Chapter 140: High-Altitude Illness

High-Yield Facts

• High-altitude illness (HAI) often affects young and otherwise healthy individuals. It progresses from acute mountain sickness (AMS) to potentially life-threatening high-altitude pulmonary edema (HAPE) and high-altitude cerebral edema (HACE).

• Acetazolamide (Diamox) has been shown to be very effective for acclimatization when staging is not possible or with individuals who are at an increased risk of HAI.

• Definitive treatment of HACE is descent. High-flow oxygen is indicated as soon as symptoms are recognized and dexamethasone, at an initial dose of 1 to 2 mg/kg orally or intramuscularly, can produce dramatic improvement.

• HAPE is the leading cause of high-altitude death other than trauma.

High-Altitude Illness

With the increasing popularity of various recreational activities, individuals tend to travel to greater altitudes raising the incidence of high altitude illness (HAI). Examples of activities that can put individuals at risk include hiking, mountain climbing, biking, skiing, snowboarding, hot air balloons, and gliding. With the ease and access to modern travel, it can be expected that the incidence of HAI will continue to rise, putting more children and adults at risk

HAI results from the decrease in barometric pressure and the individual's response to hypoxia. It can affect individuals of any age but often affects young, healthy individuals.^1,2 HAI encompasses a broad spectrum of disease ranging from acute mountain sickness (AMS), the mildest form of HAI to the potentially life-threatening high-altitude cerebral edema (HACE) and high-altitude pulmonary edema (HAPE). Symptoms of HAI may develop within hours or days after ascent. In contrast, hypoxemia occurs within minutes to hours of arrival at altitude and results in the initiation of the cascade of physiologic events that lead to AMS, HAPE, and HACE (Table 140-1).