Positive displacement flush syringe

A flush syringe assembly comprising:

• a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall with a 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 and a distal end, a stopper slidably positioned in fluid-tight engagement with said inside surface of said barrel for 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 including a distal end having a distal wall and a cavity therein defining an inside surface and a proximal end, said distal wall being flexible enough to collapse at least partially into said cavity under the liquid pressure of a flush procedure and to move back toward its original shape at the completion of the flush procedure to force additional fluid into said passageway;
• wherein said inside surface of said stopper includes a proximally directed projection configured to compress when said stopper is in a collapsed position and to urge said distal wall from said collapsed position toward its original shape.

An I.V. flush syringe assembly comprising:

• a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall with a tip extending distally therefrom having a passageway therethrough in fluid communication with said chamber;
• a tip cap releasably connected to said tip for sealing said passageway;
• a plunger including an elongate body portion having a proximal end and a distal end, a resilient stopper, a quantity of flush solution in said chamber, said stopper slidably positioned in fluid-tight engagement with said inside surface of said barrel for 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;
• structure for moving additional flush solution distally in said passageway after flush solution has been delivered from said chamber and distal motion of said plunger with respect to said barrel has stopped, including said stopper having a distal end including a distal wall and a cavity therein defining an inside surface and a proximal end, said distal wall being flexible enough to collapse at least partially, into said cavity under the liquid pressure and to move back toward its original shape at the completion of the flush procedure to force additional flush solution of at least 0.001 ml into said passageway when said syringe is connected to a peripheral catheter;
• said cavity including a spring at said inside surface, said spring configured to compress when said stopper is in a collapsed position and to urge said distal wall from said collapsed position toward its original shape.

An I.V. flush syringe assembly comprising:

• a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid, an open proximal end and a distal end including a distal wall with a tip extending distally therefrom having a passageway therethrough in fluid communication with said chamber;
• a tip cap releasably connected to said tip for sealing said passageway;
• a plunger including an elongate body portion having a proximal end and a distal end, a resilient stopper, a quantity of flush solution in said chamber, said stopper slidably positioned in fluid-tight engagement with said inside surface of said barrel for 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;
• structure for moving additional flush solution distally in said passageway after flush solution has been delivered from said chamber and distal motion of said plunger with respect to said barrel has stopped, including said stopper having a distal end including a distal wall and a cavity therein defining an inside surface and a proximal end, said distal wall being flexible enough to collapse at least partially, into said cavity under the liquid pressure and to move back toward its original shape at the completion of the flush procedure to force additional flush solution of at least 0.001 ml into said passageway when said syringe is connected to a peripheral catheter;
• wherein said inside surface of said stopper includes a proximally directed projection configured to compress when said stopper is in a collapsed position and to urge said distal wall from said collapsed position toward its original shape.