Sarah Bos

89 Efficacy of pro- and anticoagulant strategies in plasma 6 Introduction Major hepato-pancreatico-biliary (HPB) surgery is frequently associated with hemostatic complications including intraoperative bleeding and postoperative venousthrombosis, andthesecomplicationscontributetomorbidityandmortality(1). The pathogenesis of hemostatic events during or after HPB surgery is complex but is likely in part related to alterations in the hemostatic system that develop during surgery or are already present at baseline. For example, complex preoperative hemostatic abnormalities are frequently present in patients with liver disease(2). In addition, hemostatic changes occur during and after partial hepatectomy or orthotopic liver transplantation (OLT) due to hemodilution, consumption, and decreased hepatic synthesis of pro-and anticoagulant factors. Although bleeding during partial hepatectomy may be largely due to surgical and anatomical factors, perioperative changes in the hemostatic system may also contribute(3,4). During OLT, the substantially altered hemostatic system may contribute to bleeding, although surgical factors and portal hypertension contribute significantly(5,6). The risk of deep vein thrombosis following HPB surgery is between 3 and 9% even in patients receiving adequate thromboprophylaxis(7–11). In addition, in liver transplant recipients, thrombotic complications of the hepatic artery or portal vein may occur, and may directly compromise graft function and vitality(12). Prediction of bleeding or thrombosis in this setting is difficult as routine tests of hemostasis, such as the prothrombin time or platelet count, do not appear to reflect actual hemostatic status(1,13). For example, routine hemostasis tests suggest a hypocoagulable state in patients with end-stage liver disease prior to OLT, but when tested with thrombin generation tests that take the balance between pro- and anticoagulant processes into account, patients appear in hemostatic balance, and even have hypercoagulable features(14–17). Indeed, centers now report that many of their liver transplant recipients can undergo the procedure without the use of any blood product transfusions, a clinical confirmation that patients are not overtly hypocoagulable(18). Similarly, although routine hemostatic tests may suggest a hypocoagulable state following OLT or partial hepatectomy, thrombin generation tests or viscoelastic assays may show normo- to hypercoagulability(14,19–21). These laboratory data suggest that administration of prohemostatic products should be limited to actively bleeding patients, and suggest the need of a proactive approach to anticoagulant therapy. However, although this strategy has been disseminated in position papers(22), little clinical evidence on the efficacy and safety of clinically available pro- and anticoagulant drugs in these patient populations is available.