Utility of Whole Blood Hemostatometry Using the Clot Signature Analyzer®for Assessment of Hemostasis in Cardiac Surgery

Background A hemostatic monitor capable of rapid, accurate detection of clinical coagulopathy within the operating room could improve management of bleeding after cardiopulmonary bypass (CPB). The Clot Signature Analyzer is a hemostatometer that measures global hemostasis in whole blood. The authors hypothesized that point-of-care hemostatometry could detect a clinical coagulopathic state in cardiac surgical patients. Methods Fifty-seven adult patients scheduled for a variety of elective cardiac surgical procedures were studied. Anesthesia, CPB, heparin anticoagulation, protamine reversal, and transfusion for post-CPB bleeding were all managed by standardized protocol. Clinical coagulopathy was defined by the need for platelet or fresh frozen plasma transfusion. The Clot Signature Analyzer collagen-induced thrombus formation (CITF) assay measured platelet-mediated hemostasis in vitro. The activated clotting time, platelet count, prothrombin time, activated partial thromboplastin time, and fibrinogen concentration were also measured. Results The postprotamine CITF was greater in patients who required hemostatic transfusion than in those who did not (17.6 +/- 8.0 min vs. 10.5 +/- 5.7 min, respectively; P < 0.01). Postprotamine CITF values were highly correlated with platelet and fresh frozen plasma transfusion (Spearman r = 0.50, P < 0.001 and r = 0.40, P < 0.005, respectively). Receiver operator characteristic curves showed a highly significant relation between the postprotamine CITF and intraoperative platelet and fresh frozen plasma transfusion (area under the curve, 0.78-0.81, P < 0.005) with 60-80% sensitivity, specificity, positive and negative predictive values at cutoffs of 12-14 min. Logistic regression demonstrated that the CITF was independently predictive of post-CPB hemostatic transfusion, but standard hemostatic assays were not. Conclusions The Clot Signature Analyzer CITF detects a clinical coagulopathic state after CPB and is independently predictive of the need for hemostatic transfusion. Hemostatometry has potential utility for monitoring hemostasis in cardiac surgery.