Microcirculation and the effects of blood transfusion in liver transplantation

Liver disease represents a growing public health issue and is a significant cause of death worldwide. Liver transplantation remains the definitive treatment for end stage liver disease. Liver transplantation is traditionally associated with high rates of haemorrhage and intraoperative blood transfusion. There is evidence that both blood loss, and, although often necessary and lifesaving, blood transfusions are associated with adverse outcomes after liver transplantation. Cirrhosis represents a chronic inflammatory state that develops due to progressive liver damage. Cirrhosis results in circulatory alterations throughout the body, affecting different tissues and organs, and their microcirculation, in a heterogeneous manner. Non-invasive methods of microcirculatory monitoring can now be utilised to examine the effects of liver disease upon microcirculatory blood flow and vascular reactivity. Experiments to examine effect of blood transfusion, bleeding and surgery upon the microcirculation and vascular reactivity during liver transplantation were undertaken. Despite improvements in haemoglobin concentration with blood transfusion there was no significant improvement in microcirculatory flow. Over the duration of the liver transplant, in spite of alterations in haemoglobin and macrovascular measures of circulatory adequacy, there was no correlation with indices of microvascular flow. Microcirculatory flow and tissue oxygenation was well maintained even at low haemoglobin concentrations without significant alteration by blood transfusion, suggesting that even lower transfusion thresholds might safely be adopted. Further work should assess the efficacy of treating preoperative anaemia and safe transfusion thresholds in liver transplantation