I also thought Normal Saline was used as the flush at a KVO rate. The LPN on the shift I work hung an antibiotic through the PCA pump, even though the pt had another lock in the hand, before asking if this was ok. The antibiotic had already infused before she asked, so I asked that she hand the next IVPB through the lock. Not sure if this was correct but I assumed as long as their was a second option for the antibiotic it was safer to use it than to run it through the PCA.