Comparative Study of the Effect of Midazolam, Ondansetron and their Combination in Prevention of Nausea and Vomiting after Strabismus Surgery: A Randomized Double-Blind Clinical Trial

Background and purpose: Postoperative nausea and vomiting is a common complication of anesthesia. The aim of this study was to compare the effect of midazolam, ondansetron and their combination in prevention of nausea and vomiting after strabismus surgery. Materials and methods: In this randomized double-blind clinical trial, 140 patients undergoing strabismus surgery were divided into four groups (n=35 per group). The patients received midazolam 0.75 mg/kg (M), ondansetron 4 mg (O), midazolam 0.75 mg/kg + ondansetron 4 mg (MO), and saline 0.9% iv. (S) before anesthesia. Follow-up was done in the first 24 hours after surgery and incidence and severity of nausea and vomiting and other postoperative complications were compared between the four groups. Results: In this study, 10 patients (37%) in group S, 6 (19.4%) in group O, 8 (28.6%) in group M, and 2 (6.3%) in group MO developed nausea indicating significant differences between the four groups (P=0.019). The study showed no significant differences between the groups in incidence of vomiting (P= 0.18); 6 patients (22.2%) in group S, 5 (16.1%) in group O, 4 (14.3%) in group M, and 1 patient (3.1%) in group MO had vomiting. The severity of postoperative nausea and vomiting was significantly different between the four groups and group MO was found to have less severe nausea and vomiting two hours (P= 0.009) and 24 hours after surgery (P< 0.001). Conclusion: Combination of midazolam and ondansetron reduces the incidence of postoperative nausea and vomiting compared to midazolam or ondansetron alone and leads to greater patient satisfaction. According to the higher effect of MO and lack of adverse effects on hemodynamic parameters it is recommended in patients undergoing strabismus surgery. (Clinical Trials Registry Number: IRCT20180416039326N8)