Vascular Graft Cannulation Guide for Accurate Subcutaneous Needle Placement
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Solution Overview
Problem
Conventional methods for locating and cannulating vascular access grafts, such as arteriovenous fistulas and grafts, are prone to errors, leading to complications like rupture, bleeding, hematoma formation, and graft failure due to inaccurate needle placement, which is difficult to locate subcutaneously.
Innovation Solution
A guiding apparatus and method using magnetic or paramagnetic materials, applicator devices, and adhesive stickers to align and secure cannulation chambers, facilitating accurate needle insertion into vascular access grafts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If surgical techniques and instruments are improved to minimize complications during graft cannulation, then patient safety and graft functionality are improved, but the complexity and cost of the surgical procedure increase
Solution Approach 1:
The cannulation device is divided into distinct functional segments: a dilator portion for initial puncture and dilation, a needle portion for graft puncture, and a catheter delivery system. This segmentation allows each component to be optimized for its specific function while simplifying the overall procedural complexity.
Solution Approach 2:
The dilator portion is used to pre-dilate the puncture site in the graft before the needle is advanced through the same trajectory. This preliminary action creates a prepared pathway that facilitates subsequent catheter insertion and reduces resistance during the procedure.
2Ease of operation
If a percutaneous approach is used for graft cannulation, then patient trauma and hospital stay are reduced, but the risk of complications such as infection, bleeding, and graft damage increases
Solution Approach 1:
The dilator acts as an intermediary element between the initial puncture and the final catheter placement. It provides a controlled mechanism for gradually enlarging the access tract while maintaining structural support, thereby minimizing uncontrolled tissue damage and reducing the risk of bleeding and infection.
Solution Approach 2:
The catheter and delivery system utilize flexible materials that can conform to the graft structure and navigate the vascular anatomy smoothly. This flexibility reduces mechanical stress on the graft wall and minimizes the risk of graft damage while maintaining the percutaneous approach benefits.
3Productivity
If a large-bore catheter is inserted through a small puncture site, then blood flow through the graft is improved, but the risk of puncture site complications and catheter instability increases
Solution Approach 1:
The dilator is advanced through the puncture site and inflated or expanded to create a larger, stable bore in the graft before the catheter is inserted. This preliminary dilation ensures that the final catheter size can be optimized for blood flow while the puncture site stability is established by the dilator's anchoring action.
Solution Approach 2:
The catheter is delivered through a sheath or delivery system that is itself introduced through the puncture site. This nested configuration allows the catheter to be positioned within the pre-dilated tract, providing structural support and stability to the puncture site while accommodating the large-bore catheter for optimal blood flow.
Data Source
Figure 1
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Figure 5A~7
AI summary
An apparatus for guiding cannulation with a dialysis needle of an arteriovenous dialysis access graft subcutaneously implanted in a body of a subject. The guiding apparatus comprises an elongated body member comprising a base portion terminating in longitudinal edges, a distance between the longitudinal edges of the base portion being substantially equal to a lateral dimension of the aces graft, and an elongated tubular sleeve defining an pocket having a longitudinal dimension and a lateral dimension configured to receive the body member. The body member is adapted to be received in the pocket of the sleeve for securing adjacent the subcutaneous access graft such that the inner surface of the base portion is aligned with a cannulation point of the graft for guiding location of a needle insertion.