Haemostasis alterations in coronary artery bypass grafting: comparison between the off-pump technique and a closed coated cardiopulmonary bypass system.

OBJECTIVES: To compare coagulation and fibrinolysis activation in off-pump coronary artery bypass operation and in patients in whom a closed phosphorylcholine-coated cardiopulmonary bypass system was applied. Cardiopulmonary bypass induces activation of coagulative and fibrinolytic systems, which together with intraoperative haemodilution augment the risk of postoperative bleeding and transfusion of blood products.

METHODS: Thirty-six off-pump coronary artery bypass and 36 coronary artery bypass grafting patients in whom a closed, phosphorylcholine-coated cardiopulmonary bypass system with a closed-collapsible venous reservoir (Physio group) was used were prospectively enrolled. Activation of coagulation and fibrinolytic systems was assessed evaluating the release of prothrombin fragment 1.2 and plasmin-antiplasmin complex preoperatively (T0), 30 min after heparin administration (T1), 15 min after protamine administration (T2), 3 h after protamin administration (T3) and on postoperative days 1 (T4) and 5 (T5). Platelet function was evaluated through Platelet Function Analyzer 100(®).

RESULTS: During the operation, prothrombin fragment 1.2 and plasmin-antiplasmin levels were slightly higher in the Physio group, the difference being not statistically significant. In the off-pump coronary artery bypass group, prothrombin fragment 1.2 was significantly higher at T3 (618.7 ± 282.7 vs 416.6 ± 250.2 pmol/l; P = 0.006), T4 (416.7 ± 278.8 vs 310.2 ± 394.6 pmol/l; P < 0.001) and T5 (629.3 ± 295.2 vs 408.4 ± 409.7 pmol/l; P = 0.002), and plasmin-antiplasmin was significantly higher at T4 (731.1 ± 790 vs 334 ± 300.8 ng/ml; P = 0.019) and T5 (1744.4 ± 820.7 vs 860.1 ± 488.4 ng/ml; P = 0.003). Platelet Function Analyzer 100® closure time values were significantly higher in the Physio group patients at T3 (131.3 ± 105.7 vs 215.6 ± 58.9 s; P = 0.002). The off-pump coronary artery bypass patients had greater chest tube drainage (874.3 ± 371.5 vs 629.1 ± 334.5 ml; P = 0.005). The mean priming volume was 1240 ± 215 ml in the Physio group. Much more Physio patients received red blood cell transfusions (14 vs 25 patient; P = 0.009), because of higher intraoperative transfusion rates (6 vs 15 patients; P = 0.016). Despite similar preoperative haemoglobin levels (13 ± 1.2 vs 12.6 ± 1.4 g/dl; P = 0.2), postoperative haemoglobin levels were significantly lower in the Physio group.

CONCLUSIONS: The Physio cardiopulmonary bypass approach does not significantly alter haemostasis during the operation compared with off-pump coronary artery bypass providing a reduced activation in the postoperative period reducing also chest tube drainage. However, further priming volume reduction is required to decrease intraoperative red blood cell transfusion.