In situ cooling in a lung hilar clamping model of ischemia-reperfusion injury.

Experimental models for studying transplantation have up to now been unable to isolate reperfusion injury with minimal surgical manipulation and without the interference of graft rejection. Six pigs were subjected to left hilum preparation only (control group), and eight pigs were subjected to left hilum preparation plus in situ cooling ischemia and reperfusion of the lung (experimental group). The hilum was dissected free from other tissues in both groups. Lung preservation was achieved by antegrade flush perfusion via the left pulmonary artery. Pulmonary veins were clamped at the left atrium and a vent was created. The left main bronchus was clamped. Lung temperature was maintained at 4 degrees -8 degrees C, while core temperature was kept at 38 degrees C. After 3 hrs of cold ischemia the clamps were removed and the lung was reperfused. Elevated pulmonary vascular resistance and local and systemic aspects of ischemia-reperfusion syndrome were consistently reproduced. This large-animal model of in situ unilateral lung cold ischemia with warm reperfusion proved to be very reliable in reproducing all aspects of ischemia-reperfusion injury. It excludes the interference of rejection and extensive surgical manipulation. We therefore propose its use in experimental studies investigating pharmaceutical or cooling modifications affecting lung ischemia-reperfusion outcomes.