Prophylactic Ondansetron and Maternal Hemodynamics During Spinal Anesthesia for Elective Cesarean Section

Spinal anesthesia is the preferred technique for elective cesarean section, but it is frequently complicated by maternal hypotension and bradycardia. Activation of serotonin type 3 (5-hydroxytryptamine type 3; 5-HT3) receptors on cardiac vagal afferent nerves has been proposed as one mechanism of the Bezold-Jarisch reflex, which may contribute to sudden bradycardia and vasodilation after spinal anesthesia. Ondansetron is a selective 5-HT3 receptor antagonist. This randomized, double-blind, placebo-controlled trial evaluated whether a single intravenous (IV) dose of ondansetron 4 mg given 5 minutes before spinal anesthesia reduces maternal hypotension, bradycardia and the need for rescue medications (ephedrine and atropine) in women undergoing elective cesarean section. Hemodynamic variables and the pulse oximetry-derived perfusion index (PI) and pleth variability index (PVI) were recorded at predefined time points, including during a passive leg raising (PLR) maneuver before spinal anesthesia.