My hospital system differentiates between adult and pediatric picc lines, because they are different sizes, and therefore, different volumes to aspirate and flush with. But don't flush immediately before drawing labs....that would mess the labs up, establish patency, ya know, flush it with saline, and aspirate your waste, then draw labs, then flush with NS, then with Heparin. The manufacturer of the PICC lines, get a peds picc line information insert, and an adult picc line insert, then go from there, as to volumes you need to waste ahead of time, before you establish your policy. Obviously, when giving a medication, you don't need to aspirate a waste first, so you'de be skipping that step.