Effect of positive end-expiratory pressure on lung water in pulmonary edema caused by increased membrane permeability.

Pulmonary edema caused by increased membrane permeability was created in dogs by alloxan and infusion of saline solution. Pulmonary extravascular water volume was measured gravimetrically using the supernatant hemoglobin concentration to estimate red cell mass in the calculation of residual pulmonary blood volume. Three groups were studied for two hours: a control group, a group given alloxan and mechanical ventilation without positive end-expiratory pressure (PEEP), and a group given alloxan and mechanical ventilation with 10 cm H2O of PEEP. After two hours, alloxan caused moderately severe pulmonary edema in the two experimental groups, but PEEP had no effect on the accumulation of pulmonary extravascular water volume. No sustained differences in pulmonary or systemic hemodynamics were present throughout two hours of pulmonary edema. The pulmonary shunt was increased in the group without PEEP but was similar in the control group and the group with PEEP. No significant changes in alveolar dead space were noted among the three groups.