Derived pulmonary capillary pressure changes after smoke inhalation in sheep

Background and Methods: We determined derived pulmonary capillary pressure and the longitudinal distribution of pulmonary vascular resistance in chronically instrumented sheep with inhalation injury by using analysis of pressure decay curves after pulmonary artery occlusion. Results: There was an increase in derived pulmonary capillary pressure and an increase in the lung lymph flow after smoke inhalation. The pulmonary vascular, arterial, and venous resistances increased significantly in the inhalation group. Pulmonary venous resistance increased proportionately more than pulmonary arterial resistance in the inhalation group. The plasma osmotic pressure-derived pulmonary capillary pressure gradient decreased to a greater extent in the inhalation group than in the control group. Conclusions: The present experiments suggest that the estimates of derived pulmonary capillary pressure can predict filtration pressure better than pulmonary artery occlusion pressure. The derived pulmonary capillary pressure can be measured easily in man with a pulmonary arterial catheter.