Society for Obstetric Anesthesia and Perinatology Section Editor: Cynthia A. Wong REVIEW ARTICLE A Review of the Impact of Phenylephrine Administration on Maternal Hemodynamics and Maternal and Neonatal Outcomes in Women Undergoing Cesarean Delivery Under Spinal Anesthesia Ashraf S. Habib, MBBCh, MSc, MHS, FRCA Phenylephrine is effective for the management of spinal anesthesia-induced hypotension in parturients undergoing cesarean delivery under spinal anesthesia. While ephedrine was previously considered the vasopressor of choice in obstetric patients, phenylephrine is increasingly being used. This is largely due to studies suggesting improved fetal acid-base status with the use of phenylephrine as well as the low incidence of hypotension and its related side effects with prophylactic phenylephrine regimens. This review highlights the effects of phenylephrine compared with ephedrine on maternal hemodynamics (arterial blood pressure, heart rate, and cardiac output), and occurrence of intraoperative nausea and vomiting. The impact of the administration of phenylephrine as a bolus for the treatment of established hypotension compared with its administration as a prophylactic infusion is discussed. This article also reviews the impact of phenylephrine compared with ephedrine on uteroplacental perfusion, and fetal outcomes such as neonatal acid-base status and Apgar scores. The optimum dosing regimen for phenylephrine administration is also discussed. (Anesth Analg 2012;114:377–90) S pinal anesthesia is commonly used for cesarean de- livery because it avoids the risks of general anesthesia related to difficult intubation and aspiration of gastric contents. It is frequently associated with hypotension, which can have detrimental effects on the mother and neonate, including nausea, vomiting, and dizziness in the mother, as well as decreased uteroplacental bloodflow resulting in impaired fetal oxygenation and fetal acidosis. Whether the mode of anesthesia affects neonatal outcomes is controversial. A meta-analysis reported that umbilical artery pH may be lower with spinal anesthesia than with general or epidural anesthesia. 1 A large retrospective study also suggested an association between type of anesthesia and neonatal mortality of very preterm infants, with spinal anes- thesia being associated with an increased risk of neonatal mortality compared with general or epidural anesthesia. 2 On the basis of better preservation of uteroplacental circulation in animal models, ephedrine was historically considered the “gold standard” vasopressor for the man- agement of spinal anesthesia-induced hypotension. 3,4 However, studies over the last 2 decades have suggested that fetal acid-base status might be improved if phenyleph- rine or other -adrenergic agonists are used during cesar- ean delivery instead of ephedrine. 5 Consequently, the use of phenylephrine for arterial blood pressure management during cesarean delivery under spinal anesthesia has in- creased. In 2001, a United Kingdom survey of the Obstetric Anesthetists Association consultant members found that 95% of respondents used ephedrine as the first-choice vasopressor, 6 whereas in 2006, 51% indicated that phenyl- ephrine is their first-line vasopressor. a In 2007 a survey of the members of the Society of Obstetric Anesthesia and Perinatology reported that 32% used ephedrine for treating spinal-induced hypotension, 23% used phenylephrine, and 41% used either drug on the basis of heart rate. 7 However, there is still significant variation in practice regarding the choice, dosing, and method of administration of vasopres- sors during cesarean delivery. 7 This article will review the impact of phenylephrine administration on maternal hemo- dynamics, intraoperative nausea and vomiting (IONV), and neonatal outcomes including Apgar scores and acid- base status. The optimum dose and method of administra- tion of phenylephrine will also be discussed. From the Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina. Accepted for publication September 7, 2011. Funding: Departmental. The author declares no conflict of interest. Reprints will not be available from the author. Address correspondence to Ashraf S. Habib, MBBCh, MSc, MHS, FRCA, Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, NC 27710. Address e-mail to habib001@mc.duke.edu. Copyright © 2012 International Anesthesia Research Society DOI: 10.1213/ANE.0b013e3182373a3e a McGlennan A, Patel N, Sujith B, Bell R. A survey of pre-loading and vasopressor use during regional anaesthesia for caesarean section. Int J Obstet Anesth 2007;16:S27. February 2012 • Volume 114 • Number 2 www.anesthesia-analgesia.org 377