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

NCT07324512 | Not Yet Recruiting

• 1 other identifier: 2508-038-1665
• Study Type: interventional
• Target: 45
• Locations: 0 countries
• Sites: N/A

Brief 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

Outcome Measures

Primary Outcomes (1)

• Minimum Effective Volume (MEV90) of Intravenous Crystalloid Co-Loading (mL/kg)

  The smallest crystalloid co-loading dose (mL/kg) that prevents spinal-anesthesia-induced hypotension in ≥90% of participants when given with prophylactic phenylephrine.

  From intrathecal injection (start of spinal anesthesia) to end of surgery

Secondary Outcomes (15)

• Incidence of intraoperative hypotension (mmHg)

  From intrathecal injection to end of surgery

• Incidence of intraoperative hypertension (mmHg)

  From intrathecal injection to end of surgery

• Additional bolus phenylephrine requirement

  From intrathecal injection to end of surgery

• Total Phenylephrine Dose (µg)

  From intrathecal injection to end of surgery

• Estimated blood loss (mL)

  From skin incision to end of surgery

Study Arms (1)

Crystalloid Co-Loading

EXPERIMENTAL

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.

Other: Intravenous Crystalloid Co-Loading

Interventions

Intravenous Crystalloid Co-Loading OTHER

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.

Crystalloid Co-Loading

Eligibility Criteria

• Age: 19 Years+
• Sex: female
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

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

You may not qualify if:

• 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

Sponsors & Collaborators

• Seoul National University Hospital: lead

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: PREVENTION
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 14, 2025
• First Posted: January 7, 2026
• Study Start: December 27, 2025
• Primary Completion (Estimated): May 31, 2026
• Study Completion (Estimated): June 30, 2026
• Last Updated: January 7, 2026

Record last verified: 2025-10