Study design and randomization
A statistician who was not involved in the study conducted the randomization of patients into group R (ropivacaine administration) or group DR (dexmedetomidine and ropivacaine administration) on a 1:1 ratio using a computer-generated random number table. The information regarding the group assignment was placed in an opaque sealed envelope. After the patient entering into the operation room and prior to the induction of anesthesia, the numbered envelope was opened by an anesthesiology nurse, and the card inside determined into which group the patient was placed.In group R, patients received IBPB using 0.25% ropivacaine 15 ml. In group RD, patients received IBPB using 0.25% ropivacaine and 0.5 μg/kg dexmedetomidine 15 ml. The anesthetic solutions for IBPB were prepared by an anesthesiology nurse who was not involved in the study. The anesthesiologist performing the block and observing the patient was blinded to the treatment group. Data collection was done by the same anesthesiologist who was unaware of the group allocation.