Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android


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

  • Acclimatization and slow ascent are the best way of avoiding HAI.

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

  • Truncal ataxia is the cardinal sign of HACE, and immediate definitive treatment 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, with a cardinal sign of severe dyspnea at rest, is the leading cause of high-altitude death other than trauma.


High-altitude illness (HAI) has been documented for thousands of years, and with the increasing popularity of various recreational activities individuals tend to ascend to greater altitudes, raising the incidence of 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, the incidence of HAI can be expected to continue rising, putting more children and adults at increased risk.

HAI results from the decrease in barometric pressure, and the individual’s response to hypoxia and can affect individuals of any age, even young, healthy individuals.1,2 HAI seems to affect children and adults equally.3 However, the diagnosis may be delayed in young children who cannot describe their symptoms.

HAI encompasses a broad spectrum of disease. The continuum ranges 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 141-1).

TABLE 141-1An Overview of High-Altitude Illness

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.