Comparative Study of Norepinephrine and Ephedrine for Prophylaxis against Hypotension during Spinal Anesthesia for Cesarean Section

Abstract

S pinal anesthesia is the preferred method for elective cesarean sections due to considerable risks regarding airway management associated with physiological changes of pregnancy. Hypotension is reported to occur in up to 80% of spinal anesthesia cases, it can lead to serious maternal complications as well as impairment of the uterine and placental blood flow. Many approaches have been investigated to prevent spinal hypotension, e.g., fluid loading, vasopressors, or both. Lately, investigators have turned their attention to vasopressor protocols to prevent spinal hypotension. Conventionally, ephedrine was regarded as the first-choice drug to maintain maternal blood pressure. Its sympathomimetic stimulant activity on α- and β-adrenergic receptors causes positive inotropic and chronotropic effects on the heart and maintains uterine blood flow. However, repeated administration of ephedrine diminishes its vasoconstrictive effect, and its slow onset of action and relatively long duration make accurate titration of blood pressure difficult. Norepinephrine is a weak β-adrenergic and potent α-adrenergic receptor agonist. Therefore, it may be a more suitable option for maintaining maternal blood pressure with less negative effects on heart rate (HR) and cardiac output.