Prophylactic Phenylephrine Infusions to Reduce Severe Spinal Anesthesia Hypotension During Cesarean Delivery in a Resource-Constrained Environment

Abstract

Phenylephrine infusions are considered as standard management for obstetric spinal hypotension, but there remains reluctance to implement them in resource-limited contexts. This prospective, alternating intervention study of patients undergoing elective or urgent cesarean delivery under spinal anesthesia compared a vasopressor bolus strategy to fixed-rate, low-dose prophylactic phenylephrine infusion with supplemental boluses. The primary outcome was the incidence of severe hypotension (mean arterial pressure <70% baseline or systolic blood pressure <80 mm Hg). Fewer patients receiving prophylactic phenylephrine infusions had severe hypotension (47.4% [n = 120/253] vs 62.1% [n = 157/253], P = .001, estimated relative risk 0.84, 95% confidence interval, 0.69-1.02), with no significant difference in the rate of hypertension (15% [n = 39/253] vs 11% [n = 27/253], P = .11, estimated relative risk 1.39, confidence interval 0.87-2.20). Guidelines for resource-constrained settings should consider a fixed, low-dose phenylephrine infusion in combination with rescue vasopressor bolus therapy.

International consensus statement on the management of hypotension with vasopressors during caesarean section under spinal anaesthesia

“…A recent paper has described the use of a fixed low‐rate phenylephrine infusion to provide background pharmacological action, with supplementary boluses as needed. This is an easier option for the unskilled anaesthetist than a titrated infusion, with a low risk of side‐effects . In general, our suggestions are based on principles studied in resource‐rich environments and modified for local practice, based on expert opinion.…”

Prophylactic phenylephrine and fluid co‐administration to reduce spinal hypotension during elective caesarean section in a resource‐limited setting: a prospective alternating intervention study

“…Dose‐finding studies in resource‐rich environments have established that the optimal rate for administration of phenylephrine is 25–50 μg.min −1 . A fixed, low‐dose 25 μg.min −1 phenylephrine infusion is effective in reducing severe maternal hypotension in a resource‐limited setting . Fixed‐rate infusions are simpler to use and have a low side‐effect profile, due to the lower dose administered.…”

“…A fixed, low-dose 25 lg.min À1 phenylephrine infusion is effective in reducing severe maternal hypotension in a resource-limited setting [9]. Fixed-rate infusions are simpler to use and have a low side-effect profile, due to the lower dose administered.…”

A Randomised Dose-Response Study of Prophylactic Methoxamine Infusion for Preventing Spinal-induced Hypotension during Cesarean Delivery

“…Several studies about phenylephrine showed that continuous infusion was superior to an IV bolus at preventing hypotension, nausea and vomiting and other intraoperative adverse events [4,24,25] .…”