Fig. 2

Allocation of patients. All 69 patients who provided consent to participate in the study were randomly assigned into three groups (continuous infusion group, single bolus dose administration of 0.1 group, and single bolus dose administration of 0.2 group), with each group comprising 23 patients, on the day before surgery. One patient in the continuous infusion group (who did not meet the selection criteria after randomization) and one patient in the single bolus dose administration of 0.1 group (who withdrew consent after randomization) were excluded from the study. Thus, only 67 patients (continuous infusion group (n = 22), single bolus dose administration of 0.1 group (n = 22), and single bolus dose administration of 0.2 group (n = 23)) were included in the FAS