Objectives: The aim of this study was to investigate the behavior of asthma in patients traveling to high and extreme altitudes.
Methods: Twenty-four Dutch patients with mild asthma did a trekking at high and extreme altitudes (up to 6410 m = 21030 ft) in the Tibetan Everest region. Asthma symptoms, use of asthma medication, symptoms of acute mountain sickness, spirometry, peripheral oxygen saturation, and heart rate were measured at 1300 m (baseline), and at 3875, 4310, 5175, and 6410 m. Asthma symptoms were assessed by means of a modified version of the Asthma Control Test. Symptoms of acute mountain sickness were scored by the Lake Louise self-report questionnaire. The expedition staff, consisting of seven healthy persons, acted as a control group.
Results: In both asthmatics and controls, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) decreased with increasing altitude, whereas FEV1 as percent of FVC (FEV1%FVC) did not change. In both groups, peak expiratory flow (PEF) increased with increasing altitude. In general, differences in spirometric values between asthmatics and controls were not significant. Asthma symptoms did not change with increasing altitude. During ascent, less than half of the asthma patients increased their medication use. According to the Lake Louise score, no acute mountain sickness occurred, except for in the asthma group at 6410 m, which showed mild acute mountain sickness at that altitude. As expected, peripheral oxygen saturation decreased with increasing altitude in asthmatics and controls, differences between the two groups not being significant. In general, heart rate (at rest) did not change with altitude, except for an increase in asthmatics at 6410 m.
Conclusions: These results suggest that traveling to high and extreme altitudes is safe for patients with mild asthma.