A randomised controlled trial of phenylephrine and noradrenaline boluses for treatment of postspinal hypotension during elective caesarean section

Phenylephrine is currently the vasopressor of choice during elective caesarean section, but it can cause reflex bradycardia. Noradrenaline, a potent α‐agonist and weak β‐agonist, may be associated with a lower incidence of bradycardia. However, comparative information is limited. This double‐blind randomised controlled trial compared the effects of 100 μg phenylephrine and 5 μg noradrenaline administered as boluses for the treatment of postspinal hypotension during elective caesarean section in women with an uncomplicated singleton pregnancy. Hypotension was defined as a decrease of ≥ 20% from baseline systolic arterial pressure, or an absolute value < 100 mmHg. Ninety women were included in the study. The primary outcome was the incidence of maternal bradycardia < 60 beats.min−1. There was no difference in the incidence of bradycardia (37.8% with phenylephrine vs. 22.2% with noradrenaline; p = 0.167), number of hypotensive episodes, number of boluses required to treat the first hypotensive episode or reactive hypertension. The total number of boluses used was higher in the phenylephrine group (p = 0.01). Maternal heart rate at 1 min after vasopressor administration was non‐significantly lower using phenylephrine vs. noradrenaline (p = 0.034, considering p < 0.01 as statistically significant). The umbilical artery pH was higher using phenylephrine than with noradrenaline (p = 0.034). In conclusion, both vasopressors reversed postspinal hypotension without a statistically significant difference in maternal bradycardia. However, in view of the lower umbilical artery pH when using noradrenaline, further research is warranted to study its placental transfer and fetal metabolic effects.

[1]  R. Malhotra,et al.  Comparison of the potency of phenylephrine and norepinephrine bolus doses used to treat post-spinal hypotension during elective caesarean section. , 2019, International journal of obstetric anesthesia.

[2]  W. N. Kee A Random-allocation Graded Dose-Response Study of Norepinephrine and Phenylephrine for Treating Hypotension During Spinal Anesthesia for Cesarean Delivery , 2018 .

[3]  W. N. Ngan Kee,et al.  Prophylactic Norepinephrine Infusion for Preventing Hypotension During Spinal Anesthesia for Cesarean Delivery , 2018, Anesthesia and analgesia.

[4]  A. Palanisamy,et al.  International consensus statement on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia , 2018, Anaesthesia.

[5]  Warwick D. Ngan Kee,et al.  A Random-allocation Graded Dose–Response Study of Norepinephrine and Phenylephrine for Treating Hypotension during Spinal Anesthesia for Cesarean Delivery , 2017 .

[6]  W. N. Ngan Kee,et al.  Norepinephrine Intermittent Intravenous Boluses to Prevent Hypotension During Spinal Anesthesia for Cesarean Delivery: A Sequential Allocation Dose-Finding Study , 2017, Anesthesia and analgesia.

[7]  M. Vallejo,et al.  An open-label randomized controlled clinical trial for comparison of continuous phenylephrine versus norepinephrine infusion in prevention of spinal hypotension during cesarean delivery. , 2017, International journal of obstetric anesthesia.

[8]  Kim S. Khaw,et al.  Randomized Double-blinded Comparison of Norepinephrine and Phenylephrine for Maintenance of Blood Pressure during Spinal Anesthesia for Cesarean Delivery , 2015, Anesthesiology.

[9]  A. Sethi,et al.  Effect of Different Phenylephrine Bolus Doses for Treatment of Hypotension during Spinal Anaesthesia in Patients Undergoing Elective Caesarean Section , 2015, Anaesthesia and intensive care.

[10]  K. Reinhart,et al.  Comparison of Norepinephrine and Cafedrine/Theodrenaline Regimens for Maintaining Maternal Blood Pressure during Spinal Anaesthesia for Caesarean Section , 2015 .

[11]  Tanya Jones,et al.  The Dose-Dependent Effects of Phenylephrine for Elective Cesarean Delivery Under Spinal Anesthesia , 2010, Anesthesia and analgesia.

[12]  C. Lombard,et al.  Hemodynamic Effects of Ephedrine, Phenylephrine, and the Coadministration of Phenylephrine with Oxytocin during Spinal Anesthesia for Elective Cesarean Delivery , 2009, Anesthesiology.

[13]  M. Karmakar,et al.  Placental Transfer and Fetal Metabolic Effects of Phenylephrine and Ephedrine during Spinal Anesthesia for Cesarean Delivery , 2009, Anesthesiology.

[14]  W. N. Ngan Kee,et al.  Vasopressors in obstetrics: what should we be using? , 2006, Current opinion in anaesthesiology.

[15]  M. Georgieff,et al.  The effect of phenylephrine bolus administration on left ventricular function during isoflurane-induced hypotension. , 1993, Anesthesia and analgesia.

[16]  K. Lindner,et al.  Effect of Phenylephrine Bolus Administration on Global Left Ventricular Function in Patients with Coronary Artery Disease and Patients with Valvular Aortic Stenosis , 1993, Anesthesiology.

[17]  C. Rodeck,et al.  Maternal and fetal haemodynamic effects of spinal and extradural anaesthesia for elective caesarean section. , 1992, British journal of anaesthesia.

[18]  H Schneider,et al.  Transfer and metabolism of norepinephrine studied from maternal-to-fetal and fetal-to-maternal sides in the in vitro perfused human placental lobe. , 1984, American journal of obstetrics and gynecology.

[19]  J. Puolakka,et al.  The Effect of Parturition on Umbilical Blood Plasma Levels of Norepinephrine , 1983, Obstetrics and gynecology.

[20]  J. Puolakka,et al.  A fetal sacrococcygeal tumor obstructing labor after attempted home confinement. , 1983 .

[21]  M. Sandler,et al.  Placental transfer of catecholamines in vitro and in vivo. , 1972, American journal of obstetrics and gynecology.

[22]  C. Wood,et al.  METABOLISM OF C14-NOREPINEPHRINE AND C14-EPINEPHRINE AND THEIR TRANSMISSION ACROSS THE HUMAN PLACENTA. , 1964, International journal of neuropharmacology.