Variable versus fixed-rate infusion of phenylephrine during cesarean delivery: a randomized controlled trial

Abstract

BackgroundPhenylephrine is the most commonly used vasopressor for prophylaxis against maternal hypotension during cesarean delivery; however, the best regimen for its administration is not well established. Although variable infusion protocols had been suggested for phenylephrine infusion, evidence-based evaluation of variable infusion regimens are lacking. The aim of this work is to compare variable infusion, fixed on-and-off infusion, and intermittent boluses of phenylephrine for prophylaxis against maternal hypotension during cesarean delivery.MethodsA randomized controlled study was conducted, including full-term pregnant women scheduled for elective cesarean delivery. Participants were divided into three groups which received phenylephrine by either intermittent boluses (1.5 mcg/Kg phenylephrine), fixed on-and-off infusion (with a dose of 0.75 mcg/Kg/min), or variable infusion (with a starting dose of 0.75 mcg/Kg/min). The three groups were compared with regard to frequency of: maternal hypotension (primary outcome), second episode hypotension, reactive hypertension, and bradycardia. Other outcomes included heart rate, systolic blood pressure, physician interventions, and neonatal outcomes.ResultsTwo-hundred and seventeen mothers were available for final analysis. The 2 infusion groups showed less incidence of maternal hypotension {26/70 (37%), 22/71 (31%), and (51/76 (67%)} and higher incidence of reactive hypertension compared to the intermittent boluses group without significant differences between the two former groups. The number of physician interventions was highest in the variable infusion group compared to the other two groups. The intermittent boluses group showed lower systolic blood pressure and higher heart rate compared to the two infusion groups; whilst the two later groups were comparable.ConclusionBoth phenylephrine infusion regimens equally prevented maternal hypotension during cesarean delivery compared to intermittent boluses regimen. Due to higher number of physician interventions in the variable infusion regimen, the current recommendations which favor this regimen over fixed infusion regimen might need re-evaluation.

Comparison of two Norepinephrine rescue bolus for Management of Post-spinal Hypotension during Cesarean Delivery: a randomized controlled trial

“…This incidence is similar to the incidence which was reported by Wei et al who used the same dose of NE infusion [12]. However, this incidence was relatively higher than that reported in our previous studies about cesarean delivery (∼ 30%) [5,6,13]. There is a variable incidence of hypotension among previous reports in which vasopressor prophylaxis was used during cesarean delivery; this incidence ranged between 2% [14] and 49% [15].…”

Colloid Preload versus Crystalloid Co-Load in the Setting of Norepinephrine Infusion during Cesarean Section: Time and Type of Administered Fluids Do Not Matter

“…In fact, Ngan Kee has noted that although adjusting dose according to weight seems to make pharmacological sense, many clinicians may prefer to use non-weight-adjusted infusions for simplicity [ 3 ]. Additionally, in a study comparing a fixed-rate regimen of phenylephrine versus a variable-rate regimen for prevention of maternal hypotension, Hasanin et al demonstrated that the former is associated with a lower number of physician interventions and unnecessary calculations [ 31 ].…”

Anesthetic Care of the Pregnant Patient With Cardiovascular Disease: A Scientific Statement From the American Heart Association

“…[54][55][56] For example, phenylephrine (eg, starting titration at 0.5-0.75 µg•kg −1 •min −1 ) or norepinephrine (eg, starting titration at 0.05-0.075 µg•kg −1 •min −1 ) infusion can be initiated through a peripheral intravenous line on completion of the neuraxial block and titrated to maintain a heart rate >60 bpm and a mean arterial pressure near baseline. 57,58…”