Fibrinogen reduction and coagulation in cardiac surgery

Abstract

Fibrinogen as precursor of fibrin plays an essential role in clot formation. There are three main mechanisms associated with a reduction in fibrinogen concentration during cardiac surgery: hemodilution, consumption, and degradation. Moreover, early fibrinogen degradation products (FgDPs) can interfere with normal fibrin formation of intact fibrinogen. The aim of this study was to determine the relative contributions of hemodilution, consumption, and degradation to fibrinogen loss in cardiac surgery and to evaluate the effects fibrinogen degradation products on blood clot formation in vitro. First, fibrin and fibrinogen concentrations, their degradation products, hematocrit, and albumin concentrations were compared in 10 patients before and after isolated coronary artery bypass graft (CABG) surgery with cardiopulmonary bypass. Second, ex-vivo fibrinogen supplementation experiments were performed. Finally, the effects of purified FgDPs on clotting time and clot firmness were established in vitro in whole blood by ROTEM. Fibrinogen plasma concentration decreased 30% during surgery. This drop appears to be mainly caused by hemodilution, as both hematocrit and albumin levels decreased and no relevant increase in D-dimer levels and FgDPs was observed. Furthermore, the coagulation profile normalized after addition of purified fibrinogen. Early FgDPs demonstrated a significant impact on in-vitro whole blood clotting. Although early FgDPs have a pronounced effect on blood clot formation in vitro and therefore may induce or enhance in vivo coagulopathy, the drop of fibrinogen concentration seen after CABG surgery (using tranexamic acid) is primarily caused by hemodilution.

Short-term recovery pattern of plasma fibrinogen after cardiac surgery: A prospective observational study

“…[ 16 , 17 , 25 ] The typical decrease in plasma fibrinogen has been mainly attributed to hemodilution [ 22 , 26 ] as a consequence of using asanguineous fluid to prime the CPB circuit and for volume resuscitation. [ 27 ] Our results confirm the role of CPB-induced hemodilution as a major contributor to immediate post-CPB hypofibrinogenemia. Consequently, during the initial four hours after heparin reversal, we observed better preservation of plasma fibrinogen with MiECC than cCPB due to less hemodilution from the prime.…”

Thrombin generation and platelet activation in cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy - A prospective cohort study

“…Other mechanisms leading to fibrinogen loss during surgery are fibrinogenolysis or fibrinogen degradation, caused by plasmin-mediated proteolysis after activation of plasminogen through tissue plasminogen activator (t-PA). It is currently unknown to which extent these different mechanisms contribute to the decrease in fibrinogen concentration during CRS/HIPEC [ 59 ]. In our study, we observed an increase of ROTEM ML values postoperative which suggests increased fibrinolysis but simultaneously, fibrinogen values already revealed an increasing trend.…”

Society of Cardiovascular Anesthesiologists Clinical Practice Improvement Advisory for Management of Perioperative Bleeding and Hemostasis in Cardiac Surgery Patients

“…If excessive microvascular bleeding is present after heparin reversal, an assessment of platelets (PLT) and fibrinogen is required in addition to evaluation for coagulation factors deficiency. It is also important to remember that CPB is associated with significant fibrinolysis, 46,47 and therefore the use of antifibrinolytic agents [48][49][50] should be continued beyond the operating room, or restarted if already discontinued, in cases with excessive postoperative bleeding. 51,52 Patients may require transfusion of a single component but frequently more than one component is required to achieve adequate hemostasis.…”