The traditional mylar survival blanket is of limited value. As stated by OldBaldGuy, a patient who is in shock should be kept warm and dry or if not dry at least warm. The traditional survival blanket, despite claims of the reflection of as much as 90% of body heat, does little to insulate the patient from heat loss though conduction (contact with the ground, rocks, etc.). It can be helpful in creating a vapor barrier and reduce heat loss through convection (air currents).

A patient, who might be in moderate to severe hypothermia, is not producing enough body heat for the mylar survival blanket, by itself to be effective. Using one or more wool/disaster blankets (insulation) along with heat packs placed in the inner groin area and armpits (never in direct contact with bare skin) will assist in the patient from losing additional heat, as they will not really rewarm the body’s core (which is best performed in the hospital setting). Then by wrapping the entire blanket wrapped patient in the mylar survival blanket, you have created both a vapor and wind barrier. Especial attention should be made to insulating the head. A piece of plastic sheeting will accomplish the same thing, although it is generally heavier and bulkier to pack.

Pete