Minimum Effective Volume of Crystalloid Co-Loading to Prevent Spinal Anesthesia-Induced Hypotension in Cesarean Section

Seoul National University

Status: Not yet enrolling

Conditions: Spinal Induced Hypotension in Cesarean Delivery

Treatments: Other: Intravenous Crystalloid Co-Loading

Study type: Interventional

Funder types: Other

Identifiers

NCT07324512

2508-038-1665

Details and patient eligibility

About

The goal of this clinical trial is to find the minimum effective volume of IV crystalloid that should be given with phenylephrine to prevent hypotension caused by spinal anesthesia in healthy, term pregnant adults having elective cesarean delivery.

The main questions are:

What is the minimum effective volume (MEV90, mL/kg) of crystalloid co-loading that prevents spinal-anesthesia-induced hypotension in ≥90% of participants?

What maternal side effects and newborn outcomes occur with this strategy (e.g., nausea/vomiting, need for extra vasopressors, total fluids/blood loss, Apgar scores, and umbilical cord blood gases)?

There is no separate comparison group; this is a single-arm, adaptive dose-finding study.

Participants will:

Receive a predefined volume of IV crystalloid over ~10 minutes during spinal anesthesia while phenylephrine is infused. Have blood pressure and symptoms monitored; receive rescue treatment if needed. Allow the next participant's fluid volume to be adjusted based on whether hypotension occurred (biased-coin design). Be followed through postoperative day 2 for maternal and newborn outcomes.

Enrollment: 45 estimated patients

Sex: Female

Ages: 19+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Pregnant adults ≥19 years scheduled for elective cesarean delivery under spinal anesthesia
• Term pregnancy (≥37 weeks' gestation)

Exclusion criteria

• Emergency cesarean delivery
• Hypertensive disorders of pregnancy (preeclampsia/eclampsia) or hypertension
• Multiple gestation
• Body weight <50 kg or BMI >35 kg/m²
• Renal impairment or eGFR ≤90 mL/min/1.73 m²
• Heart failure or other heart disease
• History of bronchial asthma or other pulmonary disease

Trial design

Primary purpose: Prevention

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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45 participants in 1 patient group

Crystalloid Co-Loading

Experimental group

Description:

Participants undergo spinal anesthesia for elective cesarean delivery. Immediately after intrathecal injection, a predefined volume of balanced crystalloid (co-loading) is infused over \~10 minutes while a prophylactic phenylephrine infusion is initiated per protocol. The crystalloid volume for each successive participant is adjusted using a biased-coin up-and-down algorithm to identify the minimum effective volume that prevents spinal-anesthesia-induced hypotension in ≥90% of patients (MEV90, mL/kg). Blood pressure is monitored frequently; rescue phenylephrine and/or fluids are permitted to maintain predefined blood pressure ranges. Maternal adverse events and neonatal outcomes are recorded through postoperative day 2.

Treatment:

Other: Intravenous Crystalloid Co-Loading