Patient was extubated in the operating room and transferred to the surgical ward. The postoperative analgesia was performed with intravenous morphine administered through Patient Controlled-Analgesia (Automed 3300, AceMedical Co.) delivery. Morphine 1 mg was given for each request and continuous infusion was at a rate of 1 mg/h. Both groups had a 10 min lockout period and a safe higher limit of 20 mg in 4 hours. If VAS scores exceeded 4/10 scores, rescue analgesia was intravenously administered according to a standardized institutional protocol for pain treatment until the pain was relieved to a level falling below a VAS score < 4. Patient Controlled Analgesia (PCA) was continued for up to 2 days, until patients could tolerate oral opioid medications and/or anti-inflammatory analgesics. However, these medications were not considered in the analysis.