Sleep-related Periodic Breathing Does Not Acclimatize to Chronic Hypobaric Hypoxia: A 1-Year Study at High Altitude in Antarctica

摘要

To the Editor. At altitudes above 2,500 m, ventilation in healthy subjects commonly shows periodic breathing: an oscillatory behavior with alternating periods of hyperventilation followed by central apneas or hypopneas (1-3). Although an increase in altitude is correlated with an increase in the occurrence of periodic breathing (1, 4), the magnitude, the time course, and the altitude of occurrence differ markedly between studies. Some studies found an increase in periodic breathing over time at different altitudes, despite an improvement of Spo_2 (oxygen saturation as measured by pulse oximetry), and they found no relationship with acute mountain sickness (AMS) (1, 5). Other studies, however, found a decrease (6, 7) or no changes (3) in the amount of periodic breathing over time. All of these studies were performed at different altitudes and ascending rates. Furthermore, in these studies the time spent in hypobaric hypoxia was short, from several days to up to 4 weeks.