Prediction of idiopathic respiratory distress syndrome by the stable microbubble test on gastric aspirate

We evaluated the usefulness and accuracy of the stable microbubble test (SMT) performed on gastric aspirates of neonates to predict idiopathic respiratory distress syndrome (IRDS) and compared the results with those of the shake test, using the clinical characteristics of IRDS as the gold standard for the diagnosis of IRDS. One hundred forty paired samples of gastric aspirates, obtained within 1 hour of delivery from neonates with gestational ages between 27 and 42 weeks (mean, 36.6+/-3.5 weeks) and birth weights between 800 and 4,090 grams (mean 2,571+/-826 grams ) were evaluated. The sensitivity and specificity of the SMT with a predefined cut-off value of less than 20 bubbles/mm2 were 94.7% and 95%, respectively, with a positive and negative predictive value of 75% and 99.1%, respectively. The positive predictive value and specificity were increased to 100% in premature neonates. These values, especially the positive predictive value and specificity, were much higher than those obtained with the shake test. We conclude that the SMT on gastric aspirates obtained within 1 hour of delivery is a rapid and simple procedure to identify those neonates who will develop IRDS and who may benefit from prophylactic exogenous surfactant replacement.