Assessment of Venous Return During Volume Expansion: a Prospective Observational Study (PSM-PVC-RITVEN)

March 23, 2026 updated by: Abele Donati, MD, Università Politecnica delle Marche

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.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
45

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Italy
      • Ancona, Italy, 60123
        • Recruiting
        • Aou Delle Marche
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Critically ill patients

Description

Inclusion Criteria:

  • 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

Exclusion Criteria:

  • 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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Variation of the Venous Return Gradient (Pms - CVP) in Fluid Responders
Time Frame: 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).

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 Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Venous Return Gradient Variation in Fluid Responders vs Non-Responders
Time Frame: 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).
To compare the change in Pms - CVP between fluid responders and non-responders during volume expansion with 500 mL of crystalloids. 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).
Venous Return Gradient Variation in the General Population
Time Frame: 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).
To describe the changes in Pms - CVP in the overall study population 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).
Cardiac Index Variation in the General Population
Time Frame: 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).
To assess changes in cardiac index in the overall study population during volume expansion with 500 mL of crystalloids. 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).
Mean Systemic Filling Pressure (Pms) Variation in the General Population
Time Frame: 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).
To evaluate how Pms changes in the overall population during volume expansion with 500 mL of crystalloids. 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).
Central Venous Pressure (CVP) Variation in the General Population
Time Frame: 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).
To describe how CVP varies in the overall population during volume expansion with 500 mL of crystalloids. 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).
Cardiac Index Variation in Fluid Responders vs Non-Responders
Time Frame: 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).
To compare cardiac index changes between fluid responders and non-responders during volume expansion with 500 mL of crystalloids. 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).
Mean Systemic Filling Pressure (Pms) Variation in Fluid Responders vs Non-Responders
Time Frame: 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).
To compare Pms changes between fluid responders and non-responders during volume expansion with 500 mL of crystalloids. 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).
Central Venous Pressure (CVP) Variation in Fluid Responders vs Non-Responders
Time Frame: 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).
To evaluate CVP changes in fluid responders compared to non-responders during volume expansion with 500 mL of crystalloids. 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).
Systemic Vascular Resistance (SVR) Variation in Fluid Responders vs Non-Responders
Time Frame: 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).
To describe and compare changes in systemic vascular resistance between fluid responders and non-responders during volume expansion with 500 mL of crystalloids. 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).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Università Politecnica delle Marche

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
March 1, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
July 1, 2026

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
July 1, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 18, 2025

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 23, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 30, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 30, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • PSM-PVC-VENRET

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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