Effects of altitude acclimatization on pulmonary gas exchange during exercise

Abstract

Pulmonary gas exchange was studied in eight normal subjects both before and after 2 wk of altitude acclimatization at 3,800 m (12,470 ft, barometric pressure = 484 Torr). Respiratory and multiple inert gas tensions, ventilation, cardiac output (Q̇), and hemoglobin concentration were measured at rest and during three levels of constant-load cycle exercise during both normoxia [inspired PO2 (PI(O2)) = 148 Torr] and normobaric hypoxia (PI(O2) = 91 Torr). After acclimatization, the measured alveolar-arterial PO2 difference (A-aPO2) for any given work rate decreased (P < 0.02). The largest reductions were observed during the highest work rates and were 24.8 ± 1.4 to 19.7 ± 0.8 Torr (normoxia) and..