Sample size and statistical analysis
The largest difference was expected to be between groups A and C. Based on our pilot study,the heart rate change before and after intubation in group C was 11.7±2.3 beats/minutes, and the change in group A was 19±6.6 beats/minutes. Thus, the sample size was calculated with a power of 0.8 and alpha error of 0.05. At least 18 subjects per group were needed. Assuming a 10% dropout rate and to increase the credibility of this study, 80 patients were recruited (20 subjects for each group).GraphPad Prism Version 8.0.1 statistical software is used for data analysis and graphic production. When the normal distribution measurement data are expressed as means±SD, one-way ANOVA is used for comparison between groups, and Sidak multiple comparison is used for pairwise comparison between groups. The measurement data were performed using chi-square test. The missing data were treated using the mean imputation method. P<0.05 indicates that the difference is statistically significant.