Statistical analysis
NRS
The sample size was calculated based on unpublished clinical data. The mean (standard deviation) of PI value at 30 min after entering PACU was 2.81 (1.88) in dexmedetomidine group and 1.5 (1.38) in remifentanil group. To evaluate this at a significance level of 5% and power of 90%, we needed 35 patients in each group. Considering an expected dropout rate of 10%, 78 participants were required.Continuous variables were expressed as mean (standard deviation) or median (interquartile range), as appropriate, and normality was assessed using the Shapiro-Wilk test. Categorical variables were presented as numbers (percentages). Intraoperative and postoperative continuous variables were compared using the t-test or Mann-Whitney U test as appropriate. Bonferroni corrections were applied for post-hoc analyses. Categorical variables were analyzed using Pearson’s chi-square test or Fisher’s exact test, as appropriate. Changes in PI in the PACU were analyzed using the Wilcoxon signed-rank test. The correlation between NRS scores and PI values in the PACU was analyzed using Pearson’s correlation coefficient. Statistical analysis was performed using SPSS 25.0 (SPSS Inc., Chicago, IL, USA). 