Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

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Section V: Environmental Medicine

area and stop physical exertion to reduce heat production.

A person can maintain normal mental status for a brief period with a body core temperature as high as 40.5ºC. 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 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 evaporation, conduction, and radiation available. Just applying ice to the neck, armpits, and groin is insufficient. Look for an improvement in level of conscious- ness and mental status to indicate the return to a more normal temperature. General Principles

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

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If fuid replacement is needed, oral fluids are usually effective, but IV is faster. If the patient is vomiting, oral replacement is still possible by giving fluid frequently in small amounts. Without IV fluids, it may take more than 12 hours to bring the 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 Heat stroke is a serious critical system problem requiring immediate field treatment. The primary problem is dangerously elevated body core tem- perature, which is capable of 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. not be necessary. Heat Stroke

Heat Stroke

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

Low Risk

High Risk

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Fluid replacement is part of the treatment but only after core temperature is being effectively managed. IV fluid replacement is ideal but oral fluids may work if the patient can cooperate and protect her airway.The high temperaturemay 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.