Thromboelastography as a Better Indicator of Postinjury Hypercoagulable State Than Prothrombin Time or Activated Partial Thromboplastin Time

Objectives—To investigate the hemostatic status of critically ill, nonbleeding trauma patients. We hypothesized that a hypercoagulable state exists in patients early after severe injury and that the pattern of clotting and fibrinolysis are similar between burned and nonburn trauma patients. Materials and Methods—Patients admitted to the surgical or burn intensive care unit within 24 hours after injury were enrolled. Blood samples were drawn on days 0 through 7. Laboratory tests included prothrombin time (PT), activated partial thromboplastin time (aPTT), levels of activated factor XI (FXIa), D-dimer, protein C percent activity, and antithrombin III (AT III) percent activity, and thromboelastography (TEG). Results—Study subjects were enrolled from April 1, 2004, through May 31, 2005, and included nonburn trauma patients (n=33), burned patients (n=25), and healthy (control) subjects (n=20). Despite aggressive thromboprophylaxis, 3 subjects (2 burned and 1 nonburn trauma patients [6%]) had pulmonary embolism during hospitalization. Compared with controls, all patients had prolonged PT and aPTT (P<.05). The rate of clot formation (α angle) and maximal clot strength were higher for patients compared with controls (P<.05), indicating a hypercoagulable state. Injured patients also had lower protein C and AT III percent activities and higher fibrinogen levels (P<.05 for all). FXIa was elevated in 38% of patients (control subjects had undetectable levels). Discussion—TEG analysis of whole blood showed patients were in a hypercoagulable state; this was not detected by plasma PT or aPTT. The high incidence of pulmonary embolism indicated that our current prophylaxis regimen could be improved.