Journal of Applied Physiology, Vol 65, Issue 4 1686-1692, Copyright © 1988 by American Physiological Society
Ventilation-perfusion relationships during induced normovolemic polycythemia in dogs
A. A. Balgos, D. C. Willford and J. B. West
Department of Medicine, University of California, San Diego, La Jolla 92093-0623.
Previous studies on normal subjects and patients with polycythemia have
given conflicting results of the effect of polycythemia on pulmonary gas
exchange. We studied acutely induced normovolemic polycythemia in the dog
and measured arterial blood gases and ventilation-perfusion (VA/Q)
relationships using the multiple inert gas elimination technique. The mean
base-line hematocrit of 43 +/- 5% was increased to 57 +/- 4 and 68 +/- 8%,
respectively, after two exchange transfusions of packed erythrocytes.
Subsequent plasma exchange transfusions returned the mean hematocrit to 44
+/- 4%. Polycythemia caused no significant arterial hypoxemia; indeed there
was a slight improvement in the alveolar-arterial PO2 difference. The
multiple inert gas elimination measurements showed no increase in VA/Q
inhomogeneity with no increase in log SD ventilation (V) or log SD blood
flow (Q). There was a shift of mean V and mean Q to high VA/Q areas because
of a decrease in cardiac output, presumably caused by increased blood
viscosity. This study showed no deleterious effects on pulmonary gas
exchange within the hematocrit range of 36-76%.
