Lung edema formation following inhalation injury: Role of the bronchial blood flow

We investigated the contribution of the bronchial blood flow to the lung lymph flow (Q̇(L)) and lung edema formation after inhalation injury in sheep (n = 18). The animals were equally divided into three groups and chronically prepared by implantation of cardiopulmonary catheters and a flow probe on the common bronchial artery. Groups 1 and 2 sheep were insufflated with 48 breaths of cotton smoke while group 3 received only room air. Just before injury, the bronchial artery of group 2 animals was occluded. The occlusion was maintained for the duration of the 24-h study period. At the end of the investigation, samples of lung were taken for determination of blood-free wet weight-to-dry weight ratio (W/D). Inhalation injury induced a sevenfold increase in Q̇(L) in group 1 (7 ± 1 to 50 ± 9 ml/h; P < 0.05) but only a threefold increase in group 2 (10 ± 2 to 28 ± 7 ml/h; P < 0.05). The mean W/D value of group 1 animals was 23% higher than that of group 2 (5.1 ± 0.4 vs. 3.9 ± 0.2; P < 0.05). Our data suggest that the bronchial circulation contributes to edema formation in the lung that is often seen after the acute lung injury with smoke inhalation.