Statistical analysis
ESPB
The number of participants required for this trial was estimated using G*power version 3.1.9.6 (Heinrich Heine University, Düsseldorf, Germany). In the pilot study, the amount of fentanyl required during the first 24 postoperative hours in patients who received LCS was 685.5 ± 220.7 (mean ± standard deviation) µg. Assuming that the standard deviation of the two groups is the same and a 25% reduction in fentanyl consumption in the ESPB group is clinically significant, the required number of participants was calculated to be 32 per group under the condition of alpha = 0.05, beta = 0.2, and an assumed dropout rate of 10%.NCSS 2021 Statistical Software version 21.0.4 (NCSS, LLC. Kaysville, UT, USA) was used for statistical analyses. After checking the normality of the data with the Shapiro–Wilk test, we used the Mann–Whitney U test for the comparison of the continuous variables, and the chi-square test (or Fisher’s exact test) for comparing the categorical variables. Continuous variables were expressed as median with interquartile range, while categorical variables as frequency with percentage. 