Hydroxyethyl Starch Versus Crystalloid and Postoperative Major Adverse Kidney Complications

This trial aims to compare two intraoperative fluids, namely hydroxyethyl starch (HES) and balanced crystalloids in terms of major adverse kidney events after cardiac surgery. Indications for the study fluids administarion include preload augmentation and intravascular volume replacement during cardiac surgery.

Inclusion Criteria: * Patients aged 19 years or older scheduled for coronary artery bypass grafting (CABG), heart valve surgery, and/or thoracic aortic surgery Exclusion Criteria: 1. Emergency surgery; 2. Planned implantation of a durable left ventricular assist device; 3. History of starch allergy or hypersensitivity; 4. History of kidney transplantation; 5. Preoperative end-stage renal disease (ESRD) or requirement for renal replacement therapy (RRT); 6. Preoperative glomerular filtration rate \< 30 mL/min/1.73 m2; 7. Planned intraoperative and postoperative RRT; 8. Preoperative use of mechanical circulatory support devices (e.g., intra-aortic balloon pump, extracorporeal membrane oxygenation, etc.); 9. Significant clinical coagulopathy (e.g., active bleeding disorder or thrombocytopenia with a platelet count \