Abstract:OBJECTIVE: Neonatal respiratory distress syndrome (RDS)is an acute clinical neonatal disorder that requires prompt management. This study aimed to evaluate the usefulness of the stable microbubble test (SMT) on gastric aspirates in the early diagnosis of RDS in premature infants. METHODS: One hundred and one samples of gastric aspirates obtained within half an hr of delivery from premature neonates born at the Iwate Medical University, Japan, with gestational ages between 24 and 35 weeks (mean 30.1 ±3.5 weeks) were detected by the SMT. The stable microbubles per mm~2 were counted. Chest X-rays were taken within 1 hr of delivery. The clinical characteristics and X-ray results were used as the gold standard for the diagnosis of RDS. The sensitivity,specificity and positive and negative values of the SMT to predict and make an early diagnosis of RDS were evaluated. RESULTS: Of the 101 premature infants, 31 were diagnosed as RDS by the gold standard.Twenty-two infants had stable microbubbles less than 10 bubbles/mm~2,7 had stable microbubbles between 10 and 20 bubbles/mm~2,and 2 had stable microbubbles more than 20 bubbles/mm~2.In the 70 non-RDS infants,only 1 had stable microbubbles less than 10 bubbles/mm~2,2 had stable microbubbles between 10 and 20 bubbles/mm~2,and the rest had stable microbubbles more than 20 bubbles/mm~2.The sensitivity and specificity of the SMT with a cut-off value of less than 10 bubbles/mm~2 to predict RDS were 70.97% and 98.57%,respectively,with positive and negative predictive values of 95.65% and 88.46%,respectively.With a cutoff value of less than 20 bubbles/mm~2,the sensitivity,specificity and positive and negative values were 93.55%,95.71%,90.63% and 97.10% respectively. The patients with bubbles less than 10/mm~2 (whose chest X-ray showed moderate RDS) were administered with surfactant replacement.As a result the patients' symptoms were significantly improved. CONCLUSIONS: The SMT on gastric aspirates is a rapid, simple and reliable procedure to predict and make an early diagnosis of neonatal RDS. It is helpful to the prophylactic exogenous surfactant replacement.
