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Chapter 140: High-Altitude Illness

Ira J. Blumen; James Ahn

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).

TABLE 140-1An Overview of High-Altitude Illness
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TABLE 140-1 An Overview of High-Altitude Illness

Acute Mountain Sickness (AMS)

High-Altitude Cerebral Edema (HACE)

High-Altitude Pulmonary Edema (HAPE)

Altitude

Rare below 8000 ft

Affects nearly everyone who rapidly ascends to 11,000 ft

Rare below 12,000 ft

Rare below 8000 ft

More commonly associated with altitudes >14,500 ft

Onset

Within 4–8 h of a rapid ascent but can be as long as 4 d

Peaks within 24–48 h

Usually resolves by the third or fourth day

Most often within 1–3 d after ascent to altitude

Usually within 1–4 d after ascent to altitude

Most common during the second night at altitude

Symptoms

Most common: headache, sleep disturbance, fatigue, shortness of breath, dizziness, anorexia, nausea, vomiting, oliguria

Other symptoms: mild peripheral edema, weakness, lassitude, malaise, irritability, decreased concentration, poor judgment, palpitations, deep inner chill, dull pain in the posterolateral chest wall

Severe headaches, nausea, vomiting, altered mental status

Cardinal sign: truncal ataxia

Will proceed to include confusion, slurred speech, diplopia, hallucinations, seizures, impaired judgment, cranial nerve palsies (third and sixth), abnormal reflexes, paresthesia, decreased level of consciousness, coma, death

Initial ...

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