Never talk anything when a person is in a dying condition. Most of the time they will recover..and They will remember every single word u said.
Never assume that anesthesia will stop a person from hearing or seeing. Never say or do anything which will hurt them if they are awake.. One scientific research have showed that they hear everything..And can remember them with a help of hypnotist.
It would be good if same kind of carefulness is maintained with a person sleeping.