Role of the bronchial circulation in ischemia-reperfusion lung injury

Bronchial arterial (BA) perfusion could modify pulmonary arterial (PA) ischemia-reperfusion (IR) injury by promoting clearance of peribronchial edema or limiting edema formation through maintenance of pulmonary vessel integrity via bronchopulmonary anastomotic or pulmonary vasa vasorum flow. The purpose of this study was to determine the effect of BA perfusion on IR injury in isolated sheep lungs. In 12 lungs (BA++) the BA was perfused throughout 30 min of PA ischemia and 180 min of reperfusion. In 12 lungs (BA-+) BA perfusion was begun with PA reperfusion, and in 15 lungs (BA--) the BA was never perfused. After 180 min, extravascular lung water was less (P < 0.05) in BA++ and B-+ lungs [4.70 +/- 0.16 and 4.57 +/- 0.18 g/g blood-free dry lung (bfdl)] than in BA-- lungs (5.23 +/- 0.19 g/g bfdl). The reflection coefficient for albumin was greater (P < 0.05) in BA++ and BA-+ (0.57 +/- 0.06 and 0.75 +/- 0.03) than in BA-- lungs (0.44 +/- 0.04). The filtration coefficient in BA++ and BA-+ lungs (0.016 +/- 0.006 and 0.015 +/- 0.006 g.min-1 x mmHg-1 x kg-1) was not different from that in BA-- lungs (0.025 +/- 0.006 g.min-1 x mmHg-1 x kg-1). These results suggest that BA perfusion decreased reperfusion edema by attenuating the increase in pulmonary vascular permeability caused by IR injury. Moreover the result in BA-+ lungs suggests that the protective effect was mediated by BA perfusion of PA vasa vasorum rather than bronchopulmonary anastomotic flow, which was trivial compared with PA blood flow.