The effect of different doses of naloxone on postoperative hyperalgesia in patients who received high-dose remifentanil during hysterectomy procedures; a double-blind randomized clinical trial

Background: Hyperalgesia is one of the adverse effects of remifentanil, an opioid drug used for reducing pain in surgical procedures. Naloxone is used for reversing the adverse effects of opioids and can reduce this acute and persistent pain after surgery. In the present study, we aimed to investigate the effect of two doses of naloxone (high and low doses) for reducing hyperalgesia after hysterectomy. Methods: In this single-blinded randomized clinical trial, 72 patients who underwent hysterectomy with ASA class I and II were randomly divided into three groups of 24 participants. All three groups received an intraoperative infusion of 0.4 micrograms/kg/min of remifentanil. One group received 0.02 mu g/kg/min naloxone, the other group received 0.05 mu g/kg/min naloxone, and the third group received 0.2 cc/kg normal saline instead of naloxone. The results of the visual analogue scale, Ramsay score, and pressure algometry were completed for all participants half an hour before the surgery, one hour, two, and eight hours after the surgery, pethidine requirement, and postoperative nausea/vomiting and the Ramsay score were recorded. Comparison of variables among the groups was performed using one-way ANOVA and posthoc tests by SPSS software, version 21. Results: The mean age of the participants was 48.63 +/- 9.85 years. The pressure algometry of the right and left forearms and abdomen was different among the three groups after surgery (P<0.05). There was no difference in mean pethidine requirement at recovery and in general, visual analogue scale score, Ramsay score 1 hour and 8 h after the surgery, and the frequency of postoperative nausea and vomiting among the three groups (P>0.05). Conclusion: The similar efficacy and adverse effects of the two doses indicate that the low dose of naloxone is suggested for reducing remifentanil-induced hyperalgesia after hysterectomy.