Effects of pulmonary edema on regional pulmonary perfusion in the intact dog lung

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Abstract
Regional pulmonary blood flow was determined in dogs during varying degrees of pulmonary edema induced by infusing 179.2-659.4 ml/kg normal saline over 2-3 h. Pulmonary hemodynamics and regional blood flows were measured during the baseline period and at 30 min postinfusion. The degree of pulmonary edema was determined by the final extravascular lung water-to-bloodless dry lung weight ratio (W/D). In dogs developing gross alveolar edema (W/D of 10.70 .+-. 0.88 vs. 3.10 .+-. 0.30 in controls) the blood flow was shifted to upper or dependent lung regions. The shift to the upper regions was associated with an increased (P < 0.05) pulmonary arterial pressure .**GRAPHIC**. the shift to the dependent lung was not associated with a significant change in .**GRAPHIC**. Breathing 100% O2 did not prevent these shifts; apparently they were not due to localized hypoxic pulmonary vasoconstriction. The flow distribution patterns were not related to regional differences in edema. In contrast to the changes during fulminant edema, blood flow distribution did not change after moderate levels of pulmonary edema (W/D of 6.03 .+-. 0.69); gross alveolar flooding apparently is required for a redistribution of pulmonary blood flow. Flow redistribution to the upper lung during airway flooding may be due to increase in .**GRAPHIC**. the increased flow in the dependent lung during the same degree of edema may be due to bulging of alveolar vessels into the air spaces, secondary to a decrease in surface activity.