The acute coagulopathy of trauma: mechanisms and tools for risk stratification.

Trauma remains the leading cause of death, with bleeding as the primary cause of preventable mortality. When death occurs, it happens quickly, typically within the first 6 h after injury. The principal drivers of the acute coagulopathy of trauma have been characterized, but another group of patients with early evidence of coagulopathy both physiologically and mechanistically distinct from this systemic acquired coagulopathy has been identified. This distinct phenotype is present in 25% to 30% of patients with major trauma without being exposed to the traditional triggers and is associated with higher morbidity and a 4-fold increase in mortality. Despite improvements in the resuscitation of exsanguinating patients, one of the remaining keys is to expeditiously and reproducibly identify the patients most likely to require transfusion including massive transfusion with damage control resuscitation principles. Several predictive scoring systems/algorithms for transfusion including massive transfusion in both civilian and military trauma populations have been introduced. The models developed usually suggest combinations of physiologic, hemodynamic, laboratory, injury severity, and demographic triggers identified on the initial evaluation. Many use a combination of dichotomous variables that are readily accessible after the patient's arrival to the trauma bay, but others rely on time-consuming mathematical calculations and may thus have limited real-time application. Weighted and more sophisticated systems including higher numbers of variables perform superiorly. A common limitation to all models is their retrospective nature, and prospective validations are needed. Point-of-care viscoelastic testing may be an alternative to early recognize trauma-induced coagulopathy with the risk of ongoing hemorrhage and transfusion.