Grouping
anxiety
The primary endpoint of this study was to determine different anxiety levels and identify the corresponding frequency bands. The purpose of dividing the patients into three groups was not for inter-group comparisons but rather to vary the levels of anxiety. Therefore, 60 patients were randomly assigned to one of the three study groups (20 patients per group) with different anxiety levels. Group 1 (placebo group) received normal saline at a rate of 5 mL/h for 10 min at the start of surgery. Groups 2 and 3 received dexmedetomidine for over 10 min at the beginning of the surgery. Dexmedetomidine was diluted with 0.9% saline at a 4-μg/mL concentration. Groups 2 and 3 were administered dexmedetomidine at a dose of 0.2 and 0.5 μg/kg/h, respectively. Computer-generated permuted-block randomization was used with a block size of three and an allocation ratio of 1:1:1. The anesthesiologist could not be blinded because he was in charge of anesthetic care; a blinded investigator, who was not directly involved in anesthetic care, collected all data.