Effect of intravenous ondansetron on reducing the incidence of hypotension and bradycardia events during shoulder arthroscopy in sitting position under interscalene brachial plexus block: A prospective randomized trial

BACKGROUND AND AIMS: Sudden, profound hypotension and bradycardia events (HBEs) have been reported in more than 20% of patients undergoing shoulder arthroscopy in the sitting position. The present study was designed to know whether intravenous (IV) ondansetron (selective 5-hydroxy tryptamine 3-antagonist) can help in reducing the HBEs associated with shoulder arthroscopy performed in sitting position under interscalene brachial plexus block (ISBPB). METHODS: A total of 100 patients (age 20–50 years) undergoing shoulder arthroscopy performed in the sitting position under ISBPB were assigned randomly to one of the two groups: Group C received 10 ml of normal saline and Group T received 4 mg of ondansetron diluted in 10 ml of normal saline` IV. All patients received ISBPB using levobupivacaine 0.5%. Assessment of motor and sensory blockade, pulse rate, systolic blood pressure, respiration, and side effects were noted every 5 min for first 30 min and every 10 min till the end of surgery. HBEs were recorded in both groups. RESULTS: IV injection of ondansetron significantly reduces the incidence of HBEs from 11 (22.44% in Group C) to 3 (6.1% in Group T). The duration of analgesia was significantly longer in Group C (8.1 ± 3.3) in comparison with Group T (6.3 ± 4.2 h). CONCLUSION: We conclude that 4 ml of IV ondansetron can significantly reduce the HBEs during shoulder arthroscopy done in the sitting position under ISBPB.