Effect of Ondansetron on Blood Pressure during Elective Cesarean Section under Spinal Anesthesia at Baghdad Teaching Hospital

Background: Hypotension is a very common consequence of the sympathetic vasomotor block caused by spinal anesthesia for caesarean section. Maternal symptoms such as nausea, vomiting and dyspnea frequently accompany severe hypotension, and adverse effects on the fetus, including depressed Apgar scores and umbilical acidosis, have been correlated with severity and duration of hypotension. Aim: To investigate the effect of Ondansetron use on the prevention of hypotension and the amount of vasopressor needed to control the hypotension after spinal anesthesia. Methods: This is a prospective double blind, randomized trial carried out in Obstetric Operation room of Baghdad Teaching Hospital, Medical city, Iraq from November, 2018 to August, 2019. Total number of 128 women assessed for eligibility and only 87 were included and allocated into 2 groups. The Ondansetron group (45 women) received 6 mg Ondansetron IV e min before induction of spinal anesthesia. The Placebo group received 3 ml normal saline as placebo before induction. The number of rescue drugs (vasopressors, antiemetic, anti-shivering), vital signs and side effects were recorded each 3 minutes from baseline to 45th minute. Results: The incidence of hypotension, nausea, vomiting and the need for vasopressors and metoclopramide were significantly lower in Ondansetron group than placebo group (p = 0.001, 0.02, 0.003, < 0.001, and 0.001, respectively). Shivering and the need of pethidine for treating this side effect was non significantly lower in ondansetron group than placebo group. Conclusions: The preoperative administration of Ondansetron in cesarean section reduces the risk of spinal anesthesia-induced hypotension, prevents the nausea and vomiting attacks and decreases the need to vasopressors and metoclopramide.