title: Early thromboelastometric variables reliably predict maximum clot firmness in patients undergoing cardiac surgery: a step towards earlier decision making.
abstract: BACKGROUND
  While much effort has been spent on guiding coagulation and transfusion therapy in patients undergoing cardiopulmonary bypass (CPB) surgery, the use of conventional laboratory-based coagulation tests is hampered by long turnaround times and interference with heparin and protamine. To allow faster assessment of maximum clot firmness (MCF) by point-of-care thromboelastometry (ROTEM®, TEM International GmbH, Munich, Germany), we tested whether clotting time (CT), clot formation time (CFT), or early values of clot firmness (CF) predict MCF.
  
  
  METHODS
  Results of 437 ROTEM® assays (EXTEM®, INTEM®, FIBTEM®, and HEPTEM®) from 84 patients undergoing CPB surgery were analyzed. Measurements were performed prior to and after heparin administration, as well as after protamine administration and CT, CFT, and CF after 5, 10, and 15 min (A5, A10, and A15) after initial clotting (CT) were related to MCF.
  
  
  METHODS
  Regression and Bland-Altman analyses and receiver-operating characteristics (ROCs).
  
  
  RESULTS
  CFT (r = 0.87-0.95), A5 (r = 0.84-0.98; P < 0.0001), A10 (r = 0.86-0.98; P < 0.0001), and A15 (r = 0.86-0.98; P < 0.0001) demonstrated high correlation coefficients with MCF, whereas CT correlated weakly (r = 0.07-0.41). As expected, correlation coefficients increased with the time allowed to assess a specific variable. ROC analyses demonstrated excellent accuracy for CFT, A5, A10, and A15 [area under the curve (AUC): 0.9476-0.9931] to predict a subnormal MCF, whereas CT demonstrated poor accuracy (AUC: 0.5796-0.6774).
  
  
  CONCLUSIONS
  Taking into account specific bias, early values of CF (A5-A15) reliably predict maximum CF under all conditions and, therefore, allow for marked time savings in the interpretation of ROTEM® measurements. This may guide earlier and more specific treatment of CPB-related coagulation disorders.
authors.affiliation: Klinik für Anästhesiologie und Intensivmedizin, Universitätsklinikum Essen, Universität Duisburg-Essen, Essen, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Dirkmann
authors.forename: K
authors.initials: K
authors.lastname: Görlinger
authors.forename: F
authors.initials: F
authors.lastname: Dusse
authors.forename: E
authors.initials: E
authors.lastname: Kottenberg
authors.forename: J
authors.initials: J
authors.lastname: Peters
mesh_terms: D019540:Area Under Curve; D001777:Blood Coagulation; D001778:Blood Coagulation Disorders / Q000175:diagnosis*; D006348:Cardiac Surgical Procedures; D002315:Cardiopulmonary Bypass / Q000379:methods*; D005343:Fibrinolytic Agents / Q000008:administration & dosage; D006493:Heparin / Q000008:administration & dosage; D006494:Heparin Antagonists / Q000008:administration & dosage; D006801:Humans; D019095:Point-of-Care Systems; D011479:Protamines / Q000008:administration & dosage; D012372:ROC Curve; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013916:Thrombelastography / Q000379:methods*; D013997:Time Factors
chemical_list: D005343:Fibrinolytic Agents; D006494:Heparin Antagonists; D011479:Protamines; D006493:Heparin