摘要：Complications such as hypotension and bradycardia may occur during spinal anesthesia for cesarean section. The aim of this study was to determine the effect of Ondansetron on preventing hypotension following spinal anesthesia in pregnant women candidate for elective cesarean delivery. This double blind clinical trial was done on 151 pregnant women with ASA I-II who were randomly divided into two groups. The group O received 4 mg diluted Ondansetron and the group N received placebo before implication of spinal anesthesia with 0.5% hyperbaric bupivacaine. Hemodynamic variables, O2 saturation, nausea, the vomiting episodes, and antiemetic dosage were recorded after spinal anesthesia. Data was analyzed using SPSSv16 and a P< 0.05 was assumed significant. Demographic variables were similar in two groups but mean weight was higher in group O. Mean systolic blood pressure (SBP) was similar in two groups except that group N patients had higher SBP in the 2nd minute after spinal anesthesia. Mean diastolic BP (DBP) and mean arterial pressure (MAP) were lower in group N in 6, 8, 30 and 35 minutes. There was no significant difference in Mean heart rate and O2 saturation, nausea, vomiting and chills between two groups. The 1st minute Apgar score was lower in group O. The attenuating effect of spinal anesthesia on DPB and MAP is significantly decreased by Ondansetron prophylaxy during cesarean section but has no significant effect on SBP, heart rate, chills and nausea, but it can mildly decrease the incidence of vomiting after cesarean section
