Assessment of Venous Return During Volume Expansion: a Prospective Observational Study

NCT07499388 | Recruiting

• 1 other identifier: PSM-PVC-VENRET
• Study Type: observational
• Target: 45
• Locations: 1 country
• Sites: 1

Brief Summary

According to Guyton's model of venous return, the fluids that effectively increase cardiac output are those that, once administered, increase the vascular stressed volume, thereby increasing the mean systemic filling pressure (Pms) without increasing the central venous pressure (CVP). In this way, since the gradient between Pms and CVP increases, venous return-and consequently cardiac output-also increases. In cases where physiologically ineffective fluids are administered, the situation arises in which, in addition to increasing the stressed volume and thus Pms, CVP also increases. As a result, the gradient between Pms and CVP remains unchanged, and cardiac output does not increase. The hypothesis is that only a portion of the fluids administered during volume expansion are actually effective in increasing the gradient between Pms and CVP.

Conditions

Hemodynamic Changes

Outcome Measures

Primary Outcomes (1)

• Variation of the Venous Return Gradient (Pms - CVP) in Fluid Responders

  To describe the change in the venous return gradient (mean systemic filling pressure minus central venous pressure, Pms - CVP) during volume expansion with 500 mL of crystalloids in fluid responsive patients. The fluid challenge is administered according to the clinician's indication. A total of 500 mL of crystalloids is infused over 25 minutes, corresponding to an infusion rate of 1200 mL/h.

  Measurements are taken at baseline, and at 7 minutes and 30 seconds, 12 minutes and 30 seconds, and 25 minutes from the start of crystalloid infusion (corresponding to 150 mL, 250 mL, and 500 mL infused, respectively).

Secondary Outcomes (9)

• Venous Return Gradient Variation in Fluid Responders vs Non-Responders

  Measurements are taken at baseline, and at 7 minutes and 30 seconds, 12 minutes and 30 seconds, and 25 minutes from the start of crystalloid infusion (corresponding to 150 mL, 250 mL, and 500 mL infused, respectively).

• Venous Return Gradient Variation in the General Population

  Measurements are taken at baseline, and at 7 minutes and 30 seconds, 12 minutes and 30 seconds, and 25 minutes from the start of crystalloid infusion (corresponding to 150 mL, 250 mL, and 500 mL infused, respectively).

• Cardiac Index Variation in the General Population

  Measurements are taken at baseline, and at 7 minutes and 30 seconds, 12 minutes and 30 seconds, and 25 minutes from the start of crystalloid infusion (corresponding to 150 mL, 250 mL, and 500 mL infused, respectively).

• Mean Systemic Filling Pressure (Pms) Variation in the General Population

  Measurements are taken at baseline, and at 7 minutes and 30 seconds, 12 minutes and 30 seconds, and 25 minutes from the start of crystalloid infusion (corresponding to 150 mL, 250 mL, and 500 mL infused, respectively).

• Central Venous Pressure (CVP) Variation in the General Population

  Measurements are taken at baseline, and at 7 minutes and 30 seconds, 12 minutes and 30 seconds, and 25 minutes from the start of crystalloid infusion (corresponding to 150 mL, 250 mL, and 500 mL infused, respectively).

Interventions

Fluid challenge of 500ml of crystalloid DRUG

The mean systemic filling pressure (Pms) will be measured using the transient stop-flow arm technique, a method routinely used in clinical practice. This involves placing a non-invasive blood pressure cuff on the same arm where invasive arterial pressure is monitored via the radial artery. The cuff is inflated for one minute to temporarily occlude blood flow. At the end of this period, the invasive arterial pressure displayed on the monitor reflects the Pms. This brief interruption of blood flow does not pose significant risks to tissue perfusion. A fluid challenge with 500 mL of crystalloids will then be performed as per clinical indication. Pms will be measured at baseline, after the infusion of 150 mL, 250 mL, 500 mL, and one hour after the end of fluid administration. Central venous pressure (CVP) and cardiac index (CI) will be continuously monitored throughout the fluid challenge. Patients will be classified as fluid responders if stroke volume (SV) increases by more than

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)
• Sampling Method: Non-Probability Sample

Study Population

Critically ill patients

You may qualify if:

• Critically ill patients admitted to the intensive care unit
• Invasive or minimally invasive hemodynamic monitoring
• Clinical indication for volume expansion with 500 mL of crystalloids

You may not qualify if:

• Suspected or confirmed pregnancy
• Clinical conditions that may reduce the reliability of hemodynamic monitoring:
• Severe aortic stenosis or regurgitation
• Severe mitral stenosis or regurgitation
• History of peripheral arterial disease
• Clinical contraindications to the supine position

Sponsors & Collaborators

• Università Politecnica delle Marche: lead

Study Sites (1)

AOU delle Marche

Ancona, 60123, Italy

RECRUITING

MeSH Terms

Interventions

Crystalloid Solutions

Intervention Hierarchy (Ancestors)

Isotonic Solutions; Solutions; Pharmaceutical Preparations

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: MD, PhD, Full Professor, Head of ICU

Study Record Dates

• First Submitted: April 18, 2025
• First Posted: March 30, 2026
• Study Start: March 1, 2025
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2026
• Last Updated: March 30, 2026

Record last verified: 2026-03

Locations

IT (1)