Effect of intraoperative infusion of low-dose ketamine on management of postoperative analgesia

BACKGROUND: Use of opioids for perioperative analgesia is associated with sedation, respiratory depression and postoperative nausea and vomiting. N-methyl-D-aspartate receptor antagonist such as ketamine has both analgesic and antihyperalgesic properties. We studied the effect of intraoperative infusion of low-dose ketamine on postoperative analgesia and its management with opioids. MATERIALS AND METHODS: A total of 80 patients scheduled for open cholecystectomy under general anesthesia were randomly allocated into two equal groups in a randomized double-blinded way. The general anesthetic technique was standardized in both groups. Group K patients (n = 40) received bolus of ketamine 0.2 mg/kg intravenously followed by an infusion of 0.1 mg/kg/h before skin incision, which was continued up to the end of surgery. Similar volume of saline was infused in Group C (n = 40). The pain score at different intervals and cumulative morphine consumption over 24 h was observed. Secondary outcomes such as hemodynamic parameters, patient satisfaction score and incidences of side effects were also recorded. RESULTS: Intraoperative infusion of low-dose ketamine resulted in effective analgesia in first 6 h of the postoperative period, which was evident from reduced pain scores and reduced opioid requirements (P = 0.001). The incidence of side effects and patient satisfaction were similar in both groups. CONCLUSION: Intraoperative low-dose ketamine infusion provides good postoperative analgesia while reducing need of opioid analgesics, which must be considered for better management of postoperative analgesia.