When the floodwaters rose around New Orleans hospitals after Hurricane Katrina in 2005, doctors wondered whom to rescue first. Sick babies? Critically ill adults? The elderly? More than seven years later, as Hurricane Sandy hit New York City, Bellevue Hospital's basement filled with millions of gallons of floodwater from the East River. The physician heading the intensive care unit was told that most backup power was likely to fail. She would have six power outlets. Which of her 50 patients should get one?