AKI(Acute Kidney Injury) is a common complication after cardiac surgery which is associated with increased mortality and morbidity. The conventiional marker for detecting AKI is serum creatinine, however, which has many limits. RRI(Renal Resistive Index) is a non-invasive test measured by ultrasound and could be a useful tool to evaulate renal insult in the early phase. Early detection of renal insult and prevention of progression to AKI can contribute to reduing mortality and morbidity in cardiac surgical patients.

Inclusion Criteria:

• Aged 19 years and older scheduled for cardiac surgery using CPB

Exclusion Criteria:

• Emergency opeartion, pre-operative shock status requiring vasopressor or inotropics, s/p kidney transplant patients, CKD stage 4 and 5 patients, patients who have renal artery stenosis or history of renal artery stent implantation, patients who have ascites with Child-Pugh classification B or C, In case of CPB weaning failure, In case of poor lung function and PaO2 or PaCO2 cannot be maintained within normal range.

Association between renal resistive index(RRI) and AKI(Acute Kidney Injury) in cardiac surgery patients