热湿交换器和加温湿化器对呼吸机相关性肺炎发生率影响的荟萃分析

Efficacy of heat and moisture exchangers and heated humidifiers in preventing ventilator-associated pneumonia： a Meta-analysis

目的探讨热湿交换器（HME）与加温湿化器（HH）是否可降低机械通气患者呼吸机相关性肺炎（VAP）的发生。方法通过计算机检索和手工检索PubMed、Cochrane数据库，收集1990年1月1日至2010年9月1日关于HME与HH对机械通气患者VAP影响的随机对照研究（RCT），按Cochrane协作网推荐的方法，对HME与HH预防机械通气患者VAP的发生率进行荟萃分析（Meta分析）。结果共纳入11篇RCT文献，其中HME组1121例，HH组1101例，两组VAP发生率分别为14．2％（159／1121）和15．9％（175／1101），相对危险度（RR）{0．88，95％可信区间（95％CI）0．72～1．07，P=0．21，表明与HH相比，HME并不降低机械通气患者VAP的发生率。筛选机械通气时间〉7d的RCT进行亚组分析，共纳入8篇文献，其中HME组834例，HH组859例，VAP发生率分别为15．2％（127／834）和17．5％（150／859），RR=0．84，95％C10．58～1．23，P=0．37，表明在机械通气时间〉7d的患者中，HME同样不降低VAP的发生率。结论HME并不降低机械通气患者VAP的发生率，即使在机械通气时间超过7d的患者也是如此。由于有关的RCT数量相对较少、质量较低（缺少盲法），需要高质量的大规模RCT进一步证实。

Objective To demonstrate the effects of heat and moisture exchangers （HME） and heated humidifiers （HH） in preventing ventilator-associated pneumonia （VAP）. Methods PubMed and Cochrane databases were searched by computer retrieval and manual retrieval to identify relevant randomized controlled trials （RCTs） using HMEs and HHs in preventing VAP from January 1st 1990 to September 1st 2010. Meta-analysis of HME and HH in preventing VAP was conducted using the methods recommended by the Cochrane Collaboration. Results Eleven RCTs were included. Sample size： 1 121 in HME group and 1 101 in HH group. In total, the rate of VAP in HME group and HH group was 14.2% （159/1 121） and 15.9% （175/1 101） respectively, the total relative risk （RR） was 0.88, and 95o//00 confidence interval （95~CI） 0.72 - 1.07, P^0.21. Compared with HH group, there was not a reduction in the risk ratio of VAP in the HME group. Even in mechanical ventilation（MV） with a duration of at least 7 days for subgroup analysis （8 RCTs,sample size： 834 in HME group and 859 in HH group）, the rate of VAP in HME group and HH group was 15.2% （127/834） and 17.5% （150/859） respectively, the total RR was 0.84, 95%CI 0. 58 1.23, P= 0.37, suggesting that in MV with a duration at least 7 days, there was also no reduction in the risk ratio of VAP in the HME group. Conclusion This study suggests there is not a significant reduction in the incidence of VAP in patients humidified with HMEs during MV, even in patients ventilated for 7 days or longer. This finding is limited by lack of enough RCTs and blinding. Further large sample of high quality RCTs is necessary to examine the wider applicability of HMEs and their extended use.