Patent ID: 7534233

Claim:
An I.V. flush syringe assembly comprising: a barrel including a cylindrical sidewall having an inside surface defining a chamber for retaining fluid, 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 plunger including an elongate body portion having a proximal end, a distal end 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, said stopper having a distal surface; and a proximally facing annular boss on said inside surface of said distal wall surrounding said passageway, said boss being positioned so mat it contacts said distal surface of said stopper and seals said passageway before portions of said inside surface of said distal wall surrounding said boss contact said distal surface of said stopper, thereby controlling stopper deflection when fluid has been delivered from said chamber and said stopper is in contact with said distal wall.