[Effect of altitude on blood oxygenation during sleep in patients with bronchial asthma]

The aim of our study was to investigate the severity of overnight arterial blood desaturations in patients with asthma at the altitude of 3200 meters above sea level. 12 asthmatics and 12 healthy controls were investigated. Three overnight pulsoximetries were performed in all subjects, one at the lowland and on the 1st and 5th night at the altitude. Mean SaO2 at the lowland was significantly lower in asthmatics than in the controls (p < 0.01). After the ascent to high altitude severe fall in mean SaO2 was noted in both groups (from 94.3% to 85.8% in asthmatics and from 97.1% to 88.7% in controls) (p < 0.001 for both groups). After few days of acclimatization mean SaO2 rose to 88.8% in asthmatics and to 91.3% in controls, but was still significantly lower than at the lowland (p < 0.001 for both groups). At the altitude differences in mean SaO2 between two groups were not statistically significant. We conclude that severity of overnight desaturations at high altitude do not vary between asthmatics with impaired respiratory function and healthy subjects.