A Randomized Double-Blinded Comparison of Phenylephrine and Ephedrine Infusion Combinations to Maintain Blood Pressure During Spinal Anesthesia for Cesarean Delivery: The Effects on Fetal Acid-Base Status and Hemodynamic Control

Abstract

When varying combinations of phenylephrine and ephedrine were given by infusion to maintain arterial blood pressure during spinal anesthesia for cesarean delivery, as the proportion of phenylephrine decreased and the proportion of ephedrine increased, hemodynamic control was reduced and fetal acid-base status was less favorable. Combinations of phenylephrine and ephedrine appear to have no advantage compared with phenylephrine alone when administered by infusion for the prevention of hypotension associated with spinal anesthesia for cesarean delivery.

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“…Our findings are consistent with recent published data on management of maternal hypotension during spinal anesthesia [9][10][11][12][13][14][15][16][17][18] . Mercier FJ et al, 2007 16 analysed the different preventive and curative strategies for management of hypotension during spinal anaesthesia for cesarean section.…”

“…Fetal Parameters: Umbilical arterial (UA) pH and Umbilical venous (UV) pH was lower in group E. It was consistent with previous studies 4,11,12 . Depression of fetal pH and base excess with ephedrine has been postulated to be related to ephedrine induced stimulation of fetal metabolism 11 .…”

“…Different studies have reported varying degrees of bradycardia from no incidence 18 to significant incidence 4,11,17 with phenylephrine than ephedrine. This is to be expected because an increase in blood pressure with an α-agonist may lead to reactive bradycardia.…”

“…Depression of fetal pH and base excess with ephedrine has been postulated to be related to ephedrine induced stimulation of fetal metabolism 11 . Ngan Kee WD et al, 2008 11 found that UA pH and base excess was lower with ephedrine compared with phenylephrine.…”

The effects on Apgar scores and neonatal outcomes of switching from a combination of phenylephrine and ephedrine to phenylephrine alone as a prophylactic vasopressor during spinal anesthesia for cesarean section

“…However, a number of studies have suggested ephedrine has a dose-related propensity to depress fetal pH and base excess (BE) in comparison to phenylephrine [3,4,5]. In addition, umbilical artery pH in a combination group of phenylephrine and ephedrine was lower than that of phenylephrine alone group [6,7]. When diverse combinations of phenylephrine and ephedrine were infused to maintain arterial blood pressure during spinal anesthesia for cesarean section, as the proportion of phenylephrine decreased and the proportion of ephedrine increased, decreases were observed in fetal pH, BE and umbilical arterial oxygen content [7].…”