目的 观察牛肺泡表面活性物质（PS）治疗晚期早产儿及足月儿呼吸窘迫综合征（RDS）的有效性。方法 采用随机对照研究观察按照不同时间和不同剂量气管内应用PS 对胎龄≥ 35 周及氧合指数（OI）在10~20的RDS 患儿的有效性。治疗1 组（n=58）入院6 h 内应用PS 50 mg/kg，治疗2 组（n=58）在入院6 h 内应用PS70 mg/kg，对照组（n=59）在入院6 h 内不给予PS，入院6 h 后若单纯应用机械通气等综合治疗后病情无缓解应用PS 50 mg/kg，各组用药后观察12 h 无缓解可以给予第二剂PS 50 mg/kg。结果 3 组病死率差异无统计学意义；治疗2 组住院费用及机械通气时间低于治疗1 组和对照组，且治疗1 组低于对照组；治疗2 组住院时间和呼吸机相关肺炎比率低于治疗1 组和对照组；治疗1 组和治疗2 组的PS 2 次及以上应用率、最高OI 值、CPAP 应用时间及气漏综合征、肺动脉高压发生率均低于对照组。结论 早期足量应用PS 可减少晚期早产儿及足月儿PS 2 次应用、住院费用及RDS 并发症的发生，缩短机械通气及住院时间。

Objective To evaluate the efficacy of calf pulmonary surfactant (PS) in the treatment of respiratory distress syndrome (RDS) in late preterm and full-term infants. Methods A randomized controlled trial was designed to evaluate the efficacy of calf PS intratracheally given at different times and doses in infants with RDS who had a gestational age of ≥35 weeks and an oxygenation index (OI) of 10-20. The subjects were randomly assigned to treatment group 1 (n=58), treatment group 2 (n=58), and control group (n=59). Treatment group 1 was given PS (50 mg/kg) within 6 hours after admission. Treatment group 2 was given PS (70 mg/kg) within 6 hours after admission. The control group was not given PS within 6 hours after admission and was given PS (50 mg/kg) over 6 hours after admission if having no remission by conventional therapy including mechanical ventilation. For each group, a second dose of PS (50 mg/kg) was given if no remission was observed within 12 hours after the first administration. Results There were no significant differences in mortality between the three groups. Treatment group 2 had lower hospitalization expense and shorter duration of mechanical ventilation compared with treatment group 1, and treatment group 1 had lower hospitalization expense and shorter duration of mechanical ventilation compared with the control group. The incidence of ventilator-associated pneumonia and length of hospital stay in treatment group 2 was lower than those in treatment group 1 and control group. Compared with the control group, Treatment groups 1 and 2 showed decreases in 2 or more times of PS use, maximum OI, duration of continuous positive airway pressure treatment, and incidence of air leak syndrome and pulmonary hypertension. Conclusions Early use of sufficient PS in late preterm and full-term infants with RDS can reduce complications, secondary use of PS, duration of mechanical ventilation and length of hospital stay, and hospitalization expense.