The association between rotational thromboelastometry parameters and blood loss after cardiac surgery with cardiopulmonary bypass

Abstract

Background:The objectives of this study were to investigate the changes in routine laboratory tests and rotational thromboelastometry variables after cardiopulmonary bypass and to investigate the association of these variables with postoperative blood loss.Methods:Blood was obtained at baseline, at admission to the intensive care unit, and at the first postoperative day. Rotational thromboelastometry tests and measurements of haemoglobin, haematocrit, platelet count, and plasma fibrinogen level (Clauss method) were performed. Excessive bleeding was defined as >1000 mL of chest tube drainage after surgery within 24 h.Results:After cardiopulmonary bypass, haemotocrit was decreased by 21%. Platelet count and fibrinogen level decreased more (35% and 42%, respectively). The largest change was found for clot formation time of INTEM (intrinsically activated coagulation) (+73%). Platelet count was not reflected by maximal clot firmness of PLATEM (platelet component specific coagulation). The decreases in FIBTEM (fibrinogen specific coagulation) maximum clot firmness and fibrinogen at the intensive care unit admission were comparable. Test results outside the reference range were associated with higher median blood loss when compared to values within the reference range, with most significant association for fibrinogen (p < 0.001) and FIBTEM maximal clot firmness (p = 0.016). At baseline, the ability of rotational thromboelastometry parameters to predict postoperative blood loss >1000 mL is higher than the predictive value of fibrinogen (area under the curve = 0.642; 95% confidence interval: 0.487–0.796), but only areas under the curve of APTEM (extrinsically activated coagulation with exclusion of fibrinolysis component) were significantly higher (p⩽0.05). At intensive care unit admission, the highest area under the curve was 0.689 (95% confidence interval: 0.549–0.828) for FIBTEM maximum clot firmness.Conclusion:Rotational thromboelastometry could be a useful point-of-care method to monitor haemostasis because it is a faster and more informative method, and it has a slightly higher predictive ability for blood loss compared to fibrinogen.