Always check your hospital policy/procedure manual. When we flush our lines we are only flushing the open (nothing connected) lines, we don't flush the lines with fluids infusing. We use 10ml saline flush, our pharmacy stocks us with these prefilled syringes. Always clean the port with alchohol for 15 sec and dry for 15-30 sec prior to connecting IV tubing or any syringe with medication. Don't leave tubing connected once the infusion is done as it can occlude your line. There is nothing more frustrating than finding an occluded port when you need to give meds stat. good luck.