Surveillance de l'hémostase au cours de la transplantation hépatique : apport du thromboélastogramme

Monitoring of coagulation is mandatory during liver transplantation (LT). Standard coagulation tests may be routinely used. However, they give static information and may be inadequate in case of severe coagulation defect. Interest has been recently focused on thromboelastography (TEG) which could give more suitable and rapid information in these cases. Few studies have evaluated the clinical interest of TEG compared to conventionnal tests. This comparison was the aim of the present study, performed in 89 patients scheduled for LT. The anaesthetic management as well as procedure of transfusion were similar in all patients. Before unclamping, 5000 KUI · kg⁻¹ of aprotinin were injected. Routine tests and TEG were performed at the beginning and end of both preanhepatic and anhepatic phases, and 5, 30, 60, and 120 min after the revascularisation of the new liver. A phase of hypocoagulability was observed after unclamping. Biological signs included an increase in activated thromboplastin time, a reduction of α angle and maximum amplitude on TEG with a lengthening of its r + k component. A strong correlation existed between maximum amplitude and platelets, maximum amplitude and fibrinogen, α and fibrinogen at each time of the surgical procedure. Euglobulin lysis time decreased significantly after clamping, whereas fibrin degradation products increased at the same time. However, typical fibrinolysis with a clot lysis index (CLI) below 55 % was only observed in 15 patients. Twelve of them had a CLI value reaching 0 %, associated with severe generalized oozing. Aprotinin (200 000 to 600 000 KIU) corrected these abnormalities. These results show that TEG may not be very helpful to determine whether platelets or fibrinogen are involved in the phase of hypocoagulability detected after unclamping. However, TEG allows the actual diagnosis of fibrinolysis and guides therapy. Moreover, it may have a predictive value in some limited cases.