Cardiac surgery performed on cardio-pulmonary bypass (CPB) may be complicated by coagulopathy and bleeding. This prospective observational study investigated the CPB-induced changes in thrombin generation, fibrin formation, and in the platelet component of the whole blood clot elasticity. The effects of haemostatic therapy with fresh frozen plasma (FFP) and platelet concentrate on these parameters were also evaluated.
In 90 cardiac surgery patients, thrombin generation was measured using the calibrated automated thrombogram, fibrin formation was assessed as the maximum clot elasticity of the fibrin-based clot in the thromboelastometry FIBTEM test (MCE(FIBTEM)), and the platelet component was defined as the difference in maximum elasticity between the whole blood clot obtained through extrinsic activation and the fibrin-based clot (MCE(EXTEM)-MCE(FIBTEM)). Blood samples were collected before surgery, immediately after CPB, and after administration of FFP or FFP and platelet concentrate.
Following CPB, the endogenous thrombin potential decreased to 93%, from median 1485 (interquartile range 1207, 1777) to 1382 (1190, 1533) nM*min (P>0.05), MCE(FIBTEM) decreased to 62%, from 21 (19, 29) to 14 (12, 19) (P<0.001), and the platelet component to 73%, from 139 (119, 174) to 101 (87, 121) (P<0.001). Administration of 11 (10, 13) ml per kg of bodyweight (ml/kgbw) FFP (40 patients), or of 13 (10, 18) ml/kgbw FFP and 7 (5, 9) ml/kgbw platelet concentrate (18 patients) brought no statistically significant changes in these parameters.
Fibrin formation is more impaired than thrombin generation and the platelet component of the whole blood clot immediately after cardiopulmonary bypass.