Altitude Acclimatization (Ventilation and Chemoresponsiveness) during Wakefulness and Sleep,
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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Although the influence of altitude acclimatization on respiration has been carefully studied, the associated changes in hypoxic and hypercapnic ventilatory responses are the subject of controversy and neither response has been carefully evaluated during sleep at altitude. To answer these questions, six healthy males were studied at sea level and on nights 1, 4, and 7 following arrival at altitude 14,110 ft. During wakefulness ventilation and the ventilatory responses to hypoxia and hypercapnia were determined on each occasion. During both NREM and REM sleep at sea level and on all three nights at altitude, ventilation and the hypercapnic ventilatory response were measured. With acclimatization to high altitude ventilation increased during both wakefulness and sleep which reflected primarily increasing respiratory frequency. The slope of the hypercapnic response, although initially increased at altitude slope of the hypercapnic response, although initially increased at altitude day 1, did not rise further with acclimatization although the position of this response shifted significantly to the left during wakefulness and sleep. Finally, sleep induced similar decrements in both ventilation and hypercapnic responsiveness at altitude to those seen at sea level. Keywords Rapid eye movement in sleep.
- Stress Physiology