To determine the importance of static lung inflation during storage, graft performance was evaluated at different levels of intratracheal pressure and varying ischemic intervals. Lewis rat lungs were perfused with low- potassium Euro-Collins and stored for 4 or 8 hr either in atelectasis (4 hr: group I; 8 hr: group IV, respectively) or 13 (group II; V) or 26 cmH2O of airway pressure (groups III, VI). Following implantation continuous measurement of alveolar-arterial oxygen difference (AaDO2/*) and pulmonary vascular resistance (PVR) were performed. Separate ventilation allowed assessment of mechanical lung function of the graft. At the end of reperfusion (120 min) weight gain, histology, and phospholipid and protein content in the pulmonary lavage were compared between the groups. Despite significant differences in survival at 4 hr of ischemia graft function did not differ in groups I to III. In contrast, static inflation had a significant impact after 8 hr of ischemia. Lungs stored in atelectasis (group IV) could not be reperfused and failed immediately. Survival in group V was 83±11 versus 107±7 min in group VI (P<0.05). Compliance at 80 min was 27±3 in group V and 52±6 ml/cmH2O in group VI (P<0.02). Corresponding values for PVR were 232±92 and 112±16 mmHg/ml/min, respectively (P<0.05). Less inflation and longer ischemia resulted in a reduction of the large to small phospholipid aggregate ratio and deterioration of surfactant function in the bubble surfactometer. In conclusion, while the amount of static lung inflation may not be critical following short ischemia, the performance of the graft improves significantly with full inflation (26 cmH2O) following extended ischemia (8 hr).
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