Evaluation of a new platelet function analyzer in cardiac surgery: a comparison of modified thromboelastography and whole-blood aggregometry.

OBJECTIVES: Impaired hemostasis of multiple etiologies are often present in patients undergoing cardiopulmonary bypass (CPB) surgery. Platelet dysfunction is considered to be important in the early postoperative period. Therefore, a new whole-blood platelet function analyzer was compared with thromboelastography in predicting postoperative hemostatic outcomes as measured by blood loss and blood product use. DESIGN: Prospective study. SETTING: Teaching hospital. PARTICIPANTS: The study enrolled 54 patients scheduled for coronary artery bypass surgery with CPB. INTERVENTIONS: Coagulation and platelet function were assessed preoperatively, after CPB, at 3 hours, and at 24 hours after surgery by using thromboelastography and impedance aggregometry. Patients were divided into a transfused and nontransfused group on the basis of postoperative transfusion requirements. Postoperative blood loss and requirements of blood transfusions were documented until 24 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Twenty-five patients (46%) received postoperative blood transfusions. Impaired hemostasis occurred after CPB detected by thromboelastography (p < 0.01) and impedance aggregometry (p < 0.01). In contrast to thromboelastography, preoperative adenosine diphosphate-mediated aggregometry correlated with postoperative requirements for blood transfusion (Spearman r = -0.302, p < 0.05) and was significantly lower in patients receiving allogeneic blood transfusion compared with nontransfused patients (p < 0.05). Neither aggregometry nor thromboelastography was correlated with postoperative blood loss. CONCLUSION: Impedance aggregometry as well as thromboelastography are able to detect impaired hemostasis after CPB. In contrast to thromboelastography, aggregometry using a new whole-blood aggregometer identified patients with a reduced risk for postoperative transfusion requirements.