My story is not as dramatic as some, but hear it goes.
My father was near the end of his life. His kidneys shut down and was undergoing dialysis. It was apparent that he was anemic and needed a transfusion. I talked with the nurse and explained that my father grew up a witness and would not want blood at this point in his life.
I decided to intervene out of respect for him. There was little downside to the decision, his time was limited and if blood helped sustain his life it would have been only for an extra few days.