Lecithin/sphingomyelin ratio from tracheal aspirates and compliance of the respiratory system in infants with bronchopulmonary dysplasia

Abstract
In 55 infants with respiratory distress syndrome the dynamic compliance of the respiratory system (CRS) was measured by pneumotachography during the course of the disease. Lecithin/sphingomyelin ratio (L/S) was evaluated at birth and every 10th day. Thirteen infants who developed bronchopulmonary dysplasia (BPD) had lower L/S ratios at birth than those infants without BPD (mean = 1.0 versus 3.5,pRS was low (0.30 ml/cm H2O/kg) in all infants independently of outcome. In infants with BPD who survived, CRS was significantly higher from the 30th day on than in infants who died from the disease (0.35 versus 0.23 ml/cm H2O/kg). Together with an decrease in oxygen supply at this time (RS is a reliable predictor of survival in cases of BPD.