During thoracic aortic surgery, hypothermic cardiac arrest causes aortic ischemia and reperfusion (IR) periods, respectively. Aortic ischemia results in an ischemic insult to the lower extremities and successive reperfusion results in injury to remote organs, including kidneys. So, there has been considerable interest in the development of therapeutic strategies aimed at attenuating IR injury. One such group of agents that are attracting interest due to their potential protective effects on vascular endothelium is the erythropoietin.

However, the effect of erythropoietin on renal injury induced by aortic IR in humane has not been fully clarified. Therefore, the purpose of this study is to determine whether the prophylactic administration of erythropoietin reduce the incidence of acute kidney injury (AKI) in patients undergoing thoracic aorta surgery with hypothermic cardiac arrest. The investigators administrate the erythropoietin single bolus (500 IU/kg intravenously) 30 min before the commencement of ischemia. The differences between the control and study groups are observed by clinical indicators such as serum creatinine, TNF-α, NGAL.

Inclusion Criteria:

1. Adults above age of 20
2. Undergoing Thoracic Aorta Surgery with Hypothermic Cardiac Arrest

Exclusion Criteria:

1. pregnancy or lactation
2. cerebrovascular thrombosis 3. past history of pulmonary embolism or thrombosis
3. past history of thoracic aortic surgery
4. malignancy 5. preoperative acute kidney injury
5. chronic renal replacement therapy
6. allergy or hypersensitivity to erythropoetin
7. history of erythropoetin treatment
8. death during or one day after surgery
9. no consent
10. reoperation within seven days of the first surgery