Core Concepts: Post-cardiac Surgery Acute Kidney Injury

Abstract

Acute kidney injury (AKI) complicates the postoperative course in 30% of adult cardiac surgery patients. Similar rates are observed in pediatric cardiac surgery patients. In both children and adults, a diagnosis of AKI carries a marked increase of extrarenal organ morbidity and a fivefold increase in the risk of death during hospitalization. Renal ischemia, inflammation, hemolysis, and oxidative stress contribute to the development of AKI after cardiac surgery. Preventive strategies for AKI following cardiac surgery remain limited, including maintenance of renal perfusion and intravascular volume while avoiding volume overload, administration of balanced salt crystalloid intravenous fluids, and limiting the duration of cardiopulmonary bypass. Although severe AKI requiring dialysis is rare after cardiac surgery, mild AKI is common. This is significant, as it increases the incidence of new and progressive chronic kidney disease. In turn, this complication leads to adverse medium- and long-term outcomes in cardiac surgical patients. Several early-phase clinical trials are underway in cardiac surgery patients, both for the prevention and treatment of AKI. The findings of these studies may lead to the approval of new therapeutic options for this important complication of heart surgery. In conjunction with this, the development and validation of biomarkers indicative of tubular damage to predict AKI onset and prognosis may supplant creatinine-based criteria for AKI endpoints in clinical trials and become incorporated in future consensus guidelines for clinical diagnosis.