BACKGROUNDThere are two types of suction methods used clinically: closed tracheal suction system (CTSS) and open tracheal suction system (OTSS). However, the safety and efficacy of these two suction systems for patients remain to be analysed.OBJECTIVEThe objective of this study was to assess the safety and efficacy of OTSSs and CTSSs in adult mechanical ventilation.METHODSComputer searches were conducted on PubMed, Web of science, MEDLINE, CINAHL, and Cochrane Library databases. The search spanned from the inception of each database to December 2023. Two researchers independently reviewed and extracted data from the literature. Quality assessment was performed using the Cochrane Manual of Systematic Reviews, and meta-analysis was conducted using RevMan 5.3 software.RESULTSA total of 13 articles, involving 2822 patients, were included in the analysis. The meta-analysis showed that the CTSS could reduce the incidence of ventilator-associated pneumonia (odds ratio [OR] = 0.77, 95% confidence interval [CI]: [0.61, 0.98], P = 0.03). However, no significant difference existed in the microbial colonisation rate in the respiratory tract (OR = 1.40, 95% CI: [0.91, 2.15], P = 0.13), mechanical ventilation time (mean difference = -0.33, 95% CI: [-1.43, 0.78], P = 0.56), length of intensive care unit stay (mean difference = 0.23, 95% CI: [-0.90, 1.35], P = 0.69), and mortality (OR = 1.01, 95% CI: [0.84, 1.22], P = 0.89).CONCLUSIONIn comparison to the OTSS, the CTSS proves effective in reducing the incidence of ventilator-associated pneumonia. However, additional high-quality evidence is needed to evaluate respiratory microbial colonisation rates, the duration of mechanical ventilation, length of intensive care unit stay, and mortality.