Abstract
Serial lung recruitment assessment in neonates with moderate-to-severe neonatal acute respiratory distress syndrome (NARDS) is crucial. However, current methods involve ionizing radiation or invasiveness, which limits their serial use in neonates. This study evaluated the feasibility of rib-indexed quantitative lung ultrasound (LUS) as a radiation-free alternative for monitoring lung aeration in neonates with moderate-to-severe NARDS on surfactant therapy combined with prone position. A prospective observational study enrolled 35 term neonates with moderate-to-severe NARDS. Lung recruitment was assessed via anterior-posterior approach rib-indexed quantitative LUS and posteroanterior chest X-ray (CXR) before and 6 h after combined surfactant therapy and prone position. Following the intervention, it demonstrated a significant reduction in the LUS aeration score, from a pre-intervention median of 18 points (IQR 16, 22) to a post-intervention median of 15 points (IQR 12, 20) (P < 0.001). In contrast, the decrease in the CXR score (pre-intervention median 3 (IQR 3, 4) vs. post-intervention median 2 (IQR 2, 3)) did not reach statistical significance (P = 0.059). Posterior approach rib-indexed quantitative LUS showed high concordance with posteroanterior CXR in determining the rib level of the pulmonary-diaphragmatic interface (ICC > 0.95, kappa > 0.94, P < 0.001). No adverse events occurred during the LUS assessments.Conclusion: Posterior approach rib-indexed quantitative LUS is a reliable and non-invasive modality for real-time lung recruitment assessment in neonates with NARDS. It significantly detected improved lung aeration following surfactant therapy combined with prone position, whereas CXR failed to demonstrate a statistically significant improvement. Posterior approach rib-indexed quantitative LUS can also determine the rib level of the pulmonary-diaphragmatic interface, similarly to posteroanterior CXR. The superior sensitivity and safety of rib-indexed quantitative LUS offer a clinically valuable and innovative alternative for dynamic monitoring of lung recruitment in neonatal critical care. Future multi-centre studies should integrate CT validation to confirm broader applicability.Trial registration: The trial was prospectively registered with the Chinese Clinical Trial Registry (ChiCTR2300074652) on August 11, 2023.