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Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery.
Anesthesiology. 2009 Sep; 111(3):506-12.A

Abstract

BACKGROUND

Use of ephedrine in obstetric patients is associated with depression of fetal acid-base status. The authors hypothesized that the mechanism underlying this is transfer of ephedrine across the placenta and stimulation of metabolism in the fetus.

METHODS

A total of 104 women having elective Cesarean delivery under spinal anesthesia randomly received infusion of phenylephrine (100 microg/ml) or ephedrine (8 mg/ml) titrated to maintain systolic blood pressure near baseline. At delivery, maternal arterial, umbilical arterial, and umbilical venous blood samples were taken for measurement of blood gases and plasma concentrations of phenylephrine, ephedrine, lactate, glucose, epinephrine, and norepinephrine.

RESULTS

In the ephedrine group, umbilical arterial and umbilical venous pH and base excess were lower, whereas umbilical arterial and umbilical venous plasma concentrations of lactate, glucose, epinephrine, and norepinephrine were greater. Umbilical arterial Pco2 and umbilical venous Po2 were greater in the ephedrine group. Placental transfer was greater for ephedrine (median umbilical venous/maternal arterial plasma concentration ratio 1.13 vs. 0.17). The umbilical arterial/umbilical venous plasma concentration ratio was greater for ephedrine (median 0.83 vs. 0.71).

CONCLUSIONS

Ephedrine crosses the placenta to a greater extent and undergoes less early metabolism and/or redistribution in the fetus compared with phenylephrine. The associated increased fetal concentrations of lactate, glucose, and catecholamines support the hypothesis that depression of fetal pH and base excess with ephedrine is related to metabolic effects secondary to stimulation of fetal beta-adrenergic receptors. Despite historical evidence suggesting uteroplacental blood flow may be better maintained with ephedrine, the overall effect of the vasopressors on fetal oxygen supply and demand balance may favor phenylephrine.

Authors+Show Affiliations

Department of Anaesthesia and Intensive Care, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong, China. warwick@cuhk.edu.hkNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19672175

Citation

Ngan Kee, Warwick D., et al. "Placental Transfer and Fetal Metabolic Effects of Phenylephrine and Ephedrine During Spinal Anesthesia for Cesarean Delivery." Anesthesiology, vol. 111, no. 3, 2009, pp. 506-12.
Ngan Kee WD, Khaw KS, Tan PE, et al. Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery. Anesthesiology. 2009;111(3):506-12.
Ngan Kee, W. D., Khaw, K. S., Tan, P. E., Ng, F. F., & Karmakar, M. K. (2009). Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery. Anesthesiology, 111(3), 506-12. https://doi.org/10.1097/ALN.0b013e3181b160a3
Ngan Kee WD, et al. Placental Transfer and Fetal Metabolic Effects of Phenylephrine and Ephedrine During Spinal Anesthesia for Cesarean Delivery. Anesthesiology. 2009;111(3):506-12. PubMed PMID: 19672175.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Placental transfer and fetal metabolic effects of phenylephrine and ephedrine during spinal anesthesia for cesarean delivery. AU - Ngan Kee,Warwick D, AU - Khaw,Kim S, AU - Tan,Perpetua E, AU - Ng,Floria F, AU - Karmakar,Manoj K, PY - 2009/8/13/entrez PY - 2009/8/13/pubmed PY - 2009/9/18/medline SP - 506 EP - 12 JF - Anesthesiology JO - Anesthesiology VL - 111 IS - 3 N2 - BACKGROUND: Use of ephedrine in obstetric patients is associated with depression of fetal acid-base status. The authors hypothesized that the mechanism underlying this is transfer of ephedrine across the placenta and stimulation of metabolism in the fetus. METHODS: A total of 104 women having elective Cesarean delivery under spinal anesthesia randomly received infusion of phenylephrine (100 microg/ml) or ephedrine (8 mg/ml) titrated to maintain systolic blood pressure near baseline. At delivery, maternal arterial, umbilical arterial, and umbilical venous blood samples were taken for measurement of blood gases and plasma concentrations of phenylephrine, ephedrine, lactate, glucose, epinephrine, and norepinephrine. RESULTS: In the ephedrine group, umbilical arterial and umbilical venous pH and base excess were lower, whereas umbilical arterial and umbilical venous plasma concentrations of lactate, glucose, epinephrine, and norepinephrine were greater. Umbilical arterial Pco2 and umbilical venous Po2 were greater in the ephedrine group. Placental transfer was greater for ephedrine (median umbilical venous/maternal arterial plasma concentration ratio 1.13 vs. 0.17). The umbilical arterial/umbilical venous plasma concentration ratio was greater for ephedrine (median 0.83 vs. 0.71). CONCLUSIONS: Ephedrine crosses the placenta to a greater extent and undergoes less early metabolism and/or redistribution in the fetus compared with phenylephrine. The associated increased fetal concentrations of lactate, glucose, and catecholamines support the hypothesis that depression of fetal pH and base excess with ephedrine is related to metabolic effects secondary to stimulation of fetal beta-adrenergic receptors. Despite historical evidence suggesting uteroplacental blood flow may be better maintained with ephedrine, the overall effect of the vasopressors on fetal oxygen supply and demand balance may favor phenylephrine. SN - 1528-1175 UR - https://www.unboundmedicine.com/medline/citation/19672175/Placental_transfer_and_fetal_metabolic_effects_of_phenylephrine_and_ephedrine_during_spinal_anesthesia_for_cesarean_delivery_ L2 - https://pubs.asahq.org/anesthesiology/article-lookup/doi/10.1097/ALN.0b013e3181b160a3 DB - PRIME DP - Unbound Medicine ER -