Prognostic Value of Metabolic Characteristics in High-Risk Populations for Acute Kidney Injury After Cardiac Surgery

Inclusion Criteria: * All patients is going to undergo non-emergency cardiac surgeries, including cardiopulmonary bypass or non-cardiopulmonary bypass surgeries; * Patients must have the risk of developing AKI, and at least meet one of the following criteria: cardiopulmonary bypass cardiac surgery + at least one risk factor; or non-cardiopulmonary bypass surgery such as simple coronary artery bypass grafting + at least two AKI risk factors. The risk factors includes: * Age ≥ 70 years; * Diabetes (type 1 or type 2), requiring at least one oral hypoglycemic drug or insulin; * 30 ≤ eGFR ≤ 60 mL/min/1.73 m2 (CKD-EPI formula); * Recorded history of proteinuria (random urine albumin-to-creatinine ratio UACR \> 30 mg/g, or 24-hour urine albumin \> 300 mg/24 hours, or urine protein ≥ +1 in urine test strips/urine routine tests); * Previous history of hospitalization for congestive heart failure or NYHA classification III/IV; * Left ventricular ejection fraction (LVEF) ≤ 40%; ⑦ Previous history of open-chest cardiac surgery; * CABG combined with valve surgery; ⑨ Surgery involving more than one heart valve; ⑩ Emergency surgery; ⑪ Preoperative IABP Exclusion Criteria: * There were urgent indications for initiating RRT at the time of enrollment, including serum potassium ≥ 6.0 mmol/L, pH value ≤ 7.20, serum bicarbonate ≤ 12 mmol/L, oxygenation index ≤ 200 mmHg; presence of volume overload, severe respiratory failure, etc.; * Preoperati…