Background: Spinal anesthesia (SA) onset induces maternal hypotension, which can be managed by vasopressors like phenylephrine (PE). However, PE (α-adrenergic agonist) tends to reflexively decrease the heart rate (HR) and cardiac output (CO). Norepinephrine (NE), being an α-agonist with weak β-adrenergic activity, maintains the blood pressure (BP) with less tendency to decrease the HR and CO, and hence, may be a more useful alternative to PE.

Objectives: To compare the effects of prophylactic boluses of NE and PE on SA-induced hypotension during elective cesarean section, as well as assess the neonatal outcomes and adverse reactions.

Methods: Sixty parturient belonging to ASA class I and II, scheduled for elective cesarean section, were randomly allocated between 2 groups: (i) Group NE (n=30) which received 5 µg intravenous (IV) NE, and (ii) Group PE (n=30) which received 50 µg IV PE as prophylactic boluses immediately after patient repositioning. Rescue bolus interventions using 5 µg NE or 25 µg PE were given for hypotension, respectively. Maternal hemodynamic variables were measured non-invasively. Neonatal outcomes and adverse effects, if any, were also noted and compared.

Results: Pre-operative and post-operative hemodynamic parameters (HR, SBP, DBP, MAP, SpO2), adverse incidences (of hypotension, bradycardia, and nausea) as well as neonatal outcomes were comparable between the two groups (P>0.05). However, the number of patients who required additional rescue vasopressor boluses was significantly greater in Group PE than in Group NE (OR for 2 vs 0 bolus = 9.75; OR for 2 vs. 1 bolus = 11.1428).

Conclusion: NE was more efficacious in preventing SA-induced hypotension with better preservation of maternal HR than PE, and hence, can be considered as an alternative to PE.