Syringe enabled for aspirating blood into a sampling site in a closed manner and method

An in-line sampling syringe for selectively introducing a fluid to and aspirating a fluid from a downstream fluid conduit connected to a catheterized patient, said syringe comprising:

• a. an elongated housing composed of (i.) a distal component defining a distal chamber having a proximal opening and a distal outlet port to be coupled to a downstream fluid conduit and (ii) a pair of proximal wall components assembled together in an airtight manner defining a proximal chamber having a proximal opening for coupling to an external source of fluid and a distal opening that is coupled to the proximal opening of the distal component;
• b. an elongated volume regulator positioned longitudinally inside the housing that includes (i) a double rack having a distal extension with a gasket mounted on the distal end of said distal extension for separating a distal fluid chamber from a proximal air chamber, (ii) said elongated volume regulator being mounted for sliding longitudinally between a first position where the gasket is at the distal outlet port and a second position where the gasket is withdrawn from the distal outlet port, and (iii) a drive for the double rack;
• c. a curved element positioned at and in alignment with the distal outlet;
• d. retention elements defined in the distal component at the distal outlet port to mount and retain the curved element at the distal outlet port while enabling flow around the curved element relative to the distal outlet port;
• and
• e. a conduit extending from the proximal opening of the proximal chamber through the elongated volume regulator to the curved element at the distal outlet port.