Serial lecithin/sphingomyelin ratios and surfactant/albumin ratios in tracheal aspirates from term infants with respiratory failure receiving extracorporeal membrane oxygenation.

Serial tracheal aspirate samples were obtained for determination of lecithin/sphingomyelin (L/S) ratios from 47 term infants in respiratory failure. Phospholipids were extracted with Folch solution (chloroform:methanol, 2:1 by vol) and analyzed by HPLC with use of silica column and a mobile phase of acetonitrile:methanol:water (48:31:21, by vol). Surfactant/albumin (S/A) ratios were determined with the TDx Fetal Lung Maturity Assay (Abbott Labs). L/S ratios increased significantly over time in all patients (F = 19.42, P < 0.0001). The S/A ratio correlated with the L/S ratio (r = 0.554, P < 0.001). This study suggests that postnatal surfactant deficiency in term newborns with respiratory failure is a component of the newborn's lung injury.