Statistical analysis and sample size calculation
IBM SPSS statistics 26.0 statistical software was used for data analysis. All measurement data were tested by normal distribution and variance homogeneity tests. One-way analysis of variance was used when the variance homogeneity test was passed. The results were expressed as means ± standard deviation. The least significant difference post hoc test was used for multiple comparisons of the four groups. When the variance homogeneity test showed that the variance was not uniform, Welch’s test was used for analysis, and Tamhane’s test was used for multiple comparisons between the post hoc test groups. Comparison between different time points was performed by repeated measurement analysis of variance. The numerical data were expressed as frequency and percentage, and analyzed by Fisher’s χThe sample size was calculated on the basis of collecting the PPC scores for 40 patients in the four groups in the pretrial: PPC score was 2.2 points in the control group, 1.7 points in the penehyclidine hydrochloride group, 1.6 points in the dexmedetomidine group, and 1.4 points in the penehyclidine hydrochloride combined with dexmedetomidine group, α = 0.05, 1 − β = 0.80, the required sample size of each group (