Comparison of intravenous bolus phenylephrine and intravenous ephedrine during crystalloid coloading in ameliorating hypotension under spinal anesthesia for caesarean section

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Date: September-December 2015
From: Journal of Medical Society(Vol. 29, Issue 3)
Publisher: Medknow Publications and Media Pvt. Ltd.
Document Type: Report
Length: 3,090 words
Lexile Measure: 1520L

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Byline: Arun. Natarajan, Nongthombam. Singh, Laithangbam. Singh, Rajkumari. Devi, N. Devi, Ashem. Jack

Background: Maternal hemodynamic changes are common during spinal anesthesia for caesarean delivery and many agents are used for treating hypotension. In this study, we compared the efficacy of ephedrine and phenylephrine in ameliorating hypotension in spinal anesthesia for caesarean delivery during crystalloid coloading and their effect on fetal outcome. Materials and Methods: A total of 80 American Society of Anesthesiologists (ASA) grade I/II patients undergoing elective cesarean delivery under spinal anesthesia with a normal singleton pregnancy beyond 36 weeks gestation were randomly allocated into two groups of 40 each. Group 1 received bolus dose of intravenous (IV) ephedrine 6 mg and group 2 received bolus doses of IV phenylephrine 100 [micro]g. Hemodynamic variables like blood pressure and heart rate (HR) were recorded every 2 min up to delivery of the baby and thereafter every 5 min. Neonatal outcome was assessed using Apgar score at 1 min and 5 min and neonatal umbilical cord blood pH values. Results: There was no difference found in managing hypotension between the group 1 and group 2. The incidence of bradycardia was higher in phenylephrine group (group 2). The differences in umbilical cord pH, Apgar score, and birth weight between the two groups were found to be statistically insignificant. Conclusion: Phenylephrine and ephedrine are equally efficient in managing hypotension during spinal anesthesia for elective caesarean delivery. There was no difference between the two vasopressors in the incidence of true fetal acidosis and neonatal outcome.

Introduction

Spinal (subarachnoid) anesthesia is considered to be the "gold standard" technique for caesarean delivery. [sup][1] However, hypotension is the most common side effect of neuroaxial blocks in the obstetric patient. Spinal anesthesia for caesarean delivery is associated with 80% of hypotension cases without prophylactic measures. [sup][2]

Many interventions such as pelvic tilt, [sup][3] leg elevation and wrapping, [sup][4] and the prophylactic administration of fluids [sup][5] or vasopressors [sup][6] have been proposed and used to reduce the incidence of maternal hypotension. Despite all these measures, approximately 25% of patients still experience hypotension episodes. [sup][6]

Crystalloid prehydration has poor efficacy for preventing hypotension, probably because it undergoes rapid distribution. [sup][7] As an alternative, rapidly administering crystalloid at the time of initiation of anesthesia (called coloading) may be more physiologically appropriate as the maximum effect can be achieved during the time of block and consequent vasodilation evolution. [sup][8] Ephedrine has been the vasopressor of choice since it has been shown to have a more protective effect on uterine blood flow and perfusion pressure than a-adrenergic agonists. [sup][9] However, ephedrine is no longer the gold standard for prophylaxis and treatment of hypotension after spinal anesthesia for caesarean delivery. Moreover, higher dose of ephedrine causes significant maternal tachycardia and fetal acidosis. [sup][10] More recent evidence has supported the use of alpha agonists such as phenylephrine demonstrating better acid base status and similar efficacy in blood pressure control. [sup][11]

Hence, the present study was designed to compare the vasopressor effects of ephedrine and...

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Gale Document Number: GALE|A437022517