Journal of Anesthesiology and Pain

Background: Postoperative pain control is one of the problems for these patients. Opioid agents are the most important analgesics which commonly used for postoperative pain control. There are several trials for reducing the doses of opioids. It seems addition of ketamine to the opioids other than postoperative pain relief, reduces the total opioid consumption. The goal of this study was evaluation of postoperative analgesic effects of adding ketamine to morphine and tramadol after major abdominal surgery.
Methods: Eighty patients candidate for major abdominal surgery under similar general anesthesia were enrolled in this study. Postoperative pain was managed by iv patient controlled analgesia (PCA) for aal patients. After the end of surgery, they were randomly allocated into the 1) morphine (M), 2) tramadol (T), 3) ketamine and morphine (KM), and 4) ketamine and tramadol (KT) groups. Analgesic solution in PCA in M group was morphine (0.2 mg/ml), in T group was tramadol (2 mg/ml), in KM group was ketamine (2 mg/ml) and morphine (0.2 mg/ml), and in KT group was ketamine (2 mg/ml) and tramadol (2 mg/ml). Visual analogue scale (VAS), total opioid consumption, complications, and satisfaction were measured and recorded for during the first 24 hours after surgery.
Results: Demographic data was not differences between groups. Pain score in early period (1^st and 6^th hours) was significantly lower in KM group than the others. Furthermore, addition of ketamine significantly reduced total morphine and tramadol consumption. No side effects were observed in the all groups. 
Conclusions: Our finding showed that addition of ketamine to morphine could reduce pain score and total opioid consumption after major abdominal surgery.