Patent ID: 6585690
Filing Date: 2003-07-01
Classification: A61M

Abstract:
A hypodermic syringe with a selectively retractable needle comprises;an elongate barrel having an open proximal end and a distal end defining a receiver, said barrel having a hollow bore therethrough extending from said proximal end to said distal end; an elongate plunger having a distal end with an elongate first portion extending proximally therefrom and a proximal end with a second portion extending distally therefrom, said second portion having an elongate cavity therewithin with an inside diameter open to said proximal end, said plunger being sized to fit within said bore of said barrel for a slidable movement to define a chamber for receiving and expelling fluids, said inside diameter of said elongate cavity in said plunger being sufficient to accept telescopically at least a part of said first portion of said plunger, said second portion and said first portion being joined at an attachment to form a shoulder extending outwardly from said first portion, said plunger being telescopically collapsible by movement of said first portion into said elongate cavity by an application of sufficient distal force, greater than a force required to expelled fluid from said chamber, to frangibly disrupt said attachment of said first portion to said second portion; an elongate sleeve having a proximal end and a distal end, said proximal end being sized to fit over at least part of said first portion of said plunger and extend distally from said shoulder, said distal end of said plunger including a stopper sized to form a slidably substantially fluid tight seal with said bore of said barrel for forming said chamber, said sleeve having a cutting surface at said distal end being disposed inside of said stopper proximally from said distal end of said plunger; an elongate hub with a proximal flange, said hub disposed within and sized for slidable movement within said receiver at said distal end of said barrel with said proximal flange defining a distal end of said chamber in said barrel, said hub having a passageway therethrough; an elongate needle having a fluid path therethrough, said needle having a pointed distal end and a proximal end mounted in said passageway of said hub so that when said hub is disposed within said receiver at said distal end of said barrel, said pointed end of said needle extends distally outwardly and said fluid path of said needle is in fluid communication with said chamber of said barrel; an elongate spring disposed about said hub compressed between said receiver and said flange to provide a bias, so that when a sufficient distal force, greater than the force needed to expel fluid from said chamber, is applied to said plunger to frangibly disrupt said attachment between said first portion and said second portion to thereby telescopically collapse said first portion into said second portion, and wherein said cutting surface of said sleeve cuts through said stopper and through said flange of said hub thereby to release said hub from said receiver and to allow said bias of said spring to urge a sufficient movement of said hub to a position within said syringe where inadvertent contact with said pointed distal end is substantially prevented.