Ex Vivo Assessment of Porcine Donation After Circulatory Death Lungs That Undergo Increasing Warm Ischemia Times

BACKGROUND: Increased utilization of donation after circulatory death (DCD) lungs may help alleviate the supply/demand mismatch between available donor organs and lung transplant candidates. Using an established porcine DCD model, we sought to determine the effect of increasing warm ischemia time (WIT) after circulatory arrest on lung function during ex vivo lung perfusion (EVLP). METHODS: Porcine donors (n = 15) underwent hypoxic cardiac arrest, followed by 60, 90, or 120 minutes of WIT before procurement and 4 hours of normothermic EVLP. Oxygenation, pulmonary artery pressure, airway pressure, and compliance were measured hourly. Lung injury scores were assessed histologically after 4 hours of EVLP. RESULTS: After EVLP, all 3 groups met all the criteria for transplantation, except for 90-minute WIT lungs, which had a mean pulmonary artery pressure increase greater than 15%. There were no significant differences between groups as assessed by final oxygenation capacity, as well as changes in pulmonary artery pressure, airway pressure, or lung compliance. Histologic lung injury scores as well as lung wet-to-dry weight ratios did not significantly differ between groups. CONCLUSIONS: These results suggest that longer WIT alone (up to 120 minutes) does not predict worse lung function at the conclusion of EVLP. Expanding acceptable WIT after circulatory death may eventually allow for increased utilization of DCD lungs in procurement protocols.