Background: The aim of preemptive analgesia is to reduce central sensitization that arises from noxious inputs across the entire perioperative period. N-methyl d-aspartate receptor antagonists have the potential for attenuating central sensitization and preventing central neuroplasticity.
Materials and methods: Patients undergoing laparoscopic cholecystectomy were randomized into four groups of 20 patients each, who were administered the study drug intravenously 30 min before incision. Groups A, B, and C received ketamine in a dose of 1.00, 0.75 and 0.50 mg/kg, respectively, whereas group D received isotonic saline. Anesthetic and surgical techniques were standardized. Postoperatively, the degree of pain at rest, movement, and deep breathing using visual analogue scale, time of request for first analgesic, total opioid consumption, and postoperative nausea and vomiting were recorded in postanesthesia care unit for 24 h.
Results: Pain scores were highest in Group D at 0 h. Groups A, B, and C had significantly decreased postoperative pain scores at 0, 0.5, 3, 4, 5, 6, and 12 h. Postoperative analgesic consumption was significantly less in groups A, B, and C as compared with group D. There was no significant difference in the pain scores among groups A, B, and C. Group A had a significantly higher heart rate and blood pressure than groups B and C at 0 and 0.5 h along with 10% incidence of hallucinations.
Conclusion: Preemptive ketamine has a definitive role in reducing postoperative pain and analgesic requirement in patients undergoing laparoscopic cholecystectomy. The lower dose of 0.5 mg/kg being devoid of any adverse effects and hemodynamic changes is an optimal dose for preemptive analgesia in patients undergoing laparoscopic cholecystectomy.
Keywords: Ketamine; pain relief laparoscopic cholecystectomy; preemptive analgesia.