Postoperative acute renal failure is a frequent complication after cardiac surgery. The current practice cannot predict Acute Kidney Injuries (AKI) early enough to reduce a significant kidney assault and prevent an organic dysfunction leading to cortical tubular necrosis.

Several recent studies in cardiac surgery have shown that, both sonographic criteria, such as the Renal Resistive Index (IRR) and urinary biomarkers can predict AKI promptly. These urinary biomarkers are the 'tissue inhibitor of metalloproteinases' (TIMP-2) and the 'insulin-like growth factor binding protein' (IGFBP7). These two proteins are sought noninvasively, directly in the urine, within the same test called 'NephroCheckTM'. These markers, ultrasonographic and biologic, have the advantage of being easy to perform, accessible and seem to have both high sensitivity and specificity to predict AKI promptly after cardiac surgery. Thus, the IRR and the NephroCheckTM test could become essential tests to guide clinicians in determining rapidly whether a patient will develop AKI. However, so far, no study has compared these markers yet.

Therefore, the aim of this prospective observational study will be to compare the effectiveness of the IRR with the NephroCheckTM to predict AKI promptly after cardiac surgery. The secondary outcome will be to determine the threshold of these markers from which patients will be likely to develop AKI

Inclusion Criteria:

• Elective patients

• Patients scheduled to receive an extracorporeal circulation

• Patients aged 60 and older

• Patients at risk of postoperative acute kidney injury presenting at least two of the following risk factors:

  • Age > 60 years.
  • Arteritis defined as severe lower limb arteriopathy or carotid stenosis > 50%
  • Diabetes
  • Valvular or combined surgery
  • Preoperative intra-aortic balloon pump.

Exclusion Criteria:

• Unable to provide informed consent
• Comatose patients
• Patients with dementia
• Patient who underwent a previous sternotomy
• Chronic renal failure (sCr clearance < 30 ml.min-1)
• Renal artery stenosis
• Endocarditis
• Emergent surgery
• Nephrotoxic treatment
• Non-sinus cardiac rhythm

Patients undergoing elective cardiac surgery with extracorporeal circulation and who are at risk to develop postoperative Acute Kidney Injury.