Retractable Needle Assembly with Flashback Gap
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Solution Overview
Problem
Current needle assemblies for introducing catheters into blood vessels make it difficult to visually confirm proper needle placement within the vessel, as the existing methods rely on blood flashback, which can be ambiguous due to small or large flashback volumes, and lack a clear visual indication.
Innovation Solution
A needle assembly with a handle and inner sleeve configuration that allows for easy visual verification of blood flashback through a translucent outer sleeve, featuring a movable needle hub and aligned through holes for unobstructed blood flow, along with a release mechanism for safe needle retraction, ensuring clear visibility and safe handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a needle assembly is used for catheter introduction with traditional flashback method, then the needle can be inserted into the blood vessel, but the visual confirmation of proper needle placement is difficult due to ambiguous flashback volumes
Solution Approach 1:
The patent introduces a longitudinal gap between the outer and inner sleeves that extends along the needle hub, creating a new dimensional space for blood flashback. This gap provides an extended visual pathway for blood to travel and become visible, transforming the traditional point-based flashback into a linear visual indicator that can be easily observed along the length of the needle hub.
Solution Approach 2:
The patent utilizes the natural color of blood (red) as a visual indicator against the contrasting background of the needle hub and sleeves. The translucent or transparent material of the outer sleeve allows the red blood to be clearly visible through the gap, creating a high-contrast visual signal that confirms proper needle placement in the blood vessel.
2Measurement precision
If the needle hub is fixed at the first position, then the flashback passageway is open for visual confirmation, but the needle cannot be retracted for safe handling
Solution Approach 1:
The patent employs a spring-loaded needle hub that can dynamically transition between two positions: a first position where the hub is extended to allow flashback visualization, and a second position where the hub is retracted into the handle for safe handling. The spring mechanism automatically returns the hub to the retracted position after use, providing both visual confirmation capability and safety through automatic retraction.
Solution Approach 2:
The spring mechanism automatically returns the needle hub to the retracted position after the flashback observation is complete, eliminating the need for manual retraction operations. The system self-regulates the needle hub position based on the operational state, providing both flashback visibility and safe handling without requiring additional manual steps.
3Measurement precision
If the outer sleeve is made opaque, then the structure is simpler, but the blood flashback cannot be visually confirmed from the exterior
Solution Approach 1:
The patent applies different optical properties to different parts of the handle structure: the outer sleeve is made translucent or transparent in the region where flashback visibility is needed, while other portions of the handle may remain opaque for structural integrity and aesthetics. This localized transparency allows blood flashback to be visually confirmed through the gap without requiring the entire handle to be transparent.
Data Source
Figure 1
Figure 2~3
Figure 4A~4C
AI summary
A needle assembly for introducing an indwelling catheter into a blood vessel of a patient is disclosed. The needle assembly is provided with a handle having an outer sleeve (3), an inner sleeve (13) coaxially fixed to the outer sleeve, and a gap between the outer sleeve and the inner sleeve; a hollow needle (9) configured to pierce the patient to guide the catheter into the blood vessel; a needle hub fixed to the needle and movably fit in the handle, which is temporarily retained at a first position where the needle is exposed out of the handle and biased to move toward a second position where the needle retracts in the handle; a release (19) configured to releasably retain the needle hub at the first position; and a passageway composed of a first through hole (23) penetrating the inner sleeve and a second through hole (21) penetrating the needle hub. These first through hole and the second through hole are so formed as to align with each other to allow flashback of blood from the needle to the gap of the handle without a mediating member between the first through hole and the second through hole only if the needle hub is at the first position.