Description of Condition
Acute Kidney Injury (AKI) is a common and serious complication after
cardiac surgery [1]. Specifically, acute kidney injury is mostly
caused by the usage of cardiopulmonary bypass during coronary artery
bypass grafting (CABG) and valvular surgery. [2] The incidence of
acute kidney injury might also be dependent on the clinical
characteristics of patients undergoing cardiac surgery, such as reduced
left ventricular function, presence of congestive heart failure or an
elevated preoperative serum creatinine. Acute Kidney injury does not
have a universal definition. The three most popular consensus
definitions are Acute Dialysis Quality Initiative’s “RIFLE” criteria,
the Acute Kidney Injury Network (AKIN) criteria and the Kidney Disease
Improving Global Outcomes (KDIGO) criteria [3]. These criteria are
based on percentage increase in serum creatine concentration over
baseline, absolute increase in serum creatine concentration or urine
volume. [4] The pathogenesis of AKI after CPB is multifactorial, and
is mostly due to hypoperfusion, reperfusion injury, activation of the
systematic inflammatory response, and/or low cardiac output. [5]
Reperfusion will result in the formation of reactive oxygen species,
resulting in injury to tissue. [6] The activation of the systematic
inflammatory response is mostly due to the exposure of blood to the
extracorporeal CPB circuit, resulting in the activation of the immune
system, which is also mediated by the generation of reactive oxygen
species. This results in increased recruitment of neutrophils,
macrophages and lymphocytes into the renal parenchyma, leading to AKI.
[7]