Warm retrograde perfusion can remove more fat from lung grafts with fat embolism in a porcine model

Objective: In lung transplantation, unexpected pulmonary emboli, including thrombi and fat, have been observed with high probability and are associated with potential primary graft dysfunction. We evaluated a new perfusion method using warm retrograde flushing that removes more fat than conventional cold retrograde flushing. Methods: We developed a novel porcine donor model for pulmonary fat embolism by administering autologous fat in the left pulmonary artery. The left pulmonary artery and the left superior and inferior pulmonary veins were cannulated for flushing and collecting these solutions. After flushing, the left lung was reperfused under observation for 3 h. Two groups underwent warm and cold additional retrograde flush (WS; warm solution group, CS; cold solution group). Results: The fat removal rate in the antegrade flush was equal in both groups (3.0 ± 0.6% vs 3.0 ± 0.4%, p = 0.46); however, the rate was significantly greater in the WS group in retrograde flush (25.2 ± 3.2% vs 8.0 ± 1.4%, p = 0.01). Histology with Oil Red O staining and its software analysis showed more residual fat in the CS group (0.12 ± 0.01% vs 0.38 ± 0.07%, p = 0.01). There was no significant difference in the pulmonary function and hemodynamics during the 3-h period after reperfusion. Conclusion: Warm retrograde perfusion can remove more fat from lung grafts with fat embolism in a porcine donor model.