The first section has a smaller angle for gentle initial expansion, the second section has a larger angle for more aggressive expansion, the third section has a smaller angle again for controlled expansion, and the fourth section has a larger angle for final expansion. This variation in local quality optimizes the resistance profile during insertion.
2Productivity
If the outer periphery surface angle is increased to improve diameter expansion efficiency, then expansion capability is enhanced, but insertion resistance increases
Solution Approach 1:
The dilator employs periodic variation in the angle of outer periphery surfaces along the axial direction, alternating between smaller angles (first and third sections) and larger angles (second and fourth sections). This periodic action creates a rhythm of gentle and more aggressive expansion phases, improving overall diameter expansion efficiency while controlling the operator-sensed resistance through the alternating pattern.
Solution Approach 2:
The dilator design changes the geometric parameter (angle of outer periphery surface) along the axial direction to optimize performance. By varying the angle parameter across different sections, the dilator achieves both efficient diameter expansion and reduced insertion resistance, as the parameter changes create a favorable resistance profile during the expansion process.
Data Source
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AI summary
To provide a dilator which can alleviate diameter expansion resistance sensed by an operator at the time of inserting a dilator into an introduction hole to perform smooth insertion into the introduction hole, and an introducer assembly and a medical tool including such a dilator. A dilator 30 includes a first section 311, a second section 312, a third section 313, and a fourth section 314 which have different diameters from each other and are formed to be adjacent to each other in an axial direction, in that order from a distal end to a proximal end in the axial direction, an angle α1 formed by an outer periphery surface S1 of the first section with respect to the axial direction is smaller than an angle α2 formed by an outer periphery surface S2 of the second section 312 with respect to the axial direction, the angle formed by the outer periphery surface of the second section with respect to the axial direction is larger than an angle α3 formed by an outer periphery surface S3 of the third section 313 with respect to the axial direction, and the angle formed by an outer periphery surface of the third section with respect to the axial direction is smaller than an angle α4 formed by an outer periphery surface S4 of the fourth section 314 with respect to the axial direction.