Exposure to hight temperatures over time with decreased cooling and inadequate heat loss will lead to heat stroke. This can be viewed as the end stage of heat exhaustion. This diagnosis is a high medical emergency with mortality and morbidity reaching as high as eighty percent. In the outdoors and if far from medical care the outcome is poor and iffy.
Heat stroke can be an abrupt onset. The importance of hydration and monitoring ones symptoms on the trail are extremely important.
Treatment in the outdoors will be very limited as the items needed will most likely not be available hence the importance of immediate transport. Transport in an ideal situation would be for the patient not to walk and have some type of makeshift gurney or sled.
Treatment should be rapid cooling with ice or cool water immediately as well as fanning to accelerate cooling. IF THE PATIENT BEGINS TO SHIVER STOP FANNING AND COOLING FOR TEN MINUTES OR UNTIL SHIVERING STOPS. Shivering will increase core body temperature. If possible temperature should be taken every ten minutes. Again probably impossible in the outdoors.
In the Urgent care or Emergency Department cooled IV fluids, Ice packs, IV Valium to reduce seizures and a multitude of labs. Many athletes and young high school football players can be misdiagnosed as they may be brought in early and are still sweating. Assume the worse diagnosis and one can always back off on the cooling as they improve.