Intravenous Initial Bolus During Prophylactic Norepinephrine Infusion to Prevent Spinal Hypotension for Cesarean Delivery: A Randomized Controlled, Dose-finding Trial

( J Clin Anesth . 2024:97:111562. doi: 10.1016/j.jclinane.2024.111562) One of the most common complications of spinal anesthesia during cesarean delivery (CD) is hypotension, and if prolonged, it can lead to further effects such as nausea, vomiting, or fetal acidosis. To prevent hypotension, vasopressor medications are used prophylactically, including phenylephrine and norepinephrine. Recent studies have shown norepinephrine to be superior to phenylephrine, and to date, there are no guidelines surrounding optimal norepinephrine regimens for the prevention of spinal-induced hypotension. A previous study showed that a bolus dose of 0.1 μg/kg was superior to 0.05 μg/kg when the infusion rate was fixed at 0.05 μg/kg/min, and the optimal initial bolus dose is yet unknown. This study attempted to establish a dose-response relationship between initial bolus of norepinephrine and the incidence of spinal hypotension during CD, as well as determine the best initial dose with a fixed infusion rate of 0.05 μg/kg/min.