The Key Role of Renal Venous Congestion in the Development of AKI After Cardiac Surgery

Background: Acute kidney injury (AKI) is a common complication after cardiac surgery and is associated with significant morbidity and mortality. Reduced renal perfusion secondary to hemodynamic changes is conventionally considered central to the pathogenesis of cardiac surgery-associated acute kidney injury (CSA-AKI). We sought to explore the impact of central venous pressure (CVP) as a surrogate for renal venous congestion in this setting based on the findings of contemporary trials. Methods: The PubMed database was searched for articles cited therein using the keywords “cardiac surgery”, “acute kidney injury”, and “central venous pressure”. Available data from clinical trials performed between January 2020 and March 2025 were included. The studies were selected if 1) they explored the risk factors for AKI after cardiac surgery and 2) included data on CVP. Pertinent information on clinical and laboratory parameters (e.g., history of heart failure, incidence of AKI, and changes in CVP) were extracted and reviewed. Results: A total of 14 studies with 82,924 participants were included (13 retrospective and 1 prospective). The mean age of the patients was 65.5 years, and 62% were men. Cardiac surgeries commonly included coronary artery bypass grafting and valve surgery. The incidence of AKI was reported from 6.4 to 70% (mean 35%). While there was substantial variation in the timing of measurement of CVP, the threshold, and the endpoints (e.g., AKI, severe AKI, and renal replacement therapy), all studies found a significant association between CVP and CSA-AKI. Interestingly, four studies found that CVP levels even lower than 12 mmHg may be associated with CSA-AKI. Conclusion: Although low renal blood flow is a known contributor to CSA-AKI, the mean perfusion pressure (mean arterial pressure [MAP] minus CVP) has emerged as a potentially more relevant marker than MAP or CVP alone in cardiorenal medicine. This study shows that (1) CVP, as a surrogate for renal venous congestion, is strongly associated with the development of CSA-AKI, and (2) the detrimental impact of CVP may occur at levels lower than those traditionally considered normal. and 3) future studies are needed to determine whether the mean perfusion pressure, rather than its individual components (MAP and CVP), plays a more important role in the development of CSA-AKI.