Abstract: Objective Acute kidney injury (AKI) is a major complication after cardiac surgery and is an independent risk factor for mortality. However, the optimal intensity of renal replacement therapy for these patients is still controversial. Methods We recruited 151 AKI patients after cardiac surgery and treated with continuous renal replacement therapy (CRRT) during the period from Nov. 2013 to Feb. 2016 and assigned them into 2 groups based on the intensity of CRRT, the high intensity group [35(ml/kg•h), n=78) and the low intensity group [25(ml/kg • h)], n=73). The endpoints of observation were the all- cause mortality within 14, 28 and 90 days and the renal function at the 14th, 28th and 90th days after being grouped. Kaplan- Meier survival curve was used for the analyses. Results The two groups had similar baseline characteristics. There were no significant differences between the two groups in number of death within 14, 28 and 90 days. In high intensity group and low intensity group, the survival rates within 14 days were 63.4% (49/78) and 65.7% (48/73) (χ2=0.591, P=0.442) respectively, the rates within 28 days were 54.5% (43/78) and 55.6% (41/73) (χ2=1.232, P=0.267) respectively, and the rates within 90 days were 45.5% (35/78) and 47.5% (35/73) (χ2=4.560, P=0.094) respectively. The recovery of renal function in survival patients also had no differences between the 2 groups at the 14th, 28th and 90th days. Conclusions In patients with AKI after cardiac surgery, the CRRT intensity of 25 ml/kg/h and 35 ml/kg/h had no differences in mortality within 14, 28 and 90 days and in recovery of renal function in survival patients at the 14th, 28th and 90th days.

Key words: Continuous renal replacement therapy, Cardiac surgery associated acute kidney injury, Intensity, Survival