Fluid expansion improve ventriculo-arterial coupling in preload-dependent patients: a prospective observational study

Area of Science:

• Cardiovascular Physiology
• Critical Care Medicine
• Hemodynamic Monitoring

Background:

• Fluid challenge (FC) is used in intensive care units (ICUs) to assess fluid responsiveness.
• Ventriculo-arterial (V-A) coupling, reflecting the interaction between the heart and vasculature, is crucial for hemodynamic stability.
• Understanding the impact of FC on V-A coupling and its predictive value for fluid responsiveness is clinically significant.

Purpose of the Study:

• To evaluate the effect of fluid challenge (FC) on ventriculo-arterial (V-A) coupling.
• To assess the influence of FC on V-A coupling determinants: arterial elastance and ventricular elastance.
• To determine the ability of V-A coupling parameters to predict fluid responsiveness.

Main Methods:

• Thirty cardio-thoracic ICU patients undergoing FC were studied.
• Hemodynamic parameters including arterial pressure, cardiac output, arterial elastance, and ventricular elastance were measured before and after FC.
• Fluid responsiveness was defined as a >15% increase in stroke volume; V-A coupling was assessed using the arterial elastance to ventricular elastance ratio.

Main Results:

• Twenty-three patients (77%) were fluid responders.
• Fluid responders exhibited higher baseline arterial elastance and arterial elastance to ventricular elastance ratio.
• FC increased stroke volume and cardiac output, while decreasing arterial elastance and the V-A coupling ratio; changes in arterial elastance correlated with stroke volume, systemic vascular resistance, and arterial compliance.
• A baseline arterial elastance to ventricular elastance ratio >1.4 predicted fluid responsiveness with high accuracy (AUC 0.84).

Conclusions:

• Fluid responsiveness is associated with V-A coupling characterized by an increased arterial elastance to ventricular elastance ratio due to elevated arterial elastance.
• FC enhances V-A coupling by reducing arterial elastance without affecting ventricular elastance.
• Arterial elastance changes during FC are linked to systemic vascular resistance and arterial compliance.