2.5. Intervention
NRS, pain
After the patient entered the operating room, their basic information was recorded. The patient was then taught how to use the PCA pump. We asked the patients to describe their pain severity using a numerical rating scale (NRS), where zero indicated the absence of pain, and ten indicated the maximum possible pain.The general anesthesia regime (including premedication, anesthesia induction drug, muscle relaxant, anesthesia maintenance, and analgesia with morphine sulfate 0.1 mg/kg) was identical in both groups. In the ESP block group, after gaining intravenous access and establishing standard monitoring, the patients were placed in a sitting position. Then, using a curved probe under ultrasound guidance (2 to 5 MHz), the transverse processes of the lumbar vertebrae were identified as close as possible to the surgical site, and 20 ml of 0.25% bupivacaine was injected just over the transverse process with a No. 22 spinal needle in the long axis view after making contact. The same procedure was repeated on the contralateral side. Patients in the control group did not receive this ESP block.