Data will be tested for normality using the Kolmogorov-Smirnov test. Serial changes in the studied data at intubation will be analyzed with repeated-measures analysis of variance. Categorical data will be analyzed using Fischer's exact test. Repeated measure analysis of variance (ANOVA) will be used for continuous parametric variables and the differences will be then corrected by post-hoc Bonferoni test. The Kruskal-Wallis one-way ANOVA will be performed for intergroup comparisons for the non-parametric values and post hoc pairwise comparisons will be done using the Wilcoxon rank sum t test. p value < 0.05 will be considered statistically significant.