目的 探讨使用肺超声评分（LUS）对晚期早产儿并发呼吸窘迫综合征（RDS）应用机械通气（MV）和肺表面活性物质（PS）的预测价值。 方法 选择并发RDS的晚期早产儿（胎龄34^0/7~36^6/7周）进行前瞻性分析，共纳入67例并发RDS的晚期早产儿。根据患儿生后48 h内是否需要应用MV和PS，分为MV组（n=36）、非MV组（n=31）、PS组（n=30）和非PS组（n=37）。各组患儿在入院后2 h和应用PS前进行肺超声检查，并分别计算6分区、10分区和12分区LUS。绘制不同分区LUS预测晚期早产儿并发RDS应用MV和PS的受试者工作特征（ROC）曲线，采用Delong检验比较不同分区方法的预测价值。 结果 与非PS组比较，PS组患儿出生体质量、LUS、呼气末正压（PEEP）、平均气道压（MAP）、MAP×吸入氧浓度（FiO₂）/动脉血分压（PaO₂）比值、呼吸机使用时间和住院时间均升高（P<0.05或P<0.01），PaO₂/FiO₂比值降低（P<0.01）。与非MV组比较，MV组患儿出生体质量、LUS、PEEP、MAP、MAP×FiO₂/PaO₂值、呼吸机使用时间和住院时间均升高（P<0.05或P<0.01），PaO₂/FiO₂比值降低（P<0.01）。6分区LUS测PS应用时，PEEP、MAP和LUS是晚期早产儿并发RDS应用PS的危险因素［比值比（OR）>1，P<0.05］。10分区和12分区LUS预测PS应用时，MAP×FiO₂/PaO₂比值和LUS是晚期早产儿并发RDS应用PS的危险因素（OR>1，P<0.05）。6分区、10分区和12分区LUS预测MV应用时，MAP和LUS是晚期早产儿并发RDS应用MV的危险因素（OR>1，P<0.05）。6分区、10分区和12分区LUS预测晚期早产儿并发RDS的ROC曲线下面积（AUC）分别为0.909、0.904和0.915，均具有较好的预测价值；使用6分区、10分区和12分区LUS预测晚期早产儿并发RDS应用MV的AUC分别为0.868、0.872和0.887，均具有较好的预测价值。 结论 LUS可有效预测晚期早产儿并发RDS是否需要应用MV和PS，MAP联合LUS可以提高单独使用LUS预测应用MV的能力。

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 34^0/7-36^6/7 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.