Pulmonary Gas Exchange in Nonnative Residents of High Altitude

F. C. Cerny; J. A. Dempsey; W. G. Reddan

doi:10.1172/JCI107497

Pulmonary Gas Exchange in Nonnative Residents of High Altitude

F. C. Cerny, J. A. Dempsey, and W. G. Reddan

Published December 1, 1973 - More info

View PDF

Abstract

This study represented an initial attempt, by means of cross-sectional investigation, to determine the effects of chronic exposure to high altitude on pulmonary gas exchange. Single-breath D_Lco and its components were determined at rest and during muscular work in two groups of healthy, non-smoking, sea level natives who had initiated 1-16 yr of residence at 3,100 m altitude either during physical maturation (at age 10±4 yr) or as adults (at age 26±4 yr). The relative degree of acclimatization achieved in these lowland residents was assessed through their comparison both with normal sea-level values and with two additional groups of short-term sojourners and natives to 3.100 m. D_Lco at rest and work was significantly elevated above normal and above sojourner values in both groups of resident lowlanders at 3,100 m. The high D_Lco in the native to 3,100 m was closely approximated in the younger resident lowlander at rest, but only during exercise in the adult resident lowlander. The high D_Lco at rest and during exercise in the resident lowlanders was not attributable to differences in Hb concentration or in alveolar lung volume: and was accompanied primarily by an increased estimated Dm_co and to a lesser extent by an expanded Vc. The interpretation and implications of these findings were limited by the low quantitative capability of Vc and Dm_co estimates and by the cross-sectional nature of the study. Nevertheless, the higher than normal D_Lco and Dm_co in the non-native, long-term resident of 3,100 m was substantial, highly significant statistically, and consistent over a wide range of metabolic rates at rest and work. These data provide, then, a reasonable rationale upon which longitudinal experiments may be based to determine the true effects of chronic hypoxia on pulmonary gas exchange in man.