Inhibiting effect of ondansetron on nausea and vomiting caused by tramadol, a intravenous analgesic

Objective To observe the effect of ondansetron on nausea and vomiting, and explore the coadministration of ondansetron and tramadol in patients during controlled intravenous analgesia.Methods In this study, 180 patients who underwent abdominal hysterectomy, aged 22~56 years, ASA Ⅰ Ⅱ, undergoing epidural anesthesia with 2% lidocaine, were randomly allocated to group Ⅰ (tramadol 600 mg, fentanyl 0.3 mg, droperidol 5 mg and normal saline diluted to 60 ml, n =60), group Ⅱ (tramadol 600 mg, fentanyl 0.3 mg, ondansetron 4 mg and normal saline diluted to 60 ml, n =60) and group Ⅲ(tramadol 600 mg, fentanyl 0.3 mg, and normal saline diluted to 60 ml; ondansetron 4 mg was injected before PCA pump was used; n =60) and received postoperative analgesia. The Loading dose was 3~5 ml, background infusion 0.7~1 ml/h, bolus 1 ml, and lockout time 10~15 min. The analgesia effects, postoperative nausea and vomiting degree, and patients' satisfaction degree were evaluated in all groups during 48 h postoperatively. Results The analgesia effects were similar in 3 groups. The incidence of nausea and vomiting was low and there was no significant difference in 3 groups. There was no significant difference in terms of the overall satisfaction degree of pain relief, sedation and vomiting. Conclusion Ondansetron can reduce nausea and vomiting caused by tramadol for intravenous analgesia, but it is inadvisable to use the two drugs as a mixture.