Acute Kidney Injury After Cardiac Surgery

Study Overview
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Brief Summary
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The investigators seek to determine whether a reduced preoperative renal functional reserve predicts postoperative acute kidney injury in patients with normal estimated glomerular filtration rates undergoing elective cardiac surgery.

Detailed Description
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Although acute kidney injury (AKI) frequently complicates cardiac surgery, methods to determine AKI risk in patients without underlying kidney disease are lacking. Renal functional reserve (RFR) can be used to measure the capacity of the kidney to increase glomerular filtration rate under conditions of physiological stress and may serve as a functional marker that assesses susceptibility to injury. The investigators seek to determine whether a reduced preoperative RFR predicts postoperative AKI in patients with normal estimated glomerular filtration rates undergoing elective cardiac surgery. All centres will measure RFR with creatinine clearance, except University Hospital Giessen where in addition iohexol plasma-clearance will be used.

Official Title
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Preoperative Renal Functional Reserve to Predict Risk of Acute Kidney Injury After Cardiac Surgery: The IRRIV Task Force and Collaborators for the Prevention of Acute Kidney Injury

Conditions
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Acute Kidney Injury

Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Subjects older than 18 years Subjects undergoing elective cardiac surgery (with or without cardiopulmonary bypass) Subjects with an estimated GFR ≥60 ml/min/1.73 m2 (CKD-Epidemiology Collaboration equation) Subjects who signed informed consent forms Exclusion Criteria: Preexisting acute kidney injury (as determined by all available serum creatinine values from hospital and outpatient medical records within the previous 90 days) Chronic kidney disease ≥ stage III (KDIGO) Subjects undergoing transcatheter aortic valve implantation (TAVI) Pregnancy Solitary kidney Diabetes mellitus type 1 Recent cardiac arrest (within last 3 months) Liver failure or cirrhosis Total parenteral nutrition Hemoglobin <11 g/dl Sepsis History of malabsorption, chronic inflammatory bowel disease, short bowel, or pancreatic insufficiency Transplant donor or recipient Active autoimmune disease with renal involvement Rhabdomyolysis Prostate hypertrophy with International Prostate Symptom Score ≥20 Active neoplasm Decompensated heart failure / inability to pause angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers minimum 2 days before protein load Known iodine allergy (exclusion criteria only for those centres who use iohexol plasma clearance for determination of GFR) TSH <0.3 µU/l (exclusion criteria only for those centres who use iohexol) Subjects who received intravenous radiocontrast agents within the 72 hours before the protein load Subjects who received NSAIDs within 48 hours before the protein load

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Whether a reduced preoperative RFR ≤15 ml/min/1.73 m2 increased the odds ratio for postoperative acute kidney injury in patients undergoing elective cardiac surgery. | Renal functional reserve | Preoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| determine preoperative RFR accuracy based on receiver operating characteristic curve curve to predict acute kidney injury. | Renal functional reserve | Preoperative | 
| To analyze an acute kidney injury risk prediction model based on clinical covariates. | Renal functional reserve | Preoperative | 
| Mortality at 30 and 90 days | Mortality | 30 and 90 days after surgery | 
| Length of stay in intensive care unit and hospital. | Hospital stay | Postoperative | 
| Use and duration of renal replacement therapy during hospital stay. | Renal replacement therapy | Postoperative | 
| Renal replacement therapy dependence at days 30 and 90. | Renal replacement therapy | 30 and 90 days after surgery | 
| To evaluate renal function at three months after surgery. | Estimated glomerular filtration rate | 3 months after surgery | 
| To evaluate whether preoperative RFR is correlated to renal function at three months after surgery. | Renal functional reserve | Preoperative | 
| To evaluate whether chronic kidney disease is associated to preoperative RFR. | Renal functional reserve | Preoperative | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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protein load, cardiac surgery