Efficacy Of Prophylactic Intravenous Ondansetron On The Prevention Of Hypotension During Cesarean Delivery: A Dose-Dependent Study

Objective: This study was to determine the optimal dosage of ondansetron for preventing maternal hypotension during cesarean delivery. Methods: One hundred and fifty parturient women scheduled for elective cesarean section were randomly assigned to five groups (n= 30). Five minutes prior to spinal anesthesia, women were injected with 5 ml of physiological saline (S), 2 mg (O2), 4 mg (O4), 6 mg (O6), or 8 mg (O8) of ondansetron in saline, respectively. Maternal blood pressure and heart rate were measured at 2-min intervals for 30 min. The serum parameters in umbilical cord blood were analyzed after delivery. Results: Compared with group S, the incidence of maternal hypotension was significantly lower in groups O4 and O6 (P < 0.05). The umbilical venous pH was significantly higher in group O4 (P < 0.05); while the partial pressure of carbon dioxide (Pco(2)) was significantly lower in groups O4, O6, and O8 (P < 0.05); and the bicarbonate (Hco(3)(-)) and base excess in extracellular fluid (BEecf) were significantly lower in groups O6 and O8 (P < 0.05). Moreover, minimal changes of systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were observed in group O4 (P < 0.05). Conclusion: The optimal dose of ondansetron preloading was 4 mg during cesarean delivery.