Objective  To compare the effectiveness between continuous aspiration of subglottic  secretion(CASS) and intermittent aspiration of subglottic secretion (IASS)  in mechanical ventilation patients for preventing ventilator- associated pneumonia  (VAP). Methods  Randomized controlled trials published from July  1994 to July 2019 were identified  by  searching  CochraneLibrary,PubMed,MEDLINE,EMBASE,Web  of  Science,China  Biology  Medicine database, CNKI, Wangfa and VIP Database. Two reviewers independently  screened the  studies according to the inelusive and exclusive criteria,assessed the quality and extracted the data. Then RevMan 5.3  software was used for Meta-analysis. Results  Eighteen studies enrolling a total of  1951  patients met the inclusion criteria. Meta-analysis showed no significant difference between two groups for the incidence of VAP,time to VAP occurrence,the aspirated  secretion  volume,duration  of  mechanical  ventilafion,length  of  ICU  stay  (P>0.05).  The  positive rate  of  occult blood test in CASS group was higher (P<0.01).Conclusion  The results indicate no significant differences between the two groups for preventing VAP. But the risk of tracheal wall injury in CASS is higher than that in IASS.

Continuous , Aspiration , of , Subglottic , Secretion; ,  Intermittent , Aspiration , of , Subglottic , Secretion；Ventilator-Associated Pneumonia；Meta-Analysis