Plunger rod for arterial blood collection syringes

A syringe assembly comprising:

• a syringe barrel having an internal chamber extending between an open rear end and a closed front end having an opening extending therethrough;
• an elongated, hollow cylindrical plunger rod extending within the open rear end of the syringe barrel and adapted for slidable communication within the internal chamber of the syringe barrel, the plunger rod comprising a rigid tubular wall defining an internal opening and extending between an open rear end and a monolithic, integrally formed closed front end, the plunger rod including a plurality of vents extending through the rigid tubular wall adjacent the front end of the plunger rod and in fluid communication with the internal lumen, and at least one sealing ring extending circumferentially about an external surface thereof and in sliding contact with an inner surface of the syringe barrel, and
• a porous filter member maintained within the internal lumen of the plunger rod at the front end of the body and contiguous to the plurality of vents,
• wherein the porous filter member is pervious to air and impervious to liquid passing from the internal chamber of the syringe barrel through the vents and into the internal lumen of the plunger body.