A principal component analysis of postinjury viscoelastic assays: Clotting factor depletion versus fibrinolysis

IntroductionThe mechanisms driving trauma-induced coagulopathy (TIC) remain to be defined, and its therapy demands an orchestrated replacement of specific blood products. Thrombelastography (TEG) is a tool to guide the TIC multicomponent therapy. Principal component analysis (PCA) is a statistical approach that identifies variable clusters; thus, we hypothesize that PCA can identify specific combinations of TEG-generated values that reflect TIC mechanisms.MethodsAdult trauma patients admitted from September 2010 to October 2013 for whom a massive transfusion protocol was activated were included. Rapid TEG values obtained within the first 6 hours after injury were included in the PCA. PCA components with an eigenvalue >1 were retained, and, within components, variable loadings (equivalent to correlation coefficients) >|60| were considered significant. Component scorings for each patient were calculated and clinical characteristics of patients with high and low scores were compared.ResultsOf 98 enrolled patients, 67% were male and 70% suffered blunt trauma. Median age was 41 years (interquartile range 28–55) and median Injury Severity Score was 31.5 (interquartile range 24–43). PCA identified three principal components (PCs) that together explained 93% of the overall variance. PC1 reflected global coagulopathy with depletion of platelets and fibrinogen whereas PC3 indicated hyperfibrinolysis. PC2 may represent endogenous anticoagulants such as the activation of protein C.ConclusionPCA suggests depletion coagulopathy is independent from fibrinolytic coagulopathy. Furthermore, the distribution of mortality suggests that low levels of fibrinolysis may be beneficial in a select group of injured patients. These data underscore the potential of risk for concurrent presumptive treatment for preserved depletion coagulopathy and possible fibrinolysis.