Positive displacement flush syringe

摘要

A flush syringe assembly comprises 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 having a passageway therethrough in fluid communication with the chamber. A plunger including an elongate body portion having a stopper at its distal end is provided. The stopper is slidably positioned in fluid-tight engagement with the inside surface of the barrel for driving fluid out of the chamber through the passageway. The stopper includes a distal portion and a proximal portion separated by a spring element and configured to compress when fluid is being driven through the passageway by motion of the plunger and to continue to drive fluid through the passageway after motion of the plunger has stopped.

主权项

1. A flush syringe assembly for reducing reflux of blood into a vascular access device during and after a flush procedure comprising:
a barrel including a cylindrical side wall having an inside surface defining a chamber for retaining fluid, an open proximal end having an inwardly directed annular projection 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 having a radially directed projection and a secondary radially directed projection, 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, the radially directed projection on the proximal end of the plunger and the secondary radially directed projection positioned to snap past the inwardly directed annular projection on the proximal end of the barrel to retain the plunger and to prevent further distal and proximal motion of the plunger with respect to the barrel; a discontinuity including an outwardly directed fixed radial projection on said elongate body portion on said plunger having a distal surface extending beyond the cylindrical side wall of the barrel for direct engagement of the plunger with said barrel for stopping the distal motion of said plunger before said stopper fully delivers all liquid from said chamber, said stopper including a proximal stopper portion connected to said distal end of said plunger and a distal stopper portion separated from said proximal stopper portion by a spring for moving said distal stopper portion in a distal direction to drive more liquid out of said chamber after said discontinuity on said plunger engages said barrel to stop distal motion of said plunger, wherein said distal stopper portion has at least one circumferential rib engaging said inside surface of said barrel and said proximal stopper portion has at least two circumferential ribs engaging said inside surface of said barrel to engage said inside surface of said barrel so that less force is required to move the distal stopper portion along said chamber than said proximal stopper portion.