Influence of temperature of flushing solution on lung preservation

For lung transplantation the technique of flushing the donor pulmonary vascular bed may provide advantages in lung preservation such as rapid cooling and washout of blood. However, rapid cooling of the ischemic lung may also produce adverse effects. The aim of this study was to compare methods of cold flushing and topical cooling, and to evaluate the effect of temperature of the flushing solution on lung preservation. A total of 25 rabbit lungs were studied. Using an ex vivo rabbit lung model, postischemic function was assessed by the ability of the lung to oxygenate perfused blood and by measurement of pulmonary artery and airway pressures. The lungs in group I were preserved with simple immersion at 10 °C for 30 hours. The lungs in groups II through V were flushed with solution containing phosphate-buffered dextran (LPD) at different temperatures (groups II and IV, 10 °C; groups III and V, 23 °C) and stored at 10 °C for various ischemic periods (groups II and III, 30 hours; groups IV and V, 36 hours). Pulmonary vascular resistance during flushing at 10 °C was significantly higher than that at 23°C (p < 0.001). Flushing resulted in better preservation than topical hypothermia. Flushing at 23 °C resulted in superior postischemic function compared with flushing at 10 °C. We conclude that in lung preservation, uniform flushing with LPD solution improves the ischemic tolerance as compared with topical hypothermia, and that flushing with solutions at too low temperatures may have adverse effects on lung preservation.