90% Effective Dose of Phenylephrine Infusions Under Intensive and Standard Treatment

90% Effective Dose of Phenylephrine Infusions for Preventing Postspinal Anesthesia Hypotension Under Intensive and Standard Treatment During Cesarean Section

The objective of this study is to investigate the 90% effective dose of phenylephrine infusions for preventing postspinal anesthesia hypotension under intensive and standard treatment during cesarean section

Study Overview

• Status: Not yet recruiting
• Conditions: Adverse Effect
• Intervention / Treatment: Drug: Alpha-Agonist; Drug: α-adrenergic receptor agonist

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 90% effective dose of phenylephrine infusions for preventing postspinal anesthesia hypotension under intensive and standard treatment during cesarean section.

• Study Type: Interventional
• Enrollment (Estimated): 80
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Yi Chen, M.D.; Phone Number: +86-951-674-3252; Email: czzyxgp@163.com

Participation Criteria

Eligibility Criteria

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

Description

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

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
Other: Standard group; The maternal systolic blood pressure was consistently maintained above 80% of the preoperative baseline value from the initiation of spinal anesthesia until fetal delivery.	Drug: Alpha-Agonist; An initial infusion dose of prophylactic phenylephrine (0.625 ug/kg/min) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 0.125 ug/kg/min of prophylactic phenylephrine according to the responses of previous patients according to the up-down sequential allocation.; Other Names: norepinephrine
Other: Intensive 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: α-adrenergic receptor agonist; An initial infusion dose of prophylactic phenylephrine (0.625 ug/kg/min) simultaneous with spinal anesthesia. The dose administered to subsequent patients varied by increments or decrements of 0.125 ug/kg/min of prophylactic phenylephrine according to the responses of previous patients according to the up-down sequential allocation.; Other Names: norepinephrine

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
ED50 and ED90	The dose of prophylactic 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
Base excess	From umbilical arterial blood gases.	Immediately after delivery
Partial pressure of oxygen (PO2)	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 delivery
APGAR score	A= Appearance P=Pulse G=Grimace A=Attitude R=Respiration; 0(Worst)-10(Best)	5 min after 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 (Estimated): April 1, 2025
• Primary Completion (Estimated): June 30, 2025
• Study Completion (Estimated): June 30, 2025

Study Registration Dates

• First Submitted: November 21, 2023
• First Submitted That Met QC Criteria: November 28, 2023
• First Posted (Actual): November 30, 2023

Study Record Updates

• Last Update Posted (Actual): November 30, 2023
• Last Update Submitted That Met QC Criteria: November 28, 2023
• Last Verified: November 1, 2023

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Physiological Effects of Drugs; Neurotransmitter Agents; Molecular Mechanisms of Pharmacological Action; Autonomic Agents; Peripheral Nervous System Agents; Adrenergic alpha-Agonists; Sympathomimetics; Vasoconstrictor Agents; Adrenergic Agonists; Norepinephrine; Adrenergic Agents
• Other Study ID Numbers: Yi Chen-2024-4

Drug and device information, study documents

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