Sample size calculation
pain
After a pilot study on 30 participants (10 in each group), the minimum number of samples based on a 10-point pain scale 4 h after cholecystectomy using the mean and standard deviation (3.83 ± 1.94 in the control group and 5 ± 1.67 in the intervention group) was identified. By accepting α = 0.05 and a power of 80%, the standard sample size for each group was calculated as 38 patients (114 in total). Considering a 20% drop rate, 46 participants were included in each group (138 patients in total) (Fig. 
CONSORT flow diagram