Overview Line draw plus aspirating syringes, From smiths medical with a variety of lithium heparin concentrations, allow for blood sampling directly From an arterial line. The syringes use an advanced formula of dry lithium heparin for consistent and accurate readings. They are available with the following configurations: 1 ml luer slip syringe, 3 ml luer lock syringe, or 3 ml luer slip syringe.