Syringe with removable plunger for arterial blood gas sample collection

A fluid collection assembly comprising:

• (a) a fluid collection cartridge comprising:
• (i) a tubular member having a proximal end, an open distal end, and a sidewall extending between the proximal end and the distal end defining an internal chamber having an internal reservoir;
• (ii) a pierceable closure associated with the open distal end of the tubular member, the closure configured to cooperate with the sidewall of the tubular member to sealingly close the open distal end;
• and
• (iii) a plunger rod assembly including a stopper and a plunger rod removably associated with one another by an interengaging arrangement, wherein the interengaging arrangement is configured to enable the plunger rod to apply a distally directed force to the stopper and to enable removal of the plunger rod from the stopper and from the tubular member upon the application of only a proximally directed force, wherein the stopper comprises at least one mixing fin extending distally from a distal face of the stopper, and further wherein the pierceable closure comprises an internal end at least partially received within the tubular member and at least one cavity extending into the internal end of the pierceable closure, the cavity being sized to receive the at least one mixing fin of the stopper;
• (b) a needle assembly including a cannula having a distal end and a proximal end and a first needle shield covering the distal end;
• and
• (c) a holder associated with the needle assembly, the holder configured for cooperating with the fluid collection cartridge for collecting a fluid sample.

A method of collecting a blood sample comprising:

• (a) providing a fluid collection assembly comprising:
• (i) a fluid collection cartridge having:
• a tubular member having a proximal end, an open distal end, and a sidewall extending between the proximal end and the distal end defining an internal chamber having an internal reservoir;
• a pierceable closure associated with the open distal end of the tubular member, the closure configured to cooperate with the sidewall of the tubular member to sealingly close the open distal end;
• and
• a plunger rod assembly including a stopper and a plunger rod removably associated with one another by an interengaging arrangement, wherein the interengaging arrangement is configured to enable the plunger rod to apply a distally directed force to the stopper and to enable removal of the plunger rod from the stopper and from the tubular member upon the application of only a proximally directed force, wherein the stopper comprises at least one mixing fin extending distally from a distal face of the stopper, and further wherein the pierceable closure comprises an internal end at least partially received within the tubular member and at least one cavity extending into the internal end of the pierceable closure, the cavity being sized to receive the at least one mixing fin of the stopper;
• (ii) a needle assembly including a cannula having a distal end and a proximal end and a first needle shield covering the distal end;
• and
• (iii) a holder associated with the needle assembly, the holder configured for cooperating with the fluid collection cartridge;
• (b) priming the fluid collection assembly with a fluid treatment additive;
• (c) removing the plunger rod from the fluid collection cartridge;
• (d) removing the first needle shield from the distal end of the cannula;
• and
• (e) collecting a fluid sample into the internal reservoir.