Controlled Reperfusion Protects Lung Grafts During a Transient Early Increase in Permeability

Background. We have previously shown that an initial 10-minute period of low-pressure reperfusion prevents the lung graft dysfunction that follows physiologic-pressure reperfusion. Possible mechanisms were investigated in this study. Methods. Rat lungs were reperfused ex vivo using a parabiotic animal after 0-hour (groups A through C) or 24-hour (groups D through G) storage. Reperfusion pressure was either physiologic (groups A through D) or reduced by 50% for a specified time (groups E through G). The duration of reperfusion was 5 minutes (groups A, D, and E), 10 minutes (groups B and F), or 30 minutes (groups C and G), at which time endothelial permeability was measured through iodine 125–labeled albumin leakage and neutrophil sequestration through tissue myeloperoxidase activity. Results. Graft function in group D deteriorated rapidly, whereas groups E through G performed at control levels. Albumin leakage was significantly elevated in group D; with controlled reperfusion, it was elevated after 5 minutes (group E) but had returned to baseline at 10 minutes (group F) and 30 minutes (group G). Myeloperoxidase levels were not significantly different between groups. Conclusions. Endothelial permeability is transiently elevated in the early phase of lung graft reperfusion. Initial low-pressure reperfusion may be protective by preventing irreversible edema formation during this period.