Objective:To evaluate lung ultrasound (LUS) for dynamic monitoring during invasive mechanical ventilation in preterm infants with neonatal respiratory distress syndrome (NRDS) and characterize LUS features before and after ventilation.Methods:This retrospective cohort study enrolled 110 NRDS preterm infants requiring invasive mechanical ventilation within 24 hours of admission at Kunming Children's Hospital from August 2019 to June 2022. Patients were divided into control ( n=61, pre-LUS era from August 2019 to May 2021) and LUS groups ( n=49, LUS era from June 2021 to June 2022). LUS manifestations before and after ventilation were systematically analyzed, with intergroup comparisons of complications (pneumothorax, pulmonary hemorrhage, pulmonary consolidation), ventilation duration, weaning proportions within specific timeframes, and weaning failure rates using two independent t-tests, rank-sum tests, Chi square tests (Fisher's exact test) with Bonferroni correction. Results:(1) Pre-ventilation LUS showed snowflake sign in 95.9% (47/49) and ground-glass opacity in 4.1% (2/49) of infants. Post-ventilation alveolar recruitment manifested as an abrupt reduction of the snowflake sign with complete resolution by 12 hours, while ground-glass opacity demonstrated an initial increase followed by gradual decrease, with subsequent emergence of A-lines after 12 hours of ventilation. (2) The LUS group showed a higher detection rate of pulmonary consolidation compared to the control group assessed by chest X-ray [65.3% (32/49) vs. 14.8% (9/61), χ2=29.70, P=0.001]. (3) The LUS group demonstrated higher weaning proportion within 24 hours [22.4% (11/49) vs. 0.0% (0/61)], and lower proportion beyond 72 hours [40.8% (20/49) vs. 67.2% (41/61)] (Bonferroni-corrected, both P<0.008). (4) Ventilation duration was significantly shorter in the LUS group [54.0 (25.0-128.5) vs. 107.5 (52.3-143.8) hours, Z=－2.85, P=0.004] with comparable weaning failure rates [10.2% (5/49) vs. 9.8% (6/61), χ2<0.01, P>0.999]. Conclusion:LUS patterns differ significantly pre- and post-ventilation in NRDS infants, enabling dynamic monitoring of pulmonary changes during mechanical ventilation to facilitate treatment adjustment and timely extubation.

Objective:To evaluate lung ultrasound (LUS) for dynamic monitoring during invasive mechanical ventilation in preterm infants with neonatal respiratory distress syndrome (NRDS) and characterize LUS features before and after ventilation.Methods:This retrospective cohort study enrolled 110 NRDS preterm infants requiring invasive mechanical ventilation within 24 hours of admission at Kunming Children's Hospital from August 2019 to June 2022. Patients were divided into control ( n=61, pre-LUS era from August 2019 to May 2021) and LUS groups ( n=49, LUS era from June 2021 to June 2022). LUS manifestations before and after ventilation were systematically analyzed, with intergroup comparisons of complications (pneumothorax, pulmonary hemorrhage, pulmonary consolidation), ventilation duration, weaning proportions within specific timeframes, and weaning failure rates using two independent t-tests, rank-sum tests, Chi square tests (Fisher's exact test) with Bonferroni correction. Results:(1) Pre-ventilation LUS showed snowflake sign in 95.9% (47/49) and ground-glass opacity in 4.1% (2/49) of infants. Post-ventilation alveolar recruitment manifested as an abrupt reduction of the snowflake sign with complete resolution by 12 hours, while ground-glass opacity demonstrated an initial increase followed by gradual decrease, with subsequent emergence of A-lines after 12 hours of ventilation. (2) The LUS group showed a higher detection rate of pulmonary consolidation compared to the control group assessed by chest X-ray [65.3% (32/49) vs. 14.8% (9/61), χ2=29.70, P=0.001]. (3) The LUS group demonstrated higher weaning proportion within 24 hours [22.4% (11/49) vs. 0.0% (0/61)], and lower proportion beyond 72 hours [40.8% (20/49) vs. 67.2% (41/61)] (Bonferroni-corrected, both P<0.008). (4) Ventilation duration was significantly shorter in the LUS group [54.0 (25.0-128.5) vs. 107.5 (52.3-143.8) hours, Z=－2.85, P=0.004] with comparable weaning failure rates [10.2% (5/49) vs. 9.8% (6/61), χ2<0.01, P>0.999]. Conclusion:LUS patterns differ significantly pre- and post-ventilation in NRDS infants, enabling dynamic monitoring of pulmonary changes during mechanical ventilation to facilitate treatment adjustment and timely extubation.