Use of Ultrasound to Assess Hemodynamics in Acutely Ill Patients

Early diagnosis of acute kidney injury (AKI) and preventive measures can likely decrease the severity of the injury and improve patient outcomes. Current hemodynamic monitoring variables, including blood pressure, heart and respiratory rates, temperature, and oxygenation status, have been used to identify patients at high risk for AKI. Despite the widespread use of such variables, their ability to accurately and timely detect high-risk patients has been questioned. Therefore, there is a critical need to develop and validate tools that can measure new and more kidney-specific hemodynamic and laboratory variables, potentially assisting with AKI risk stratification, implementing appropriate and timely preventive measures, and hopefully improved outcomes. The new ultrasonography techniques provide novel insights into kidney hemodynamics and potential management and/or therapeutic targets. Contrast-enhanced ultrasonography, Doppler flow patterns of hepatic veins (HV), portal vein (PV), and intra- kidney veins (iKV), and ultrasound elastography are among approaches that may provide such information, particularly related to vascular changes in acute kidney injury, venous volume excess or congestion, and fluid tolerance. This review summarizes the current state of these techniques and their relevance to kidney hemodynamic management.