Comparison of prophylactic phenylephrine versus noradrenaline boluses for hemodynamic stability during elective cesarean delivery under spinal anesthesia-an observational study

Background: Profound hypotension and bradycardia following spinal anesthesia (SA) during cesarean delivery (CD) result in catastrophic maternal and fetal consequences. Phenylephrine with its appealing α agonist property proved to be a valid vasopressor for correction of hypotension during SA but with side effects like reflex bradycardia and fall in cardiac output. Noradrenaline is a rational substitute to phenylephrine due to its mild β and prominent α adrenergic properties, but is reserved as an inotrope mainly for medical crisis management. We conducted a comparative observational study of noradrenaline with phenylephrine using bolus doses for preventing hypotension and fetal outcome during CD under SA. Methodology: Hemodynamic changes and fetal outcomes were studied in 102 pregnant patients undergoing cesarean section out of which 51 patients received a prophylactic bolus dose of phenylephrine100 μg and the rest received Noradrenaline 8 μg immediately after SA and the same bolus dose was repeated to maintain SBP ≥ 90% of the baseline. In this study, we compared the maternal hemodynamic variables, Apgar score, and maternal complications. Results: Mean heart rate (90.1 vs. 87.3), mean Systolic blood pressure (119.6 vs. 109.2), mean arterial pressures (89.5 vs. 78.6) and mean diastolic pressures (74.6 vs. 67.3) in the noradrenaline group were significantly higher only at one minute of SA (P < 0.05), but later part the differences become statistically not significant (P > 0.05). Maternal complications such as bradycardia, hypotension, nausea, vomiting and the fetal outcomes were comparable between the groups. Conclusion: Prophylactic Noradrenaline is equally effective as prophylactic phenylephrine in preventing spinal hypotension with better hemodynamic stability.