Effects of acetazolamide on overnight oxygenation and acute mountain sickness in patients with asthma.

The aim of the study was to assess effects of acetazolamide in prevention of acute mountain sickness (AMS) and on overnight oxygenation, in patients with asthma treated at the altitude of 3,200 m. Sixteen patients with asthma, 6 males and 10 females, mean age 32 yrs, were first investigated at low altitude (760 m). They presented with mild airways obstruction, normal arterial blood gases, and normal oxygenation at night studied by pulse oximetry. After initial investigations, patients were divided by random number into the treated (T) and control (C) groups of eight patients each. T group patients received acetazolamide, 750 mg daily for 2 days, before the ascent and on the first day at altitude (3,200 m). Symptoms of AMS developed in seven patients from group C and in three from group T. The overnight pulse oximetry, performed on the first night at altitude, revealed that group T patients had statistically higher (p < 0.05) initial, 91 vs 87%, mean, 90 vs 86%, and minimum, 84 vs 75%, arterial oxygen saturation than group C patients. Overnight pulse oximetry was repeated on the 5th, 10th and 17th day at altitude, and showed that in group C patients, from the 5th day onwards, oxygenation improved to the level observed in group T patients on the first night. We conclude that pretreatment with acetazolamide before the ascent prevented patients with asthma from developing symptoms of AMS, and alleviated acute changes in arterial oxygen saturation brought about by the high altitude hypoxia.