Cardiac surgery patients have a high risk of AKI. The development of AKI is associated with higher mortality and a higher risk for complications in patients undergoing cardiac surgery. However, there are no effective clinical strategies for preventing prevalence of AKI. RIPC as a simple, inexpensive way of protecting tissues against ischemic damage, may also reduce kidney injury. That makes RIPC under the area of interests of many researches which apply this method to prevent AKI. Investigators conducted a single-center, double-blind trial involving patients at high risk of postoperative AKI, in which want to check wether RIPC reduce the prevalence of AKI, according Kidney Disease: Improving Global Outcomes (KDIGO) definition, by increase in SCr. Furthermore researchers want to investigate a benefit from RIPC in reduction of level of SCr and higher glomerular filtration rate (GFR) 72 hours after off-pump coronary artery bypass as well as reduction of postoperative expression of NGAL an early biomarker of AKI.