Lars Bagge

Heparin-coated cardiopulmonary bypass circuits and 25% reduction of heparin dose in coronary artery surgery—a clinical study

Cardiopulmonary bypass with systemic heparinization causes trauma to blood cells and coagulation defects. Artificial surfaces could be coated by end-linkage binding of heparin (Carmeda Bioactive Surface, CBAS). Use of such surfaces during cardiopulmonary bypass in animals resulted in less postoperative blood loss and better preservation of blood cells. In this study heparin-coated circuits were employed during coronary artery grafting in 7 patients (Group HC). Concomitantly, the heparin dose was reduced by 25% and an activated clotting time (ACT) of 300 sec was accepted. Additional 7 patients were operated with standard circuits (Group C), requiring ACT above 400 sec with normal doses of heparin. There were no thromboembolic complications in Group HC. The postoperative bleeding was generally low and without significant intergroup differences. Coagulation parameters displayed significantly lower ACT and anti-Factor Xa during bypass in Group HC. A tendency towards less blood cell trauma was observed with heparin-coated circuits. The protamine dose could be reduced by 50%, which significantly reduced the protamine/heparin quotient. This study indicates that routine cardiopulmonary bypass could be performed safely with heparin-coated circuits and reduced intravenous doses of heparin and protamine. It is suggested that the use of heparin-coated circuits may lead to less blood cell trauma.

Fibrinolysis Inhibition and Fibronectin in the Blood in Patients with the Delayed Microembolism Syndrome

Various parameters of fibrinolysis inhibition and the plasma concentration of fibronectin (alpha 2-surface binding glycoprotein, cold insoluble globulin) were measured in patients at risk of developing acute progressive respiratory sufficiency following trauma or sepsis - the delayed microembolism syndrome (DMS). Most parameters measuring fibrinolysis inhibition were significantly higher in the five patients with DMS than in five patients who did not develop the syndrome. Thus, the primary fibrinolysis inhibitor (alpha 2-antiplasmin) was enhanced and the alpha-form of this inhibitor, with affinity to plasminogen, showed the greatest increment and might be of major importance for the delayed elimination of fibrin from the lungs occurring in these patients. The fibronectin concentrations were not lower in patients with DMS than in those who did not develop the syndrome.

Haemostasis at Low Heparin Dosage During Cardiopulmonary Bypass with Heparin-coated Circuits in Pigs

Cardiopulmonary bypass (CPB) causes activation of cascade systems. Although heparin coating of CPB circuits improves biocompatibility, the effects on coagulation remain controversial. Theoretically, heparin coating should permit the reduction of systemic anticoagulation during CPB. We investigated influences on haemostatic variables in animal CPB, comparing heparin-coated circuits and reduced systemic heparinization (group HC) with uncoated circuits and full heparinization (group C). Twenty pigs underwent 2-h CPB. Seven (HC, n = 4; C, n = 3) were weaned from CPB and studied for up to 4 h. Total administered heparin was 470 +/- 6 IU/kg (mean +/- SEM) in group C and 100 +/- 0 IU/kg in group HC. Protamine dosage was significantly reduced in group HC. In group C, levels of prothrombin complex, factor VIII and adhesive platelets were reduced significantly during CPB, and postoperatively there were significantly lower values of prothrombin complex, fibrinogen antithrombin III, factor VIII and adhesive platelets but a significantly increased concentration of von Willebrand factor and cumulative bleeding after 4 h. In conclusion, heparin-coated CPB circuits combined with lowered heparin dosage reduced coagulation factor consumption and preserved platelet function, possibly contributing to improved postoperative haemostasis.