Renal Oxygenation-Guided AKI Reduction Trial

ROGAR is an investigator-initiated, multicenter, prospective, randomized, parallel-group superiority trial enrolling approximately 1,200 adults aged 45 years or older undergoing elective open, laparoscopic, or robot-assisted hepatectomy under general anesthesia. Participants will be randomized 1:1 to renal oxygenation-guided management or usual perioperative care using a centralized allocation system stratified by study center.

All participants will undergo continuous bilateral renal regional oxygen saturation (RrSO₂) monitoring using near-infrared spectroscopy. Before randomization, kidney location and suitability for monitoring will be confirmed by ultrasound, and a baseline RrSO₂ value will be established for each side before anesthesia.

In the intervention group, RrSO₂ values will be visible to the anesthesia team. A decrease of 10% or more from the corresponding side-specific baseline will trigger confirmation of signal validity followed by a standardized stepwise management algorithm addressing clinically relevant determinants of oxygen delivery and perfusion. RrSO₂ and hemodynamic responses will be reassessed after each intervention. In the control group, RrSO₂ will be continuously recorded but concealed from the clinical team and will not guide perioperative management.

Inclusion criteria

• Age ≥45 years.
• Scheduled for elective open, laparoscopic, or robot-assisted hepatectomy.
• Planned general anesthesia with tracheal intubation and an expected surgical duration ≥2 hours.
• Stable preoperative serum creatinine available before randomization, with baseline estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m².
• Body mass index <30 kg/m² and bilateral renal cortex-to-skin distance ≤4 cm on ultrasound, allowing reliable bilateral renal NIRS monitoring and stable baseline RrSO₂ signals.
• American Society of Anesthesiologists physical status I-III.
• Ability to understand the study and provide written informed consent.

Exclusion criteria

• Pre-existing or unstable renal dysfunction, including eGFR <60 mL/min/1.73 m², AKI before randomization, unstable or progressively increasing serum creatinine, end-stage kidney disease, chronic dialysis, previous kidney transplantation, or other significant renal disease that may interfere with postoperative AKI assessment.
• Concomitant surgery expected to directly affect renal function assessment, including nephrectomy, kidney transplantation, or renal artery or vein reconstruction.
• Emergency or rescue surgery, or inability to provide valid informed consent before surgery.
• Inability to obtain reliable bilateral renal RrSO₂ monitoring because of excessive tissue depth, positioning, skin lesions, scars, infection, hematoma, severe edema, jaundice, or other technical or anatomical factors despite appropriate sensor repositioning and troubleshooting.
• Severe systemic disease or high perioperative risk, including severe cardiac or pulmonary dysfunction, recent major cardiovascular or cerebrovascular events, severe anemia, or any condition judged by the investigator to make participation unsafe.
• Participation in another interventional clinical trial that may affect perioperative management, AKI risk, or the primary outcome, or any other condition judged by the investigator to make participation unsuitable.