Heparin-coated cardiopulmonary bypass circuits reduce blood cell trauma. Experiments in the pig.

Blood cell trauma and postoperative bleeding remain important problems in cardiopulmonary bypass (CPB). We compared heparin-coated with non-coated circuits in the pig. Twenty animals were perfused for 2 h at normothermia using membrane oxygenators (Bentley Bos 50). Two groups were studied. In the non-coated group (NC, n = 11) the CPB circuits used were without a heparin coating. This group had systemic heparinization of 400 IU/kg to maintain an ACT (activated clotting time) of over 400 s during CPB. In the coated group (C, n = 9), all surfaces exposed to blood in the CPB circuits were heparin-coated. This group had the heparin dose reduced to 25% (100 IU/kg) without further administration regardless of ACT. During CPB, group C displayed shorter ACT (per definition), higher platelet count, platelet adhesion and lower fibrinolysis and haemolysis (P less than 0.05) as compared to group NC. No thromboembolic events were detected during CPB. Three animals in group NC and 4 animals in group C were weaned from CPB and protaminized. Four hours postoperatively, the leucocyte consumption was two-fold greater and blood loss about four-fold greater in group NC as compared with group C (P less than 0.05). Perfusion with heparin-coated surfaces reduces blood cell trauma. The decreased postoperative blood loss observed in group C is probably explained by the reduced dosages of heparin and protamine.