Statistical analysis
PONV, shivering, ’ dizziness, headache
All statistical analyses were performed using the IBM SPSS software Version.23.0 (IBM, Armonk, NY: IBM Corp). The normality of quantitative variables was examined with the Kolmogorov–Smirnov test. Quantitative variables are expressed as mean or median (interquartile range, IQR). Student T-test was used to compare the mean values of age, weight, height, operation time, anesthesia time, PACU discharge time, cytokines, and so on. The overall QoR-15 score and the cumulative use of sufentanil after surgery are reported as the median (IQR) and were analyzed using the Manne-Whitney U-test. An estimated median difference and 95% CI of differences were given for each statistical comparison. Categorical variables were reported as numbers and percentages. The proportion of ASA classification and the number of PONV patients were compared by the χ2 test. Fisher's precise test was used to compare the groups’ dizziness, shivering, or headache rates