EXOGENOUS SURFACTANT THERAPY IN 38-HOUR LUNG GRAFT PRESERVATION FOR TRANSPLANTATION

Previous work in our laboratory has documented alterations in surfacta nt composition and function after prolonged lung graft storage and tra nsplantation in dogs (Am Rev Respir Dis 1993;148:208-15). To determine whether exogenous surfactant therapy was beneficial, we pretreated 13 canine double lung blocks with prostacyclin, flushed them with 4 degr ees C modified Euro-Collins solution, and stored them at 4 degrees C f or 37 to 38 hours. After left lung transplantation and immediately bef ore reperfusion, eight dogs were administered 50 mg of bovine lung lip id extract surfactant per kilogram (50 mg/ml) directly into the left m ain bronchus and five Served as nontreated control animals. Blood gase s, peak inspired pressures, and individual pulmonary artery blood flow s were measured every 30 minutes during 6 hours of reperfusion. The na tive right and transplanted left lungs were then lavaged and surfactan t large and small aggregates and protein yields were analyzed. All non treated animals had physiologic evidence of severe ischemia-reperfusio n lung injury during reperfusion. Three of eight dogs treated with bov ine lung lipid extract surfactant had near normal lung function at 6 h ours of reperfusion, as reflected by maintenance of an oxygen tension/ inspired oxygen fraction ratio of more than 400 mm Hg and a normal car bon dioxide tension. Five of eight dogs did not respond to surfactant therapy and had decreases in gas exchange identical to those of the co ntrol animals. Blood flow through the left pulmonary artery was mainta ined in the three animals that responded to exogenous surfactant, wher eas flow significantly decreased to the left lung in all other animals , reflecting the patterns of gas exchange. In addition, the ratio of p oorly functioning small surfactant aggregates to the well-functioning large aggregates isolated from lung lavage after 6 hours of reperfusio n was decreased in surfactant-treated animals, especially in those exh ibiting a beneficial physiologic response to surfactant therapy. We co nclude that therapy with bovine lung lipid extract surfactant can resu lt in excellent preservation of lung grafts after prolonged storage an d transplantation, but that the results are not consistent, Further in vestigations are required to determine the factors responsible for the differential response to surfactant therapy.