Ultrasound-Based Prediction of Hemodynamic Instability During CVVHDF Initiation

Occurrence of hypotension (mean arterial pressure <65 mmHg), requirement for fluid bolus (≥500 mL), or initiation/increase of vasopressor or inotrope support within the first 60 minutes after CVVHDF initiation.

Measurement of left ventricular outflow tract velocity time integral obtained by transthoracic echocardiography before dialysis initiation.

Measurement of mitral annular plane systolic excursion obtained by M-mode transthoracic echocardiography in the apical four-chamber view to assess left ventricular longitudinal systolic function prior to CVVHDF initiation.

Measurement of tricuspid annular plane systolic excursion obtained by M-mode transthoracic echocardiography in the apical four-chamber view to evaluate right ventricular systolic function prior to CVVHDF initiation.

Calculation of pulse pressure variation derived from invasive arterial blood pressure waveform analysis in mechanically ventilated patients to assess dynamic preload responsiveness prior to CVVHDF initiation.

Measurement of the Renal Resistive Index (RRI), obtained by pulsed-wave Doppler ultrasonography of the segmental or interlobar renal arteries, to evaluate intrarenal vascular resistance and renal perfusion prior to initiation of continuous veno-venous hemodiafiltration (CVVHDF). The Renal Resistive Index is calculated as (peak systolic velocity - end diastolic velocity) / peak systolic velocity, with values ranging from 0 to 1. Values greater than 0.7 are considered indicative of increased intrarenal vascular resistance and poorer renal perfusion (worse outcome).

Ultrasonographic measurement of inferior vena cava diameter obtained from the subcostal long-axis view to assess intravascular volume status prior to CVVHDF initiation.

Assessment of systemic venous congestion using the Venous Excess Ultrasound Score (VExUS) prior to initiation of continuous veno-venous hemodiafiltration (CVVHDF). The Venous Excess Ultrasound Score is a grading system ranging from 0 to 3, incorporating inferior vena cava diameter and Doppler flow patterns of the hepatic, portal, and intrarenal veins. Higher scores indicate more severe systemic venous congestion and are associated with worse clinical status.