细菌过滤器联合加热湿化器对预防呼吸机相关性肺炎的效果

目的研究细菌过滤器联合加热湿化器对呼吸机相关性肺炎（VAP）发生率的影响。 方法采用前瞻性随机对照试验方法，选择2017年3月至2020年3月在南京医科大学第一附属医院ICU需行机械通气≥48 h的患者210例，将其随机分为细菌过滤器组（104例）和对照组（106例）。对照组患者采用加热湿化器，不联合任何过滤装置，实验组采用加热湿化器联合细菌过滤器。采用单因素logistic回归分析研究VAP发生的危险因素，采用Kaplan-Meier法比较2组患者VAP的累积发生率，采用亚组分析及Cox生存回归分析研究细菌过滤器预防VAP的效果。 结果细菌过滤器组气管切开患者比例较对照组低，差异有统计学意义（19.2% vs 38.7%，χ²=9.634，P=0.002）。2组VAP患病率比较，差异无统计学意义（22.1% vs 34.0%，χ²=3.647，P=0.066），Logistic回归分析显示，细菌过滤器未能有效减少VAP的发生率（OR=0.552，95% CI=0.299~1.019，P=0.058）；Kaplan-Meier分析未显示细菌过滤器在预防VAP方面具有显著优势（log-rank检验，P=0.060）；亚组分析及Cox生存回归分析显示，在机械通气＜25 d的患者中，细菌过滤器显著减少VAP的发生率（HR=0.373，P=0.004）。 结论在机械通气＜25 d的患者中，细菌过滤器联合加热湿化可以显著减少VAP的发生率，但随着机械通气时间的延长而不再有意义。

Impact of bacterial filters combined hot-water humidification on prevention of ventilator-associated pneumonia

ObjectiveTo explore the effects of bacterial filters (BFs) combined hot-water humidification on reducing the incidence of ventilator-associated pneumonia (VAP). MethodsA prospective randomized controlled trial was performed in ICU of Nanjing Medical University from March 2017 to March 2020 that enrolled patients under mechanical ventilation for ≥48 hours. These patients were randomly assigned to the bacterial filter (BF) group (104 cases) or non-bacterial filter (NBF) group (106 cases). NBF group was treated with hot-water humidification (HH) while BF group was treated with HH combined BF. Univariate logistic analysis was applied to explore the risk factors for VAP. The Kaplan-Meier method was used to compare the cumulative incidence of VAP in group 2 patients. Cox proportional-hazards regression and post hoc subgroup analysis were used to determine the effects of the filter on the incidence of VAP. ResultsThe proportion of patients with tracheotomy was low and statistically significant (19.2% vs 38.7%, χ²=9.634, P=0.002), the prevalence of VAP in two groups had no difference without statistical significance (22.1% vs 34.0%, χ²=3.647, P=0.066). Logistic regression analysis revealed that the bacterial filter failed to effectively reduce VAP occurrence (OR=0.552, 95% CI=0.299-1.019, P=0.058). The Kaplan-Meier analysis did not show significant advantages of bacterial filters in preventing VAP (log-rank test P=0.060). Subgroup analysis and Cox survival regression analysis showed that bacterial filters significantly reduced VAP occurrence in patients with mechanical ventilation of＜25 d (HR=0.373, P=0.004). ConclusionBacterial filters can significantly reduce the incidence of VAP in patients under mechanical ventilation for＜25 days with hot-water humidification, although this benefit became insignificant for prolonged mechanical ventilation.