Study of Peripheral Microcirculatory Dysfunction in End-stage Liver Disease Patients During Liver Transplantation Using Near Infrared Spectroscopy

End - stage liver disease patients scheduled for liver transplantation will be enrolled. They will receive normal standard of care. The VOT assessment using a non-invasive, integrated research device (InspectraTM StO2 Vascular Occlusion test (VOT) Research Device Hutchinson Corp Minn, MN, USA) and 15 mm Inspectra thenar sensor probe. An integrated blood pressure cuff is placed on the right arm and inflated to a pressure sufficient to produce arterial inflow occlusion (50mmHg above systolic pressure). The cuff remains inflated until a StO2 value of 40% is achieved. During the inflation and deflation, various StO2 parameters are measured and recorded at designed time point. Specific VOT parameters of interest: Baseline StO2 (reflective of perfusion/metabolism ratio) Ischemia slope (partly reflective of basal O2 consumption) Ischemia area (partly reflective of basal O2 consumption) Time till 40% ischemic threshold (partly reflective of basal O2 consumption) Recovery slope (biphasic and reflective of shear stress and endothelial vasoreactivity) Recovery area (reflective of endothelial vasoreactivity) Hyperemia area (reflective of endothelial vasoreactivity and tissue metabolic rate) To determine effect of core versus peripheral temperatures, a conventional skin thermocouple will be placed under adhesive patch used to secure NIRS optodes in position on thenar eminence Data collection Demographic data: a)age, b)sex, c)diagnosis, d)Model of End-stage Liver Disease (MELD) score, Body Mass Index (BMI) Clinical parameter : the investigator will collect clinical data including VOT parameters (from above), hemodynamics parameter, chemical parameters and medications used in specific time frame : time frame pre-operative (for base line data) pre-anhepatic phase (15 min. before the inferior vena cava (IVC) clamps) anhepatic phase (30 min. after the IVC clamps), reperfusion phase (30 min. after the release the IVC clamps), immediately post operation (at the skin closure) hemodynamics : SpO2 (Pulse oxygen saturation), MAP (mean arterial pressure), HR (heart rate), CVP (Central venous pressure), PAP (Pulmonary artery pressure), CI (Cardiac output index), PCWP (Pulmonary artery wedge pressure), SVRI (Systemic vascular resistance index), PVRI (Pulmonary vascular resistance index), temperature chemical : Hb, Platelets, INR (international normalized ratio) (PT : Prothrombin time), PTT (partial thromboplastin time), Lactate, base excess Medications : Volatile agents, Vasopressors (Concentration at recorded time points) Then we will compare the dynamic changes of StO2 parameters in different time points (as mentioned) and compare to the hemodynamics and chemical parameters.