Coagulopathies

Coagulopathies

The most common cause of intraoperative coagulopathy is thrombocytopenia secondary to hemodilution.  Thrombocytopenia is a condition where the circulating platelet count falls below 50,000 platelets per microliter.  As a result of such low circulating platelet levels, people have bleeding tendencies similar to those experienced by hemophiliacs (deficiency of Factor VIII), except that bleeding occurs primarily from small capillaries and venules, as opposed to the larger vessels involved with hemophilia.44

Heparin induced thrombocytopenia (HIT) complicates heparin therapy in about 2% to 5% of patients undergoing cardiopulmonary bypass.  While manifesting mildly without causing excessive bleeding in most patients, it has occasionally led to life threatening hemorrhage, acute arterial thrombosis, myocardial infarction, stroke and limb ischemia.  Recent studies found that this condition results from a specific IgG antiheparin antibody which binds to repeating antigenic determinants in heparin.  This antiheparin antibody in turn binds to the surface of the platelet.  There is no reliable method for predicting which patients will develop HIT.41

Low fibrinogen levels (<150 mg/dl) can contribute to coagulopathy.  It is important therefore, to assure that fibrinogen levels exceed that threshold.  Surgery in general, causes most patients to become more hypercoagulable.  That response is nonspecific and appears to occur within the first hour of surgery/anesthesia60.
In terms of clinical management, treatment of coagulopathy focuses on monitoring preoperative, intraoperative, and postoperative laboratory values pertaining to the patient’s coagulation profile.  Therapy is guided in accordance to clinical need and by measured values deviating from acceptable ranges.

41.    Woodman RC, Harker LA. Bleeding Complications Associated with Cardiopulmonary Bypass. Blood. 1990;76:1680-97,