Statistical analysis
nerve block
REGRESSION
Continuous data were assessed for skewness by using the Shapiro–Wilk test and were expressed as mean ± standard deviation (SD) or median (IQR). Categorical variables were presented as the number (%). Numerical variables were analyzed using independent samples t-test or Mann–Whitney U test. Categorical variables were compared using Pearson χUnivariate analysis using logistic regression was performed to calculate the predictors of POST as odds ratios (ORs) with 95% confidence intervals (CIs). If these variables yielded In our preliminary investigation based on 17 cases per group, it was showed that the mean score of POST evaluated by the quadrant scaling was 1.12 ± 0.82 at 6 h following i-gel insertion (grade 0–3: 4/8/4/1). Correspondingly, the quadrant scale of the cases with nerve block was grade 0–3: 6/10/1/0. We calculated the sample size based on the Wilcoxon-Mann–Whitney test. For an error of 0.05 and 80% power, a sample size of 61 patients per group would be required. In order to compensate for dropouts, 140 patients were enrolled in this trial.