Altitude illness is related to low hypoxic chemoresponse and low oxygenation during sleep

作者：Nespoulet Hugo; Wuyam Bernard^*; Tamisier Renaud; Saunier Carole; Monneret Denis; Remy Judith; Chabre Olivier; Pepin Jean Louis; Levy Patrick

来源：European Respiratory Journal, 2012, 40(3): 673-680.

DOI：10.1183/09031936.00073111

• Breathing
• hypoxia
• hypoxic
• hypoxic pulmonary vasoconstriction
• sleep

Altitude illness remains a major cause of mortality. Reduced chemosensitivity, irregular breathing leading to central apnoeas/hypopnoeas, and exaggerated pulmonary vasoconstriction may compromise oxygenation. All factors could enhance susceptibility to acute mountain sickness (AMS).
We compared 12 AMS-susceptible individuals with recurrent and severe symptoms (AMS+) with 12 "AMS-nonsusceptible" subjects (AMS-), assessing sleep-breathing disorders in simulated altitude as well as chemoresponsive and pulmonary vasoconstrictive responses to hypoxia.
During exposure to simulated altitude, mean blood oxygen saturation during sleep was lower in AMS+ subjects (81.6 +/- 2.6 versus 86.0 +/- 2.4%, p<0.01), associated with a lower central apnoea/hypopnoea index (18.2 +/- 18.1 versus 33.4 +/- 24.8 events.h(-1) in AMS+ and AMS- subjects, respectively; p = 0.038). A lower hypoxic (isocapnic) chemoresponsiveness was observed in AMS+ subjects (0.40 +/- 0.49 versus 0.97 +/- 0.46 L-min(-1).%; p<0.001). This represented the only significant and independent predictive factor for altitude intolerance, despite a higher increase in pulmonary artery systolic pressure in response to hypoxia, a lower lung diffusing capacity and a higher endothelin-1 level at baseline in AMS+ subjects (p<0.05). AMS+ subjects were more hypoxaemic whilst exhibiting fewer respiratory events during sleep owing to lower hypoxic (isocapnic) chemoresponsiveness.
In conclusion, the reduction in peripheral hypoxic chemosensitivity appears to be a major causative factor for altitude intolerance.

• 出版日期2012-9