A way of constantly administering
drugs, usually (always?) medically...
Needle goes through arm, into vein.
Needle is attached to a tube.
Tube is attached to a bag of neutral solution (mild saline, usually/always). This bag very slowly drips into the tube, which drains into the person, which causes the person to need to urinate every hour even though they haven't had a drop to drink.
To administer drugs via the drip, you can either inject the drug into the tube that leads to the patient (the tube has a little side thingy to allow this), or you can hang a second bag full of drugs slightly higher than the saline bag. The higher bag will drain until empty, then the saline bag will take over, flushing the tube. The former method is used for pain medication... the latter for antibiotics or chemotherapy.
Writing this node has made me want to puke because of all the talk about chemo.