Statistical Analysis
In the characterization of the sample, qualitative variables were expressed through absolute and relative frequencies, while quantitative variables were expressed through mean and standard deviations or standard error. The interactions between the group and moment of hemodynamic variables and ventilatory mechanics were evaluated through the EGE, and, when significant, the Bonferroni multiple comparisons test was used as a complement. Median and interquartile ranges were adopted to analyze the amount of secretion and the non-parametric Wilcoxon Signed-Rank test was used to compare groups. The significance level was 5%. Based on a previous study (WINPEP) [+], in order to detect a minimum difference of 1.4 g in the increase in secretion removal, with an error α = 5% and a power of 80%, the minimum number of calculated subjects was 122 (61 in each group), already accounting for possible losses.