Changes in spirometric parameters and arterial oxygen saturation during a mountain ascent to over 3000 meters

OBJECTIVE: To ascertain whether climbing a mountain over 3000 meters high produces any alterations in ventilation, whether such alterations are modified by acclimatization, and whether they correlate with changes in arterial oxygen saturation (SaO(2)) or the development of acute mountain sickness (AMS). SUBJECTS AND METHODS: The following parameters were measured in 8 unacclimatized mountaineers who climbed Aneto (3404 m) and spent 3 days at the summit: forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), airway response to inhaled terbutaline, SaO(2), and the symptoms of AMS. RESULTS: At the summit, mean (SD) FEV1 declined by 12.3% (5.7%) and mean FVC by 7.6% (6.7%) while the ratio of FEV, to FVC remained normal. The means for both parameters were higher on the following day. No airway response to bronchodilator treatment was observed. The restriction disappeared entirely on descent At the peak, SaO(2) increased progressively as the climbers became acclimatized. During the ascent, FEV, correlated with SaO(2) (r = 0.79). One participant who suffered from AMS had a ratio of FEV, to FVC less than 70% and the worst SaO(2) during the 3 days on the summit. Obstruction preceded the AMS symptoms, did not respond to bronchodilator treatment, and disappeared when the climber descended. CONCLUSIONS: The mountaineers who climbed over 3000 meters presented restriction that correlated with hypoxemia. This restriction did not respond to bronchodilator treatment, improved with acclimatization, and disappeared on descent. One person with AMS presented obstruction that did not respond to terbutaline and disappeared on descent.