///2015 Abstract Details
2015 Abstract Details2019-08-02T16:54:43-06:00

A double blind randomized controlled trial of a prophylactic phenylephrine infusion versus bolus phenylephrine for the treatment of spinal induced hypotension in obese parturients

Abstract Number: T-64
Abstract Type: Original Research

Ronald B George MD FRCPC1 ; Dolores M McKeen MD FRCPC2; Terrence K Allen MBBS FRCA3; Carrie M Polin MD4; Ashraf S Habib MB ChB MSc FRCA5

Introduction: Hypotension is the most common complication of spinal anesthesia for cesarean delivery (CD).1 It is associated with maternal nausea, vomiting, and fetal acidosis.1 All previous research regarding the use of phenylephrine (PE) has excluded obese subjects. Our objective was to compare the incidence of intraoperative nausea and vomiting (IONV) in obese patients who receive a prophylactic PE infusion versus those who receive PE boluses for the treatment of spinal induced hypotension.

Methods: This study was a multi-centre, double blinded randomized controlled trial. With institutional REB approval and written informed consent, healthy, non-laboring obese (BMI>35) women, singleton gestation, ≥36 weeks undergoing elective CD were recruited. Participants were randomized to receive PE prophylactic infusion (50mcg/min) or a PE bolus (100mcg) to treat hypotension. A standard spinal technique (12mg hyperbaric 0.75% bupivacaine 15mcg, fentanyl, 150mcg morphine) was performed. Maternal systolic blood pressure (SBP) was maintained within 20% of baseline using a predetermined algorithm. The incidence of IONV and postoperative nausea and vomiting (PONV), need for rescue antiemetics and incidence of hypotension were compared between groups.

Results: Analysis included 160 parturients. The mean BMI of participants was 41 ± 4 kg/m2. There was no difference in group demographics (Table 1). The incidence of intraoperative nausea (ION) was significantly greater in the bolus group compared to the infusion group (p < 0.001) without any difference in intraoperative vomiting (IOV). This was associated with a significantly greater need for intraoperative rescue antiemetic in bolus participants (p=0.04). The incidence of postoperative vomiting (POV) was greater in the bolus group (p=0.02), however there were no differences in the incidence or severity of postoperative nausea (PON) or need for antiemetic. The infusion group had a significantly lower incidence of hypotension but greater incidence of hypertension (>20% SBP above baseline). There were no differences in umbilical cord pH between the groups.

Discussion: In obese women having a cesarean delivery with spinal anesthesia a prophylactic phenylephrine infusion leads to less ION requiring intervention. Infusions of phenylephrine in obese women may also lead to less POV.


1. BJA 2006;96:95-9.

SOAP 2015