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Liver transplantation remains the only curative treatment for patients with end-stage liver disease. Despite a steadily increasing demand for suitable donor livers, the current pool of donor organs fails to meet this demand. To resolve this discrepancy, livers traditionally considered to be of suboptimal quality and function are increasingly utilized. These marginal livers, however, are less tolerant to the current standard cold preservation of donor organs. Therefore, alternative preservation methods have been sought and are progressively applied into clinical practice. Ex situ machine perfusion is a promising alternative preservation modality particularly for suboptimal donor livers as it provides the ability to resuscitate, recondition, and test the viability of an organ prior to transplantation. This review addresses the modalities of machine perfusion currently being applied, and particularly focuses on the hemostatic management employed during machine perfusion. We discuss the anticoagulant agents used, the variation in dosage, and administration, as well as the implications of perfusion for extended periods of time in terms of coagulation activation associated with production of coagulation factors during perfusion. Furthermore, in regard to viability testing of an organ prior to transplantation, we discuss the possibilities and limitations of utilizing the synthesis of liver-derived coagulation factors as potential viability markers. [ABSTRACT FROM AUTHOR]

There is increasing evidence that portal hypertension plays a major role in bleeding risk during orthotopic liver transplantation (OLT). We investigated the association between preoperative blood levels of von Willebrand factor (VWF) and soluble CD163 (sCD163), which are established markers of portal hypertension, and blood loss and transfusion requirements during OLT. We measured levels of VWF and sCD163 in preoperative serum samples of 168 adult patients undergoing a primary OLT between 1998 and 2012. Preoperative levels of VWF and sCD163 correlated with the model of end-stage liver disease (MELD) score ( r  = 0.414, p  < 0.001 and r  = 0.382, p  < 0.001, respectively). Patients with high VWF or sCD163 levels (VWF and sCD163 levels above the median) had a substantially increased risk of needing red blood cell transfusion compared with patients with low VWF or sCD163 levels (VWF and sCD163 levels below the median) (odds ratio 3.5 [95% confidence interval, CI 1.7–7.0] and 2.3 [95% CI 1.1–4.5], respectively). Blood loss was highest in patients with both high VWF or sCD163 levels and a high preoperative international normalized ratio. Elevated blood levels of markers of portal hypertension are associated with increased blood loss and transfusion requirements during OLT and support the notion that portal hypertension is an important contributor to perioperative blood loss. [ABSTRACT FROM AUTHOR]

Hepatobiliary surgery is a well-known risk factor for thrombotic complications but is also associated with substantial perioperative blood loss. Given the central role of the liver in hemostasis, hepatobiliary surgery is frequently accompanied by complex changes in the hemostatic system. Increasing knowledge of these changes has resulted in an improved understanding of the etiology of some of the hemostatic complications. In the early postoperative period a prolongation of conventional coagulation test times, such as the prothrombin time, is frequently seen. Together with a decreased platelet count, this suggests a hypocoagulable state. The concomitant decline of anticoagulant factors and development of a von Willebrand factor/ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) imbalance, however, suggest a hypercoagulable state, potentially contributing to the risk of thromboembolism. Postoperative thromboprophylaxis should be initiated early to avoid thrombosis, and intensified prophylaxis might benefit highrisk patients. The risk of hemorrhagic complications during hepatobiliary surgery has diminished over time, mainly due to improved surgical and anesthesiological techniques. However, bleeding can still be profound in individual patients and is difficult to predict using (global) hemostasis tests. A restrictive transfusion and fluid infusion policy tomaintain a low central venous pressure is crucial in prevention of perioperative bleeding. However, when active bleeding occurs, proactive prohemostatic management is required. [ABSTRACT FROM AUTHOR]