Respiration physiology
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Respiration physiology · Jun 1983
Dependence of high altitude sleep apnea on ventilatory sensitivity to hypoxia.
Respiration in man exposed to 5400 m was studied during sleep over a period of 6-8 h at night. Subjects were adult males, and belonged to distinct groups: one was Sherpa high altitude residents of the Himalayas and the other consisted of causasian sojourners from near sea level. All the volunteers had spent at least 32 days at or above 5400 m before the study. ⋯ None of the Sherpa highlanders with low ventilatory sensitivity to hypoxia showed any sustained periodic breathing with apnea. The large breathing oscillations and periodic apnea correlated well with the ventilatory sensitivity to hypoxia (r = 0.85), supporting the hypothesis that a high gain of the peripheral chemoreflex is conductive to periodic breathing. Sherpas by attenuating chemoreflexes have reduced instability as well as cost of breathing at high altitude.