Statistical analysis
SD
SECONDARY
The sample size was calculated based on the time of emergence. According to the results of our previous study, the emergence time was 7.7 min with a standard deviation (SD) of 1.2. In our pilot trial, we found that the administration of subanesthetic s-ketamine could reduce the emergence time by 10.6%. Then, we hypothesized that the s-ketamine could decrease the emergence time by 15%. Considering 80% power, 20% dropout, and adopting a ratio of 1:1, 22 participants were required in each group.Statistical analyses were performed using SPSS Statistics 23 (IBM, Armonk, NY) and GraphPad Prism 8.0.1 (GraphPad Software, San Diego, CA). Per-Protocol (PP) analysis was used to analyze all outcomes. According to withdrawal criteria, 5 patients were excluded at the data analysis even though they have received the interventions. The remaining patients will be categorized and analyzed according to their allocation and they have strictly followed the trial procedure. The results are expressed as mean ± SD, median, or n (%). The primary endpoint was compared between the two groups using a two-tailed t-test. For the secondary outcomes, ordinal and continuous data were computed using two-tailed t test or two-way ANOVA corrected with the Bonferroni test, while non-normally distributed data and rates were analyzed with the Mann–Whitney U test and the chi-squared test, respectively. The relationship between Ai values and EEG features was explored by using Pearson’s Correlation. If 