呼吸机管路内细菌污染与呼吸机相关性肺炎的相关性研究

Correlation between bacterial contamination in ventilator circuits and ventilator-associated pneumonia

目的探讨呼吸机管路内细菌与下呼吸道感染时间的相关性,为预防呼吸机相关性肺炎(VAP)提供依据。方法选取2015年6月-2016年6月入住综合ICU行机械通气的Ⅱ型呼吸衰竭患者122例,于上机后在不同时间段采集下呼吸道分泌物、呼吸机湿化罐、进气口及出气口冷凝水集水杯、螺纹管呼气接口内壁标本进行细菌培养,观察不同部位细菌生长情况,记录机械通气时间、ICU住院时间、呼吸机相关性肺炎发生率等。结果 122例机械通气患者,共收集培养标本1 898份,呼吸机湿化罐、进气口及出气口冷凝水集水杯、螺纹管呼气接口内壁细菌生长率与机械通气时间呈正相关(r=0.8545,0.9636,0.9636,0.9394;P<0.05);出气口冷凝水集水杯细菌出现最早,呼吸机湿化罐细菌出现最晚;各部位与下呼吸道分泌物细菌培养均以革兰阴性菌为主;全部患者中发生VAP19例,VAP发生率15.57%,随着机械通气时间的延长,VAP发生率逐渐增加,机械通气时间<5d与>7d分组比较,VAP发生率差异有统计学意义(P<0.05);19例VAP患者中,出气口冷凝水集水杯、螺纹管呼气端接口端内壁、进气口冷凝水集水杯及呼吸机湿化罐与下呼吸道分泌物细菌培养一致性分别为66.48%、63.45%、40.26%及54.32%,进气口冷凝水集水杯及呼吸机湿化罐的细菌出现时间与下呼吸道病原菌的出现时间基本一致。结论呼吸机管路细菌污染状况及VAP的发生与机械通气时间均存在相关性,呼吸机管路细菌污染可能是造成VAP发生的原因之一,建议定期更换呼吸机管路。

OBJECTIVE To explore the correlation between bacteria in ventilator circuits and time of lower respiratory tract infections so as to provide guidance for prevention of ventilator-associated pneumonia （VAP）.METHODS A total of 122 patients with type Ⅱ respiratory failure who were hospitalized for mechanical ventilation in the intensive care unit （ICU） from Jun 2015 to Jun 2016 were enrolled in the study.The specimens were collected from lower respiratory tract secretions,humidifier,condensation water collectors of air inlet and outlet,and interior walls of outlet tube for bacterial culture after the ventilators were used for different time periods.The growth of bacteria in different sites was observed;mechanical ventilation duration,length of ICU stay,and incidence of VAP were recorded.RESULTS Totally 1 898 specimens were collected from the 122 mechanical ventilation patients.The rates of bacterial growth in humidifier,condensation water collectors of air inlet and outlet,and interior walls of outlet tube were positively correlated with the mechanical ventilation duration （r =0.8545,0.9636,0.9636,0.9394;P〈0.05）.The bacteria emerged earliest in condensation water collectors of air outlet,latest in humidifier.Gram-negative bacteria were dominant among the bacteria that were cultured from the various sites and lower respiratory tract secretions.Of all the patients,19 had VAP,with the incidence of VAP 15.57%;the incidence of VAP increased with the mechanical ventilation duration,and there was significant difference in the incidence of VAP between the patients with mechanical ventilation duration less than 5 days and the patients with mechanical ventilation duration more than 7 days （P〈0.05）.Among the 19 patients with VAP,The consistencies of condensation water collectors of air outlet,interior walls of outlet tube,condensation water collectors of air inlet,and humidifiers with bacterial culture of lower respiratory tract secretions were 66.48%,63.45%,40.26%,and 54.32 %,respectively.The time of occurrence of bacteria in air inlet of condensation water collectors and humidifier was basically same with the time of occurrence of pathogens in lower respiratory tract.CONCLUSION The bacterial contamination of ventilator circuits and incidence of VAP are associated with the mechanical ventilation duration,the bacterial contamination of ventilator circuits may be one of the causes of VAP,and regular replacement of ventilator circuits is recommended.