[Evaluation of the renal function in cardiac surgery with CPB: role of the cystatin C and the calculated creatinine clearance].

Objectives: The evaluation of the renal function in cardiac surgery is difficult. The gold standard remains the creatinine clearance in clinical practice. Cystatin C was recently proposed in order to evaluate the renal function. The aim of our study was to evaluate the cystatin C in cardiac surgery with CPB.

Patients And Methods: After informed consent and ethical committee agreement, 60 patients operated in cardiac surgery with CPB were prospectively included. Cystatin C,measured and calculated (Cockcroft and MDRD methods) creatinine were compared with the Student t-test and with the Bland and Altman method. p<0,05 was considered as a significant threshold.

Results: The reproducibility of the calculated creatinine clearance was better when the urinary collecting time was below 400 minutes. The estimation of the creatinine clearance by the Cockcroft and MDRD methods is better when the clearance is low. A significant correlation between the creatinine clearance and the cystatin C does exist, but the correlation coefficient was low. In case of acute renal dysfunction, the increase of the creatinine occurred earlier than the increase of the cystatin C.

Conclusion: In cardiac surgery with CPB, the evaluation of the renal function was not improved by the cystatin C.