ObjectiveTo systematically evaluate the risk factors for hypoxemia after coronary artery bypass grafting (CABG).MethodsEight electronic databases including PubMed, EMbase, CENTRAL, Web of Science, CNKI, CBM, VIP and Wanfang data were searched by computer to collect cochort and case-control studies about CABG and hypoxemia published from inception to March 2020. Two authors independently assessed the quality using the Newcastle-Ottawa Scale (NOS), and a meta-analysis was performed by RevMan 5.3 software.ResultsA total of 15 studies involving 4 277 patients were included in this study and among them 1 273 patients suffered hypoxemia. Meta-analysis showed that age (OR=1.55, 95%CI 1.22 to 1.96, P=0.000 3), smoking (OR=3.22, 95%CI 2.48 to 4.17, P<0.000 01), preoperative chronic pulmonary diseases (OR=4.75, 95%CI 3.28 to 6.86, P<0.000 01), diabetes (OR=2.49, 95%CI 1.86 to 3.33,P<0.000 01), left ventricular ejection fraction (OR=3.15, 95%CI 2.19 to 4.52, P<0.000 01), number of coronary artery lesions (OR=2.20, 95%CI 1.63 to 2.97, P<0.000 1) were independent risk factors for hypoxemia after CABG; body mass index (OR=1.31, 95%CI 0.97 to 1.77, P=0.08) and cardiopulmonary bypass time (OR=3.40, 95%CI 0.72 to 15.94, P=0.12) were not associated with hypoxemia.ConclusionCurrent evidence shows that age, preoperative chronic pulmonary diseases, smoking, diabetes, left ventricular ejection fraction, number of coronary artery are risk factors for hypoxemia after CABG, which can be used to identify high-risk patients and provide guidance for medical staff to develop perioperative preventive strategies to reduce the incidence of hypoxemia. The results should be validated by large-scale standard studies in the future.