Preemptive analgesia with intravenous ketamine has been utilized as a part of multi-modal analgesia for acute postoperative pain following laparoscopic cholecystectomy with mixed outcomes. We tested the effectiveness of low-dose ketamine for acute and chronic postoperative pain after laparoscopic cholecystectomy in a randomized controlled experiment. The study involved 50 individuals who had a laparoscopic cholecystectomy under general anesthesia. All the patients were separated into two equal groups. The ketamine and control groups were given 0.5 mg/kg ketamine and 2 mL of normal saline, respectively, at 15 minutes before incision. Patients in the ketamine group had a significantly lower numeric pain rating scale score at 0 minutes than those in the control group. The numeric pain rating scale score of the ketamine group was considerably greater than the control group after a half-hour interval. At other time periods, there was no significant difference in numeric pain rating scale scores between the two groups. The ketamine group had a greater duration of analgesia and sedation score than the control group. The cumulative tramadol demand at 24 hours and the incidence of chronic pain did not differ significantly across the groups. Substantial analgesic effect of intravenous ketamine lasted only up to 30 min postoperatively. There was no discernible effect in terms of chronic pain prevention.
Keywords: N-methyl-D-aspartate receptor; acute pain; analgesia; cholecystectomy; chronic pain; ketamine; laparoscopic; numeric pain rating scale; postoperative pain; pre-emptive analgesia.