Venous Doppler-derived congestion phenotypes are associated with acute kidney injury after cardiac surgery: a prospective cohort study

Venous congestion may contribute to cardiac surgery-associated acute kidney injury (AKI), but the temporal and clinical relevance of postoperative Doppler abnormalities remain uncertain. In this prospective single-center cohort, 200 adults undergoing cardiac surgery with cardiopulmonary bypass at Clermont-Ferrand University Hospital, France, between August 2022 and April 2023 were assessed on postoperative Day 2 using portal and intrarenal venous Doppler. Patients were classified a priori as having no, moderate, or severe congestion according to the combination of portal vein pulsatility and intrarenal venous flow. The primary outcome was AKI by Day 7. Renal trajectories between Days 2 and 7 and the association with the complete venous excess ultrasound (VExUS) score were explored. No, moderate, and severe congestion were present in 52 (26.0%), 74 (37.0%), and 74 (37.0%) patients, respectively. AKI by Day 7 occurred in 9.6%, 21.6%, and 28.4% of patients across the three groups ( p = 0.04). In multivariable analysis, moderate or severe congestion was associated with AKI by Day 7 (adjusted OR: 3.01, 95% CI: 1.07–8.49; p = 0.04). Among 118 patients without AKI on Day 2, incident AKI occurred in 3/42 (7.1%), 2/44 (4.5%), and 7/32 (21.9%) patients with no, moderate, and severe congestion, respectively ( p = 0.045). Complete VExUS grades 0, 1, 2, and 3 were present in 54, 70, 26, and 50 patients, respectively; corresponding AKI rates by Day 7 were 14.8%, 20.0%, 26.9%, and 26.0% ( p = 0.46). The AUC was 0.62 (95% CI 0.53–0.70) for the simplified phenotype and 0.57 (95% CI 0.48–0.67) for VExUS ( p = 0.25). Day-2 venous congestion was associated with AKI by Day 7 and with incident AKI after Day 2 in exploratory analyses. The incident-AKI association was non-monotonic and based on only 12 events, and the observational design does not establish causality or clinical utility. The simplified phenotype and complete VExUS both showed modest discrimination. Prospective studies with serial assessment and systematic recording of post-assessment management are warranted.