Hypothermia is a very real and potentially deadly condition if not recognized and treated promptly.
Hypothermia occurs when the body loses more "core" heat than it can produce and retain.
An uninsulated human body losses most heat from the head, neck and chest [especially sides and armpits] and to a lesser degree the groin.
Hypothermia can occur at any time during the year, winter or summer and is not restricted to cold weather. Hypothermia can occur at temperature of 10 C or less.
As the body cools, your ability to generate heat is reduced because a colder body doesn’t generate as much heat as a warmer body. Shivering stops, the body cools further and eventually the victim’s heart fails. [Wang]
Untreated, the condition will progress to where there is decreased level of consciousness, body functions gradually cease and death will result.
Numbness of hands and feet
Followed by unconsciousness
A severely hypothermic patient must be handled very gently.
Cover the patient well.
It is especially important to cover/insulate the patient from the ground, as significant heat loss will occur through conduction (heat transfer from a warm body to a cold surface). If a spinal injury is suspected, a "body role" can be used (with proper assistance) to place blankets under the patient.
Constantly talk to and reassure the patient.
If having to remain in one place for an extended period of time awaiting assistance, a fire for warmth should be considered.
Fires should be strategically placed to warm both the patient and the responder(s), but remember that your patient may have lost some feeling or may be in a decreased level of consciousness, and may not be able to communicate well. Consequently you must be alert to the condition of your patient and that they are not too hot or burned by the fire’s radiant heat.
Dr. Larry Wang, professor of biological science, Universtiy of Alberta