Table 2 Demographic and Clinical Characteristics of subgroup analysis(ECMO vs non-ECMO)

The objective of this study is to explore the risk factors associated with invasive ventilation and ECMO. Efficient indicators for IMV and ECMO were believed to significantly reduce the mortality rate of severe patients because of the reasonable medication and timely operation. In subgroup analyses, 89 patients received invasive mechanic ventilation were divided into two groups (ECMO group vs non-ECMO group).Patients who received ECMO were more likely to be younger, to have coronary heart disease (p=0.01), and higher PCT, Aspartate aminotransferase (AST), Tbil, Mb, Fibrinogen (Fbg), prothrombin time (PT), d- dimer>0.5, shorter interval time from admission to invasive mechanical ventilation and lower PaO2/FiO2 compared with the non-ECMO. Variables with P<0.02 in the univariate analysis were included in the multivariate regression analysis. In multivariate analysis, age older than 65 (OR 0.175, 95%CI 0.036-0.855, p=0.031) and higher PaO2/FiO2 (OR 0.014, 95%CI 0.001-0.143, p<0.001) were associated with lower odds of ECMO treatment. It should be noted that more survivors were in the ECMO group than non-ECMO group (52.6% vs 13.7% p<0.001), indicating the effectiveness of ECMO.