The Hypoxic Profile during Trekking to the Pyramid Laboratory

Pomidori, Luca, Daniela Bonardi, Federica Campigotto, Valter Fasano, Alessandra Gennari, Gabriele Valli, Paolo Palange, and Annalisa Cogo. The hypoxic profile during trekking to the Pyramid Laboratary. High Alt. Med. Biol. 10:233-237, 2009.-The oxygen saturation values reported in the high altitude literature are usually taken during a few minutes of measurement either at rest or during exercise. We aimed to investigate the daily hypoxic profile by monitoring oxygen saturation for 24h in 8 lowlanders (4 females, ages 26 to 59) during trekking from Lukla (2850m) to the Pyramid Laboratory (5050m). Oxygen saturation was measured (1) daily at each altitude (sm), (2) for 24-h during ascent to 3500m, 4200m, and on day 1 at 5050m (lm), and (3) during a standardized exercise (em). Results: (1) the sm and lm values were 90.9% (±0.5) and 86.4% (±1.1) at 3500m; 85.2%(±1.1), and 80% (±1.9) at 4200m; 83.8%(±1) and 77% (±1.7) at 5050m (p≤0.05); (2) the daily time spent with oxygen saturation ≤90% was 56.5% at 3500m, 81% at 4200m, and 95.5% at 5050m; (3) during exercise, oxygen saturation decreased by 10.58%, 13.43%, and 11.24% at 3500, 4200, and 5050m, respectively. In conclusion, our data show that the level of hypoxemia during trekking at altitude is more severe than expected on the basis of a short evaluation at rest and should be taken into account.