目的　分析新生儿机械通气并发下呼吸道感染的易感因素、致病菌的变迁 ,以寻求防治措施。方法　1996～ 1999年行机械通气 1天以上的 133例患病新生儿按照胎龄、体重及插管时间分组 ,分析发生下呼吸道感染有无差异。所有病原学分析全部采取插管内采气道分泌物培养。结果　新生儿机械通气插管时间大于 3天 ,下呼吸道感染的发生率明显增高 ,低出生体重儿、早产儿其机械通气后下呼吸道感染的发生率和足月、正常出生体重儿比较 ,有升高的趋势 ,但统计学无显著意义。致病菌以克雷伯杆菌、大肠埃希菌、绿脓杆菌、不动杆菌为主。结论　临床上合理应用机械通气 ,及早撤机 ,根据致病菌的变化合理应用抗生素 ,能有效地预防及治疗新生儿因气管插管、机械通气并发的下呼吸道感染 Objective To analyze the susceptibility factors of neonatal mechanical ventilation complicated with lower respiratory tract infection and pathogenic bacteria to seek control measures. Methods A total of 133 sick newborns with mechanical ventilation for more than one day from 1996 to 1999 were divided into groups according to gestational age, weight and time of intubation to analyze whether there was any difference in lower respiratory tract infection. All etiological analyzes were performed with intratracheal airway secretions. Results Neonatal mechanical ventilation intubation time is greater than 3 days, the incidence of lower respiratory tract infection was significantly increased, low birth weight infants, premature infants with lower respiratory infection after mechanical ventilation and the incidence of full-term, normal birth weight compared with children High trend, but no significant statistical significance. Pathogenic bacteria to Klebsiella, Escherichia coli, Pseudomonas aeruginosa, Acinetobacter mainly. Conclusions The rational use of mechanical ventilation in clinical practice and early weaning, according to the changes of pathogens rational use of antibiotics, can effectively prevent and treat neonatal tracheal intubation, mechanical ventilation complicated by lower respiratory tract infection