• Visti T Foss, Robin Christensen, Kim Z Rokamp, Peter Nissen, Niels H Secher, and Henning B Nielsen.
• Department of Anaesthesia, Næstved Hospital Næstved, Denmark.
• Front Physiol. 2014 Jan 1;5:81.

BackgroundDuring 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 (ScO2) but whether that is the case for patients exposed to spinal anesthesia is not known.ObjectivesTo evaluate the impact of phenylephrine vs. ephedrine on ScO2during 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.InterventionEphedrine (0.8-3.3 mg/min) vs. phenylephrine infusion (0.02-0.07 mg/min).ResultsFor the duration of surgery, administration of ephedrine maintained ScO2 (compared to baseline +2.1 ± 2.8%; mean ± SE, while phenylephrine reduced ScO2 (-8.6 ± 2.8%; p = 0.005) with a 10.7% difference in ScO2between groups (p = 0.0106). Also maternal heart rate was maintained with ephedrine (+3 ± 3 bpm) but decreased with phenylephrine (-11 ± 3 bpm); difference 14 bpm (p = 0.0053), but no significant difference in mean arterial pressure (p = 0.1904) or CO (p = 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; p = 0.744).ConclusionIn 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.Trial RegistrationClinical trials NCT 01509521 and EudraCT 2001 006103 35.

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