A randomized trial of phenylephrine infusion versus bolus dosing for nausea and vomiting during Cesarean delivery in obese women

• Published in: Canadian journal of anesthesia Vol. 65; no. 3; pp. 254 - 262
• Main Authors: George, Ronald B., McKeen, Dolores M., Dominguez, Jennifer E., Allen, Terrence K., Doyle, Patricia A., Habib, Ashraf S.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2018; Springer Nature B.V
• Subjects: Adult; Anesthesia; Anesthesia, Obstetrical - methods; Anesthesia, Spinal - methods; Anesthesiology; Antiemetics - administration & dosage; Blood Pressure - drug effects; Cardiology; Cesarean section; Cesarean Section - methods; Critical Care Medicine; Double-Blind Method; Female; Health risk assessment; Humans; Hypotension - prevention & control; Incidence; Infusions, Intravenous; Injections, Intravenous; Intensive; Medicine; Medicine & Public Health; Nausea; Obesity; Obesity - complications; Pain Medicine; Pediatrics; Phenylephrine - administration & dosage; Pneumology/Respiratory System; Postoperative Nausea and Vomiting - epidemiology; Postoperative Nausea and Vomiting - prevention & control; Pregnancy; Reports of Original Investigations; Studies; Vasoconstrictor Agents - administration & dosage; Vomiting; Women
• ISSN: 0832-610X; 1496-8975; 1496-8975
• DOI: 10.1007/s12630-017-1034-6

Purpose Hypotension is common after spinal anesthesia for Cesarean delivery. It is associated with nausea, vomiting, and fetal acidosis. Previous research on phenylephrine excluded obese subjects. We compared the incidence of intraoperative nausea and vomiting (IONV) in obese patients who received a prophylactic phenylephrine infusion vs those who received bolus dosing for the treatment of spinal-induced hypotension. Methods In this multicentre, double-blinded randomized controlled trial, 160 obese women undergoing elective Cesarean delivery under spinal anesthesia were randomized to receive a prophylactic phenylephrine infusion initiated at 50 μg·min −1 (and titrated according to a predefined algorithm) or 100 μg phenylephrine boluses to treat hypotension. Maternal systolic blood pressure was maintained within 20% of baseline. The primary study outcome was the incidence of IONV. Results Intraoperative nausea and vomiting were significantly reduced in the infusion group compared to the bolus group (46% vs 75%, respectively; relative risk [RR], 0.61; 95% confidence interval [CI], 0.47 to 0.80; P < 0.001). This was associated with significantly reduced need for intraoperative rescue antiemetics (26% vs 42%, respectively; RR, 0.62; 95% CI, 0.40 to 0.97; P = 0.04), but no difference in the incidence of vomiting. Postoperative vomiting at two hours was reduced in the infusion group (11% vs 25%; RR, 0.44; 95% CI, 0.21 to 0.90; P = 0.02);however, there were no differences in the incidence or severity of postoperative nausea, need for rescue antiemetics at two hours and 24 hr, or the incidence of postoperative vomiting at 24 hr. Conclusion In obese women undergoing Cesarean delivery with spinal anesthesia, prophylactic phenylephrine infusion was associated with less intraoperative nausea, less need for rescue antiemetics, and reduced early postoperative vomiting. Trial registration www.clinicaltrials.gov ( NCT01481740). Registered 22 July 2011.