Syringe assemblies for use in flush applications are provided. Syringe assemblies according to one aspect of the present invention include a plunger rod and a syringe barrel that incorporate one or more pulsing elements on the plunger rod or barrel that are rotatable to create pulsatile movement or continuous and unimpeded movement a plunger rod within a syringe barrel. One or more embodiments pertain to syringe assemblies permit both pulsatile movement of the plunger rod within the barrel and continuous and unimpeded movement of the plunger rod in the distal direction along substantially the entire length of the syringe barrel upon application of force to the plunger rod in only the distal direction. Methods of flushing a catheter are also provided.