Medical syringe with retractable needle and modified plunger handle with concave pressure application surface
Inventors
Shaw, Thomas J. • Myers, Hannah Monique
Assignees
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Publication Number
US-12042639-B2
Publication Date
2024-07-23
Expiration Date
Abstract
A medical syringe having a forwardly projecting needle that is selectively retractable following use and also having a specially configured plunger handle and thumb cap that cooperate to form a concave pressure application surface (“CPAS”). The concave pressure application surface at the rear of the plunger handle enables the subject medical syringe to achieve functional advantages, each with an associated therapeutic benefit, that are not achieved with use of the prior art devices.
Core Innovation
The disclosed medical syringe includes a barrel and a rearwardly biased, selectively retractable needle assembly coupled to the barrel, where the needle assembly comprises a forwardly projecting needle. The syringe further includes a plunger slidably engaging an inside cylindrical wall of the barrel and comprising a plunger handle, a thumb cap, and an end plug. The thumb cap and the end plug cooperate to form a rearwardly facing concave pressure application surface (CPAS) against which a forwardly directed thumb force is applied by a user.
The end plug comprises one or more outwardly projecting annular protrusions that loosely engage with one or more cooperatively aligned recesses on an inner wall of the thumb cap. This loose engagement allows venting of air around the end plug from an inside of the barrel when the plunger handle is fully advanced inside the barrel and the needle assembly is retracted within the barrel. A dimensional requirement is provided for the CPAS geometry, in which the CPAS depth-to-aperture diameter ratio is about 0.06 to about 0.085, with a preferred value of about 0.078.
Additional aspects describe thumb-cap venting features, including thumb-cap channels to facilitate air venting around the end plug from inside the barrel during the condition of the plunger handle being fully advanced and the needle assembly being retracted. The plunger handle and thumb cap are configured so that the thumb cap nests within a barrel annular recess when the plunger is fully advanced and the needle assembly is retracted.
Claims Coverage
The document includes two independent claims: one independent claim directed to the medical syringe structure and one independent claim directed to a method for administering an injection using that syringe. Across the independent claims, the coverage centers on a thumb-driven CPAS formed by a thumb cap and end plug, and on an end-plug venting arrangement allowing air venting during selective needle retraction, with additional geometric constraint options for the CPAS depth-to-diameter ratio.
Thumb-driven concave pressure application surface (CPAS) formed by thumb cap and end plug
A medical syringe in which the thumb cap and the end plug cooperate to form a rearwardly facing concave pressure application surface (CPAS) against which a forwardly directed thumb force is applied by a user.
Loosely engaged annular protrusions and cooperatively aligned recesses for venting air around the end plug
An end plug comprising one or more outwardly projecting annular protrusions that loosely engage with one or more cooperatively aligned recesses on an inner wall of the thumb cap to allow venting of air around the end plug from an inside of the barrel when the plunger handle is fully advanced and the needle assembly is retracted.
CPAS depth-to-diameter ratio constraint for thumb force focusing
The CPAS is configured with a depth-to-diameter ratio of about 0.06 to about 0.085, with the CPAS being associated with coaxial alignment with the plunger handle.
Administering an injection by applying forwardly directed thumb force to the CPAS
A method for administering an injection that provides a medical syringe having the above barrel, rearwardly biased selectively retractable needle assembly, and CPAS, and thereafter applies a forwardly directed thumb force to the CPAS while administering the injection.
Overall, the independent-claim coverage requires a medical syringe having a rearwardly facing concave CPAS formed by cooperating thumb cap and end plug, with an end-plug venting arrangement (outward annular protrusions loosely engaging thumb-cap recesses) that allows air venting when the plunger handle is fully advanced and the needle assembly is retracted. The independent method claim further requires administering an injection by applying a forwardly directed thumb force to the CPAS, optionally incorporating the CPAS geometric depth-to-diameter ratio constraint.
Stated Advantages
Improves thumb-force focusing.
Reduces misdirection and slippage.
Improves comfort during injection.
Is particularly suited for high-viscosity medicine.
Documented Applications
Administering an injection using the medical syringe by applying forwardly directed thumb force to the CPAS while the needle assembly is selectively retractable and air is vented around the end plug during the retraction condition.
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