View of Cerebral Perfusion in Liver Transplantation

Liver transplant surgeries cause intraoperative problems that are difficult to manage from hemodynamic, respiratory, neurological, hematological, and metabolic perspectives due to the nature of liver failure, which affects many organs and systems. Particularly during the anhepatic period, when the healthy graft is integrated into the recipient's vascular system, clamping of the inferior vena cava, one of the two main veins of the hepatic veins, is often required for its connection. This means that a sudden interruption occurs in the blood volume returning to the heart from the lower part of the body, which constitutes half of the total cardiac output.

Cerebral perfusion is also affected during the anhepatic period, and previous studies have observed impaired cerebral perfusion using cerebral oximetry. However, not every clinic has a cerebral oximetry device, and there are factors that limit its use. Some of these factors include high cost, hyperbilirubinemia, variables that disrupt regional blood flow, diabetes, hypertension, and low hemoglobin.

Ultrasound devices are more commonly available in large clinical centers that perform liver transplant surgeries, even for other purposes. It is possible to evaluate the blood flow to the brain using carotid Doppler ultrasonography. The aim of this study is to measure patients' carotid peak systolic and end-diastolic flow and carotid peak systolic flow variability using carotid Doppler ultrasonography and to compare these measurements with cerebral oximetry measurements.

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Inclusion criteria

• Adult patients aged 18-65 years scheduled for elective liver transplantation
• Written informed consent obtained prior to participation

Exclusion criteria

• Fulminant hepatic failure
• Hepatic encephalopathy
• Hepatorenal or hepatopulmonary syndrome
• Pre-existing cerebrovascular disease or carotid stenosis
• Severe cardiopulmonary comorbidity
• Refusal to participate