At last a topic I can reply to with some useful information.

I took a course on ice safety this winter, dealing with how to prevent falling through river and lake ice, and what to do if you (or a member of your party) falls through. The instructor indicated that warming shock is a problem for people with severe hypothermia, but not for mild hypothermia.

Mild hypothermia is indicated by shivering, slurred (but coherent) speak, and the ability to pass a simple dexterity test like bringing a cup to the lips and drinking.

The line between these can be recognized by three important signs:
Hypothermia is severe when
- shivering stops
- the patient is no longer verbally coherent
- muscle control is so poor that the patient fails the cup test

For mild hypothermia, the patient should be made dry and warm, and given food, fluids and exercise.

Severe hypotheria patients should be given the hypo-wrap treatment.