Infusion vs. Bolus: Phenylephrine for Cesarean Delivery

Systemic hypotension is a frequently encountered effect of spinal anesthesia in parturients undergoing cesarean delivery. It may be particularly hazardous if it leads to uterine hypoperfusion and decelerations of fetal heart rate. Vasoactive medications such as phenylephrine are commonly used to counteract the sympatholytic effect of intrathecal local anesthetic. The literature is lacking in regards to the benefits of a prophylactic continuous infusion of phenylephrine versus bolus administration. Garg and colleagues performed a meta-analysis of 15 studies exploring this question which included 2,153 patients. These studies suggest that using intermittent boluses of phenylephrine results in higher rates of hypotension and vomiting but with a lower incidence of reflexive bradycardia and hypertension. There were no differences seen in fetal outcomes. More studies examining the optimal dosage of continuous phenylephrine infusions and outcomes are needed. A visual summary of this article is presented in this infographic, though the reader is strongly encouraged to review the cited article for a more thorough understanding of the illustrated concepts.