Acute mountain sickness

Definition

Acute mountain sickness is an illness that can affect mountain climbers, hikers, skiers, or travelers who climb too fast. It usually occurs when people rapidly reach a high altitude (typically above 8,000 feet or 2,400 meters). 

Alternative Names

Causes

Acute mountain sickness occurs from the combination of reduced air pressure and a lower concentration of oxygen at high altitude. Symptoms can range from mild to life-threatening, and can affect the nervous system, lungs, muscles, and heart.

In most cases the symptoms are mild. In severe cases fluid collects in the lungs (pulmonary edema) causing extreme shortness of breath, which further reduces how much oxygen a person gets. Brain swelling may also occur (cerebral edema). This can cause confusion, coma, and, if untreated, death.

The chance of getting acute mountain sickness increases the faster a person climbs to a high altitude. The severity of the symptoms also depend on this factor, as well as how hard the person pushes (exerts) himself or herself. People who normally live at or near sea level are more prone to acute mountain sickness.

Approximately 20% of people will develop mild symptoms at altitudes between 6,300 to 9,700 feet, but pulmonary and cerebral edema are extremely rare at these heights. However, above 14,000 feet, a majority of people will experience at least mild symptoms. Some people who stay at this height can develop pulmonary or cerebral edema.

References

Wright A, Brearey S, Imray C. High hopes at high altitudes: pharmacotherapy for acute mountain sickness and high-altitude cerebral and pulmonary oedema. Expert Opin Pharmacother. 2008; 9(1): 119-27.

Marx J. Rosen’s Emergency Medicine: Concepts and Clinical Practice. 5th ed. St. Louis, Mo: Mosby; 2002:2040-2042.

Murray J, Nadel J. Textbook of Respiratory Medicine. 3rd ed. Philadelphia, Pa: WB Saunders; 2000:1853.

Auerbach PS. Wilderness Medicine. 4th ed. St. Louis, Mo: Mosby; 2001:12-19.