Stepped Needle for Intraosseous Access Depth Control
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Solution Overview
Problem
Current intraosseous device placement is subjective and prone to errors due to varying bone density and patient-specific skin and tissue thickness, leading to potential missed placements or penetration beyond the medullary cavity.
Innovation Solution
A stepped needle design with a gradual increase in outer diameter along the needle shaft, where the stepped increase in diameter provides a substantial resistance to prevent further insertion into the bone cortex, ensuring accurate placement within the medullary cavity without penetrating its far wall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a uniform diameter needle is used for intraosseous access, then the needle can be easily manufactured and inserted, but the user cannot objectively determine when the needle has reached the medullary cavity or when to stop insertion
Solution Approach 1:
The patent applies a visual indicator system where the needle features a stepped increase in outer diameter that creates a visible and tactile reference point. This stepped portion acts as a mechanical indicator that allows the user to objectively determine when the needle tip has reached the appropriate depth in the medullary cavity, eliminating the need for subjective assessment of bone density changes.
Solution Approach 2:
The patent introduces a dimensional feature (the stepped increase in outer diameter) along the needle shaft that provides an additional reference dimension for depth measurement. This stepped portion creates a mechanical stop that corresponds to a specific insertion depth, allowing the user to know when to stop based on a physical dimension rather than subjective feel.
2Ease of operation
If the needle is inserted based on subjective assessment of bone density, then the insertion process is simple, but the placement accuracy varies due to patient-specific anatomical variations
Solution Approach 1:
The patent incorporates the stepped increase in outer diameter as a pre-calculated feature during manufacturing. This stepped portion is positioned at a specific distance from the needle tip that corresponds to the appropriate insertion depth for reaching the medullary cavity. The feature is built into the needle before use, allowing consistent depth control across different patients without requiring real-time judgment.
Solution Approach 2:
The stepped portion of the needle provides tactile feedback to the user during insertion. When the stepped increase in diameter contacts the bone cortex, it creates a noticeable resistance change that signals the needle has reached the appropriate depth. This mechanical feedback system replaces subjective assessment with an objective physical signal that can be felt during the procedure.
3Measurement precision
If skin and subcutaneous tissue thickness is used as a reference for needle insertion depth, then insertion can be guided by external measurements, but accuracy is reduced due to great variation in tissue thickness between patients
Solution Approach 1:
The patent extracts the depth reference function from external measurements (skin and tissue thickness) and relocates it to the needle itself through the stepped increase in outer diameter. This internal reference point is independent of patient anatomy, allowing consistent depth control regardless of variations in skin thickness, subcutaneous tissue, or bone cortex thickness between different patients.
Data Source
AI summary
An apparatus and method for a stepped needle for an intraosseous device that uses the outer surface of the bone cortex as a reference point. Since the thickness of the bone cortex does not vary significantly between patients, the accuracy of needle placement can be improved. The device includes a needle with a stepped increase in outer diameter disposed along the needle shaft. The abrupt change in outer diameter provides a substantial increase in insertion force. The stepped increase prevents any further insertion into the bone cortex. Embodiments can include a tapered needle lumen for medullary access confirmation and an overtube that is rotatably and slidably engaged to protect surrounding tissues and prevent needle stick injuries. Further, a needle hub can be rotatable or slidable, and can transition an overtube to an extended position to prevent accidental needle stick injuries.