NCT07499388

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

• Status: Recruiting
• Phase: —
• Study type: Observational
• Enrollment: 45 (estimated)
• Sponsor: Università Politecnica delle Marche · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Not accepted

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

Interventions

Type	Name	Description
DRUG	Fluid challenge of 500ml of crystalloid	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

Timeline

• Start date: 2025-03-01
• Primary completion: 2026-07-01
• Completion: 2026-07-01
• First posted: 2026-03-30
• Last updated: 2026-03-30

Locations

1 site across 1 country: Italy