ObjectiveTo investigate application value of lung ultrasound in the dynamic assessment of pulmonary surfactant（PS）in the treatment of preterm neonates with respiratory distress syndrome（RDS）.MethodsThirty preterm neonates with RDS transferred from our obstetrics department to the neonatal intensive care unit were selected prospectively. Lung ultrasound was performed and scored before and after PS use at 6 h

12 h

18 h

and 24 h

dynamic changes of lung ultrasound and its score at different times were observed.ResultsBefore PS use

16 cases（53.3%）showed bilateral white lung by lung ultrasound

14 cases（46.7%）showed alveolar interstitial syndrome

and 11 cases（36.7%）showed subpleural lung consolidation.After PS use at 6 h

3 cases（10.0%）showed bilateral white lung

and 2 cases（6.7%）showed subpleural lung consolidation

which was significantly better than that before PS use. The differences were statistically significant（χ2=11.09

6.29

P=0.001

0.012）.After PS use at 12 h

18 h

and 24 h

bilateral white lung and lung consolidation were not observed by lung ultrasound in all preterm neonates with RDS. Compared with before PS use

the difference was statistically significant（χ2=19.18

P<0.001）

but the difference was not statistically significant compared with that after PS use at 6 h（χ2=1.40

P=0.24）. The lung ultrasound scores at 6 h

12 h

18 h

and 24 h after the PS use were 19.3±4.0

17.4±3.9

17.6±4.0

and 17.9±4.2

respectively

which were lower than that before PS use（22.3±2.6）

and the differences were statistically significant（all P<0.05）. However

the differences of lung ultrasound score after PS use at 6 h

12 h

18 h

and 24 h were not statistically significant.ConclusionLung ultrasoundcan dynamically evaluate the effect of PS in the treatment of preterm neonates with RDS. The pulmonary condition can be improved significantly by lung ultrasound after PS use at 6 h.