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Exercise-induced VA/Q inequality in subjects with prior high-altitude pulmonary edema

1996; American Physiological Society; Volume: 81; Issue: 2 Linguagem: Inglês

10.1152/jappl.1996.81.2.922

8750-7587

Andrea Podolsky, Marlowe W. Eldridge, R. S. Richardson, D. R. Knight, Elaine C. Johnson, Susan R. Hopkins, D. H. Johnson, H. Michimata, Bruno Grassi, John Feiner, S. S. Kurdak, Philip E. Bickler, John W. Severinghaus, P. D. Wagner,

Neuroscience of respiration and sleep

Ventilation-perfusion (VA/Q) mismatch has been shown to increase during exercise, especially in hypoxia. A possible explanation is subclinical interstitial edema due to high pulmonary capillary pressures. We hypothesized that this may be pathogenetically similar to high-altitude pulmonary edema (HAPE) so that HAPE-susceptible people with higher vascular pressures would develop more exercise-induced VA/Q mismatch. To examine this, seven healthy people with a history of HAPE and nine with similar altitude exposure but no HAPE history (control) were studied at rest and during exercise at 35, 65, and 85% of maximum 1) at sea level and then 2) after 2 days at altitude (3,810 m) breathing both normoxic (inspired Po2 = 148 Torr) and hypoxic (inspired Po2 = 91 Torr) gas at both locations. We measured cardiac output and respiratory and inert gas exchange. In both groups, VA/Q mismatch (assessed by log standard deviation of the perfusion distribution) increased with exercise. At sea level, log standard deviation of the perfusion distribution was slightly higher in the HAPE-susceptible group than in the control group during heavy exercise. At altitude, these differences disappeared. Because a history of HAPE was associated with greater exercise-induced VA/Q mismatch and higher pulmonary capillary pressures, our findings are consistent with the hypothesis that exercise-induced mismatch is due to a temporary extravascular fluid accumulation.