The effects of ondansetron and metoclopramide used for postoperative nousea and vomiting prophylaxis on the QT interval

Abstract

The aim of this study is to compare the effects of ondansetron and metoclopramide on the QT interval. 100 patients between 18-65 age and with ASA physical status I-II were enrolled in this study. General Anesthesia was induced with 2-3 mg/kg propofol, 1 ?g/kg remifentanil and O,1 mg/kg vecuronium. Anesthesia was maintained with 4% inspired desflurane (in an air - oxygen mixture). The patients randomly divided into three groups. After intubation, the patients received one of the three study medications. The study medication consisted of either saline (Group-K) or 4 mg ondansetron (Group-O) or 10 mg metoclopramide. Hemodinamic parameters, oxygen saturation and body temperature values were recorded before induction, after intubation and during the surgery after delivering of the study drugs. Synhcronous ECG samples were recorded too. The QT intervals were measured and corrected for heart rate (QTc) according to the formula of Bazett. The three study groups were similar with respect to their demographic characteristics, the type of surgery, hemodinamic parameters and body temperature. Basal QTc values were also similar in the groups. After intubation QTc prolongation values were 13.2±11 (Group-K), 20.4±8 (Group-O), 19.0+10 (Group-M) ms in groups respectively. After administration the study drugs at intraoperative and postoperative all measurement times, the QT interval was found more prolonged in ondansetron group then the other two groups. In the control group at 30. min, and in the metoclopramide group at 15. min the QTc values were the same as the values measured before induction. In the ondansetron group all the values measured intraoperatively were higher when compared with the baseline values. Although it is reported that metoclopramide prolongs the QT interval in healthy volunteers, there is no study which investigates this effect during surgery. In the patient received ondansetron the QTc values are longer and this prolongation lasted more than in the patient received metoclopramide. These results suggest that, instead of using ondansetron, using metoclopramide for the PONV prophilaxis would be safer on the high risk patients whose QT interval is long.