title: Cardiac output changes with phenylephrine and ephedrine infusions during spinal anesthesia for cesarean section: A randomized, double-blind trial.
abstract: Hypotension is a common side effect of spinal anesthesia. Phenylephrine and ephedrine are the two most frequently used vasopressors to treat spinal hypotension during cesarean delivery. In this randomized double-blind study, we aimed to evaluate cardiac output (CO) changes with phenylephrine or ephedrine infusions titrated to maintain baseline systolic blood pressure (bSBP) during spinal anesthesia. Women (n = 40) scheduled for elective cesarean delivery received either phenylephrine 100 μg/min or ephedrine 5 mg/min infusions. Baseline hemodynamics (cardiac output, heart rate, systolic blood pressure) were recorded in the left lateral tilt position before fluid preload, and recorded every minute after spinal anesthesia until delivery. Umbilical cord blood gases were analyzed within 5 minutes of delivery. Good systolic blood pressure control was attained in both groups with minimal periods of hypotension (SBP <80% of bSBP) or hypertension (SBP >120% of bSBP). Cardiac output and heart rate increased over time with ephedrine, but decreased with phenylephrine. The maximum increase in CO from the baseline was 12%, in the ephedrine group, and this occurred 20 minutes after spinal injection. Cardiac output fell by more than 17% in the phenylephrine group, maximal at 10 minutes following spinal injection. Despite good systolic blood pressure control and increased cardiac output with ephedrine, administration of ephedrine was associated with significantly more fetal acidosis [Median (Interquartile range, IQR) UApH - phenylephrine = 7.33 (7.31-7.34) and ephedrine = 7.22 (7.16-7.27), P < .05].
authors.affiliation: University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: W
authors.initials: W
authors.lastname: Mon
authors.affiliation: University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Stewart
authors.affiliation: University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: R
authors.initials: R
authors.lastname: Fernando
authors.affiliation: St.Richard's Hospital, Chichester, UK.
authors.forename: K
authors.initials: K
authors.lastname: Ashpole
authors.affiliation: University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: N
authors.initials: N
authors.lastname: El-Wahab
authors.affiliation: Guy's and St. Thomas' Hospitals NHS Foundation Trust, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: MacDonald
authors.affiliation: Princess Alexandra Hospital, Harlow, UK.
authors.forename: P
authors.initials: P
authors.lastname: Tamilselvan
authors.affiliation: University Hospital of South Manchester NHS Foundation Trust, Wythenshawe, UK.
authors.forename: M
authors.initials: M
authors.lastname: Columb
authors.affiliation: University College London Hospitals NHS Foundation Trust, London, UK.
authors.forename: Y M
authors.initials: YM
authors.lastname: Liu
mesh_terms: D000328:Adult; D000773:Anesthesia, Obstetrical / Q000009:adverse effects* / Q000379:methods; D000775:Anesthesia, Spinal / Q000009:adverse effects* / Q000379:methods; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D002302:Cardiac Output / Q000187:drug effects*; D002585:Cesarean Section / Q000009:adverse effects; D004311:Double-Blind Method; D017558:Elective Surgical Procedures / Q000009:adverse effects; D004809:Ephedrine / Q000008:administration & dosage / Q000627:therapeutic use*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007022:Hypotension / Q000097:blood / Q000453:epidemiology / Q000517:prevention & control*; D016343:Monitoring, Intraoperative / Q000379:methods; D008991:Monitoring, Physiologic / Q000379:methods; D010656:Phenylephrine / Q000008:administration & dosage / Q000627:therapeutic use*; D011247:Pregnancy; D011897:Random Allocation; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D014662:Vasoconstrictor Agents; D002245:Carbon Dioxide; D010656:Phenylephrine; D004809:Ephedrine
keywords: Cardiac output; Cesarean section; Ephedrine; Fetal acidosis; Hypotension; Phenylephrine