Statistical analysis and sample size
SPSS for Windows, version 22.0 (SPSS Inc., Chicago, IL, United States) was used for data analyses. Whether the distribution of continuous variables was normal or not was determined by the Kolmogorov-Smirnov test. The Levene test was used for the evaluation of the homogeneity of variances. Unless specified otherwise, continuous data were described as median (Q1: first quartile – Q3: third quartile) for skewed distributions. Categorical data were described as a number of cases (%). Statistical analysis differences in not normally distributed variables between two independent groups were compared by Mann Whitney U. Categorical variables were compared using Pearson’s Chi-Square test or Fisher’s Exact test. A p-value of < 0.05 was considered statistically significant. Bonferroni correction was used for analysis of VAS scores, statistical significance was adjusted to p < 0.0083, due to measurements from 6 time points.The sample size was calculated using G*Power© software version 3.1.9.2 (Institute of Experimental Psychology, Heinrich Heine University, Dusseldorf, Germany). The sample size was calculated for the Mann-Whitney U-test, which was used for testing the main hypothesis of (VASr scores in the 1st postoperative hour) of the preliminary study. Depending on the preliminary study research results (VASr scores in the 1