Oxidative Stress in Acute Hypobaric Hypoxia

Irarrázaval, Sebastián, Claudio Allard, Juan Campodónico, Druso Pérez, Pablo Strobel, Luis Vásquez, Inés Urquiaga, Guadalupe Echeverría, and Federico Leighton. Oxidative stress in acute hypobaric hypoxia. High Alt Med Biol. 18:128-134, 2017.-The effects of acute hypobaric hypoxia endured by mountaineers were studied, specifically as evidenced by acute mountain sickness (AMS) and oxidative stress damage. Ten male volunteers were exposed to acute hypobaric hypoxia, and AMS was evaluated through arterial oxygen saturation (SaO₂), cardiac rate, and the Lake Louise Score (LLS). Oxidative stress was determined through blood profile tests performed 24 hours before and after high-altitude exposure, assessing the oxidative damage and antioxidant profiles. Dietary habits were assessed using the Chilean Mediterranean Diet Index. During ascent (i.e., first 8 hours), all volunteers presented AMS (LLS ≥3 points), as manifested by a median LLS increment of four points, a 15 bpm cardiac rate, and 17% decrease in SaO₂. Additionally, plasma lipid oxidative damage increased after the expedition, as evaluated through malondialdehyde, which was directly correlated with the LLS (R² = 0.720, p = 0.003) and inversely correlated with SaO₂ (R² = 0.436; p = 0.035) at a high altitude. Preascent carbonyl levels were inversely correlated to SaO₂ (R² = 0.490; p = 0.008) and directly correlated to cardiac rate (R² = 0.225, p = 0.016) at a high altitude. Moreover, dietary habits were inversely correlated with increased carbonyls during the expedition (R² = 0.436; p = 0.047). In conclusion, acute hypobaric hypoxia induced AMS and an increment in oxidative stress markers 24 hours after altitude exposure in the volunteers. Furthermore, oxidative stress damage was related to AMS severity. Finally, volunteers with closer adherence to a Mediterranean diet presented a lower increase in oxidative damage during ascent, reflecting the potential preventive role of diet against AMS.