ED90 of Norepinephrine and Phenylephrine Infusions in Preeclamptic Patients

Determination of ED90s of Phenylephrine and Norepinephrine Infusion for Strict Blood Pressure Management Targets in Preeclamptic Patients Undergoing Cesarean Section: A Randomized Sequential Allocation Study

The objective of this study is to investigate the ED90 of norepinephrine and phenylephrine infusions for preventing postspinal anesthesia hypotension under intensive treatment in preeclamptic patients during cesarean section

Study Overview

• Status: Completed
• Conditions: Adverse Effect
• Intervention / Treatment: Drug: Norepinephrine; Drug: Phenylephrine

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. The 2016 ASA guidelines for obstetric anesthesia suggest avoiding hypotension following spinal anesthesia in women and emphasize the use of vasopressors, specifically alpha-receptor agonists, as the preferred strategy to prevent and manage post-spinal anesthesia hypotension. The 2018 International Consensus in the United Kingdom and Northern Ireland recommends maintaining maternal systolic blood pressure above 90% of the baseline value following lumbar anesthesia, while avoiding dropping below 80% of the baseline value. Currently, the threshold for maintaining blood pressure above 80% of the baseline value is widely adopted as a standard; however, limited evidence supports the advantage of sustaining maternal blood pressure above 90% of the baseline value. The objective of this study is to investigate the ED90 of norepinephrine and phenylephrine infusions for preventing postspinal anesthesia hypotension under intensive treatment in preeclamptic patients during cesarean section

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• China
  • Ningxia
    • Yinchuan, Ningxia, China, 750004
      • General hospital of Ningxia University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• 18-45 years
• Primipara or multipara
• Singleton pregnancy ≥32 weeks
• American Society of Anesthesiologists physical status classification II to III
• Scheduled for cesarean section under spinal anesthesia

Exclusion Criteria:

• Baseline blood pressure ≥160 mmHg
• Body height < 150 cm
• Body weight > 100 kg or body mass index (BMI) ≥ 40 kg/m2
• Eclampsia or chronic hypertension
• Hemoglobin < 7g/dl
• Fetal distress, or known fetal developmental anomaly

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Norepinephrine group; The maternal systolic blood pressure was consistently maintained above 90% of the preoperative baseline value from the initiation of spinal anesthesia until fetal delivery.	Drug: Norepinephrine; An initial infusion dose of prophylactic norepinephrine (0.05 ug/kg/min) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 0.01 ug/kg/min of prophylactic norepinephrine according to the responses of previous patients according to the up-down sequential allocation.; Other Names: Vasopressor
Experimental: Phenylephrine group; The maternal systolic blood pressure was consistently maintained above 90% of the preoperative baseline value from the initiation of spinal anesthesia until fetal delivery.	Drug: Phenylephrine; An initial infusion dose of prophylactic phenylephrine (0.5 ug/kg/min) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 0.1 ug/kg/min of prophylactic phenylephrine according to the responses of previous patients according to the up-down sequential allocation.; Other Names: Vasopressor

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
ED50 and ED90	The doses of prophylactic norepinephrine and phenylephrine that would be effective in preventing postspinal anesthesia hypotension in 50% (effective dose, ED 50) and 90% (ED90) of patients	1-15 minutes after spinal anesthesia

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
pH	From umbilical arterial blood gases.	Immediately after delivery
Partial pressure of oxygen (PO2)	From umbilical arterial blood gases.	Immediately after delivery
Base excess (BE)	From umbilical arterial blood gases.	Immediately after delivery
The incidence of post-spinal anesthesia hypotension	Systolic blood pressure (SBP) < 80% of the baseline	1-15 minutes after spinal anesthesia.
The incidence of nausea and vomiting.	Presence of nausea and vomiting in patients after spinal anesthesia	1-15 minutes after spinal anesthesia.
The incidence of severe post-spinal anesthesia hypotension.	Systolic blood pressure (SBP) < 60% of the baseline.	1-15 minutes after spinal anesthesia.
The incidence of hypertension.	Systolic blood pressure (SBP) >120% of the baseline.	1-15 minutes after spinal anesthesia.
The incidence of bradycardia.	Heart rate < 60 beats/min.	1-15 minutes after spinal anesthesia.
APGAR score	A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration; 0(Worst)-10(Best)	1 min after fetal delivery
APGAR score	A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration; 0(Worst)-10(Best)	5 min after fetal delivery

Collaborators and Investigators

• Sponsor: General Hospital of Ningxia Medical University
• Investigators: Study Chair: Yi Chen, M.D., General Hospital of Ningxia Medical University

Study record dates

Study Major Dates

• Study Start (Actual): October 3, 2024
• Primary Completion (Actual): May 20, 2025
• Study Completion (Actual): May 20, 2025

Study Registration Dates

• First Submitted: November 25, 2023
• First Submitted That Met QC Criteria: November 28, 2023
• First Posted (Actual): December 6, 2023

Study Record Updates

• Last Update Posted (Estimated): October 6, 2025
• Last Update Submitted That Met QC Criteria: September 30, 2025
• Last Verified: September 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Organic Chemicals; Pharmacologic Actions; Chemical Actions and Uses; Therapeutic Uses; Hydrocarbons; Hydrocarbons, Cyclic; Hydrocarbons, Aromatic; Amines; Catechols; Phenols; Benzene Derivatives; Alcohols; Amino Alcohols; Ethanolamines; Biogenic Monoamines; Biogenic Amines; Catecholamines; Cardiovascular Agents; Norepinephrine; Phenylephrine; Vasoconstrictor Agents
• Other Study ID Numbers: Yi Chen-2024-11

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No