An Evaluation of the Effectiveness of Preemptive Ketamine for Postoperative Analgesia in Elective Thyroidectomy

Background: The use of preincision low-dose ketamine as a preemptive analgesic modality has been widely suggested. However, findings from previous studies have remained inconclusive. Materials and Methods: Eighty-two patients scheduled to have elective thyroidectomy under general anesthesia were recruited. The patients were randomly allocated into one of two groups, to receive either 0.5 mg/kg of ketamine intravenously or an equal volume of normal saline, 10 min before surgical incision. At the end of surgery, pain scores, time to first request for analgesic and total opioid requirement in 24 h postoperatively were recorded. Results: There was no significant difference in the postoperative pain scores, time to first requirement for analgesic, postoperative opioid consumption and satisfaction with analgesia between the two groups. The median pain scores at recovery, 2, 6, 12, and 24 h postoperatively for the ketamine and saline groups were not significantly different ( P values 0.208, 0.185, 0.412, 0.590, and 0.854 respectively). The times to first request for analgesic were 86.00 ± 56.58 min in the ketamine group and 79.90 ± 68.05 min in the saline group ( P = 0.357). The 24-h opioid (morphine) consumptions were 11.00 ± 3.16 mg in the ketamine group and 13.21 ± 5.87 mg in the control group ( P = 0.275). Conclusion: This study concluded that the administration of preincision low-dose ketamine (0.5 mg/kg) did not produce a preemptive analgesic effect in patients who had an elective thyroidectomy.