Lung Ultrasound for Predicting Resolution of Transient Tachypnea of the Newborn: A Diagnostic Accuracy Study.

Background: Transient tachypnea of the newborn (TTN) is a self-limited condition, but can persist for prolonged durations. None of the existing tools can accurately predict the timing of TTN resolution. Research Question: In term and late preterm neonates (population), can lung ultrasound (LUS) score (index test) predict delayed resolution of TTN, defined as persistence of respiratory distress beyond 6 hours of age (disease), monitored with Downes score (reference test)? Study Design and Methods: In this prospective study, term and late preterm neonates requiring neonatal ICU admission with a diagnosis of TTN were included. Respiratory distress was monitored with hourly Downes score, and resolution was noted when Downes score was 0 in the neonate not requiring any respiratory support. Baseline characteristics, physiological monitoring, respiratory support parameters, and LUS clips were recorded within 2 hours of age and compared between early and delayed resolution groups. LUS findings were neither revealed to the treating team, nor used in the management of neonates. LUS scoring was later performed by blinded assessors. Results: Among 113 enrolled neonates, 37 (32.7%) had delayed resolution of TTN. The mean birth weight and gestation were lower in the delayed resolution group, along with a higher requirement for resuscitation at birth. The median LUS score was significantly higher in the delayed (7; interquartile range, 5.5-9) compared with the early resolution group (4; interquartile range, 2-5.5). The diagnostic accuracy of LUS score was determined by receiver operating characteristic curve analysis (area under the curve, 0.84; 95% CI, 0.76-0.92; Interpretation: LUS is a promising tool to predict delayed resolution of TTN. Early prediction of TTN resolution may guide decision for neonatal ICU admission and help avoid unnecessary admissions in cases likely to resolve within 6 hours.