Statistics
FO2 insp. and FO2 pre-insp. measurements are expressed as mean and SD. ANOVA was performed with a post-hoc Tukey’s test to analyse between-group differences. In addition, to test the predictive factors associated with FO2 insp. and FO2 pre-insp., multiple regression analyses were performed to determine whether VT, f and oxygen flow rate were significant predictors. Statistical analyses were performed using SPSS 17.0 software (SPSS Inc., Chicago, IL). A p value of <0.05 was considered statistically significant.