Study design and randomization
ESPB block
The study was approved by the Institutional Ethics Committee (Approval No. 2202ER384-1) and was registered in the Center of Chinese Clinical Trials Registry at All the patients were randomly divided into three groups using a computer-generated random-number list and a 1:1:1 allocation ratio. Group R received 30 mL of 0.5% ropivacaine. Group RD1 received 0.5% ropivacaine plus 0.5 µg/kg Dex and Group RD2 received 0.5% ropivacaine with 1 µg/kg Dex. An independent anaesthesia nurse who was not involved in the study prepared the study medication on the day of surgery in a randomized order hidden in an opaque envelope, which were opened after the patients had entered the operating theater. To ensure blinding, the volume of the study medication was standardized at 30 mL for all groups and injected by ultrasound-guided ESPB block. All the other investigators and all the patients were blinded to the group allocation throughout the entire perioperative period. The patients were also taught how to complete the global QoR-15 questionnaire and the VAS score before the surgery.