Diagnostic Accuracy of Doppler Resistive Indices for Early Diagnosis of Acute Kidney Injury .

Inclusion Criteria: * adult patients \>= 18 years * undergoing cardiac surgery with cardiopulmonary bypass and transesophageal echocardiography (TEE) probe placement Exclusion Criteria: * chronic kidney diseases (estimated GFR \< 60 ml/min/1.73m2) * prior carotid endarterectomy * known carotid artery stenosis of 50% or greater * dissection or aneurysm involving renal or carotid arteries * scheduled aortic or aortic valve surgery * heart transplant * intraaortic balloon pump, ventricular assist device, or exctracorporeal membrane oxygenation support.