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.

Bilateral renal regional oxygen saturation will be continuously monitored and displayed to the designated anesthesiologist. A decrease of 10% or more from the corresponding side-specific baseline will trigger assessment of signal validity and a standardized, clinically individualized optimization process addressing volume status, perfusion pressure, cardiac output, heart rate, ventilation and oxygenation, and hemoglobin concentration. Responses after each intervention will be reassessed and recorded.

Device: INVOS 5100C regional oxygen saturation monitoring system · Other: RrSO2-guided perioperative management

Bilateral renal regional oxygen saturation will be continuously recorded, but values and trends will be hidden from the anesthesia and surgical teams and will not be used to guide care. Participants will receive usual perioperative management according to current clinical practice and local standards.

Device: INVOS 5100C regional oxygen saturation monitoring system · Other: Usual perioperative management

A near-infrared spectroscopy system will be used to continuously record bilateral renal regional oxygen saturation from before anesthesia induction until the end of the intraoperative monitoring period. The device is used in both study arms; display of the values differs by randomized allocation.

When either renal RrSO2 decreases by at least 10% from its side-specific baseline, signal artifact and sensor displacement will first be excluded. The anesthesiologist will then assess and treat reversible causes using clinically appropriate measures that may include a small isotonic crystalloid bolus based on goal-directed volume assessment, titrated norepinephrine, dobutamine, treatment of hemodynamically significant bradycardia, optimization of ventilation and oxygenation, and red blood cell transfusion when predefined criteria are met. RrSO2 and hemodynamic responses will be reassessed after each action.

Perioperative anesthesia and hemodynamic management will follow current clinical practice and institutional standards. Renal RrSO2 values will remain hidden and will not be used for clinical decisions.

Plazo: From the end of surgery through postoperative day 7 or hospital discharge, whichever occurs first

Proportion of participants who develop acute kidney injury (AKI), defined by any of the following: an increase in serum creatinine of ≥0.3 mg/dL (26.5 μmol/L) within 48 hours; an increase in serum creatinine to ≥1.5 times the preoperative baseline within 7 days; or initiation of new renal replacement therapy within 7 days. Urine-output criteria will not be used for the primary outcome.

Plazo: Through postoperative day 7 or hospital discharge, whichever occurs first

Highest postoperative acute kidney injury (AKI) stage according to Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Outcomes will include the highest KDIGO stage (no AKI, stage 1, stage 2, or stage 3) and the incidence of severe AKI, defined as KDIGO stage 2 or 3.

Plazo: From the end of surgery until hospital discharge, assessed up to 30 days after surgery.

The highest serum creatinine concentration measured after surgery during the index hospitalization will be identified for each participant and reported in micromoles per liter (μmol/L).

Plazo: From the end of surgery through postoperative day 7 or hospital discharge, whichever occurs first, assessed for up to 7 days.

Among participants who develop AKI, the clinical course of AKI will be characterized according to prespecified definitions of transient AKI, persistent AKI, and kidney recovery.

Plazo: Through postoperative Day 7 or hospital discharge, whichever occurs first

The proportion of participants who newly initiate renal replacement therapy (RRT) for acute kidney injury from the end of surgery through postoperative Day 7 or hospital discharge, whichever occurs first. Renal replacement therapy includes any form of intermittent or continuous kidney replacement therapy initiated during the assessment period.

Plazo: Through postoperative day 30

The proportion of participants who are receiving renal replacement therapy through postoperative Day 30.

Plazo: From the end of surgery to hospital discharge,assessed up to 30 days after surgery.

In-hospital outcomes will included ICU length of stay, postoperative hospital length of stay.

Plazo: Through postoperative day 30

Postoperative morbidity will be assessed by the Clavien-Dindo grade, and the Comprehensive Complication Index (CCI). The CCI will be calculated from all postoperative complications occurring within 30 days after surgery after assigning a Clavien-Dindo grade to each event and ranges from 0 (no complication) to 100 (death).

Plazo: At baseline and postoperative day 30

Health-related quality of life will be assessed using the validated Chinese version of the EuroQol 5-Dimension 5-Level (EQ-5D-5L).

Plazo: From randomization through postoperative day 30

Total direct medical costs incurred from randomization through postoperative Day 30 will be assessed in Chinese yuan (CNY).

Plazo: From the end of surgery through postoperative Day 30

The outcome will be the proportion of participants who die from any cause within 30 days after surgery. The date of death will be recorded when available.

Effect of Renal Oxygenation-Guided Perioperative Management on Acute Kidney Injury After Elective Hepatectomy: A Multicenter, Randomized, Controlled, Parallel-Group Superiority Trial