The effect of low-dose naloxone on analgesia of tramadol

Objective To explore the effect of low-dose naloxone on analgesia of tramadol.Methods Eighty patients undergoing general anesthesia for elective total abdominal hysterectomy were randomly divided into four groups.All patients received 2mg/kg tramadol 30 minutes before the end of surgery,followed by a continuous infusion with 20mg/kg tramadol with no naloxone(groupⅠn=20),2.4μg/kg naloxone(groupⅡn=20),4.8μg/kg naloxone(group Ⅲ n=20),9.6μg/kg(group Ⅳ n=20),diluted to 100ml.Pain assessments were recorded one hour after starting the PCIA and then at 6、12 and 24 hours by using visual analogue scale(VAS).Nausea Vomiting score,sedation score and side effect were also recorded.Results Seventy-five patients were included in this study.The intravenous tramadol administration provided the satisfied analgesia.There was no significant difference in VAS scores among naloxone groups and control group,compared with control group,sedation was less in group Ⅱ Ⅲ and Ⅳ at 6,12 and 24 hours,P0.05.The incidence of nausea vomiting in the naloxone group was lower than control group,P0.05.Conclusion A small-dose naloxone infusion could reduce tramadol induced side effects without reversing its analgesia effects.