Noninvasive Monitoring of Graft Oxygenation With NIRS-Liver in ICU After LDLT

Introduction: Living donor liver transplantation (LDLT) is associated with a high risk of early vascular complications, which requires effective tools for real-time graft monitoring. Liver near infrared spectroscopy (NIRS-liver) is a new non-invasive method that allows continuous assessment of regional hepatic oxygenation (LSrO₂).


Methods: A prospective observational study was conducted involving 124 adult patients who underwent LDLT. On admission to the intensive care unit, a NIRS device (NONIN SenSmart X-100) was used, the sensors were positioned over the graft area under ultrasound guidance. LSrO₂ values were continuously recorded for 48 hours after surgery. Laboratory parameters (Hb, lactate, liver enzymes, coagulation profile) and ultrasound parameters (hepatic artery blood flow velocity, resistance index [RI]) were simultaneously monitored. Correlation between LSrO₂ and clinical and laboratory parameters was assessed after 3, 12, 24 and 48 hours using Pearson and Spearman coefficients. Vascular complications were analyzed using descriptive statistics, χ²-test, odds ratio and ROC-analysis.


Results: Vascular complications were observed in 21.8% of cases (n=27), predominantly arterial (12.9%), with the most common being early hepatic artery thrombosis (4.8%) and early stenosis (3.2%). A significant positive correlation was observed between LSrO₂ and hemoglobin at all time points (r=0.507 at 24 h, p< 0.0001). Platelet count correlated with LSrO₂ only at 48 h (r=0.401, p=0.0001). Hepatic artery blood flow velocity showed a strong association with LSrO₂ at 24 h (r=0.328, p=0.002) and 48 h (r=0.248, p=0.023). RI correlated significantly at 3 h (r=0.350, p=0.001). Elevated lactate levels were inversely correlated with LSrO₂ at 24 hours (r=–0.329, p=0.002). Other variables (ALT, GGT, albumin, INR) did not show a significant association.


Conclusions: NIRS-liver provides reliable monitoring of liver graft oxygenation in real time. Significant correlations with hemoglobin, arterial blood flow, and lactate levels confirm its physiological validity. Integration of NIRS into postoperative monitoring protocols may improve early detection of graft perfusion deficits and vascular complications.