Effect of Remote Ischemic Preconditioning on the Incidence of Acute Kidney Injury in Patients Undergoing Coronary Artery Bypass Graft Surgery

Background: Acute kidney injury (AKI) following coronary artery bypass graft (CABG) surgery is a major complication occurring in 1% to 53% of patients (depending on how it is defined) with the pooled rate of 18.2% and unfortunately 2.1% of them require renal replacement therapy. Cardiopulmonary bypass (CPB)-associated AKI increases mortality 2-4 fold regardless of AKI definition. It is also associated with increased risk of postoperative stroke, acute myocardial infarction, cardiac tamponade, heart failure, and lengthened intensive care unit and hospital stays. Even minor elevations of postoperative serum creatinine (SCr) have been associated with a significant increase in 30-day mortality, from a 3-fold increase risk for a small elevation of up to 0.5 mg/dL from baseline to an 18-fold increase risk of death with a SCr rise greater than 0.5 mg/dL. The pathogenesis of CPB-associated AKI is complicated and includes hemodynamic, inflammatory and other mechanisms that interact at a cellular level. To date, despite several clinical trials of pharmacologic interventions, none of them have demonstrated conclusively efficacy in the prevention of AKI after cardiac surgery. Remote ischemic preconditioning (RIPC) is a phenomenon in which brief ischemia of one organ or tissue, provokes a protective effect that can reduce the mass of infarction caused by vessel occlusion and reperfusion. In CABG surgery, cardiomyocyte injury caused by myocardial protection failure is predominantly responsible for adverse outcomes. RIPC was shown to reduce troponin release 24 h postoperatively in children undergoing corrective surgery for congenital heart disease. Other studies demonstrated that RIPC using brief ischemia and reperfusion of the upper limb reduces myocardial injury in adult patients undergoing CABG surgery. Due to the similarities between the mechanisms of ischemia-reperfusion injury produced by RIPC and those proposed for AKI after CPB, we decided to test the hypothesis that R