Journal of Applied Physiology, Vol 39, Issue 3 469-474, Copyright © 1975 by American Physiological Society
Effect of altitude relocations upon AaDo2 at rest and during exercise
J. C. Cruz, L. H. Hartley and J. A. Vogel
The supine pulmonary venous admixture (shunt) has been measured at Cerro de
Pasco, 4,350 m altitude in eight subjects native to high altitude (HAN)
under resting condition. Alveolar-arterial O2 tension difference (AaDO2)
was also determined at rest and during exercise. The same subjects were
studied again after 10 days' sojourn at sea level in Lima at 150 m
altitude. They were compared with four subjects from sea level (SLN) who
were studied first at Lima and after 2 and 10 days at Cerro de Pasco. At
altitude, AaDO2 was smaller in HAN than SLN both at rest and during
exercise. Shunt was the same in both groups. It is concluded that HAN show
more even ventilation/perfusion relationship (VA/Q) at altitude, probably
due to their high pulmonary artery pressure. On the contrary, SLN show less
even VA/Q on altitude exposure, since their shunt decreased 37%. At sea
level, HAN increased their AaDO2 due partially to an increase of 110% in
their shunt, and in part due to less even VA/Q as shown by augmented VD/VT
ratios. Each group tended to have a more effective gas exchange in its own
environment.
