Comparison of Phenylephrine and Norepinephrine for Spinal-induced Hypotension

Hypotension after spinal anaesthesia for cesarean deliveries is frequently encountered. Phenylephrine an α-agonist is commonly used for the prevention and treatment of spinal-induced hypotension. Phenylephrine causes baroreceptor-mediated bradycardia leading to subsequent reduction in cardiac output. Preservation of heart rate and cardiac output is important in high-risk conditions such as placental insufficiency, fetal distress and maternal cardiac disease. Recently, norepinephrine has been found as effective as phenylephrine in treatment of spinal induced hypotension. When norepinephrine is used as a bolus, it is effective at maintaining blood pressure while also conferring a greater heart rate and cardiac output compared to phenylephrine.