"You Aren't Dead Until You're Dead Warm"

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If anyone watches Greys Anatomy you probably saw the episode with the large ship crash, when Grey falls in the water and "dies." And they said "you aren't dead until you are dead warm." Well I asked my dad, and he said that's true (he is a doctor so he is a good source =P). So what I'm wondering is if something like Titanic happened now, would we be able to remove the people who "died" in the water, and maybe revive some of them. Get them warm and get their hearts going again. I wouldn't expect that everyone would be brought back to life, but do you think it is possible that some of them could be revived?