Outer Needle Assembly Air Discharge Ventilation Path
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Solution Overview
Problem
Existing outer needle assemblies for dialysis and infusion fail to adequately discharge air from the bore when tilted during puncture, leading to air retention due to liquid separation and turbulence, which obstructs ventilation.
Innovation Solution
The outer needle assembly design includes a tapered portion and a small-diameter section to facilitate smooth blood flow, preventing air entrapment by maintaining consistent cross-sectional area and reducing turbulence, with a ventilation path to expel air effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer needle assembly is tilted during puncture to facilitate insertion, then insertion ease is improved, but air discharge is hindered causing air retention in the bore
Solution Approach 1:
The ventilation path is positioned at the proximal end of the outer needle, creating a spatial separation between the puncture site and the air discharge point. This dimensional arrangement allows air to be expelled through a different location than where the needle penetrates the blood vessel, enabling effective air removal even when the needle is tilted during insertion.
Solution Approach 2:
The ventilation path is pre-configured at the proximal end to automatically discharge air before blood flow begins. This preliminary air removal action prevents air entrapment during the subsequent blood filling process, ensuring that the bore is cleared of air before fluid communication is established.
2Reliability
If a gap is provided between the outer needle base and rubber stopper part to form a ventilation path, then air discharge capability is improved, but liquid leakage risk increases
Solution Approach 1:
The gap forming the ventilation path is strategically positioned at the proximal end of the outer needle where it interfaces with the rubber stopper part. This localized arrangement creates an air discharge pathway without compromising the sealing integrity at the blood vessel interface, allowing air to escape while preventing liquid leakage through the needle-bore connection.
Solution Approach 2:
The rubber stopper part acts as an intermediary element that seals the outer needle base while accommodating the ventilation path gap. This intermediary structure enables air discharge through the controlled gap while maintaining the sealing function required to prevent liquid leakage from the needle-bore connection point.
3Productivity
If the inner needle is removed quickly to minimize procedure time, then operation speed is improved, but air may not be sufficiently discharged from the bore
Solution Approach 1:
The ventilation path is designed to automatically discharge air during the rapid removal of the inner needle before the outer needle is fully inserted into the blood vessel. This preliminary air removal action occurs within the brief time window of needle assembly disassembly, ensuring air is expelled before the procedure progresses to blood flow establishment.
Solution Approach 2:
The ventilation path utilizes the natural flow dynamics during inner needle removal to automatically expel air from the bore without requiring additional manual intervention. The air discharge occurs self-service fashion as a byproduct of the rapid disassembly process, maintaining air removal effectiveness even at high operation speeds.
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
Prevents air retention in the needle assembly by ensuring air is expelled through the ventilation path, even when the needle tip is tilted, maintaining effective fluid communication.
Implementation Method 1
a tapered part formed on the proximal end side with respect to the puncture part, the tapered part having an inner diameter dimension which increases toward the proximal end side
Implementation Method 2
a ventilation path for discharging air in the first internal space to an outside communicates with the first internal space
Data Source
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AI summary
An outer needle assembly 10 comprises an outer needle 48 wherethrough an inner needle 16 passes, and a passage forming member 50 connected to the outer needle 48 and including a valve body 64 inside such that a first internal space 78 on a distal side of the valve body 64 is longer than a second internal space 79 on a proximal side thereof. A ventilation path 80 for discharging air to an outside communicates with the first internal space 78 near the valve body 64. The first internal space 78 comprises: a puncture part 56 formed in a puncturing portion of the outer needle 48; a tapered part 57 formed on the proximal side of the puncture part 56 with an inner diameter increasing toward the proximal side; and a small-diameter part 89 formed on the proximal side of the tapered part 57 with an inner diameter smaller than or equal to that of a proximal end of the tapered part 57.