AUTHOR=Foss Visti T., Rokamp Kim Z., Christensen Robin D., Nissen Peter , Secher Niels H., Nielsen Henning B.

TITLE=Effect of phenylephrine vs. ephedrine on frontal lobe oxygenation during caesarean section with spinal anesthesia: an open label randomized controlled trial

JOURNAL=Frontiers in Physiology

VOLUME=5

YEAR=2014

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2014.00081

DOI=10.3389/fphys.2014.00081

ISSN=1664-042X

ABSTRACT=<p><bold>Background:</bold> During caesarean section spinal anesthesia may provoke maternal hypotension that we prevent by administration of phenylephrine and/or ephedrine. Phenylephrine is however reported to reduce the near infrared spectroscopy-determined frontal lobe oxygenation (ScO<sub>2</sub>) but whether that is the case for patients exposed to spinal anesthesia is not known.</p><p><bold>Objectives:</bold> To evaluate the impact of phenylephrine vs. ephedrine on ScO<sub>2</sub>during caesarean section with spinal anesthesia in a single center, open-label parallel-group study with balanced randomization of 24 women (1:1). Secondary aims were to compare the effect of the two drugs on maternal hemodynamics and fetal heart rate.</p><p><bold>Intervention:</bold> Ephedrine (0.8–3.3 mg/min) <italic>vs.</italic> phenylephrine infusion (0.02–0.07 mg/min).</p><p><bold>Results:</bold> For the duration of surgery, administration of ephedrine maintained ScO<sub>2</sub> (compared to baseline +2.1 ± 2.8%; mean ± SE, while phenylephrine reduced ScO<sub>2</sub> (−8.6 ± 2.8%; <italic>p</italic> = 0.005) with a 10.7% difference in ScO<sub>2</sub>between groups (<italic>p</italic> = 0.0106). Also maternal heart rate was maintained with ephedrine (+3 ± 3 bpm) but decreased with phenylephrine (−11 ± 3 bpm); difference 14 bpm (<italic>p</italic> = 0.0053), but no significant difference in mean arterial pressure (<italic>p</italic> = 0.1904) or CO (<italic>p</italic> = 0.0683) was observed between groups. The two drugs also elicited an equal increase in fetal heart rate (by 19 ± 3 vs. 18 ± 3 bpm; <italic>p</italic> = 0.744).</p><p><bold>Conclusion:</bold> In the choice between phenylephrine and ephedrine for maintenance of blood pressure during caesarean section with spinal anesthesia, ephedrine maintains frontal lobe oxygenation and maternal heart rate with a similar increase in fetal heart rate as elicited by phenylephrine.</p><p><bold>Trial registration:</bold> Clinical trials NCT 01509521 and EudraCT 2001 006103 35.</p>