Statistical analysis
The sample size of the study was calculated from the incidence of EA at 0 min entering the PACU of the preliminary experiment based on 15 participants each group, consequently, subjects (32 per each) were required to attained a power of 80% and a type I error of 0.05. To account for a potential 10% dropout rate, we enrolled 35 subjects each group.Statistical analysis was performed by SPSS (ver.25.0, IBM Co., Armonk, NY, USA). For normally distributed data, means and standard deviation (mean ± SD) were used, and the difference was compared with the Student’ s t-test. For non-normally distributed data, median (interquartile distance) M (P