Lung Ultrasonography for the Diagnosis of Respiratory Distress Syndrome in Late Preterm Infants: Changing Incidence – A Single Center Experience

ABSTRACT

PURPOSE: Ultrasonography is non-ionizing, easy to operate, and performed at bedside in neonatal intensive care unit (NICU). We investigated the incidence of respiratory distress syndrome (RDS) with or without using lung ultrasound (LUS) in late preterm infants with postnatal respiratory difficulties. METHODS: We retrospectively reviewed medical records of 494 late preterm infants born at 34–36 weeks' gestation at Keimyung University Dongsan Medical Center. Fifty infants with postnatal respiratory difficulties were admitted to the NICU between May 2015 to October 2015 (period I), and forty-one were between November 2015 to February 2016 (period II). The diagnosis of RDS was based on chest radiography in period I. LUS was additionally performed at bedside in period II. All infants with RDS were received exogenous surfactant therapy. RESULTS: The overall incidence of RDS with surfactant replacement therapy was decreased in period II period II (9.4%, 20/212) compared to period I (14.5%, 41/282) (P=0.088). In terms of infants with postnatal respiratory difficulties, the incidence of RDS in period II (48.8%, 20/41) was significantly lower than that in period I (82.0%, 41/50) (P=0.001). There are no difference in the rate of reintubation, repeated doses of surfactant, oxygen demand at 48 hours after birth, air leak syndrome, pulmonary hemorrhage, persistent pulmonary hypertension of newborn, and mortality (P> 0.05). CONCLUSION: We could decrease the incidence of RDS with surfactant replacement therapy by using LUS in late preterm infants with postnatal respiratory difficulties. Further prospective studies are needed to apply LUS clinically to diagnose RDS.