Study of Peripheral Tissue Oxygenation in End-stage Liver Disease Patients During Liver Transplantation

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

End - stage liver disease can cause many problems to the patients including fatigue, weakness,jaundice, confusion, abdominal pain and distension. Another important problem is the cardiovascular system (heart and blood vessels). There will be the impairment of heart function to pump blood to the distal part of the body. Blood vessels are also affected by the imbalance of chemical agents which are not detoxified by diseased liver, resulting in impairment of oxygen carrying capacity and tissue oxygen exchange. Mechanism of this process is still poorly understood.

This is a study about the peripheral vascular dysfunction by means of vascular occlusion test (VOT). Blood pressure cuff is inflated (to occlude the proximal vessels and induce distal part ischemia), then deflated and observing the distal tissue oxygenation (StO2)change by the probe (Near-infrared spectroscopy : NIRS) at the hand. From our knowledge, there is no study in patients undergoing liver transplantation.

The study investigator would like to observe the change in peripheral tissue oxygenation in different time points during the liver transplantation. We hypothesize that there is a change in microcirculatory function and StO2 in end-stage liver disease patients detected by VOT and NIRS.

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

1. Demographic data: a)age, b)sex, c)diagnosis, d)Model of End-stage Liver Disease (MELD) score, Body Mass Index (BMI)

2. 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

     1. pre-operative (for base line data)
     2. pre-anhepatic phase (15 min. before the inferior vena cava (IVC) clamps)
     3. anhepatic phase (30 min. after the IVC clamps),
     4. reperfusion phase (30 min. after the release the IVC clamps),
     5. 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.

Inclusion Criteria:

• Adult patients suffering from end-stage liver disease scheduled for liver transplantation.

Exclusion Criteria:

• Patients with known peripheral vascular disease
• Patients receiving Oxygen therapy