^ Given that misspeaking a single command to the holodeck, can result in its creating a sentient being who tries to hijack your ship, I don't think I'd want to rely on it for my heart transplant.
They need UPS systems on starships. Think of a hospital today: they can't risk losing power during a orthoscopic / laparoscopic procedure. They could keep the gasoline generators in the shuttlebay and store the gasoline in the nacelles.
(... put put put put put put put ...)