Abstract
Background
We investigated breathing patterns and oxygenation in mountaineers climbing to extreme altitude to evaluate effects of hypoxemia and acclimatization.
Methods
In 34 mountaineers (mean age 45y, 7 women) portable recordings of respiratory inductive plethysmography, pulse oximetry and ECG were performed during a climb to the summit of Muztagh Ata, China (7546m). Breath by breath ventilation was analyzed and periodic breathing quantified by spectral analysis.
Results
Repeated recordings during 2 climbs from 4497-5533m within 5-8 days revealed an increase in oxygen saturation and periodic breathing and a decrease in heart rate (table). During the climb from 6865-7546m hypoxemia was pronounced.
Conclusions
Mountaineers were able to climb to extreme altitude despite severe hypoxemia. The heart rate reserve was utilized to a greater extent than the ventilatory reserve. With acclimatization, periodic breathing increased despite a higher oxygen saturation, consistent with a persistently high ventilatory drive while the heart rate reduction suggested a decrease in sympathetic tone.
- © 2012 ERS