Prophylactic Norepinephrine and Phenylephrine Boluses for Postspinal Anesthesia Hypotension

Overview

The purpose of this study is to investigate the potency between prophylactic norepinephrine and phenylephrine boluses for postspinal anesthesia hypotension in patients undergoing caesarean section.

Full Title of Study: “Prophylactic Norepinephrine and Phenylephrine Boluses for Postspinal Anesthesia Hypotension in Patients Undergoing Caesarean Section: A Randomized Sequential Allocation Dose-finding Study.”

Study Type

  • Study Type: Interventional
  • Study Design
    • Allocation: Randomized
    • Intervention Model: Parallel Assignment
    • Primary Purpose: Treatment
    • Masking: Double (Participant, Care Provider)
  • Study Primary Completion Date: January 3, 2023

Detailed Description

Post-spinal anesthesia hypotension is a frequent complication during spinal anesthesia for cesarean section. The incidence of post-spinal anesthesia hypotension is as high as 62.1-89.7% if prophylactic measures are not taken. Vasopressor has been highly recommended for routine prevention and/or treatment of post-spinal anesthesia hypotension. As a potential substitute drug for phenylephrine, norepinephrine has gradually been used in parturients undergoing cesarean section. There's some evidence that prophylactic infusion of norepinephrine could effectively reduce the incidence of post-spinal anesthesia hypotension in parturients undergoing cesarean section. However, few studies had been indicated the ED50 (prevent postspinal hypotension in 50% of patients) and ED90 of prophylactic norepinephrine bolus and its potency compared to phenylephrine for postspinal anesthesia hypotension in patients undergoing caesarean section. The purpose of this study is to investigate the potency between prophylactic norepinephrine and phenylephrine boluses for postspinal anesthesia hypotension in patients undergoing caesarean section.

Interventions

  • Drug: Phenylephrine
    • An initial prophylactic bolus dose of phenylephrine (37.5μg) simultaneous with spinal anesthesia. If the patient did not respond adequately to the current dose (SBP decreased to < 80% of baseline), the dose was considered to have failed and the subsequent dose for the following patient was increased to the next higher dose level. The dose administered to subsequent patients varied by increments or decrements of 12.5 μg according to the responses of previous patients according to the up-down sequential allocation.
  • Drug: Norepinephrine
    • An initial prophylactic bolus dose of norepinephrine (3μg) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 1 μg according to the responses of previous patients according to the up-down sequential allocation.

Arms, Groups and Cohorts

  • Active Comparator: Phenylephrine group
    • Prophylactic phenylephrine bolus simultaneous with spinal anesthesia
  • Experimental: Norepinephrine group
    • Prophylactic norepinephrine bolus simultaneous with spinal anesthesia

Clinical Trial Outcome Measures

Primary Measures

  • The dose that would be effective in preventing postspinal anesthesia hypotension in 50% (effective dose, ED 50) and 90% (ED90) of patients
    • Time Frame: 1-15 minutes after spinal anesthesia
    • Systolic blood pressure (SBP) < 80% of the baseline

Secondary Measures

  • The incidence of post-spinal anesthesia hypotension
    • Time Frame: 1-15 minutes after spinal anesthesia
    • Systolic blood pressure (SBP) < 80% of the baseline
  • The incidence of severe post-spinal anesthesia hypotension.
    • Time Frame: 1-15 minutes after spinal anesthesia
    • Systolic blood pressure (SBP) < 60% of the baseline
  • The incidence of bradycardia.
    • Time Frame: 1-15 minutes after spinal anesthesia
    • Heart rate < 60 beats/min.
  • The incidence of nausea and vomiting.
    • Time Frame: 1-15 minutes after spinal anesthesia
    • Presence of nausea and vomiting in patients after spinal anesthesia
  • The incidence of hypertension.
    • Time Frame: 1-15 minutes after spinal anesthesia
    • Systolic blood pressure (SBP) >120% of the baseline.
  • pH
    • Time Frame: Immediately after delivery
    • From umbilical arterial blood gases.
  • Partial pressure of oxygen (PO2)
    • Time Frame: Immediately after delivery
    • From umbilical arterial blood gases.
  • Base excess (BE)
    • Time Frame: Immediately after delivery
    • From umbilical arterial blood gases.
  • APGAR score
    • Time Frame: 1 min after delivery
    • A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration
  • APGAR score
    • Time Frame: 5 min after delivery
    • A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration

Participating in This Clinical Trial

Inclusion Criteria

  • 18-45 years – Primipara or multipara – Singleton pregnancy ≥37 weeks – American Society of Anesthesiologists physical status classification I to II – Scheduled for cesarean section under spinal anesthesia Exclusion Criteria:

  • Body height < 150 cm – Body weight > 100 kg or body mass index (BMI) ≥ 40 kg/m2 – Eclampsia or chronic hypertension or baseline blood pressure ≥180 mmHg – Hemoglobin < 7g/dl – Fetal distress, or known fetal developmental anomaly

Gender Eligibility: Female

Minimum Age: 18 Years

Maximum Age: 45 Years

Are Healthy Volunteers Accepted: No

Investigator Details

  • Lead Sponsor
    • General Hospital of Ningxia Medical University
  • Provider of Information About this Clinical Study
    • Sponsor
  • Overall Official(s)
    • Yi Chen, M.D., Study Chair, General Hospital of Ningxia Medical University

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