Intraoperative Assessment of Microcirculatory Function Using Vascular Occlusion Test During Liver Transplantation

Early allograft dysfunction (EAD) remains one of the most important complications following orthotopic liver transplantation (OLT). Currently, there is no established intraoperative biomarker that reliably predicts graft dysfunction at an early stage. Near-infrared spectroscopy (NIRS) combined with the vascular occlusion test (VOT) is a non-invasive method for assessing tissue oxygenation and microcirculatory reserve. This prospective observational study aims to investigate whether VOT-derived parameters, including desaturation slope, recovery slope and post-ischemic hyperemic area under the curve (AUC-H), can predict EAD in liver transplant recipients. Measurements will be performed at four predefined intraoperative timepoints: after induction of anesthesia, during the anhepatic phase, during the neohepatic phase and at the end of surgery. The primary outcome is the occurrence of EAD according to Olthoff criteria.

Inclusion Criteria: * Adult patients aged 18 years or older * Patients scheduled to undergo orthotopic liver transplantation * Ability to obtain intraoperative Near-Infrared Spectroscopy measurements * Written informed consent obtained before enrollment Exclusion Criteria: * Age younger than 18 years * Refusal or inability to provide informed consent * Emergency liver transplantation without sufficient time for enrollment * Inability to perform the Vascular Occlusion Test or obtain reliable NIRS measurements * Severe peripheral vascular disease or local upper-limb conditions interfering with monitoring