Near‐Infrared Spectroscopy (NIRS) for Early Postoperative Monitoring of Graft Oxygenation in Living Donor Liver Transplantation: A Prospective Observational Study

ABSTRACT Background Near‐infrared spectroscopy (NIRS) provides a continuous and noninvasive method for assessing hepatic graft oxygenation. Establishing reference LSrO 2 values and evaluating their correlation with perfusion‐related parameters may improve early detection of vascular complications after living donor liver transplantation (LDLT). Aim To determine the clinical utility of NIRS for early postoperative graft monitoring after LDLT and to define physiological hepatic LSrO 2 values in healthy individuals. Methods This prospective observational study included 83 adult LDLT recipients and 30 healthy volunteers. Volunteers underwent single‐time hepatic LSrO 2 assessment to establish reference values. In recipients, continuous NIRS monitoring of liver regional oxygen saturation (LSrO 2 ) was performed during the first 48 postoperative hours. Correlations between LSrO 2 and hemodynamic, laboratory, and Doppler parameters were evaluated at 3, 12, 24, and 48 h. ROC analysis was used to determine a diagnostic threshold of LSrO 2 . Results Healthy volunteers demonstrated a mean hepatic LSrO2 of 76.8 ± 0.89 (95% CI: 76.47–77.13). LDLT recipients had significantly lower LSrO 2 values (74.49 ± 3.74, 95% CI: 73.66–75.32; p < 0.001). LSrO 2 correlated positively with hemoglobin ( r = 0.507 at 24 h), hepatic artery flow velocity ( r = 0.328 at 24 h), and platelet count ( r = 0.401 at 48 h), and inversely with lactate ( r = –0.329 at 24 h). A cutoff LSrO 2 value of 72% predicted perfusion‐related complications with an AUC of 0.76 (95% CI: 0.4319–1.0000), sensitivity 68.8%, specificity 82.1%, and a Youden index of 0.51. Conclusion NIRS demonstrated promise as a reliable adjunct method for early postoperative graft monitoring following LDLT. LSrO 2 values below 72% may indicate early perfusion impairment. Establishing reference LSrO 2 values in healthy volunteers enhances the interpretability of postoperative measurements and supports the integration of NIRS into standard monitoring protocols.

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