[Incidence, prevention and therapy of acute mountain sickness]

The symptoms and signs of acute mountain sickness are present in about half of the tourists trekking in Nepal to an altitude of 42000 m. The most common symptoms are headache and nausea. Pulmonary rales are found in more than 10% of trekkers, while high altitude pulmonary edema is rare. Retinal hemorrhages occur almost exclusively above 5000 m. A careful history and physical examination are generally sufficient for medical evaluation of fitness for high altitude. There are no specific tests to predict performance at altitude. The most effective prophylaxis of acute mountain sickness is "slow" ascent, which is arbitrarily defined as an increase in sleeping altitude of 300-400 m per 24 hours. Sufficient fluid intake is also very important. Prophylactic administration of acetazolamide reduces the incidence and severity of acute mountain sickness. Mild forms of acute mountain sickness are treated by a rest day, whereas patients with severe disease should descend as soon as possible.