Intrarenal Vein Congestion Score but Not Venous Excess Ultrasonography Is Associated with Kidney Perfusion and Etiology of AKI

Background: Proper diagnosis of acute kidney injury (AKI) etiology contributes to adequate treatment and a more favorable renal prognosis. Recently, a 4-point Venous Excess Ultrasound (VExUS) was introduced for AKI prediction. Due to the poor diagnostic performance of Vena Cava Inferior (VCI) maximal diameter in congestion assessment, interlobular renal vein Doppler flow patterns evaluation expressed as IntraRenal Vein Congestion Score (IRVCS) can be more appropriate for AKI etiology diagnosis. The study aimed to investigate the usefulness of IRVCS in predicting AKI etiology. Methods: Twenty-four patients (10F, 14M; age 64 ±11) hospitalized due to AKI of unknown origin were evaluated in duplex Doppler ultrasound with the assessment of VExUS (grade 0-3): VCI; Hepatic Veins Systolic to Diastolic ratio, Portal Vein Pulsatility Index (PVPI), Real Vein Doppler. Moreover, Peak Systolic (PSV) and End-Diastolic Velocities (EDV) in interlobar renal arteries and IRVCS (stage 0-3) were investigated. Serum blood NT-proBNP and creatinine with eGFR-CKD-EPI calculation were tested. At discharge, the more probable etiology of AKI was identified as hypovolemia, hypervolemia, and inflammation. Results: Mean creatinine was 3.48 ±1.82 mg/dL (CKD-EPI 22.97 ±13.15 mL/min/1.73m2) and NT-proBNP 9169.1 (IQR 5667.2) pg/mL. Abnormal IRVCS was found in 7 (29%) patients (2 – stage 1, 4 – stage 2, and 1 – stage 3), but VExUS revealed congestion in 12 (50%) patients (11 - grade 1, 1 - grade 3); p< 0.001. IRVSC significantly correlated with NT-proBNP (r=0.573; p=0.010), PSV (r= -0.557; p=0.011), EDV (r= -0.442; p=0.045), PVPI (0.485; p=0.026), and VExUS (r= 0.461; p=0.035). However, VExUS correlated only with VCI (r=0.753; p< 0.001) and IRVSC. Hypovolemic AKI etiology was recognized in 8 patients, hypervolemic in 7, and inflammation in 9. Logistic regression revealed that only IRVSC could substantially predict the hypervolemic etiology of AKI (OR 2.763; 95%CI: 1.008-7.570; p= 0.048). VExUS had no corresponding predictive properties (OR 2.070; 95%CI: 0.580-7.388; p= 0.262). Conclusion: IntraRenal Vein Congestion Score is significantly associated with renal perfusion and can help predict the hypervolemic etiology of AKI. The presented data suggest that IRVCS is more appropriate than VExUS in diagnosing the etiology of AKI. Funding: Government Support – Non-U.S.