Sarah Bos

68 CHAPTER 5 Plasma fibrinogen levels decrease during partial hepatectomy and liver transplantation,(40,47) and recover over time to supraphysiological levels.(48) In patients with cirrhosis, plasma fibrinogen has both hypo- and hypercoagulable features. Specifically, hypersialation impairs fibrin polymerization and thus delays clot formation.(49) However, the ultimately formed fibrin clot has a decreased permeability as compared with clots generated from healthy individuals.(50) As fibrin clot permeability is considered the “gold standard” of fibrin clot quality, we previously concluded that the fibrin clot of patients with cirrhosis has a net prothrombotic nature.(47,50) During liver transplantation, the permeability of the plasma clot increases and the quality of fibrin clot during transplant becomes substantially impaired.(51) Fibrin clot structure, to our knowledge, has not been studied in samples taken during partial hepatectomy. Fibrinolysis During partial hepatectomy and liver transplantation, plasma levels of liver- derived fibrinolytic proteins (i.e., plasminogen, antiplasmin, thrombin-activatable fibrinolysis inhibitor) decreases, whereas levels of endothelial-derived fibrinolytic proteins (i.e., tissue-type plasminogen activator [tPA] and plasminogen activator inhibitor type 1 [PAI-1]) increases.(36,52) The net effect of the complex changes in the fibrinolytic system during and after hepatobiliary surgery is an intraoperative hyperfibrinolytic status in part of the patients, likely because release of t-PA overwhelms the circulating and acutely released PAI-1.(53,54) Following any surgery, a temporary hypofibrinolytic state occurs due to a temporary elevation of PAI-1 (the postoperative fibrinolytic shutdown).(55) Following partial hepatectomy, one study has shown normalization of plasma fibrinolytic potential at day 1, with a “second wave” of hypofibrinolysis between days 3 and 7.(36) Interestingly, a strikingly similar “two wave” hypo- fibrinolytic state was observed following pancreas resection, indicating that the sustained hypofibrinolytic state is at least in part unrelated to decreased synthetic function of the liver.(36) Following liver transplantation, plasma fibrinolytic potential slowly normalizes over time.(56) Plasma hypofibrinolysis thus characterizes the early postoperative period of hepatobiliary surgery. Summary of Hemostatic Status during and after Hepatobiliary Surgery Table 1 summarizes changes in the hemostatic system during and after partial liver resection and liver transplantation. Maintained hemostatic balance characterizes the hemostatic function of patients during and after hepatobiliary surgery despite intra- operative decreases in plasma levels of hemostatic proteins, decreasing platelet count, and increasing PT. Intra- operatively, the hemostatic balance has distinct hypo- and hypercoagulable features. Specifically, hypofibrinogenemia and