Pivotable Sheath Safety Needle Assembly
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Solution Overview
Problem
Existing needle assemblies face challenges in providing effective safety mechanisms that prevent accidental exposure and waste of medication, with issues such as dead space creation, risk of retraction mishaps, and increased biohazard waste volume in current designs like hinged recap, retractable cannula, and sliding barrel devices.
Innovation Solution
A safety needle assembly featuring a tubular needle holder with a rotatable collar and pivotable sheath that automatically locks over the cannula, allowing easy exposure and safe covering without dead space or excessive length changes, utilizing a sheath with locking tabs and flat surfaces for secure engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hinged recap device is used to cover the cannula after use, then safety is improved, but dead space is created between the cannula and syringe resulting in medication waste
Solution Approach 1:
The sheath is designed to nest over the cannula in a telescoping manner, with the sheath containing the cannula when in the covering position. This nested configuration eliminates dead space between components while maintaining safety coverage, as the sheath directly encompasses the cannula without intermediate gaps.
2Reliability
If a retractable cannula device is used to retract the cannula into the syringe barrel, then safety is improved, but the risk of inadvertent retraction increases causing waste of syringe and medication
Solution Approach 1:
The sheath is pre-positioned in a ready state adjacent to the cannula before use, and the locking mechanism is pre-configured to engage automatically when the sheath is placed over the cannula. This preliminary preparation ensures that safety coverage is immediately available without requiring complex retraction actions that could lead to inadvertent activation and waste.
3Reliability
If a retractable cannula device is used, then safety is improved, but the velocity of cannula retraction could result in spraying or splashing of fluids increasing exposure risk
Solution Approach 1:
The sheath is pre-positioned and ready to be placed over the cannula in a controlled manner, eliminating the need for high-velocity retraction movements. The sheath simply slides over the cannula at controlled speed, preventing fluid spraying or splashing that would occur with rapid retraction mechanisms.
4Reliability
If a sliding barrel design is used to cover the cannula, then safety is improved, but the length of the syringe is doubled from unused to used position increasing biohazard waste volume
Solution Approach 1:
The sheath nests over the cannula in a telescoping configuration, adding minimal length to the overall assembly. When the sheath is in the covering position, it contains the cannula within its length, creating a compact nested structure that does not double the syringe length like sliding barrel designs.
5Reliability
If a sliding barrel design is used, then safety is improved, but the syringe/needle assembly does not adequately fit into sharps containers creating exposure hazards
Solution Approach 1:
The nested telescoping configuration of the sheath over the cannula creates a compact assembly with reduced overall volume and length. This compact nested structure allows the syringe/needle assembly to fit properly into standard sharps containers, eliminating exposure hazards associated with oversized assemblies.
Data Source
AI summary
A safety needle assembly includes a needle holder assembly, a cannula fixed to the needle holder assembly, a protector positioned over the cannula and removable to expose the cannula, and a sheath. The sheath is pivotally mounted on the needle holder assembly to permit the sheath to be pivoted relative to the needle holder assembly in a direction toward the cannula from a non-covering position in which the cannula is exposed after removal of the protector to a covering position in which the cannula is covered by the sheath. The sheath can also be provided with flat surfaces adapted to successively engage a portion of the needle holder assembly as the sheath is pivoted relative to the needle holder assembly. The needle holder assembly can include a tubular syringe barrel or a tubular needle holder adapted to receive an evacuated tube.