The role of amino acids and protein administration in preventing cardiac surgery-associated acute kidney injury

Acute kidney injury (AKI) persists as one of the most common complications after cardiac surgery. Beyond being burdened by high morbidity and mortality rates, effective therapeutic options are still lacking. To date, the management of cardiac surgery-associated AKI (CSA-AKI) mainly focuses on preventive strategies, e.g. the implementation of standardized care bundles. Interestingly, recent experimental studies have suggested a potential nephroprotective role for both amino acids (AA) and proteins. As such, these compounds show multiple beneficial renal effects, spanning enhancement of renal blood flow, improved oxygenation, and recruitment of renal functional reserve. Moreover, clinical studies have investigated the therapeutic potential of single AA, AA combinations, and proteins. A recent large multicenter randomized controlled trial showed reduced AKI incidence in cardiac surgery patients receiving intravenous AA supplementation. However, these interventions have not yet demonstrated beneficial effects on major clinical outcomes, such as survival. Given the well-established AA safety profile and the underlying biological rationale supporting their use, this review summarizes the existing literature on the effects of various formulations and combinations of perioperative AA and protein on renal outcomes when administered in cardiac surgery patients.