MITIGATION OF INJURY IN CANINE LUNG GRAFTS BY EXOGENOUS SURFACTANT THERAPY

Background: Exogenous surfactant therapy of lung donors improves the p reservation of normal canine grafts, The current study was designed to determine whether exogenous surfactant can mitigate the damage in lun g grafts induced by mechanical ventilation before procurement. Methods ann results: Five donor dogs were subjected to 8 hours of mechanical ventilation (tidal volume 45 ml/kg), This produced a significant decre ase in oxygen tension (p = 0.007) and significant increases in brancho scopic lavage fluid neutrophil count (p = 0.05), protein concentration (p = 0.002), and the ratio of poorly functioning small surfactant agg regates to superiorly functioning large aggregates (p = 0.02), Five ot her animals given instilled bovine lipid extract surfactant and underg oing mechanical ventilation in the same manner demonstrated no signifi cant change in oxygen tension values, lavage fluid protein concentrati on, or the ratio of small to large aggregates, All 10 lung grafts were then stored for 17 hours at 4 degrees C. Left lungs were transplanted and reperfused for 6 hours, After 6 hours of reperfusion the ratio of oxygen tension to inspired oxygen fraction was 307 +/- 63 mm Hg in lu ng grafts administered surfactant versus 73 +/- 14 mm Hg in untreated grafts (p = 0.007), Furthermore, peak inspired pressure was significan tly (p < 0.05) lower in treated animals from 90 to 360 minutes of repe rfusion, Analysis of lavage fluid of transplanted grafts after reperfu sion revealed small to large aggregate ratios of 0.17 +/- 0.04 and 0.7 7 +/- 0.17 in treated versus untreated grafts, respectively (p = 0.009 ). Conclusions: Instillation of surfactant before mechanical ventilati on reduced protein leak, maintained a low surfactant small to large ag gregate ratio, and prevented a decrease of oxygen tension in donor ani mals, After transplantation, surfactant-treated grafts had superior ox ygen tension values and a higher proportion of superiorly functioning surfactant aggregate farms in the air space than untreated grafts, Exo genous surfactant therapy can protect lung grafts from ventilation-ind uced injury and may offer a promising means to expand the donor pool.