Altitude Sickness, How High is Too High

When skiing, mountain climbing, or hiking, please remember that the altered consciousness and dizziness accompanied by the rapid breathing that you are noticing may not be from the natural high that you are experiencing but from the effects of altitude sickness.



Altitude sickness can affect any one of any sex, age or physical fitness. It can occur at any altitude above 5000 ft. (lake Tahoe), but it is more common above 8000 ft. (Machu Picchu, Peru). In a study of hikers in the Swiss Alps, 13% developed symptoms at 10,000 ft. and 34% became symptomatic at 12,000 ft.
BMJ. 1990 Oct 13;301(6756):853-5.
Maggiorini M, Buhler B, Walter M, Oelz O.

It may be prevented by climbing slowly. It is usually not a problem to climb up to 5000 ft in 1 day. Above 8000 ft, a rate of 1500 ft (460 m)/day is recommended. When climbing above 10,000 ft, it would be best to acclimatize by staying at 6000-8000 ft. for 2-4 days. however, many of us hurry through our vacations due to a lack of time and skip the acclimatization process. Staying hydrated can also help.



Early symptoms are headache, insomnia, and swelling of legs which may start 12-24 hours after arriving at the altitude. If ignored, the symptoms may progress to vomiting, dizziness, difficulty breathing, and in worst case scenario death from brain herniation due to increased intracranial pressure.

If any of these symptoms occur, the definitive treatment is to descend. Supplemental oxygen is helpful if available.
There are medications such as Diamox (acetazolamide), and Decadron (dexamethasone) which help the symptoms. Ask your doctor about them if you are prone to altitude sickness. They may be taken preventively.

References:
http://www.ismmed.org
The Medical Letter on Drugs and Therapeutics, May, 2004; (21) pp. 33-40
The MERCK Manual, Sec. 20, Ch. 281
Photo: www.nationalgeographic.com/.../ altitude.jpg