A comparative study of prophylactic intravenous granisetron, ondansetron, and ephedrine in attenuating hypotension and its effect on motor and sensory block in elective cesarean section under spinal anesthesia

Context Although spinal anesthesia avoids the risks involved in managing the airway of the parturient, an undesired side effect often seen is hypotension. Prophylactic intravenous (i.v.) administration of vasopressors such as ephedrine or of serotonin receptor antagonists such as granisetron and ondansetron has been used to overcome this problem. Aims The aim of the study was to compare granisetron and ondansetron with the traditionally used vasopressor ‘ephedrine’ in reducing hypotension following spinal anesthesia and their effect on sensory and motor blockade in parturients undergoing cesarean section. Settings and design This study was designed as a randomized, prospective, double-blind, placebo-controlled trial. Materials and methods Eighty parturients of ASA I or II grade, aged 2040 years, scheduled for elective cesarean section were randomly allocated into four equal groups (G, O, E, and C). ‘Group G’ received 1 mg i.v. granisetron, ‘group O’ received 4 mg i.v. ondansetron, ‘group E’ received 10 mg i.v. ephedrine, and ‘group C’ received 10 ml normal saline. All of the studied drugs were diluted in 10 ml normal saline and administered over a period of 1–5 min before induction of spinal anesthesia. Mean arterial blood pressure, heart rate, sensory and motor blockade, nausea, shivering, bradycardia and vasopressor need were assessed. Results The reduction in mean arterial pressure was significantly lower in the therapeutic groups, with the best results recorded in the O group and nearly comparable results in G and E groups. Heart rate was statistically different only at 10 and 15 min. No significant difference was seen in motor block or in the incidence of bradycardia. Significantly faster recovery of sensation was detected in the G group. Groups G, O, and E had significantly less vasopressor need and lower incidence of nausea. Conclusion In the cesarean section, prophylactic use of i.v. granisetron, ondansetron, or ephedrine reduced the severity of spinal-induced hypotension, nausea, and vasopressor need, but faster recovery of sensory block was noticed with granisetron.