Objective:To evaluate lung ultrasound (LUS) for assessing lung aeration heterogeneity in neonatal respiratory distress syndrome (NRDS) across gestational ages and analyze its correlation with oxygenation.Methods:This retrospective cohort study enrolled 125 ventilated NRDS neonates from the neonatal intensive care unit of Hebei Children's Hospital (from March 2023 to May 2024), who were stratified as <32 gestational weeks ( n=47) and ≥32 gestational weeks ( n=78). All underwent LUS, chest X-ray, and blood gas analysis within 2 h of admission. The lung ultrasound score (LUSsc) quantified impaired lung volume percentage (graded: A=normal, B=coalescent B-lines, C=dense B-lines/focal consolidation, D=lobar consolidation). Aeration heterogeneity was measured by coefficient of variation (CV, within-patient) and Gini-Simpson index (between-patients), while oxygenation was assessed by arterial oxygen partial pressure/inhaled oxygen concentration (P/F). Group comparisons, including basic information, lung aeration, and lung aeration heterogeneity, used two independent sample t-tests, Mann-Whitney U tests, Chi square tests, or Wilcoxon tests; partial correlation analyzed aeration-oxygenation relationships. Results:(1) Analysis of impaired lung volume percentage revealed similar distribution patterns between groups, with the <32-week cohort ( n=47, 564 lung segments) showing proportions of 15.6% (88/564), 14.9% (84/564), 35.5% (200/564), and 34.0% (192/564) for graded patterns A through D, respectively, while the ≥32-week cohort ( n=78, 936 segments) demonstrated corresponding proportions of 15.7% (147/936), 16.3% (153/936), 31.7% (297/936), and 36.2% (339/936), with no statistically significant difference between groups ( Z=－0.24, P=0.812). (2) Within-patient heterogeneity analysis revealed no significant CV difference between <32-week group and ≥32-week group [0.33 (0.20-0.84) vs. 0.43 (0.21-0.73), Z=－0.99, P=0.321]. (3) Between-patient heterogeneity was significantly higher in the ≥32-week group, as reflected by the Gini-Simpson index [0.12 (0.09-0.14) vs. 0.09 (0.06-0.14), Z=－1.99, P=0.046], with heterogeneous aeration predominantly located in non-gravity-dependent regions—specifically the left upper lung in the <32-week group and anterior lungs in the ≥32-week group. (4) Correlation analyses demonstrated significantly inverse relationships between CV and LUSsc in <32-week and ≥32-week groups ( r=－0.912, P<0.001; r=－0.886, P<0.001), while the ≥32-week group additionally showed positive CV-P/F correlation ( r=0.373, P=0.001) and inverse LUSsc-P/F association ( r=－0.287, P=0.013). Conclusions:LUS effectively evaluates aeration and its heterogeneity in early NRDS. Infants ≥32 weeks exhibit greater between-patient heterogeneity, with ventilation parameters correlating significantly with oxygenation status.

Objective:To evaluate lung ultrasound (LUS) for assessing lung aeration heterogeneity in neonatal respiratory distress syndrome (NRDS) across gestational ages and analyze its correlation with oxygenation.Methods:This retrospective cohort study enrolled 125 ventilated NRDS neonates from the neonatal intensive care unit of Hebei Children's Hospital (from March 2023 to May 2024), who were stratified as <32 gestational weeks ( n=47) and ≥32 gestational weeks ( n=78). All underwent LUS, chest X-ray, and blood gas analysis within 2 h of admission. The lung ultrasound score (LUSsc) quantified impaired lung volume percentage (graded: A=normal, B=coalescent B-lines, C=dense B-lines/focal consolidation, D=lobar consolidation). Aeration heterogeneity was measured by coefficient of variation (CV, within-patient) and Gini-Simpson index (between-patients), while oxygenation was assessed by arterial oxygen partial pressure/inhaled oxygen concentration (P/F). Group comparisons, including basic information, lung aeration, and lung aeration heterogeneity, used two independent sample t-tests, Mann-Whitney U tests, Chi square tests, or Wilcoxon tests; partial correlation analyzed aeration-oxygenation relationships. Results:(1) Analysis of impaired lung volume percentage revealed similar distribution patterns between groups, with the <32-week cohort ( n=47, 564 lung segments) showing proportions of 15.6% (88/564), 14.9% (84/564), 35.5% (200/564), and 34.0% (192/564) for graded patterns A through D, respectively, while the ≥32-week cohort ( n=78, 936 segments) demonstrated corresponding proportions of 15.7% (147/936), 16.3% (153/936), 31.7% (297/936), and 36.2% (339/936), with no statistically significant difference between groups ( Z=－0.24, P=0.812). (2) Within-patient heterogeneity analysis revealed no significant CV difference between <32-week group and ≥32-week group [0.33 (0.20-0.84) vs. 0.43 (0.21-0.73), Z=－0.99, P=0.321]. (3) Between-patient heterogeneity was significantly higher in the ≥32-week group, as reflected by the Gini-Simpson index [0.12 (0.09-0.14) vs. 0.09 (0.06-0.14), Z=－1.99, P=0.046], with heterogeneous aeration predominantly located in non-gravity-dependent regions—specifically the left upper lung in the <32-week group and anterior lungs in the ≥32-week group. (4) Correlation analyses demonstrated significantly inverse relationships between CV and LUSsc in <32-week and ≥32-week groups ( r=－0.912, P<0.001; r=－0.886, P<0.001), while the ≥32-week group additionally showed positive CV-P/F correlation ( r=0.373, P=0.001) and inverse LUSsc-P/F association ( r=－0.287, P=0.013). Conclusions:LUS effectively evaluates aeration and its heterogeneity in early NRDS. Infants ≥32 weeks exhibit greater between-patient heterogeneity, with ventilation parameters correlating significantly with oxygenation status.