Supplementary Material for: A Multicenter Lung Ultrasound Study on Transient Tachypnea of the Neonate

<b><i>Background and Aim:</i></b> Discordant results that demand clarification have been published on diagnostic lung ultrasound (LUS) signs of transient tachypnea of the neonate (TTN) in previous cross-sectional, single-center studies. This work was conducted to correlate clinical and imaging data in a longitudinal and multicenter fashion. <b><i>Methods:</i></b> Neonates with a gestational age of 34–40 weeks and presenting with TTN underwent a first LUS scan at 60–180 min of life. LUS scans were repeated every 6–12 h if signs of respiratory distress persisted. Images were qualitatively described and a LUS aeration score was calculated. Clinical data were collected during respiratory distress.<b><i> Results:</i></b> We enrolled 65 TTN patients. Thirty-one (47.6%) had a sharp echogenicity increase in the lower lung fields (the “double lung point” or DLP sign). On admission, there was no significant difference between patients with and without DLP in Silverman scores (4 ± 1.5 vs. 4 ± 2.1; <i>p</i> = 0.9) or LUS scores (7.6 ± 2.6 vs. 5.6 ± 3.8<i>; p</i> = 0.12); PaO₂/FiO₂ (249 ± 93 vs. 252 ± 125; <i>p</i> = 0.91). All initial LUS scans (performed at the onset of distress) and 99.5% of all scans showed a regular pleural line with no consolidation, with only 1 neonate showing consolidation in the follow-up scans. The Silverman and LUS scores were significantly correlated (rho = 0.27; <i>p</i> = 0.02). <b><i>Conclusion:</i></b> A regular pleural line with no consolidation is a consistent finding in TTN. The presence of a DLP is not essential for the LUS diagnosis of TTN. A semi-quantitative LUS score correlates well with the clinical course and could be useful in monitoring changes in lung aeration during TTN.