Sleep-disordered breathing and oxidative stress in preclinical chronic mountain sickness (excessive erythrocytosis)

Chronic mountain sickness (CMS) is considered to be a loss of ventilatory acclimatization to high altitude (>2500 m) resulting in marked arterial hypoxemia and polycythemia. This case-control study explores the possibility that sleep-disordered breathing (SOB) and associated oxidative stress contribute to the etiology of CMS. Nocturnal respiratory and Sa(O2), patterns were measured using standard polysomnography techniques and compared between male high-altitude residents (aged 18-25) with preclinical CMS (excessive erythrocytosis (EE), n = 20) and controls (n = 19). Measures of oxidative stress and antioxidant status included isoprostanes (8-ISO-PGF2(alpha)), superoxide dismutase and ascorbic acid. EE cases had a greater apnea-hypopnea index, a higher frequency of apneas (central and obstructive) and hypopneas during REM sleep, and lower nocturnal Sa(O2) compared to controls. 8-iso-PGF2(alpha) was greater in EE than controls, negatively associated with nocturnal Sa(O2), and positively associated with hemoglobin concentration. Mild sleep-disordered breathing and oxidative stress are evident in preclinical CMS, suggesting that the resolution of nocturnal hypoxemia or antioxidant treatment may prevent disease progression. (C) 2013 Elsevier B.V. All rights reserved.