A Review of Phenylephrine Versus Norepinephrine for the Treatmemnt of Maternal Hypotension During Spinal Anesthesia for Cesarean Delivery

Maternal hypotension is a common sequala of spinal anesthesia used during cesarean delivery. The current first line vasopressor used for treatment of maternal hypotension is phenylephrine. Administration of phenylephrine can cause a physiologic decrease in cardiac output that could contribute to adverse maternal or fetal outcomes. This systematic review was conducted to investigate the use of norepinephrine as an alternative vasopressor for the treatment of maternal hypotension. A database search was conducted using electronic sources including CINAHL, MEDLINE, Google Scholar and PubMed. Inclusion and exclusion criteria were used to narrow search results and the Critical Appraisal Skills Program checklist was applied to critically appraise selected randomized control trials. Five articles were selected to be included in this review. Key outcomes were compared between studies and included incidence of maternal hypotension, maternal cardiac output effects, incidence of bradycardia, incidence of intraoperative nausea and vomiting, and fetal effects on Apgar score and umbilical cord gases. Overall, norepinephrine was found to be of similar effectiveness to phenylephrine for the treatment of maternal hypotension. When compared to phenylephrine, norepinephrine was found to maintain maternal heart rate better, and had a lower incidence of maternal bradycardia. No difference was found between intervention groups in fetal Apgar scores and differences in fetal cord gases were varied between studies. This systematic review found that norepinephrine has similar efficacy to phenylephrine in ability to manage maternal hypotension with lower prevalence of bradycardia. Further research is needed into the overall safety of norepinephrine before routine clinical utilization.