Ventilation and Ventilatory Control in High Altitude Pulmonary Edema and Acute Mountain Sickness

摘要

When the 12 subjects were taken from low altitude (1600M in Denver, CO) to high altitude (4300M on Pike's Peak) they underwent acclimatization over 5 days. The surprising finding was that on day 4 and day 5 their ventilations were predicted by the acute isocapnic hypoxic response at low altitude. It was as though, after acclimatization, the relatively pure response to acute hypoxia was a major determinant of ventilation. On arrival at high altitude (Pike's Peak day 1) the ventilation showed only a small increase above the Denver value, as though the response to hypoxia were inhibited. Total ventilaltion, however, was not the most sensitive measure of acclimatization because we found it was influenced by metabolic increases at rest and dead space increases during exercise.. A more sensitive measure and one that provided useful inter-individual comparisons involved the use of an Sa02-PC02 stimulus response curve, similar to that proposed by Rahn and Otis. Examination of these curves in relation to high altitude values suggested that it was hypoxic depression at high altitude that was responsible for the poor ventilatory response and the development of symptoms in some individuals at high altitude.