Interventions
postoperative pain, NRS, pain
INFILTRATION
Prior to the study procedure, the patients were given instruction on how to operate the PCA pump and assess their pain using the numerical rating scale (NRS). Once they entered the operating room, a solution of Ringer's lactate was infused via an 18-Gauge intravenous cannula that had been placed in a peripheral vein on their forearm. During the procedure, various vital signs were continuously monitored, including ECG, heart rate, invasive blood pressure, respiratory rate and pulse oxygen saturation. To establish general anesthesia, a combination of 0.30 mg/kg of etomidate, 0.4 mg/kg of sufentanil and 0.2 mg/kg of cisatracurium was administered. Propofol, sevoflurane, remifentanil and cisatracurium were used to maintain anesthesia throughout the procedure. All surgical procedure was performed by the same surgeon. After the surgery, the surgeon injected 15 mL into each side of the surgical incision for wound infiltration. All patients were given PCA for postoperative pain relief. The PCA protocol included hydromorphone hydrochloride (10 mg), tropisetron hydrochloride (5 mg) and normal saline (85 ml). The PCA was programmed to administer a 1 mL bolus with a lockout time interval of 10 min and no baseline infusion. The PCA was given when the patient reported a pain score of ≥ 4 on the NRS or requested it.