Sample size
The sample size was corrected for repeated measures by blood glucose level at 11 different time points based on the results of the pilot trial with SPSS software. According to the pilot trial, the blood glucose level on the postoperative day 1 was largely adequate to prove a difference between the two groups, and the mean [SD] blood glucose levels were (TIVA 10.9 ± 2.2 vs. TIHA 11.7 ± 2.4 mmol/L ). The method used for sample size determination was matched-pair design formula with a type I error of 5% (α = 0.05) and 90% power (β = 0.1). The result showed that at least 51 patients were required in each group to show the differences of blood glucose level between the groups. Considering a 10% loss-to-follow-up rate, the final sample size was determined to be minimally 56 patients each group.