Statistical analysis
atelectasis
ATELECTASIS
Data analysis was performed using IBM Statistical Package for the Social Science (SPSS) software (version 22.0; SPSS Inc., Chicago, IL, USA). The Kolmogorov‒Smirnov and Shapiro‒Wilk tests were conducted to assess the normality of the variables. Continuous variables are presented as either the mean ± standard deviation or median (25–75%), depending on the normality of the data and mean (95% confidence interval). Categorical variables were described using n (%). Static compliance, dynamic compliance, airway resistance, driving pressure and oxygenation were compared within and between groups using generalized linear models, with the baseline value as a covariate, and with minimal significant difference post hoc analysis. These outcomes are expressed as means and confidence intervals (95%). Incidence of atelectasis, length of ICU stay, length of hospital stay, duration of mechanical ventilation, extubation success and in-hospital mortality were compared using the Mann‒Whitney test (for nonnormally distributed variables) or the chi-squared test (for categorical variables). Analyses were conducted according to the intention to treat principle. All tests were 2-sided, and a p value <0.05 was considered statistically significant.