[Effect of ondansetron in lower extremity bone surgery on morphine and tramadol consumption using patient controlled analgesia].

In this study, we aimed to assess the effect of administration of ondansetron on morphine and tramadol consumptions. After approval by the ethics committee, 120 patients with ASA status I or II, who will undergo elective lower extremity surgery, were included in the study. Patients were randomly divided into 4 groups following the anesthesia induction. Group I received tramadol as PCA with an infusion of 0.3 mg/kg following a loading dose of 1.5 mg/kg administered 1 hour before the end of the surgery. Group II received ondansetron 0.1 mg/kg following induction of anesthesia, additionally. Group III received morphine as PCA with an infusion following a loading dose of 0.15 mg/kg administered 30 minutes before the end of surgery. Group IV received ondansetron 0.1 mg/kg following induction of anesthesia, additionally. Pain scores(VAS), nausea, vomitting and sedation scores, analgesic consumptions and adverse effects were recorded at 5th, 15th, 30th, 45th minutes and 4th, 8th, 12th and 24th hours postoperatively. Postoperative VAS, nausea, vomitting and sedation scores were similar among the groups. The analgesic consumption was found significantly higher at 4th, 8th, 12th and 24th hours in group II. No statistically significant difference was found in analgesic consumption between group III and IV at all times. We concluded that, ondansetron, when administered as nausea prophylaxis in patients receiving tramadol and morphine as PCA, did not effect morphine consumption whereas did increased tramadol consumption.