The investigators hypothesized that using new intravenous infusion pump of patient-controlled analgesia (parecoxib sodium 1 mg/mL + normal saline) would significantly improve postoperative pain control compare to conventional intravenous infusion pump of patient-controlled analgesia (fentanyl citrate 20 mg/mL/kg + ondansetron hydrochloride 16 mg/8 mL + normal saline). This prospective randomized controlled trial was designed to evaluate the benefit of new intravenous infusion pump of patient-controlled analgesia (parecoxib sodium 1 mg/mL + normal saline) for postoperative analgesia after laparotomic liver resection.