Early renal perfusion phenotypes and renal recovery in critically ill patients with or at risk for acute kidney injury: a prospective multicenter cohort study

BACKGROUND: Acute kidney injury (AKI) in critical illness is heterogeneous, and conventional Kidney Disease: Improving Global Outcomes (KDIGO) classification may not capture early physiologic differences relevant to renal recovery. METHODS: Critically ill adults with or at risk for AKI were enrolled within 24 h of intensive care unit admission in a prospective multicenter cohort from six ICUs in China. Doppler ultrasound-derived semi-quantitative renal perfusion (SQP) and renal resistive index (RRI) were measured at admission, 24 h, and 48 h. Group-based trajectory modeling identified perfusion phenotypes, and associations with renal outcomes were evaluated using multivariable models. RESULTS: Among 456 patients, 216 (47.4%) had AKI at ICU admission and 253 (55.5%) met AKI criteria within 72 h. Two SQP phenotypes were identified: sustained-high perfusion (n = 224, 49.1%) and sustained-low perfusion (n = 232, 50.9%). Sustained-high SQP was associated with lower odds of persistent AKI in the primary model (adjusted odds ratio, 0.56; 95% CI, 0.35-0.89; P = 0.015), although this association was attenuated in expanded sensitivity models. Sustained-high SQP was also associated with less renal non-recovery within 7 days, faster recovery among patients with AKI at admission, and less RRT use on day 3 and day 7. RRI trajectories did not discriminate renal outcomes. CONCLUSIONS: Serial SQP phenotyping identified persistent low- and high-perfusion strata associated with kidney-specific recovery outcomes and may provide complementary bedside physiologic information, but external validation is required.Trial registration: ClinicalTrials.gov NCT05866250.