The current international Continuous Renal Replacement Therapy (CRRT) replacement fluid doses of 35 ml/kg/h is better, but the result is according to white people, black people . It is Whether the best amount of replacement fluid for Chinese people, it is unclear. Especially,there is little evidence about the optimal dose from randomized trials in Cardiac surgery associated acute kidney injury (CSA-AKI )required CRRT,According to the clinical situation, the design of replacement fluid to 25 ml/kg/h.The observation of two doses 14 days, 28 days, 90 days survival and renal function.