Yes if you have any CVC,including PICCs,all infusions need to be shut off for at least one full minute. if the patients medication cannot be shut off for one full minute (such as Dopamine or levophed for its vasopressor effect) than another means to draw the blood needs to take place. If you have a multi-staggered tip design as in many of the percutaneous placed jugular or subclavian catheters its best to use the proximal lumen. Most piccs do not have this design and every thing exits at the same place from their respective lumens. You must discard at least two times the priming volume of that line and usually 3-5 ml covers that,though i have seen protocols that say up to 10 ml. Obtain your speciman being careful not to mix up your discard and your speciman. Flush your lumen with a pulsatile flush and resume any infusions. One minute is enough considering the volume dumped into the SVC where the catheter tip lies. if you place your infusions off for longer than that you risk clotting the line off.