Patent ID: 6409701
Filing Date: 2002-06-25
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 having a distal inward shoulder, said barrel having a hollow bore therethrough extending from said proximal end to said distal end; an elongate plunger having a proximal end and a distal end, said plunger including an inner rod extending a distance distally from said proximal end, a hollow sleeve having a proximal end and a distal end, sized to fit slidably, extend beyond and disposed over said inner rod, a hollow cutter extending distally from said inner rod to a distal cutting surface within said hollow sleeve, and a stopper disposed over said distal end of said hollow sleeve to cover said cutting surface, said stopper being sized to fit slidably within said hollow bore of said barrel to define a chamber to draw and expel fluid, said plunger further including a displaceable collar that substantially prevents a movement of said inner rod with respect to said hollow sleeve, said collar being displaced by application of a distal force, greater than a force required to expel fluid from said chamber in said barrel, to said plunger, said collar being displaced by engagement with said proximal end of said barrel, and, when said collar is displaced, allows a movement with respect to said hollow sleeve of said inner rod having said cutter attached thereto, and causes said cutting surface to cut through said stopper; an elongate hub having a stem with a proximal flange and an engagement, said stem disposed within and sized for slidable movement within said receiver at said distal end of said barrel with said flange having a distal surface and a proximal surface, said proximal surface of said flange defining a distal end of said chamber in said barrel, said hub having a passageway therethrough; a clip having a proximal foot with an opening therethrough and a distal grip, said clip being disposed on said stem of said hub with said proximal foot at said distal surface of said flange and said grip at said engagement on said stem; 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 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 stem of said hub compressed between said receiver and said distal grip of said clip to provide a bias, so that when sufficient distal force, greater than the force needed to expel fluid from said chamber, is applied to said plunger to cause said cutting surface to cut through said stopper, said cutting surface then engages said flange and cuts through said flange thereby to engage said clip and to cause said clip to release said engagement on said stem 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 of the needle is substantially prevented.