The CPB; fibrinoLysis Or Thrombosis? (CLOT) study, understanding the effects of CPB on coagulation and fibrinolysis to improve treatment of blood loss after cardiac surgery.

Background
Excessive postoperative blood loss (>2L/24 hours or >200 mL/hour) is one of the
most common complications of cardiac surgery, and a risk factor for prolonged
mechanical ventilation, pneumonia, wound infection, sepsis, and mortality. A
surgical cause of bleeding is only found in half of patients undergoing
reoperation/re-exploration for bleeding. In the remainder of patients the cause
is multifactorial and probably an acquired/surgical related hemostatic defect
is responsible for diffuse, excessive blood loss.
Cardiac surgery with concomitant CPB can profoundly alter the hemostatic
balance. Excessive activation of the hemostatic system, which is related to
high doses of heparin, interaction of blood with the extensive, non-endothelial
CPB surfaces, activation of the extrinsic clotting pathway secondary to
surgical trauma and transfusion of pericardial blood with a thrombin-mediated
factor consumptive process as result, primary fibrinolysis, and hemodilution
contribute to dysfunction of the coagulation, fibrinolytic, and inflammatory
systems that lead to a postoperative coagulopathy and, in some cases, excessive
bleeding.
With the *CPB; fibrinoLysis Or Thrombosis* CLOT study, a study to investigate
the effects of CPB on coagulation and fibrinolysis, we would like to broden our
knowledge of the hemostatic blance before, during, and after cardiac surgery.
The relative contributions of a factor consumptive process and fibrinolysis
during operation, caused by the CPB and related proceedings, on the hemostatic
balans of a patient during and after cardiac surgery will be studied. With the
obtained data we would like to differentiate between a pro-thrombotic, a (post)
factor consumptive process, and a (post)fibrinolytic state after cardiac
surgery to improve the treatment of excessive blood loss at the ICU and to
enlarge its cost-effectiveness.

Hypothesis
This study will test the hypothesis that the hemostatic balance of a patient
after cardiac surgery is rather (post)DIC or (post)fibrinolytic, than
pro-thrombotic.
Further we hypothese that longer use of CPB is associated with predomination of
fibrinolysis to a disseminated intravascular coagulation (DIC) process.

The aim of the study is to understand the effects of CPB on coagulation and
fibrinolysis to improve treatment of excessive blood loss (>2L/24 hours or >200
mL/hour) after cardiac surgery.
The objective of this study is to differentiate between a pro-thrombotic, a
(post)DIC, and a (post)fibrinolytic state after cardiac surgery. This
differentiation might lead to an improvement of patient care and extend the
cost effectiveness in the care of patients after cardiac surgery.

This is a multi center observational study in the LUMC in Leiden and Haga
Hospital in The Hague, the Netherlands.

The measurements necessary to asses the defined study endpoints are not
expected to negatively influence the result of treatment or patient condition.