Wilderness and Rescue Medicine 8th Edition

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Section V: Environmental Medicine

dehydrated patient back to normal. Look for less thirst, increased urine production, and an improved sense of well-being as an indication of success. In most cases, field treatment for heat exhaustion will be definitive and evacuation will not be necessary.

the patient has time to become dehydrated. The skin may be still wet with sweat. The patient will feel hot. Treatment of Heat Stroke In the field, a hot patient with altered mental sta- tus has heat stroke and immediate and aggressive cooling is required. Immersion in cold water is ideal. As an alternative, you can maximize heat loss from the entire body surface by evapora- tion, conduction, and radiation if available. Just applying ice to the neck, armpits, and groin is insufficient. Look for an improvement in level of consciousness and mental status to indicate the return to a more normal temperature.

General Principles

Heat Exhaustion

Treatment: • Reduce exercise and heat exposure • Give oral fluids; drink to thirst • IV or SC fluids if S/Sx of volume depletion and po is not working • Evacuate if not improving

Low Risk

High Risk

© 2018 WMA

General Principles

Heat Stroke

Heat Stroke Heat stroke is a serious critical system problem requiring immediate field treatment. The primary problem is dangerously elevated body core tem- perature which causes significant damage to the central nervous system and other vital organs. Aggressive cooling is required. The patient may also be in volume shock from dehydration, but this is not the focus of immediate field treatment. The mechanism of injury may be extreme heat production from vigorous exercise or exposure to high ambient temperatures and confining cloth- ing. Generally, it is some combination of the two, like wildland firefighting or a forced march in hot weather. The patient may have become heat exhausted first or progressed directly to heat stroke. Medications can also play an important role. People taking diuretics and psychotropic medications are at greater risk of developing heat stroke and other heat-related problems. A person can maintain normal mental status for a brief period with a body core temperature as high as 40.5°C. But eventually, mental status changes will develop followed rapidly by a drop on the AVPU scale. The skin may have the clas- sic hot, red, and dry appearance, but this is not always the case. With extreme heat exposure, a critical rise in core temperature can occur before

Emergency Treatment: • Stop exercise • Remove from hot environment • Immediate and aggressive cooling

Low Risk

High Risk

© 2018 WMA

Fluid replacement is part of the treatment but only after core temperature is effectively man- aged. IV fluid replacement is ideal but oral fluids may work if the patient can cooperate and pro- tect their airway. The high temperature may have caused brain injury with the anticipated problem of elevated intracranial pressure (ICP). A condi- tion called rhabdomyolysis may develop, leading to kidney failure. Advanced life support (ALS) intervention is a priority and emergency evacua- tion is justified. These patients are best served by treatment and observation in the hospital.