title: Effect of phenylephrine vs. ephedrine on frontal lobe oxygenation during caesarean section with spinal anesthesia: an open label randomized controlled trial.
abstract: BACKGROUND
  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 (ScO2) but whether that is the case for patients exposed to spinal anesthesia is not known.
  
  
  OBJECTIVE
  To 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.
  
  
  METHODS
  Ephedrine (0.8-3.3 mg/min) vs. phenylephrine infusion (0.02-0.07 mg/min).
  
  
  RESULTS
  For 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).
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  Clinical trials NCT 01509521 and EudraCT 2001 006103 35.
authors.affiliation: Department of Anaesthesia, Næstved Hospital Næstved, Denmark.
authors.forename: Visti T
authors.initials: VT
authors.lastname: Foss
authors.affiliation: Musculoskeletal Statistics Unit, Department of Rheumatology, The Parker Institute, Frederiksberg Hospital, University of Copenhagen Copenhagen, Denmark.
authors.forename: Robin
authors.initials: R
authors.lastname: Christensen
authors.affiliation: Department of Anaesthesia, Næstved Hospital Næstved, Denmark.
authors.forename: Kim Z
authors.initials: KZ
authors.lastname: Rokamp
authors.affiliation: Department of Anaesthesia, Rigshospitalet, University of Copenhagen Copenhagen, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Nissen
authors.affiliation: Department of Anaesthesia, Rigshospitalet, University of Copenhagen Copenhagen, Denmark.
authors.forename: Niels H
authors.initials: NH
authors.lastname: Secher
authors.affiliation: Department of Anaesthesia, Rigshospitalet, University of Copenhagen Copenhagen, Denmark.
authors.forename: Henning B
authors.initials: HB
authors.lastname: Nielsen
keywords: cerebral autoregulation; drug effect; fetal; heart rate; near infrared spectroscopy; vasoconstrictor agents