摘要Background:One-lung ventilation (OLV) is a common ventilation technology during thoracic surgery that can cause serious clinical problems.We aimed to conduct a meta-analysis to compare oxygenation and intrapulmonary shunt during OLV in adults undergoing thoracic surgery with dexmedetomidine (Dex) versus placebo to assess the influence and safety of using Dex.Methods:Randomized controlled trials comparing lung protection in patients who underwent thoracic surgery with Dex or a placebo were retrieved from PubMed,EMBASE,MEDLINE,Cochrane Library,and China CNKI database.The following information was extracted from the paper:arterial oxygen partial pressure (PaO2),PaO2/inspired oxygen concentration (PaO2/FiO2,oxygenation index [OI]),intrapulmonary shunt (calculated as Qs/Qt),mean arterial pressure (MAP),heart rate (HR),tumor necrosis factor-α (TNF-α),interleukin (IL)-6,superoxide dismutase (SOD),and malondialdehyde (MDA).Results:Fourteen randomized controlled trials were included containing a total of 625 patients.Compared with placebo group,Dex significantly increased PaO2/FiO2 (standard mean difference [SMD] =0.98,95％ confidence interval [CI] [0.72,1.23],P ＜ 0.00001).Besides,Qs/Qt (SMD=-1.22,95％ CI [-2.20,-0.23],P =0.020),HR (SMD=-0.69,95％ CI [-1.20,0.17],P =0.009),MAP (SMD=-0.44,95％ CI [-0.84,0.04],P =0.030),the concentrations ofTNF-α (SMD =-1.55,95％ CI [-2.16,-0.95],P ＜0.001),and IL-6 (SMD =-1.53,95％ CI [-2.37,-0.70],P =0.0003) were decreased in the treated group,when compared to placebo group.No significant difference was found in MDA (SMD =-1.14,95％ CI [-3.48,1.20],P =0.340) and SOD (SMD =0.41,95％ CI [-0.29,1.10],P =0.250) between the Dex group and the placebo group.Funnel plots did not detect any significant publication bias.Conclusions:Dex may improve OI and reduce intrapulmonary shunt during OLV in adults undergoing thoracic surgery.However,this conclusion might be weakened by the limited number of pooled studies and patients.