Patients were assigned to one of three groups by computer-generated randomization, fentanyl group (group F, N=30), oxydodone group (group O, N=30), or control group (group C, N=30). 10 minutes before completion of surgery, patients received 2 mL mixture of fentanyl 1 ㎍/kg or oxycodone 0.08 mg/kg with isotonic saline or isotonic saline 2 mL intravenously in accordance with allocated study groups by an anesthesiologist who was blinded to group treatment.