Telescoping Tuohy Needle Hub for Epidural Length Adjustment
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Solution Overview
Problem
Standard 3.5″ Tuohy needles are often inadequate for reaching the epidural space in obese patients, leading to increased difficulty, failure rates, and time delays in epidural anesthesia procedures, as well as potential discomfort and infection risks due to the need for longer needles and repeated sterile field exposure.
Innovation Solution
A telescoping epidural needle device with a hub that allows extension from 3.5″ to 5″, featuring a locking mechanism with protrusions and indentations for secure length adjustment without rotating the needle shaft, ensuring sterility and comfort by minimizing extraneous needle length outside the patient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a standard 3.5'' Tuohy needle is used, then the procedure is simple and quick for normal patients, but it is inadequate for reaching the epidural space in obese patients with BMI > 30
Solution Approach 1:
The needle assembly incorporates a telescoping mechanism with inner and outer sheaths that can dynamically adjust the effective needle length. The hub can be rotated to extend or retract the inner sheath relative to the outer sheath, allowing the needle length to be changed from 3.5 inches to 5 inches based on patient requirements. This dynamic adjustment capability resolves the contradiction by providing both the short length needed for normal patients and the extended length needed for obese patients using a single versatile device.
2Length of moving object
If a longer needle is retrieved and used for obese patients, then the needle length is sufficient to reach the epidural space, but substantial time is added to the procedure and sterile field is compromised
Solution Approach 1:
The extendable needle assembly is pre-packaged as a complete sterile unit with both the inner and outer sheaths already assembled and sterilized together. The anesthesiologist opens a single sterile package containing the entire assembly, eliminating the need to retrieve a separate longer needle from non-sterile storage. The needle can then be extended in-place during the procedure, avoiding the time-consuming process of removing sterile gloves, opening new packages, and re-gloving. This preliminary preparation of the complete assembly resolves the time loss issue.
3Length of moving object
If the needle length is extended for obese patients, then the epidural space can be reached, but the risk of infection increases due to extended sterile field exposure
Solution Approach 1:
The complete extendable needle assembly with both sheaths is sterilized together as a single unit before use. This ensures that the interface between the inner and outer sheaths is already sterile when assembled, eliminating the risk of contamination that would occur if sheaths were assembled separately in the operating room. The pre-sterilized assembly maintains the sterile field integrity throughout the procedure, resolving the infection risk issue.
4Adaptability or versatility
If a telescoping hub mechanism is added to allow needle extension, then the needle can accommodate both normal and obese patients, but the device complexity increases
Solution Approach 1:
The telescoping hub mechanism employs a nested structure where the inner sheath is positioned inside the outer sheath, similar to nested dolls. The inner sheath contains the needle, while the outer sheath surrounds it. By rotating the hub, the inner sheath extends or retracts relative to the outer sheath. This nesting approach provides the length adjustment functionality with minimal additional components, resolving the complexity issue by using a space-efficient design.
Solution Approach 2:
The hub is divided into distinct functional segments: the outer sheath, the inner sheath, the locking mechanism with protrusions and indentations, and the rotation interface. This segmentation allows each component to perform its specific function independently while working together as a unified system. The modular segmented design makes the complex mechanism easier to manufacture, assemble, and maintain, resolving the device complexity issue.
Data Source
AI summary
The Tuohy needle of the present invention includes a hub design that allows for the needle to be extended mid-procedure from 3.5″ to 5″. The extendable needle of the present invention allows practitioners to better accommodate overweight and obese patients and introduce a simpler procedure workflow.