The effect of ondansetron in preventing the hypotensive bradycardic events during shoulder arthroscopy done under interscalene block in the sitting position

Abstract Purpose This study was conducted to test whether blocking the serotonin receptors by intravenous [IV] ondansetron; can help in reducing the hypotensive bradycardic events [HB events] associated with shoulder arthroscopy done in the sitting position under interscalene plexus block [ISB]. Methods One hundred and fifty patients, scheduled for shoulder arthroscopy in the sitting position under ISB, were randomly assigned to one of three groups receiving either: 4 mg ondansetron, or 8 mg ondansetron or saline. Results IV injection of ondansetron 4 mg or 8 mg significantly reduced the incidence of HB events from 20.4% in the saline group to 6.1% after injection of 4 mg ondansetron and 6% after injection of 8 mg ondansetron; p value [0.030]. Conclusion IV ondansetron either 4 mg or 8 mg reduces the HB events during shoulder arthroscopy in the sitting position under ISB.