The Pre-acclimatization Augmented Extreme Altitude Expedition

The participants assigned to the preacclimatization group spend a minimum of six hours during sleep, throughout the acclimatization period (four weeks preceding the expedition) in a nitrogen concentration tent (Hypoxico OHG, Traunstein, Germany) set to an environmental PO2 corresponding to an altitude of 2500 masl, with a progression to 5500 masl within 28 days in steps of 1000 m every seven days. Respiratory Polygraphy is used to detect periodic breathing, SpO2, and heart rate continuously during sleep and is performed before and after the designated preacclimatization period, and repetitively when increasing normobaric hypoxia in the group with nitrogen concentration tent preacclimatization.