The bag on the floor is where that stuff drains back out. Because if it doesn't drain out, than you are just putting water down the tube, and its just going into the patient's stomach. The poison is still in there. So then the tube is drained, and the contents of the drainage bag are then emptied into a hopper which is a giant toilet where the bag or basins can be dumped and washed out.
Another drainage bag is connected to the tube, and the procedure is repeated with bags of water connected, and drained in and out of the patinet's stomach until the contents of the patient's stomach appear clear. It depends on what the patient took, but sometims after this is finished activated charcoal is put down the NG tube. Its put into the tube via a syringe, and mixed with water because it needs some help getting it to go down or it may clump and clog up in the tube. This is where you hope the patient doesn't vomit. If they do, prepare to be covered in a black and VERY gooey mess. EEEK.
2. Dr: What did you take?
3. Patient: I took a whole bottle of clonidine.
4. Dr: HOLY COW!!!!!!!!!!!!!!!! Someone get a set up in here for gastric Lavage.
5. Patient: What on earth is that?
6. Dr.: Its where I stick a tube in your mouth, and I put water down that tube, and after that, I drain out, and do it again and again. After that i put charcoal down the tube, and let it stay there.
7. Patient: NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO
8. Other nurse: I have the tube ready. Open wide.