Spring-Biased Stylet and Cannula Needle Assembly
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Solution Overview
Problem
Existing needle assemblies, such as Veress needles, face challenges in accommodating tissues with varying properties, leading to potential tissue damage and patient discomfort due to inconsistent insertion resistance and the need for extensive manipulation during procedures.
Innovation Solution
A releasable spring-biased stylet detachably attached to a tubular cannula via a connecting member, where the stylet is configured to protrude beyond the cannula's sharpened tip when no force is applied, protecting tissues during insertion and retracting to expose the tip when necessary, allowing for adaptation to different tissue types and reducing procedural discomfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a sharp needle tip is used to penetrate tissue, then penetration ability is improved, but tissue damage increases
Solution Approach 1:
The needle assembly is divided into two functional parts: a sharp outer cannula for penetration and a blunt inner stylet for tissue protection. The sharp outer cannula penetrates tissue efficiently while the blunt inner stylet follows behind to minimize damage and allow for controlled advancement.
Solution Approach 2:
The inner stylet acts as an intermediary element between the sharp outer cannula and the tissue. It provides a protective interface that reduces direct contact between the sharp tip and tissue, allowing the sharp cannula to penetrate while the blunt stylet manages tissue interaction and minimizes harm.
2Object-affected harmful factors
If a blunt stylet protrudes beyond the cannula tip to protect tissue, then tissue protection is improved, but penetration ability worsens
Solution Approach 1:
The needle assembly separates the penetration function (sharp outer cannula) from the protection function (blunt inner stylet). During insertion, the sharp outer cannula leads the way to penetrate tissue, while the blunt inner stylet follows, providing protection only after penetration has been achieved.
Solution Approach 2:
The relative positions of the outer cannula and inner stylet are dynamic rather than fixed. The stylet can move independently within the cannula, allowing it to retract when penetration is needed and protrude when protection is needed, adapting to different stages of the procedure.
3Stability of the object's composition
If the stylet is fixed to the cannula, then structural stability is improved, but adaptability to different tissue types worsens
Solution Approach 1:
The connection between the stylet and cannula is designed to be dynamic rather than rigidly fixed. The stylet can move independently within the cannula, allowing it to respond to varying tissue resistance and properties during insertion, providing adaptability while maintaining structural integrity.
Solution Approach 2:
The system allows for changes in the relative position and configuration of its components based on tissue properties encountered during insertion. The stylet can be advanced, retracted, or positioned at different depths within the cannula depending on the specific tissue type and procedure requirements.
4Ease of operation
If extensive manipulation is required during the procedure, then precise control is improved, but patient discomfort increases
Solution Approach 1:
The needle assembly is pre-configured with the inner stylet positioned to protrude beyond the outer cannula tip before insertion. This preliminary positioning ensures immediate tissue protection upon insertion, reducing the need for subsequent manipulation adjustments and minimizing patient discomfort during the procedure.
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
The solution enables minimally invasive procedures with reduced tissue damage and patient discomfort by adapting to varying tissue properties, allowing for efficient sampling and other medical interventions with less manipulation, while providing visual or tactile indicators for tissue hardness detection.
Implementation Method 1
a spring member configured to urge the stylet in a distal direction along the longitudinal axis, such that the stylet is axially spring-biased in said distal direction
Data Source
AI summary
A medical device is disclosed comprising an elongated needle assembly having a distal end, a proximal end and a longitudinal axis A, the needle assembly comprises a tubular cannula having a sharpened distal end, a proximal cannula portion, and a longitudinal bore along the longitudinal axis A, and a stylet configured to extend through the bore of the cannula, and having a blunt distal end and a proximal stylet portion. The needle assembly is provided with a spring member configured to urge the stylet in a distal direction along the longitudinal axis, such that the stylet is axially spring-biased in said distal direction. The medical device further comprises a connecting member configured to detachably attach said stylet to said cannula, wherein said stylet is configured to be attached to the tubular cannula by the connecting member such that the blunt distal end protrudes just beyond the sharpened distal end of the cannula when no force is applied to the distal end of the stylet in a proximal direction along said longitudinal axis, and wherein the connecting member is configured to enable detachment of the proximal portions from each other such that the stylet may be fully withdrawn from the longitudinal bore.