Phenylephrine, ondansetron, or combination of both for prevention of intraoperative nausea and vomiting in patients undergoing lower segment cesarean section: A prospective, double-blind randomized control trial

Background: Intraoperative nausea and vomiting (IONV) are common complications in patients undergoing lower segment cesarean section (LSCS) under subarachnoid block. This study aimed to compare the combination of phenylephrine and ondansetron with ondansetron and phenylephrine alone in preventing IONV in patients undergoing LSCS under subarachnoid block. Materials and Methods: This prospective, double-blind, randomized, comparative study included 195 patients posted for elective LSCS under subarachnoid block. They were randomly allocated into three groups of 65 each. Group A received phenylephrine (25 mcg/min) and ondansetron 4 mg, group B received phenylephrine (25 mcg/min), and group C received only ondansetron 4 mg. Primary outcome measured was the incidence of IONV. Secondary outcomes measured were hemodynamic parameters, incidence of intraoperative hypotension, and vasopressor requirement. Categorical data were presented as numbers (proportion) and compared using the Chi-square test. Results: The proportion of subjects who experienced IONV was highest in group C (24.6%) compared with groups A (9.2%) and B (10.7%) (P = 0.025). The mean number of episodes of IONV was significantly lower in patients who received a combination of phenylephrine and ondansetron compared with phenylephrine or ondansetron (0.126 ± 0.42 vs. 0.107 ± 0.312 vs. 0.307 ± 0.58; P = 0.0233). The number of episodes of intraoperative hypotension was significantly high in group C (0.23 ± 0.49) compared with other groups (P = 0.041). Conclusion: Infusion of 25 mcg/min of phenylephrine with 4 mg ondansetron and infusion of 25 mcg/min of phenylephrine alone reduce the incidence of IONV in patients undergoing elective LSCS under subarachnoid block when compared with ondansetron alone.