Efficacy of Erythropoietin to Prevent Acute Kidney Injury in Chronic Kidney Disease Patients Undergoing Cardiac Surgery

Inclusion Criteria: * age \> 18 years. * serum creatinine levels \> 1.2 mg/dL and baseline creatinine clearance levels \< 60 mL/min (as measured in their most recent sample,drawn within 2 months prior to the beginning of the study) * patients who need cardiac surgery Exclusion Criteria: * patients with acute kidney injury * end stage renal disease (requiring dialysis) * unstable renal function (as evidenced by a change in serum creatinine of \> 0.5 mg/dL, or \> 25%, within 14 days prior to the study) * allergy to any of erythropoietin * suffered from congestive heart failure, cardiogenic shock or emergent cardiac surgery. * receiving erythropoietin within 14 days before the study