Norepinephrine Infusion for Preventing Postspinal Anesthesia Hypotension during Cesarean Delivery

Abstract

EDITOR’S PERSPECTIVE What We Already Know about This Topic Hypotension after spinal anesthesia for cesarean delivery is common, usually treated with phenylephrine or ephedrine Norepinephrine was recently introduced in obstetric anesthesia but the optimal dose is unknown What This Article Tells Us That Is New This randomized, double-blinded trial compared prophylactic norepinephrine infusions of 0.025, 0.050, or 0.075 μg · kg-1 · min-1, started after bupivacaine spinal anesthesia, in full-term parturients having elective cesarean delivery The primary outcome, maternal hypotension (systolic blood pressure less than 80% of baseline), occurred less frequently after both 0.050 and 0.075 μg · kg-1 · min-1 compared 0.025 μg · kg-1 · min-1 norepinephrine Background Norepinephrine has been recently introduced for prophylaxis against postspinal hypotension during cesarean delivery; however, no data are available regarding its optimum dose. The objective of this study is to compare three infusion rates of norepinephrine for prophylaxis against postspinal hypotension during cesarean delivery. Methods The authors conducted a double-blinded, randomized, controlled study including full-term pregnant women scheduled for cesarean delivery. Norepinephrine infusion was commenced after subarachnoid block. Patients were randomized into three groups, which received norepinephrine with starting infusion rates of 0.025 μg · kg-1 · min-1, 0.050 μg · kg-1 · min-1, and 0.075 μg · kg-1 · min-1. Infusion was stopped when intraoperative hypertension occurred. The primary outcome was the frequency of postspinal hypotension (defined as decreased systolic blood pressure less than 80% of the baseline reading). The three groups were compared according to the following: systolic blood pressure, heart rate, frequency of intraoperative hypertension, frequency of bradycardia, and neonatal outcomes. Results Two hundred eighty-four mothers were included in the analysis. The frequency of postspinal hypotension was lower for both the 0.050-μg · kg-1 · min-1 dose group (23/93 [24.7%], odds ratio: 0.45 [95% CI: 0.24 to 0.82], P = 0.014) and the 0.075-μg · kg-1 · min-1 dose group (25/96 [26.0%], odds ratio: 0.48 [95% CI:0.26 to 0.89], P = 0.022) compared with the 0.025-μg · kg-1 · min-1 dose group (40/95 [42.1%]). The two higher-dose groups (the 0.050-μg · kg-1 · min-1 group and the 0.075-μg · kg-1 · min-1 group) had higher systolic blood pressure and lower heart rate compared with the 0.025 μg · kg-1 · min-1 group. The three groups were comparable in the frequency of intraoperative hypertension, incidence of bradycardia, and neonatal outcomes. Conclusions Both the 0.050-μg · kg-1 · min-1 and 0.075-μg · kg-1 · min-1 norepinephrine infusion rates effectively reduced postspinal hypotension during cesarean delivery compared with the 0.025-μg · kg-1 · min-1 infusion rate.

Effects of continuous infusion of phenylephrine vs. norepinephrine on parturients and fetuses under LiDCOrapid monitoring: A randomized, double-blind, placebo-controlled study

“…10,26 Numerous studies have reported reduced incidence of hypotension, intraoperative nausea, vomiting, and dizziness with prophylactic bolus of phenylephrine or norepinephrine at various doses. 8,27,28 In present study, nausea was lower in phenylephrine group.…”

“…Stewart et al emphasized that even with fetal compromise, there is a need to maintain fetal oxygen delivery. 8 The increase in the UV PO 2 and SO 2 values indicates that phenylephrine and norepinephrine enable greater oxygen delivery to the fetus. The changes in the UV glucose levels noted in this study during the vasopressor infusions re ected the changes in the maternal blood glucose levels due to stress reaction.…”

“…14 In the norepinephrine group, parturients received a continuous infusion of norepinephrine at the rate of 0.05 μg/kg/min according to their standard weight. 8 In the control group, parturients received a continuous infusion of LR as the same speed.…”

“…Thus, recently, norepinephrine is considered a potential vasopressor of choice during CD at a maintenance dose of 0.05 μg/kg/min. 8 These pharmacologic properties make norepinephrine and phenylephrine attractive choices as vasopressors in CD. However, new evidence points to post-SA hypotension reversal by phenylephrine without signi cant maternal bradycardia.…”

Effects of continuous infusion of phenylephrine vs. norepinephrine on parturients and fetuses under LiDCOrapid monitoring: A randomized, double-blind, placebo-controlled study

“…Thus, recently, norepinephrine is considered a potential vasopressor of choice during CD at a maintenance dose of 0.05 µg/kg/min. 8 However, new evidence points to post-SA hypotension reversal by phenylephrine without significant maternal bradycardia. 9 In addition, prophylactic use of phenylephrine at 0.25 µg/kg/min results in better neonatal outcomes and reduced maternal mortality.…”