Ketamine does not decrease postoperative pain after remifentanil‐based anaesthesia for tonsillectomy in adults

Background:  There are conflicting results concerning the pre-emptive effect of ketamine on central sensitization following surgery. The aim of this prospective, randomized, double-blind, placebo-controlled study was to assess the effect of the N-methyl-D-aspartate receptor antagonist ketamine on postoperative morphine consumption and pain score after remifentanil-based anaesthesia in adult patients scheduled for tonsillectomy. Methods:  We studied 40 adult patients undergoing elective tonsillectomy. Total intravenous anaesthesia was induced and maintained with remifentanil (0.125–1.0 µg kg−1 min−1) and propofol target-controlled infusion. Patients in group K received a bolus dose of ketamine 0.5 mg kg−1 immediately after anaesthetic induction, followed by a continuous infusion of 2 µg kg−1 min−1. Saline was administered in the same sequence in group S. Propofol, remifentanil, and the study drug infusions were discontinued at the end of surgery. Results:  Intraoperative remifentanil consumption (0.57 ± 0.18 in group K vs. 0.55 ± 0.14 µg kg−1 min−1 in group S), morphine requirement in the PACU (11 ± 3 in group K vs. 9 ± 4 mg in group S) and in the ward (22 ± 11 in group K vs. 25 ± 14 mg in group S), median time to first analgesia in the ward (338 ± 126 in group K vs. 328 ± 144 min in group S), and VAS pain scores were comparable in both groups. Conclusion:  Small-dose of ketamine does not seem to be a useful adjunct to remifentanil-based anaesthesia during short, painful surgical procedures.