Active — Not RecruitingNot Applicable

Critical Closing Pressure and PCO₂ Gap in Fluid Resuscitation for Septic Shock

China60 participantsStarted 2025-04-18

Plain-language summary

This study is based on the following key hypotheses: PvaCO₂ (Venous-to-Arterial CO₂ Gap) Hypothesis: Changes in PvaCO₂ (ΔPvaCO₂) following fluid resuscitation correlate with changes in cardiac output (CO) and can serve as a reliable predictor of fluid responsiveness in septic shock patients. The relationship between PvaCO₂ and CO is influenced by metabolic factors (VCO₂), hemodynamic status, and the Haldane effect (oxygenation-dependent CO₂ binding to hemoglobin). Pcrit (Critical Closing Pressure) \& TPP (Tissue Perfusion Pressure) Hypothesis: Elevated Pcrit and reduced TPP (TPP = MAP - Pcrit) are associated with impaired microcirculatory flow and worse clinical outcomes (e.g., 28-day mortality, organ dysfunction). Restoring the "vascular waterfall" phenomenon (Pcrit \> mean systemic filling pressure) may improve macrocirculation-microcirculation coupling and tissue oxygenation. 2\. Study Design Overview 2.1 Study Type Prospective observational cohort with a retrospective validation arm using external databases (e.g., MIMIC-IV). Single-center study (Peking Union Medical College Hospital ICU). 2.2 Study Population Inclusion Criteria Adults (18-80 years) with septic shock (Sepsis-3 criteria + vasopressor-dependent hypotension + lactate \>2 mmol/L). Requires invasive hemodynamic monitoring (arterial line, central venous catheter). Undergoing fluid challenge (clinically indicated). Exclusion Criteria Pregnancy, non-septic shock (e.g., cardiogenic), mechanical circulatory support (ECMO/IABP). Severe COPD, intracardiac shunts, or conditions interfering with CO₂/VO₂ measurements. 2.3 Interventions \& Measurements Fluid Resuscitation Protocol 500 mL 4% gelatin infused over 15 min (pressure bag at 300 mmHg). Hemodynamic/metabolic data collected pre- and post-fluid challenge (within 10 min). Key Data Collected Hemodynamics: MAP, CVP, CO (PiCCO/ultrasound), Pcrit (derived from MAP-CO curve fitting). TPP = MAP - Pcrit. Metabolic Parameters: PvaCO₂, CvaCO₂, VCO₂, VO₂ (Es-COVX module). Lactate, ScvO₂, Hb, arterial/venous blood gases. Outcomes: Primary: 28-day mortality. Secondary: Lactate clearance, AKI incidence, ICU length of stay, vasopressor requirements.

Who can participate

Age range

18 Years – 80 Years

Sex

ALL

See this in plain English?

AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.

Inclusion Criteria: * Age 18-80 years. Diagnosis of septic shock per Sepsis-3 criteria. Requirement for invasive hemodynamic monitoring (arterial and central venous catheters). Clinical indication for fluid challenge (e.g., hypotension, signs of hypoperfusion). Exclusion Criteria: * Pregnancy or lactation. Other types of shock (e.g., cardiogenic, obstructive). Mechanical circulatory support (e.g., ECMO, IABP). Severe respiratory or cardiovascular contraindications.

Questions worth asking your doctor

Bring these to your next appointment. They're a starting point for a shared conversation — not a sign you qualify or a recommendation to enrol.

1Based on my diagnosis and history, is this trial worth exploring for me — or is there a standard treatment we should try first?
2What does this trial's phase tell us about how much is already known about its safety and benefit?
3What would taking part actually involve for me — visits, tests, time, and travel?
4What are the known and possible risks or side effects I should weigh, and how would they be monitored?
5If this trial isn't the right fit, what other options or trials would you suggest I look into?

Generated to help you prepare — always confirm anything about your own eligibility and care with the study team and your doctor.

Questions for the trial coordinator

The trial coordinator is the person who runs the study day to day. These cover the practical side — logistics, costs, and what taking part would actually mean for your life. The study team confirms whether you meet the criteria; these are questions to ask, not a sign you qualify.

1What does taking part actually involve week to week — how many visits, where, and how long does each one take?
2What costs are covered by the study, and what might I have to pay for myself, including travel, parking, or time off work?
3What happens during screening, and what happens if the study team confirms I don't meet the criteria after those tests?
4Who pays for the scans, blood work, and other tests the trial requires — the study, my insurance, or me?
5How will being in the trial affect my regular care, and will my own doctor stay informed and involved?
6Can I leave the trial at any point if I change my mind, and what would happen to my care if I do?

A starting point for the conversation — always confirm anything about your own eligibility, costs, and care with the study team and your doctor.

What they're measuring

Cardiac output

Timeframe: From enrollment to the end of treatment at 2 days

Trial details

NCT IDNCT07043192

SponsorPeking Union Medical College

Sponsor typeOTHER

Study typeOBSERVATIONAL

Primary completion2026-02-01

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