Retractable Inner Needle for Extracorporeal Circulation Safety
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Solution Overview
Problem
Indwelling needles for extracorporeal circulation with a simple double lumen structure have thick tip ends, causing patient pain and risking accidental pricking of medical personnel, and require complex blood circuit setups with separate inlet and discharge pumps.
Innovation Solution
A double-tube indwelling needle design with an outer needle and an inner needle, where the inner needle is held by a holding member to move between a projecting and housed position, allowing blood circulation without the need for separate puncture and circulation members, reducing the risk of accidental exposure and pain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a simple double lumen structure is used for the indwelling needle, then the structure is simplified and manufacturing is easier, but the tip end portion becomes excessively thick causing patient pain and risk of accidental pricking
Solution Approach 1:
The inner needle is nested within the outer needle, with the inner needle's tip end retractable into the outer needle's tip end. This nesting structure allows the needle to maintain a thin profile during manufacturing while enabling the sharp tip to be exposed only when needed for puncture, thereby reducing patient pain and accidental pricking risk without complicating manufacturing
Solution Approach 2:
The needle tip end structure is made dynamic through the retractable inner needle mechanism. The tip end can transition between an exposed state (for puncture) and a retracted state (for safety), allowing the needle to adapt its configuration based on operational requirements. This dynamic adjustment resolves the contradiction between needing a sharp exposed tip and maintaining a thin safe profile
2Reliability
If two separate indwelling needles are used for blood introduction and discharge, then separate introducing and discharging passages are ensured, but the structure becomes complicated and operational efficiency decreases
Solution Approach 1:
Two separate indwelling needles are merged into a single integrated needle structure with dual lumens. The outer needle contains an inner needle, creating two independent fluid passages within one device. This merging maintains the reliability of separate blood introduction and discharge pathways while simplifying the overall blood circuit structure and improving operational efficiency
3Ease of operation
If the inner needle is removed after puncture, then the sharp tip is no longer needed, but the removed needle tip may erroneously prick medical personnel
Solution Approach 1:
The design incorporates preliminary anti-action by providing a retraction mechanism that automatically retracts the sharp inner needle tip into the outer needle housing after puncture. This preliminary safety feature prevents the sharp tip from causing accidental pricks to medical personnel during subsequent handling, while maintaining ease of operation through automated retraction rather than manual removal
Data Source
AI summary
A seal member and outer cylinder needle (OCN) tip part for blocking, in a fluid-tight state, both external peripheral space (EPS) end parts formed between the external-peripheral-surface of an inner needle (IN) and internal peripheral surface of an OCN, for slidably holding the IN in close contact; an opening part formed on the OCN external-peripheral-surface and for intravascular communication with the EPS; an OCN connection part for communicating between the EPS and blood circuit end; an IN connection part for communicating between the IN internal space and other blood circuit end. The movable IN positioned between the projecting position where the tip part protrudes from the OCN tip and the housed position housing the tip inside the OCN. The IN punctures the blood vessel interior while holding the projecting position, and moved to the housed position after puncture allowing blood to extracorporeally circulate via the OCN and IN connection part.