Objective:To study the clinical value of lung ultrasound score (LUSsc) within 2 h after birth for pulmonary surfactant (PS) use in preterm infants with respiratory distress syndrome (RDS).Methods:From July 2019 to May 2021, preterm infants with RDS hospitalized in our hospital and received pulmonary ultrasound within 2 h after birth were prospectively enrolled. 12-area LUSsc was calculated. The infants were assigned into <32 weeks group and 32-36 weeks group according to gestational age (GA). Simple random sampling was carried out in each group with 1/5 as the validation set and the other 4/5 as the training set. The infants were also assigned into PS group and non-PS group according to PS usage within 24 h after birth. Receiver operator characteristic (ROC) curve of LUSsc predicting PS usage was drawn and validated.Results:A total of 857 RDS infants were enrolled, including 313 in <32 weeks group and 544 in 32-36 weeks group. For <32 weeks group, area under curve (AUC) of LUSsc>8.5 predicting PS use was 0.779 (95% CI 0.722-0.837), with 76.4% sensitivity and 81.4% specificity. The accuracy of using LUSsc>8.5 as cut-off predicting actual clinical PS application was 82.3% (Kappa value 0.692, P<0.05, McNemar's test P>0.05).For 32-36 weeks group, AUC of LUSsc>9.5 predicting PS use was 0.785 (95% CI 0.723-0.848), with 71.1% sensitivity and 81.7% specificity. The accuracy of using LUSsc>9.5 as cut-off predicting actual clinical PS application was 92.6% (Kappa value 0.772, P<0.05, McNemar's test P>0.05). Conclusions:LUSsc within 2 h after birth is independent predictor of PS use in preterm infants with RDS. For <32 weeks group, LUSsc>8.5 suggests PS application and for 32-36 weeks group the cut-off is LUSsc>9.5.

Objective:To discuss the predictive value of lung ultrasound score(LUS)for the use of mechanical ventilation(MV)and pulmonary surfactant(PS)in the preterm infants with late-onset respiratory distress syndrome(RDS).Methods:The prospective analysis was conducted on the late-onset preterm infants(gestational age 340/7-366/7 weeks)complicated with RDS;in total,67 late-onset infants complicated with RDS were included.The infants were divided into MV group(n=36),non-MV group(n=31),PS group(n=30),and non-PS group(n=37)based on the necessity to use MV and PS within 48 h after birth.Lung ultrasound examination was performed on all the infants 2 h after admission,and before the application of PS,and the LUS for 6-zone,10-zone,and 12-zone partitions were calculated.Receiver operating characteristic(ROC)curve for the prediction of MV and PS application in the infants with late-onset RDS were drawn by LUS with different partitions,and the predictive values of different partition methods were compared by DeLong method.Results:Compared with non-PS group,the birth weight,LUS,positive end expiratory pressure(PEEP),mean airway pressure(MAP),MAP×fraction of inspired oxygen(FiO2)/PaO2 value,duration of mechanical ventilation,and hospital stay of the infants in PS group were increased(P<0.05),and the ratio of PaO2/FiO2 was decreased(P<0.01).Compared with non-MV group,the birth weight,LUS,PEEP,MAP,MAP×FiO2/PaO2 value,duration of mechanical ventilation and hospital stay of the infants in MV group were increased(P<0.05),and the ratio of PaO2/FiO2 was decreased(P<0.01).PEEP,MAP,and LUS were identified as the influencing factors for application of PS in the late-onset preterm infants complicated with RDS when employing 6-zone LUS to predict the application of PS[odds ratio(OR)>1,P<0.05].When employing 10-zone and 12-zone LUS for the use of PS,MAP×FiO2/PaO2 and LUS were the influencing factors(OR>1,P<0.05).The area under curve(AUC)for predicting the application of PS in the late-onset infants complicated with RDS by 6-zone,10-zone,and 12-zone LUS were 0.909,0.904,and 0.915,respectively,all showing good predictive values;the AUCs for predicting the application of MV by 6-zone,10-zone,and 12-zone LUS were 0.868,0.872,and 0.887,respectively,all showing good predictive values as well.Conclusion:LUS can effectively predict the necessity for whether or not applying MV and PS in the late-onset infants complicated with RDS,and MAP combined with LUS can enhance the capability to predict the application of MV.