Acute Kidney Injury After Cardiac Surgery (NEPHROCAR)

Impact of the Early Hemodynamic Evaluation Guided by Urinary Biomarkers on the Acute Kidney Injury After Cardiac Surgery

Acute kidney injury (AKI) is common after cardiac surgery. The diagnosis is based on the criteria defined by the Kidney Disease Improving Global Outcomes (KDIGO) classification: oliguria and elevation of serum creatinine. However, oliguria is not specific of AKI and elevation of serum creatinine is too late. Therefore, new methods have been developed to earlier assess the risk of AKI. Among those methods, it has been shown that the increase of urinary dosage, in the hours following the surgery, of two proteins (Tissue Inhibitor of Metallo-Protease 2 (TIMP2) and Insulin Growth Factor Binding Protein 7 (IGFBP7)) is associated with an increased risk of occurrence of AKI in patients hospitalized in intensive care unit. The Nephrocheck® test combines the urinary dosage of those two proteins TIMP2 and IGFBP7. Insofar as post-surgery low cardiac output is one curable cause of AKI, the early detection of early kidney risk allows corrective measures to stabilize hemodynamic state and thus to reduce the risk of AKI.

The usual diagnostic markers of AKI are defaulted. Indeed, oliguria tends to overstate the impact of AKI, up to 40-50% of patients. Postoperative increased serum creatinine is a late marker for the AKI. Furthermore, perioperative hemodilution and serum creatinine kinetic delay the postoperative peak of serum creatinine from 48 to 72 h. Nephrocheck® test combines the urinary dosage of 2 proteins (TIMP2 and IGFBP7). These 2 proteins are excreted by the tubular cell in case of suffering whatever the origin, for example tissue hypoxia by low renal blood flow or a systemic inflammatory response. In a medical ICU, the test performed within 4 to 12 hours after kidney aggression can predict the onset of persistent AKI beyond 4 weeks. Until randomization, all patients are treated according to the standard of care for the center. This includes a blood test upon arrival in the intensive care unit and continuous monitoring of vital parameters.

Nephrocheck® test is realized 4 hours after the end of the cardiopulmonary bypass If the test is positive, hemodynamic evaluation is carried out and adapted therapy to result of this evaluation is initiated. If the test is negative, patient management is carried out according to the usual protocol. A second test is realized 6 hours after the first test whatever the result of it.

According to the KDIGO classification: Stage 1; Increase in serum creatinine ≥ 26.5 μmol / l or 1.5 to 1.9 times baseline serum creatinine Stage 2; Increase in baseline serum creatinine from 2.0 to 2.9 times Stage 3; An increase of 3.0 times the baseline serum creatinine or serum creatinine ≥ 354 μmol / l or initiation of renal replacement therapy

Recording (YES/NO) of the recourse of catecholamin required during the medical care, within 48 hours postoperatively

Recording (YES/NO) of the recourse of a particular extracorporeal system within 48 hours postoperatively : Extracorporeal Life Support, heart pumps (Impela® like devices), or Intra-aortic balloon pump.

Proportion of patients with an oliguria defined according to the KDIGO criteria : Stade 1 ; diuresis < 0.5 mL/kg/h for 6 à 12 h Stade 2 ; diuresis < 0.5 mL/kg/h for more than 12h Stade 3 ; diuresis < 0.3 mL/kg/h for more than 24h or anuria ≥ 12h ;

Only for the patients in the Nephrocheck arm, variations between pre and postoperative Nephrocheck® test results will be assessed

Inclusion Criteria: On-pump cardiac surgery ; Informed and written consent of the patient or inclusion according to the emergency procedure; Affiliated patient or beneficiary of a social protection Exclusion criteria: Left and / or right ventricular assist device; Heart transplant; Chronic kidney disease with renal replacement therapy before surgery; Hemorrhagic shock requiring surgical hemostasis at the time of randomization