Evaluation of the renal function in patients in the postoperative period of cardiac surgery: does AKIN classification predict acute kidney dysfunction?

OBJECTIVES To identify the frequency of the Acute Kidney Injury and to compare the application of the AKIN classification with the separate use of the serum creatinine in the postoperative period of cardiac surgery. METHODS This study was prospectively developed in a teaching and specialized research hospital in cardiology of the public health system of the state of São Paulo. Forty-four patients submitted to the elective cardiac surgery since the immediate post-surgical period up to the 2nd post-surgical period were followed. RESULTS It was possible to verify that from the forty-four patients, 75% were hypertensive, 27% were diabetic and mostly were male (64%), with an average age of 55+16 years old. It was observed that advanced age and the elevated body mass index shows a significant correlation to renal dysfunction (p<0, 05). According to the AKIN classification, the urinary flow criterion identified more renal dysfunction than creatinine criterion. It was verified that the renal dysfunction occurred more frequently in the postsurgery period and the majority (82%) from the 63,6% of the patients which were submitted to the revascularization of the myocardium surgery. CONCLUSION The majority of patients (75%) evolved initially with renal dysfunction signaled it mainly by the urinary flow criterion from the AKIN classification, a higher number compared to the separated creatinine. This fact confirms that the serum creatinine association with the urinary flow has a higher discriminatory performance for the early identification of this syndrome comparatively with the routinely use of the isolated creatinine.