[Prevention and therapy of altitude sickness]

Climbing in the Alps and trekking in the Andes or in the Himalayas became more and more popular in the last years. This is the reason why more and more tourists develop symptoms of acute mountain sickness (AMS) at an altitude higher than 2500 m a.s.l. To avoid an unpleasant stay at altitude, an accurate acclimatization is necessary. This can be achieved by a slow ascent at a climbing rate of 300 to 600 m in one day. If that is not possible, climbers should spend at least nine or more nights at an altitude higher than 2500 m a.s.l. in the last 30 days before ascent. This would improve performance at high altitude and significantly decrease symptoms of AMS. If acclimatization for one or another reason may not be possible or if somebody is still susceptible to AMS, pharmacological prophylaxis and treatment can be used. Drug of first choice for AMS prophylaxis is acetazolamide, a carboanhydrase inhibitor who increases ventilation. Acetazolamide has been used in a dosage of 250 to 500 mg 12 to 24 h. before ascent. If climbers have a history of high-altitude pulmonary edema (HAPE), nifedipine, a potent vasodilator which decreases pulmonary artery pressure, is the drug of the first choice and should be taken in a dosage of 3 x 20 mg, beginning one day before climbing and continuing during climbing. Prophylactic administration of nifedipine has no effect on symptoms of AMS in subjects who are not susceptible to HAPE.(ABSTRACT TRUNCATED AT 250 WORDS)