Effects of pH and temperature on lung preservation: A study with an isolated rat lung reperfusion model

After the rat lung was flushed with 40 mmol/L phosphate-buffered saline solution containing 160 mEq/L of sodium and the heart-lung block was immersed in the same solution for 6 hours, the lung was reperfused with diluted autologous blood and ventilated for 30 minutes. Pulmonary artery pressure, airway pressure, difference in oxygen tension between inflow and outflow perfusate, and wet to dry weight ratio of the tissue were determined. Lungs treated at pH 7.75 showed a significantly lower pulmonary artery pressure and wet to dry weight ratio than those treated at pH 7.26 or 7.96. Organs preserved at 10 degrees C showed a significantly lower pulmonary artery pressure than those preserved at 5 degrees or 15 degrees C. When the effect of smaller temperature variations was examined, the 12 degrees C group showed a significantly lower pulmonary artery pressure than the 10 degrees C group. Thus, the isolated rat lung reperfusion model appears to provide an efficient screening system to examine the preservation solution or other conditions for lung preservation. Under the present experimental conditions, the optimal pH and temperature for rat lung preservation seem to be 7.75 and 12 degrees C, respectively.