When you work in the emergency department, you don't pronounce someone dead unless they're warm and dead. In the setting of severe hypothermia, people who may appear to be "dead" can be revived back to life. I was reminded of that when I was reading this story on CNN about Anna Bågenholm who almost died in 1999 while skiiing. She was severely hypothermic, she had no cardiac activity, and she looked like she was dead. However, as her body was warmed, she came back to life.
We don't see too many stories like this, but when you're working in a cold environment where people may develop severe hypothermia, it's important to remember the saying, "they're not dead until they're warm and dead."