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.Objectives: 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.Intervention: 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).Conclusion: 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.Trial registration: Clinical trials NCT 01509521 and EudraCT 2001 006103 35.

Comparison of ephedrine and phenylephrine in incidence of headache during spinal anesthesia in cesarean delivery

“…In the study performed by Foss et al maternal heart rate was not impressed by ephedrine, but it decreased as a result of phenylephrine infusion [13]. The same result was observed regarding the effect of phenylephrine and ephedrine on fetal heart rate [13].…”

“…Furthermore, investigations on the effect of either of ephedrine and phenylephrine on placental vascular resistance did not detect any differences and supported the equal value for both of them [15]. Also, no differences were observed between the effect of ephedrine and phenylephrine on chemical components of umbilical arterial and venous [13].…”

“…Foss et al studied the effect of phenylephrine and ephedrine on frontal lobe oxygenation during caesarean section with spinal anesthesia, and the results of this study demonstrated the equal effect of both of ephedrine and phenylephrine to maintain the systolic, diastolic and mean arterial blood pressure [13]. Also, in the study conducted by Lundorff et al comparing two different anesthesia method, ephedrine was used to treat hypotension.…”

“…They did not found any superiority for combination therapy than bolus injection of ephedrine in stabilizing hemodynamic subsequences of spinal anesthesia [12]. Also, it has been shown that administration of phenylephrine reduced the frontal lobe oxygenation, while infusion of ephedrine did not significantly affect the level of ScO 2 [13]. Even in some cases of spinal anesthesia in cesarean section, surprisingly, no effect on hypotension was observed ISSN 0970-938X www.biomedres.info…”

Cerebral oxygenation in health and disease

“…However, possible extracranial contamination of the NIRS signal, especially with the utilization of vasopressors, challenges these conclusions. Keeping this limitation in mind, Foss et al (2014) explored the influence of phenylephrine and ephedrine, on S c O 2 during cesarean section with spinal anesthesia. Both vasopressors were effective at maintaining mean arterial pressure (MAP).…”