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Mountain Sickness (cont.)

What is altitude sickness?

Altitude sickness (sometimes termed mountain sickness) is an illness due to the decreasing the amount of oxygen at above sea level altitudes ranging usually about 4800 ft or 1500 m that may range from a mild headache and weariness to a life-threatening build-up of fluid in the lungs or brain, and even fatality at moderate to high altitudes.

Altitude sickness usually occurs when people travel from lower altitudes in less than one day to higher altitudes (8000 feet or 2438 m or higher), but depending upon the individual's health, altitude sickness may occur at considerably lower altitudes, even 4800 feet or 1500 m. Altitude sickness has a spectrum of symptoms and is a general term that covers three major syndromes.

  1. Acute mountain sickness (AMS)
  2. High-altitude pulmonary edema (HAPE)
  3. High-altitude cerebral edema (HACE)

In this article:

  • Moderate to high-altitude is considered 4800 feet to about 6400 feet (1500-2000 m) above sea level
  • High-altitude is considered to be about 6400 to 11,200 feet (2000-3500 m)
  • Very high-altitude is considered 11,200 feet to 18,000 feet (3500-5600 m)
  • Extreme altitude is above 18,000 feet.

High-altitude cerebral edema and high-altitude pulmonary edema most commonly occur at very high-altitude; however, they can occur in some people at high-altitude.

What is acute altitude sickness?

Acute altitude sickness or acute mountain sickness is the mildest and most common form of altitude sickness. Because more people are travel to areas of high elevation for recreational and professional sports, for example, skiing, hiking, mountain climbing, and biking; acute mountain sickness has become a greater public health concern. Roughly one-fourth of Colorado ski area vacationers, two-thirds of climbers on Mount Rainier, and half the people who fly to the Khumbu region of Nepal develop acute altitude sickness.

A more serious form of altitude sickness is high-altitude edema. This illness occurs when fluid builds up within the lungs, a condition that can make breathing extremely difficult. Usually, this happens after the second night spent at a high altitude, but it can happen earlier or later.

What is high-altitude pulmonary edema?

High-altitude pulmonary edema often comes on quickly. If left untreated, it can progress to respiratory collapse and ultimately to death. High-altitude pulmonary edema is the number one cause of death from altitude sickness.

What is high-altitude cerebral edema?

A severe form of altitude sickness is high altitude cerebral edema, in which fluid builds up within the brain. As the brain swells with fluid, the person's mental state changes. Loss of coordination, coma, and, finally, death can follow unless the problem is recognized and treated promptly.

Medically Reviewed by a Doctor on 12/15/2015

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