Some institutions call it "KVO," or "keep vein open," and it's a rate of 20 mL or 30 mL an hour - 0.9 Normal Saline Solution is used.
I usually only use this when I'm running an antibiotic on a syringe, a PCA pump, or Y'd with a Potassium or Magnesium Rider.
In the case of the PCA, the pain medicine is not going fast enough to ensure the IV line does not clot off - so it needs some "help" from a running drip.
As far as the antibiotic or the Riders, these medicines are harsh on the veins and sometimes cause burning. The patient feels better if these medications are diluted with saline.
I hope I helped! I just woke up and haven't had my coffee yet!
Welcome to the board, I'm new also! My name is Brittany.