The effect of preincisional and postincisional morphine on postoperative pain in major abdominal surgery : a randomized clinical trial

Abstract

Objective : To determine whether the intravenous morphine administered before surgical incision results in lowering the postoperative analgesic requirement when compared with the same dose administered after surgical incision. Design : Randomized double-blind controlled trial. Setting : Chulalongkorn University Hospital which is the tertiary care center. Methods : One hundred and eight consecutive surgical patients between 20-65 years old who were anticipating elective major abdominal surgery under general anesthesia were recruited. The preincisional group received 0.15 mg/kg of morphine intravenously 15 minutes before surgical incision followed by normal saline at 15 minutes after incision. The postincisional group received normal saline 15 minutes before incision followed by morphine at 15 minutes after incision. Total morphine consumption within the first 48 hours after surgery was determined from patient-controlled analgesia (PCA) machine. Results : The mean analgesic consumption during the first 48 hours postoperatively were 45.94 (S.D.25.65) and 60.2 (S.D.33.05) mg. in preincisional and postincisional group respectively (p value=0.016). The time measured from the end of anesthesia to the first request of analgesia were not significantly different. Conclusion : The intravenous morphine administered before surgical incision reduced postoperative analgesic consumption during 48 hours postoperatively by 24% when compared with those administered after surgical incision.