Does prophylactic ondansetron reduce norepinephrine consumption in patients undergoing cesarean section with spinal anesthesia?

PURPOSE: Spinal anesthesia-induced hypotension (SAIH) during cesarean delivery is not rare and frequently leads to materno-fetal discrepancy and collapse. More recently, norepinephrine has been proposed for the prevention and treatment of SAIH with fewer tendencies to decrease heart rate and cardiac output. Ondansetron has been reported to reduce the incidence of SAIH in patients undergoing cesarean section. The aim of the present study was to assess the effect of prophylactic ondansetron on the incidence of SAIH, norepinephrine consumption, and adverse effects.

METHODS: We recruited 108 parturients with uncomplicated pregnancies undergoing elective cesarean delivery under spinal anesthesia. The parturients were divided into two groups randomly. The first group (n = 54) received 8 mg ondansetron IV (group O) and the second group (n = 54) received the same volume (4 ml) of saline (group S), 5 min before spinal anesthesia. The incidence of hypotension, cumulative episodes of hypotension, total norepinephrine consumption, and adverse effects were recorded.

RESULTS: There was no significant difference between the two groups in demographic data, parturient characteristics, and duration of surgery. No significant difference was found in the incidence of hypotension in the saline and ondansetron groups (p = 0.767). However, the cumulative episodes of hypotension and norepinephrine consumptions were significantly greater in group S than in group O (p = 0.009) (p = 0.009). There was also no significant difference in the incidence of adverse effects between the two groups.

CONCLUSION: Eight milligrams of intravenous ondansetron given 5 min before spinal anesthesia attenuated but did not prevent spinal anesthesia-induced hypotension in parturients undergoing elective cesarean delivery.