I too work in oncology. We flush PICC lines with 10cc NS, and follow with 200 units of Heparin (2cc). Same for Hickmans. Groshongs only get 10cc saline flushes. Port a caths get 10cc saline and 500 units of Heparin. All central line dressing and cap changes are done MWF. Lines not in use are flushed daily. Some will draw out heparin before flushing to reduce systemic exposure but it depends on the patients coag status because sometimes it may not even make a difference.