Effects of hemodilution, blood loss, and consumption on hemostatic factor levels during cardiopulmonary bypass

Objectives: The purpose of this study was to determine quantitatively the effects of consumption, hemodilution, and blood loss on coagulation and fibrinolytic factor levels during cardiopulmonary bypass. Design: A combination of measured levels of prothrombin, antithrombin, fibrinogen, plasminogen, and antiplasmin along with their activation markers F1.2, thrombin-antithrombin complex, fibrinopeptide A, plasmin-antiplasmin complex, and D-dimer were used with a computer model of each patient's vascular and hemostatic systems to estimate the cardiopulmonary bypass-associated loss of each factor because of hemodilution, blood loss, and consumption. Setting: University hospital. Participants: Nine patients undergoing coronary artery bypass graft surgery. Interventions: None. Measurements and Main Results: At baseline, it was estimated that on average 2%, 3%, and 25%, respectively, of the baseline liver secretion of plasminogen, prothrombin,and fibrinogen were consumed by activation of these proteins. During cardiopulmonary bypass, thrombin and plasmin generation were increased, whereas fibrin generation was decreased because of heparin. Compared with baseline, hemodilution during cardiopulmonary bypass resulted in an average 35% ± 7% decrease in the concentration of coagulation and fibrinolytic proteins, whereas blood loss was responsible for an average 6% ± 5% decrease in these proteins. Blood loss varied substantially among patients, resulting in <1% to 14% decreases in hemostatic protein levels. On average, consumption because of activation resulted in less than a 1% drop in the concentration of coagulation and fibrinolytic factors during cardiopulmonary bypass. Conclusions: Hemodilution is the primary cause of the drop in coagulation and fibrinolytic proteins during routine cardiopulmonary bypass, followed by blood loss, whereas consumption accounts for less than a 1% drop in most patients.