This study aims to investigate the effects of Cardiovascular Autonomic Neuropathy (CAN) on Acute Kidney Injury (AKI) and clinical outcomes in patients undergoing isolated Coronary Artery Bypass Graft (CABG) surgery requiring extracorporeal circulation(ECC).

Preoperative data including demographics, comorbidities, kidney function tests, hemodynamic parameters, and baseline regional cerebral oxygen saturation (rSO2) will be recorded. Intraoperative data will include hemodynamics, urine output, blood gases, cardiopulmonary bypass and aortic cross-clamp times, cardioplegia details, number of coronary anastomoses, and rSO2 changes at defined time points.

Postoperatively, kidney function, neurological status, mechanical ventilation duration, inotropic drug use, transfusion requirements, complications, ICU and hospital length of stay, and mortality will be evaluated. Acute Kidney Injury will be classified according to KDIGO criteria.

The primary objective is to analyze the effect of CAN on AKI. Secondary objectives include assessing the impact of CAN on other clinical outcomes and exploring the relationship between CAN and intraoperative cerebral oxygen changes.

This study has been approved by the Acıbadem University and Acıbadem Healthcare Institutions Medical Research Ethics Committee (ATADEK) and will be conducted following ethical principles and good clinical practice.

This is a prospective, multicenter study investigating the effects of Cardiovascular Autonomic Neuropathy (CAN) on Acute Kidney Injury (AKI) and other clinical outcomes in adult patients undergoing isolated Coronary Artery Bypass Graft (CABG) surgery with planned extracorporeal circulation (ECC). The study aims to determine whether CAN is associated with AKI incidence and other postoperative outcomes.

Study Population:

Adults aged 18 years or older scheduled for elective isolated CABG surgery with planned ECC.

Inclusion Criteria:

Elective isolated CABG surgery Age ≥18 years

Exclusion Criteria:

Emergency or revision surgeries

Orthopedic conditions preventing standing tests

Chronic respiratory diseases affecting test reliability (COPD, asthma, chronic bronchitis)

Uncontrolled hypertension

Use of antiarrhythmic drugs affecting heart rate-based tests

Chronic kidney failure

Preoperative Assessment:

CAN diagnosis using Valsalva maneuver, sitting-to-standing test, and cold/heat test (positive if ≥2 tests are abnormal).

Collection of demographic data, comorbidities, laboratory tests (BUN, creatinine, GFR, ), hemodynamic parameters, and baseline regional cerebral oxygen saturation (rSO2).

Intraoperative Monitoring:

Hemodynamic parameters, urine output, blood gases, cardiopulmonary bypass and aortic cross-clamp times, and number of coronary anastomoses recorded.

Regional cerebral oxygen saturation (rSO2) continuously monitored during ECC, with values recorded for analysis but not used for clinical decisions.

Mean arterial pressure maintained at 60-100 mmHg; crystalloids infused at ≥100 ml/h; ephedrine administered if MAP <60 mmHg.

Postoperative Evaluation:

Kidney function monitored at 24h, 48h, and 7 days postoperatively using KDIGO criteria.

Evaluation of neurological outcomes, mechanical ventilation duration, inotropic support, transfusion requirements, postoperative complications (reoperation, mediastinitis, myocardial infarction), ICU and hospital length of stay, and mortality.

Study Objectives:

Primary: Assess the effect of CAN on AKI incidence.

Secondary: Evaluate CAN's impact on other clinical outcomes

Ethics and Compliance:

Approved by Acıbadem University and Acıbadem Healthcare Institutions Medical Research Ethics Committee (ATADEK), approval number 2020-21/13.

Conducted according to ethical principles and Good Clinical Practice (GCP) standards.

Inclusion Criteria:

• Adults aged 18 years or older

Scheduled for elective isolated Coronary Artery Bypass Graft (CABG) surgery with planned extracorporeal circulation (ECC)

Provide informed consent

Exclusion Criteria:Emergency or revision CABG surgeries

Chronic kidney failure or dialysis

Severe chronic respiratory disease (COPD, asthma, chronic bronchitis) affecting test reliability

Uncontrolled hypertension

Use of antiarrhythmic drugs affecting heart rate-based autonomic tests

Orthopedic or neurological conditions preventing standing tests

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This study includes adult patients (≥18 years old) scheduled for elective isolated Coronary Artery Bypass Graft (CABG) surgery with planned extracorporeal circulation (ECC). Participants will be evaluated preoperatively for cardiovascular autonomic neuropathy (CAN) using standardized tests. Patients with chronic kidney failure, severe chronic respiratory disease, uncontrolled hypertension, or conditions preventing autonomic testing are excluded. Both male and female adults are eligible, and all participants must provide informed consent.

Individual participant data will not be shared. The data will be used solely for the purposes of this study."