Timing of Renal Replacement Therapy for Cardiac Surgery Associated Acute Kidney Injury (CSA-AKI)

Abstract

Cardiac surgery-associated acute kidney injury (CSA-AKI) occurs in 5–30% of patients and is linked to increased morbidity, mortality, and healthcare costs. Severe CSA-AKI often necessitates renal replacement therapy (RRT), yet the optimal timing of initiation remains controversial. This literature review synthesizes current evidence on the pathophysiology of CSA-AKI, definitions and rationales for early versus late RRT, comparative outcomes, and existing guideline recommendations. CSA-AKI arises from ischemia–reperfusion injury, systemic inflammation, oxidative stress, and microcirculatory dysfunction, compounded by perioperative hemodynamic instability and nephrotoxic exposures. Early RRT—commonly initiated within hours of KDIGO stage 2 AKI—may mitigate fluid overload, metabolic derangements, and inflammatory injury, with potential benefits in selected patients. Late RRT—delayed until persistent AKI or urgent indications—can avoid unnecessary intervention, reduce procedural risks, and preserve residual renal function. Comparative studies, including ELAIN, STARRT-AKI, and Crescenzi et al., reveal no universal survival advantage for either approach, with patient selection and clinical context being decisive factors. Current guidelines, such as KDIGO and ADQI, recommend individualized timing based on clinical urgency, hemodynamic status, and multidisciplinary input, with a preference for continuous modalities in unstable patients. Evidence supports a tailored strategy that balances the benefits of early intervention against the risks of overtreatment, while highlighting the need for standardized definitions and CSA-AKI–specific randomized trials to guide future protocols