Journal of Applied Physiology, Vol 50, Issue 6 1198-1205, Copyright © 1981 by American Physiological Society
Role of pulmonary edema in the acute pulmonary response to sepsis
D. R. McCaffree, B. A. Gray, B. E. Pennock, J. Coalson, C. Bridges, F. B. Taylor and R. M. Rogers
There is evidence that both bronchoconstriction and accumulation of lung
water may contribute to the early alterations in lung function following
septicemia. Eigher of these may be mediated by blood components. To assess
these proposed mechanisms the changes in hemodynamics, pulmonary mechanics,
gas exchange, and gravimetric lung water were measured in the first 4 h
after Escherichia coli infusion in the anesthetized dog and baboon. These
species were selected because of previously demonstrated differences in the
response to gram-negative sepsis. Both species developed systemic
hypotension and early hypoxemia. The dogs had early transient increases in
venous admixture (Qva/Qt) but not shunt or dead space, while the baboon had
a more persistent increase in Qva/Qt and a late increase in dead space,
Increases in nonelastic resistance and decreases in lung compliance were
preceded or accompanied by decreases in the leukocyte count in both
species, but the platelet count, fibrinogen, and total hemolytic complement
had different changes in the two species. Postmortem lung analysis revealed
increased lung weight in both species but the wet weight-to-dry weight
ratio was not increased in either species. The fractional water content of
the excess lung mass was less than that of whole blood. Histological
examination revealed large numbers of extravasated leukocytes in the lungs,
which may be sufficient to explain the increase in lung weight. We conclude
that pulmonary edema does not play a role in the early pulmonary response
to E. coli bacteremia in either species. The physiological changes observed
are more consistent with bronchoconstriction.
