Prediction of Fluid Responsiveness Using the Femoral Vein-to-Artery Diameter Ratio

Recruiting now

Conditions studied: Fluid Responsiveness, Acute Circulatory Failure, Shock

In brief

This prospective single-center observational study aims to evaluate whether the ultrasound-measured femoral vein-to-femoral artery diameter ratio can predict fluid responsiveness in mechanically ventilated adult intensive care patients with acute circulatory failure or shock. Only patients who already have PiCCO monitoring as part of routine clinical care and for whom a fluid challenge is clinically indicated will be included. No additional invasive procedure will be performed for study purposes. Cardiac index will be measured with PiCCO before and after administration of 500 mL balanced crystalloid over 10 minutes, and femoral vein and femoral artery diameters will be measured by bedside ultrasonography. Fluid responsiveness will be defined as an increase of more than 10% in cardiac index after fluid administration. The study will assess the diagnostic performance of the femoral vein-to-femoral artery diameter ratio as a practical bedside parameter to support hemodynamic decision-making in critically ill patients.

Key facts

Study ID

NCT07546656

Run by

Istanbul University - Cerrahpasa

People needed

100

Starts

2026-05-01

Expected to finish

2027-03-01

Last updated by the study team

2026-05-11

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• Adult patients aged 18 years or older
• Admission to the intensive care unit where the study is being conducted
• Receiving invasive mechanical ventilation
• Clinical indication for a fluid challenge due to acute circulatory failure or shock, as determined by the responsible intensive care physician
• PiCCO monitoring already in place as part of routine clinical care
• Clinical conditions allowing collection of pre- and post-fluid challenge cardiac index and ultrasonographic measurements
• Technical feasibility of femoral vein and femoral artery diameter measurements by ultrasonography

You may not qualify if…

• Age younger than 18 years
• Failure to obtain written informed consent from the patient or legally authorized representative before enrollment
• Absence of PiCCO monitoring as part of routine clinical care or no clinical plan for fluid challenge
• Inability to complete pre- and post-fluid challenge measurements (e.g., early death, urgent surgery, transfer)
• Local conditions preventing reliable femoral ultrasonographic assessment, including open wound, infection, dressing, major anatomic obstacle, poor image quality, known femoral vein thrombosis, or severe vascular pathology on the relevant side
• Conditions likely to significantly impair the reliability of thermodilution measurements (e.g., severe tricuspid regurgitation or significant intracardiac shunt)
• Major treatment changes during the fluid challenge that preclude comparable measurements (e.g., major vasopressor dose change, major ventilator setting change, new arrhythmia)
• Missing or inadequate data judged by the investigators to compromise data integrity, including absence of measurements required for the primary outcome

Where it is running

• Istanbul University Cerrahpasa Medical Faculty — Istanbul, Istanbul, Turkey (Türkiye) (enrolling)

Full record on ClinicalTrials.gov

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