Abstract
Introduction
acute Kidney Injury (AKI) affects up to 40–50% of ICU patients and remains a major cause of morbidity and mortality despite advances in renal replacement therapy (RRT).1 Conventional fluid-removal strategies rely on cumulative fluid balance (CFB) or central venous pressure, both of which correlate poorly with true organ-level venous congestion. Venous Excess Ultrasound (VExUS) is a non-invasive, bedside Doppler protocol integrating inferior vena cava, hepatic, portal, and intrarenal venous flow to quantify systemic congestion. Conventional strategies and VExUS have not been compared in randomised manner before.
Objectives
To determine whether VExUS-guided UF hastens renal recovery compared to CFB-guided UF in critically ill AKI patients on SLEDD.
Methods
An open-label randomised controlled trial was conducted in the Medical ICU of AIIMS Bhopal (January 2024–August 2025) after ethical approval (IHEC-PGR). Seventy-eight patients with KDIGO-defined AKI requiring RRT were randomized (1:1) into:
Group I (CFB arm): UF volume determined by adjusted cumulative fluid balance of previous 48 h.
Group II (VExUS arm): UF prescribed according to venous congestion grade (Grade 0 = no UF; Grade 1 = 750 + 250 ml UF; Grade 2 = 1.25L + 250ml UF; Grade 3 = 1.75 L + 250 ml UF).1–5
All patients received 5hours SLEDD. Primary endpoint was time to renal recovery (urine output > 400 ml/24 h). Secondary outcomes included 28-day RRT-free days, hemodynamic stability (mean arterial pressure and vasopressor use), change in oxygenation (P/F ratio), ICU mortality, and length of stay. Analyses were by intention to treat using Mann–Whitney U, Chi-square, and Cox proportional-hazards models (p < 0.05 significant).
Results
Seventy-eight patients completed follow-up (39 per arm). Baseline characteristics, SOFA scores, and etiologies of AKI (sepsis ≈ 49%) were similar. There was no significant association between baseline VExUS score and KDIGO stage, suggesting that systemic venous congestion as assessed by VExUS, may be independent of the conventional staging of AKI severity. Median time to renal recovery in the VExUS group was 6 (4–8) days versus standard care 7 (5-11) days; (p = 0.180). The Kaplan-Meier curves demonstrated comparable probabilities of remaining dialysis-dependent over time in both groups, indicating that the Doppler-guided ultrafiltration strategy did not confer a significant advantage in accelerating renal recovery. There was a non- significant trend toward slower recovery in the VExUS arm (HR 0.60; 95% CI 0.35–1.03; p = 0.065). Higher baseline illness severity (SOFA) independently predicted delayed recovery (HR 0.54; 95% CI 0.31–0.96; p = 0.036). Twenty-eight–day mortality was comparable (25.6% standard care vs 38.5% VExUS; p = 0.332). Hemodynamic stability during SLEDD was similar across groups at all measured time points. Among survivors, RRT-free days, and the number of SLEDD sessions did not differ significantly.
Conclusion
In critically ill patients with AKI undergoing SLEDD, VExUS-guided ultrafiltration was hemodynamically safe, feasible and physiologic for AKI management in critical care, but did not hasten renal recovery or affect mortality in comparison to conventional methods of ultrafiltrate removal. Large sampled multicentric studies are warranted to validate these findings and find out the scope of VExUS guided fluid removal in ICU populations.
Keywords: Acute Kidney Injury, Venous Excess Ultrasound (VExUS), Ultrafiltration, SLEDD, Renal Replacement Therapy, Critical Care
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