Respiratory exercises during high altitude (HA) exposure help to maintain a better oxygen saturation (SpO2) counteracting the effects of hypoxia

Decrease in SpO2 at HA is the main cause of acute mountain sickness (AMS) and development of interstitial lung edema. Aim: to evaluate the effect of a respiratory training (RT) on SpO2, AMS and interstitial lung edema during the ascent to Regina Margherita Hut (4559 m). 16 subjects (12 M, 4 F) age 22-61 yrs, performed an 8 weeks RT, taught and supervised by Apnea Academy's instructors: 30 min/day; a sequence of inspiratory and expiratory apnea of the same duration plus 3 sets of 5 minutes of ventilation with maximal inspiration and expiration. At the end of the 8 weeks they reached a village at 1635 m and were randomized in trial (T) and control (C) group. Day 1: walk to 3498 m; Day 2: to 4167 m; Day 3: to Regina Margherita Hut and back to 1635 m. T stopped every 3 hours to perform RT. Both groups during the climb underwent: 24h SpO2 monitoring, Lake Louise Scoring System (LLS) for the diagnosis of AMS, lung ultrasound analysis to assess the presence of B lines (sign of interstitial lung edema). Results: (ANOVA repeated measures): SpO2 was significantly higher in T during both the climb and the nights through all 3 days (p<0.001). One subject in C stopped at day 1 due to severe AMS; 1 subject in C developed moderate AMS at day 2, but no significant difference was found in LLS between C and T. B lines were significantly higher in C only at Day 3 (p < 0.05). Conclusion: Respiratory exercises performed during HA ascent, helps to maintain a better SpO2 during the climb and the sleep. The better oxygenation reduces the evidence of B lines after a long exposure. This is the first step of assessment of a new way to counteract HA hypoxia.