A systematic review of phenylephrine vs. noradrenaline for the management of hypotension associated with neuraxial anaesthesia in women undergoing caesarean section

Abstract

Summary Phenylephrine is recommended for the management of hypotension after spinal anaesthesia in women undergoing caesarean section. Noradrenaline, an adrenergic agonist with weak β‐adrenergic activity, has been reported to have a more favourable haemodynamic profile than phenylephrine. However, there are concerns that noradrenaline may be associated with a higher risk of fetal acidosis, defined as an umbilical artery pH < 7.20. We performed a systematic review of trials comparing noradrenaline with phenylephrine, concentrating on primary outcomes of fetal acidosis and maternal hypotension. We identified 13 randomised controlled trials including 2002 patients. Heterogeneity among the studies was high, and there were too few data to calculate a pooled effect estimate. Fetal acidosis was assessed in four studies that had a low risk of bias and a low risk of confounding, that is, studies which used a prophylactic vasopressor and where women received the allocated vasopressor only. There were no significant differences between these studies. No significant differences were observed for hypotension. Two trials found a significantly lower incidence of bradycardia when using noradrenaline. Cardiac output was significantly higher after noradrenaline in two of three studies. For other secondary outcomes including nausea, vomiting and Apgar scores at 1 and 5 min, no studies found significant differences. The evidence so far is too limited to support an advantage of noradrenaline over phenylephrine. Concerns of a deleterious effect of noradrenaline on fetal blood gas status cannot currently be assuaged by the available data from randomised controlled studies.

Incidence of Hypotension and Associated-risk Factors in Epidural Anesthesia With 2% Lidocaine and Epinephrine During Elective Cesarean Section, Efficacy and Safety Assessment

“…The explanation is that parturients with BSBP above 120mmhg and under 140mmhg has physiologically, stable vascular smooth muscle, therefore devoid of hyperactivity with a systemic vascular resistance and then a high safety margin. This argument is supported by other similar studies [2,34] . Parturients with body weight ≤ 60 kg developed also severe hypotension during surgery than parturients above 60kg [p = 0.005, AOR=1.24 [95%CI:1.26-3.98]].…”

Norepinephrine or phenylephrine during spinal anaesthesia for Caesarean delivery: a randomised double-blind pragmatic non-inferiority study of neonatal outcome

“…A recent systematic review of studies comparing norepinephrine and phenylephrine found that there was high heterogeneity among studies and too few data to calculate a pooled effect estimate for the outcome of fetal acidosis. 25 A recent network meta-analysis of vasopressors used during neuraxial anaesthesia for Caesarean delivery ranked different agents according to their likelihood of adversely affecting fetal acidebase status and reported that norepinephrine ranked higher (lower probability) than phenylephrine for adversely affecting both UA pH and BE. 26 Because of the imprecision inherent in collating multiple direct and indirect comparisons, the rank orders in that study were considered possibilities rather than absolute ranks.…”

<p>Control of Spinal Anesthesia-Induced Hypotension in Adults</p>

“…50,51 Further studies are necessary before it can be considered that norepinephrine is preferable to phenylephrine for the prevention of SA induced hypotension. It is not yet the time for a paradigm shift as to the choice of vasopressor agent [52][53][54] even if some preliminary results are interesting. 55…”