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.