Patent ID: 7713245
Filing Date: 2010-05-11
Classification: A61M

Abstract:
1. A plunger for an operable retracting needle syringe including a syringe barrel having an inside surface defining a chamber, an open proximal end, a distal end including a needle assembly having a hub connected to said distal end of said barrel and a needle having a sharp distal end, a proximal end connected to said hub and a lumen therethrough in fluid communication with said chamber, said hub further including a biased spring operatively connected to a hollow cutting sleeve having a proximally facing sharp edge capable of cutting through said hub and said plunger wherein said plunger comprises: a hollow elongate body portion having a proximal end, a closed distal end and a side wall therebetween defining a cavity therein and including a longitudinal axis, said distal end including an end wall having an outside surface and an inside surface; a stopper at said distal end of said plunger including a peripheral portion having an outside surface for forming a seal with said inside surface of said barrel, said stopper having at least one radial element extending from about a center of said outside surface of said end wall to said peripheral portion; said distal end of said body portion including at least one primary chamfer in said cavity at an intersection of said inside surface of said end wall and said side wall, said primary chamfer supporting said end wall and said at least one radial element when said hollow sleeve cuts through said end wall, and a secondary chamfer on each side of said at least one primary chamfer, each of said secondary chamfers being smaller than said primary chamfer.