Background:Spinal anesthesia is the preferred anesthetic technique for cesarean section due to its rapid onset, efficacy, and safety profile. However, it is frequently associated with significant hypotension, with an incidence of up to 70–80% if not prophylactically managed. This maternal hypotension may lead to nausea, vomiting, decreased uteroplacental perfusion, and adverse neonatal outcomes. This study compares the efficacy and safety of bolus doses of norepinephrine and phenylephrine in managing spinal-induced hypotension during cesarean delivery.

Methods:This prospective study was conducted on 100 parturients undergoing elective lower segment cesarean section under spinal anesthesia who developed hypotension. Participants were randomized into two equal groups (n = 50 each): Group NE received 8 µg norepinephrine IV boluses, and Group PE received 100 µg phenylephrine IV boluses for the treatment of hypotension (defined as a drop in systolic BP ≥ 20% from baseline or < 90 mmHg). Hemodynamic parameters (SBP, DBP, MAP, HR) were recorded. Incidence of adverse effects, number of vasopressor boluses, and neonatal outcomes (Apgar scores, umbilical arterial blood gas analysis) were also evaluated.

Results:Both vasopressors effectively restored blood pressure. Group NE had significantly better preservation of heart rate (mean HR at 5 minutes: 78.6 ± 6.2 bpm vs 66.2 ± 5.7 bpm, p < 0.001). MAP at 3 minutes post-bolus was comparable between groups (NE: 93.8 ± 6.1 mmHg vs PE: 92.3 ± 5.9 mmHg, p = 0.24). The incidence of bradycardia was significantly higher in Group PE (28% vs 6%, p = 0.004), and more patients in the PE group required atropine. Fewer rescue vasopressor boluses were needed in Group NE (mean: 1.2 ± 0.7 vs 1.8 ± 0.9, p = 0.002). Neonatal outcomes including Apgar scores at 1 and 5 minutes and umbilical pH were comparable between groups (p > 0.05), indicating no compromise in fetal well-being.

Conclusion:Both norepinephrine and phenylephrine were effective in managing spinal-induced hypotension during cesarean delivery. However, norepinephrine demonstrated a more favorable hemodynamic profile with better preservation of heart rate, fewer incidences of bradycardia, and reduced need for rescue boluses, without affecting neonatal outcomes. Norepinephrine may be considered a safer and more physiologically balanced alternative to phenylephrine in this setting.