Well I happen to be a nurse and I have never saved anyone's life. I see people being given two days who have lived for years! Others being given 6 months and have lived for two years. I have seen great debates about moving people off life-support machines. Some recover after two years; others have their machines taken off in a very short time.
I saw your request but chose to answer. I am speaking from the standpoint that my experience is that only God is in charge, although doctors and nurses like to think they are. There are so many mysteries in this life. When I started nursing many years ago, it used to be said that we cannot live past five minutes without oxygen. Now we see people with hearts that are being stopped and have stopped for much longer.
There is always a Higher Source. If your loved ones fall ill, never forget to pray and have faith. At the same time, remember that the Supreme generally obeys the cosmic order, so also seek His Will. Much love.