"ONCE A YEAR,
GO SOMEPLACE YOU'VE
NEVER BEEN BEFORE."
Travellers to mountain areas should be prepared to recognize and respond to the symptoms of altitude illness, which are caused by the lower level of oxygen available at high elevations. Although the human body can adjust to changes in altitude, the process (called acclimatization) takes time.
Each person has his or her own "acclimatization line." Below it, travelers probably won't experience altitude illness, but going above it causes symptoms to begin. For most people, this line initially lies somewhere near 2,700 m (8,900 ft), but it can be adjusted by following preventive techniques. Travelers who have had altitude problems previously, have heart or lung problems, are unable to acclimatize on the way to altitude, or plan to go to extremely high altitudes should discuss prevention and treatment options with a health care provider.
Three types of altitude illness can occur:
Acute mountain sickness (AMS) typically appears at altitudes above 2,500 m (8,200 ft), although illness can begin at elevations as low as 1,500 m (4,900 ft) in some individuals. Symptoms usually appear within a few hours of ascent and may include one or many of the following symptoms: headache, insomnia, irritability, dizziness, muscle aches, fatigue, loss of appetite, nausea or vomiting, and swelling of the face, hands, and feet. Travelers who experience mild AMS symptoms should limit their activity level and remain at the same altitude for 1-2 days before ascending any farther. Aspirin or ibuprofen can be used for headache. If symptoms become worse during a day of rest,descend until symptoms begin to improve.
High altitude cerebral edema (HACE) is a dangerous form of altitude illness that can lead to coma and death. HACE can be thought of as a worsening of AMS symptoms, with additional changes in consciousness and/or coordination. Persons affected may hallucinate, appear confused, and begin to stumble or stagger, and they can have severe headaches and extreme fatigue. It is crucial to help victims descend to receive drug and oxygen treatment since they may be too confused to see the problem themselves. People who have recently experienced HACE should not ascend again, even if they have improved.
High altitude pulmonary edema (HAPE) is a buildup of fluid in the lungs that can occur along with HACE or separately. Like HACE, it is a medical emergency. Victims become breathless and very tired when walking and may experience a sense of fullness or pressure in the chest. Eventually they are short of breath even while resting. At this point, the illness can rapidly progress to death. Victims must be guided down to receive drug and oxygen treatment as soon as the illness is recognized as HAPE. They should be kept warm and assisted as much as possible because exertion will make the condition worse. Some people have chosen to ascend again after recovering from HAPE, but this is not recommended.