[Monitoring blood coagulation in larger liver operations].

Bleeding is causally related to about 50% of postoperative deaths following liver resection. Main factors contributing to increased perioperative bleeding in liver surgery include surgical trauma, reduced activity of clotting factors and inhibitors due to impaired hepatic synthesis, low platelet count and poor platelet function as well as impaired clearance of activated clotting factors by the reticuloendothelial system of the liver (Kupffer cells). Hemostasis may be further impaired by transfusion of blood components, since citrate added for conservation is not adequately metabolized by the failing liver. Surgical bleeding leads to a loss of pro- and anticoagulatory factors as well as to activation of coagulation. Finally, hyperfibrinolysis induced by release of tissue plasminogen activator (t-PA, primary hyperfibrinolysis) and disseminated coagulation (secondary hyperfibrinolysis) contribute to increased bleeding. Therefore early diagnosis and treatment of coagulation disorders is of paramount importance during liver surgery. Screening parameters of hemostasis and fibrinolysis should be available on a 24-hour basis in centers performing liver surgery. Screening for disorders of secondary hemostasis includes evaluation of prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen concentration and the activity of the most important inhibitor, antithrombin III (AT III). Thrombelastography is the leading method for diagnosis of hyperfibrinolysis, which can also be assessed by determination of D-dimer, fibrinogen and fibrin degradation products. Evaluation of primary hemostasis is frequently restricted to platelet count, which is only a rough parameter. In contrast, measurement of in vitro bleeding time and volume enables repeated quantification of platelet function in patients with impaired hemostasis.