What is Altitude Sickness?
Altitude sickness (mountain sickness) is an illness that ranges from a mild headache and weariness to a life-threatening build-up of fluid in the lungs or brain at high altitudes. Acute altitude sickness is the mildest and most common form. Because more people are traveling to areas of high elevation for skiing and mountain climbing, acute altitude 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 (HAPE). 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. HAPE often comes on quickly. If left untreated, it can progress to respiratory collapse and ultimately to death. HAPE is the number one cause of death from altitude sickness. Another severe form of altitude sickness is high altitude cerebral edema (HACE), 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.