Cardiopulmonary Bypass, Hemolysis, Free Iron, Acute Kidney Injury and the Impact of Bicarbonate

Cardiac surgery with cardiopulmonary bypass (CPB) is one of the most common major surgical procedures worldwide often associated with acute kidney injury (AKI) – a frequent and serious complication of cardiac surgery and affects up to 50% of patients. The major determinants of AKI after CPB are hemodynamic and inflammatory factors and the release of heme and labile iron contributing to oxidation from reactive oxygen species. The generation of reactive oxygen species is catalyzed by free labile iron which is most active at acid pH. To date, no simple, safe, and effective intervention to prevent CPB-associated AKI in a broad patient population has been found. However, there is recent evidence from experimental and clinical studies that sodium bicarbonate protects from oxidant renal injury in different settings, at least in part, by scavenging of hydroxyl radicals, peroxynitrite and other reactive species.