Acute dyspnea is a common reason for emergency department (ED) admission and is frequently caused by acute heart failure with pulmonary edema. Rapid differentiation between cardiogenic and non-cardiogenic causes of dyspnea is essential to guide early treatment and risk stratification. However, no single gold standard exists for the assessment of venous congestion in the acute setting.
This prospective observational study aims to evaluate the diagnostic accuracy of respiratory variation in inferior vena cava (IVC) diameter measured by point-of-care ultrasound (POCUS) in identifying acute pulmonary edema in patients presenting to the ED with acute respiratory failure. In addition, the study investigates whether integration of IVC ultrasound with lung ultrasound, bedside cardiac ultrasound, and selected clinical and laboratory variables - such as hemoglobin and plasma protein changes - improves diagnostic performance and prognostic stratification.
Adults aged ≥18 years.
PaO₂ < 60 mmHg on room air, or
Oxygen saturation (SpO₂) < 90% on room air, or
PaO₂/FiO₂ ratio < 300.
Refusal to provide informed consent (or consent by legal representative when applicable).
Inadequate ultrasound window or technically insufficient ultrasound assessment.
Acute respiratory failure secondary to chest trauma.
Cardiac arrest at presentation or during emergency department stabilization.