pulmonary edema
"Right after surgery, I had a fever, confusion, my blood pressure and rate of breathing went very low. I had not pee'd for several hours,  I had an oxygen level of 60 while I was sleepy and out of it. I was given 60mg of Lasix and not even 15 minutes later I was non stop peeing, my blood pressure and rate of breathing picked up quite a lot. 

I can't even imagine that the pee kept going on and on with the girls using bedpans for me. I was just out of surgery so that was necessary. Doctor kept

the oxygen level up to an 8 for the rest of the night. I believe that the medicine saved my life even though I threw up on it."