Serial Changes in Acute Hypoxic and Hypercapnic Ventilatory Responses during High Altitiude Acclimatization
Increased ventilation is important for persons going to high altitude and this is attributable to hypoxic stimulation of the peripheral chemoreceptors. However, the hypocapnia induced by hyperventilation and central hypoxic ventilatory depression substantailly attenuate the initial ventilatory response to hypoxia. Huang et al. (5) demonstrated that the combination of hypocapnia and sustained hypoxia might have blunted the ventilatory response on the first day after arrival on Pikes Peak (4300 m). Acute mountain sickness (AMS) occurs as acommon feature of ascent to high altitude usually within a few hours of ascent and lasting a few days. It has been recognized that ventilation is depressed in persons with symptoms of AMS (4). The reason for the hypoventilation in symptomatic persons is unknown. Moore et al. (8) suggest that hypoventilation in symptomatic compared to asymptomatic subjects is responsible for attenuated ventilatory response to acute hypoxia. In order to investigate the influence of altitude acclimatization on chemoresponsiveness, we consecutively examined hypoxic (HVR) and hypercapnic (HCVR) ventilatory responses in 7 lowlanders during sojourn in Lhasa (3700m), China.
KeywordsVentilatory Response Acute Hypoxia Acute Mountain Sickness Serial Change Peripheral Chemoreceptor
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