Key result
Norepinephrine maintains maternal cardiac output during cesarean delivery vs a ~13% decline with phenylephrine.
Why the study?
Norepinephrine has emerged as a potential alternative to phenylephrine for treating spinal anesthesia-induced hypotension during cesarean delivery, with uncertain systemic hemodynamic effects.
Does norepinephrine intermittent bolus dosing improve maternal normalized cardiac output compared to phenylephrine in parturients undergoing spinal anesthesia for elective cesarean delivery?
RCT (n=56)
Does norepinephrine intermittent bolus dosing improve maternal normalized cardiac output compared to phenylephrine in parturients undergoing spinal anesthesia for elective cesarean delivery?
p-value: p=<0.001
Norepinephrine intermittent bolus dosing effectively treats spinal anesthesia-induced hypotension during cesarean delivery while better maintaining maternal cardiac output and stroke volume compared to phenylephrine.
May warrant norepinephrine boluses to avoid CO reduction in cesarean hypotension; leaves open outcome benefits in larger trials.
BACKGROUND: Norepinephrine, a potent α-adrenergic agonist with β-adrenergic effects, has recently emerged as a potential alternative to phenylephrine that does not lower cardiac output (CO) and heart rate (HR) during cesarean deliveries. We examined the systemic hemodynamic effects of both agents in this setting, using intermittent bolus doses to treat spinal anesthesia-induced hypotension. METHODS: A total of 56 parturients consenting to spinal anesthesia for elective cesarean delivery were randomly assigned to phenylephrine (100 μg/ml) or norepinephrine (5 μg/ml) intermittent bolus dosing. The primary study outcome was maternal normalized CO, examining and other hemodynamic variables, maternal side effects, and fetal outcomes secondarily. RESULTS: In terms of systolic blood pressure and HR, there were significant within-group differences over time (P < 0.001 and P < 0.001, respectively). Normalized CO and stroke volume (SV) also showed significant differences between groups (P < 0.001 and P = 0.002, respectively). In the phenylephrine group, normalized CO and SV declined (relative to baseline values) by as much as 13% and 9%, respectively; whereas in the norepinephrine group, normalized CO did not differ significantly from baseline, and SV increased up to 5% (relative to baseline). Normalized total peripheral resistance likewise displayed significant within-group differences over time (P < 0.001). CONCLUSIONS: During elective cesarean delivery, intermittent bolus doses of norepinephrine proved effective for treating spinal anesthesia-induced hypotension, while maintaining CO and SV. No maternal complications or fetal effects were evident.
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Cho et al. (2020) conducted an RCT in Spinal anesthesia-induced hypotension (n=56). Norepinephrine vs. Phenylephrine (100 μg/ml intermittent bolus) was evaluated on Maternal normalized cardiac output (p=<0.001). Intermittent bolus doses of norepinephrine maintained maternal cardiac output compared to phenylephrine, which caused up to a 13% decline (P<0.001 between groups), during cesarean delivery.
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