Patent ID: 7387615
Filing Date: 2008-06-17
Classification: A61M

Abstract:
1. A single use syringe assembly comprising: a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid and a discontinuity, an open proximal end and a distal end including a distal wall with an elongate tip extending distally therefrom having a passageway therethrough in fluid communication with said chamber; a needle cannula having a proximal end, a distal end and a lumen therethrough, said proximal end of said cannula being connected to said elongate tip so that said lumen is in fluid communication with said passageway; an elongate needle shield hingedly connected to said barrel, said needle shield having two side walls defining a longitudinal opening and a back wall between said side walls defining a recess having an interior surface, said needle shield capable of pivoting from an open position wherein said needle cannula is exposed, to a closed needle protecting position wherein said distal end of said needle cannula is within said longitudinal opening of said shield; and a plunger including an elongate body portion having a proximal portion, a distal portion, a contractible portion, a discontinuity, and a stopper slidably positioned in fluid-tight engagement with said inside surface of said barrel for drawing fluid into and driving fluid out of said chamber by movement of said stopper relative to said barrel, said elongate body portion extending outwardly from said open proximal end of said barrel; wherein when an additional distally directed force is applied to said plunger after fluid has been delivered from said chamber, said plunger shortens at said contractible portion so that said plunger discontinuity moves distally to engage said barrel discontinuity to lock said plunger in said barrel; and wherein said plunger further comprises at least one break point for allowing said plunger to break upon application of excessive force intended to move said plunger proximally after said plunger has been locked to said barrel.