The kidney is one of the most vital organs in the human body. Renal perfusion is primarily supplied by the renal artery, while the removal of metabolites and venous drainage are provided by the renal vein. Although anatomical variations may exist, the renal artery typically originates from the abdominal aorta. In patients undergoing liver transplantation, renal function may be affected by multiple factors. Impairment of renal function significantly influences postoperative mortality, morbidity, graft survival, and length of hospital stay.
Intraoperative assessment of renal perfusion has traditionally relied on monitoring hourly urine output and serum renal function tests. However, these methods may be insufficient and delayed in evaluating renal function, particularly during clamping of the inferior vena cava for hepatic graft venous anastomosis. Although Doppler ultrasonography can provide information regarding blood flow, it does not offer direct insight into the adequacy of tissue perfusion.
Near-infrared spectroscopy (NIRS) is a non-invasive technique that has gained increasing attention in recent years due to its ability to accurately assess tissue oxygenation. Based on the Beer-Lambert law, NIRS enables the measurement of tissue oxygen saturation without the need for invasive procedures. The technique requires no intervention and is not associated with known complications or adverse effects.
NIRS is most commonly used in clinical practice to assess cerebral oxygenation via measurements obtained from the frontal region. The aim of the present study is to evaluate renal oxygenation using near-infrared spectroscopy and to determine whether this technique provides clinically useful information during the liver transplantation procedure.