Resting pulmonary diffusion capacity for CO and O2 at high altitude.

Abstract

The possible increase of pulmonary diffusing capacity at high altitude is still controversial. During an expedition on Monte Rosa, Italy, experiments were performed on five male subjects, 27–44 years of age, at rest after a sojourn of 7–10 days at an elevation of 4,560 m, using two independent methods. Pulmonary diffusing capacity for CO (DlCO) was determined with the steady-state method at three levels of oxygenation with inspiratory O2 pressures of 80, 150, and 400 mm Hg both at sea level and at altitude. The evaluation of the O2 pressure diffusion gradients in hypoxia, obtained from the alveolar-arterial O2 pressure gra dients and the arterio-alveolar CO2 pressure gradients in hypoxia, permitted the estimation of the diffusing capacity for O2 (DlO02). There was no significant difference between sea level and high altitude in DlCO at the three levels of oxygenation, in the O2 diffusion gradient and in DlCOCO2 with hypoxia. alveolar-arterial O2 pressure gradient; arterio-alveolar CO2 pressure gradient; high altitude adaptation; acid-base balance of the blood Submitted on June 17, 1964