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

Introduction: The 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.

Methods: Adult 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.

Results: Of 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.

Conclusion: PCA 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.