NCT07324512

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

Determination of the Minimum Effective Volume of Crystalloid Co-Loading for Preventing Spinal Anesthesia-Induced Hypotension in Cesarean Section: A Biased Coin Design Study

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 45 (estimated)
• Sponsor: Seoul National University Hospital · Academic / Other
• Sex: Female
• Age: 19 Years
• Healthy volunteers: Accepted

Summary

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.

Conditions

• Spinal Induced Hypotension in Cesarean Delivery

Interventions

Type	Name	Description
OTHER	Intravenous Crystalloid Co-Loading	Balanced crystalloid is infused intravenously immediately after intrathecal injection as a co-load. A predefined volume (mL/kg) is administered over \~10 minutes. The volume for successive participants is adapted by a biased-coin up-and-down algorithm to estimate the minimum effective volume (MEV90) that prevents spinal-anesthesia-induced hypotension. Rescue fluids are allowed per protocol.

Timeline

• Start date: 2025-12-27
• Primary completion: 2026-05-31
• Completion: 2026-06-30
• First posted: 2026-01-07
• Last updated: 2026-01-07