Preoperative Renal Resistive Index Predicts Risk of Acute Kidney Injury in Patients Undergoing Cardiac Surgery

Objective To investigate whether an elevated preoperative renal resistive index (RRI) predicts acute kidney injury (AKI) in patients undergoing cardiac surgery. Design Prospective cohort study. Setting University hospital. Participants Cohort of 96 adult cardiac surgical patients. Interventions Resistive index was measurement the day before surgery. Measurements and Main Results Renal Doppler was used to measure the resistive index in renal cortical or arcuate arteries the day before surgery. An elevated RRI was defined as≥0.7. AKI was defined as an absolute increase in postoperative compared with preoperative serum creatinine levels by≥26 µmol/L or a relative increase by≥50% or a postoperative urine output Conclusions Patients with an elevated preoperative RRI have an increased risk of developing AKI after cardiac surgery. In combination with other markers, the RRI might be a tool for identifying patients with an increased risk of developing AKI.