Increased focus on traumatic coagulopathy over the last decade has led to more aggressive use of hemostatic agents in resuscitation of the massively bleeding patient. Novel formulations of plasma factors and other therapeutics have opened for early intervention to prevent coagulopathy and may even be utilized in the prehospital setting. Careful selection of patients to receive hemostatic agents early during the resuscitation is of great importance due to the potential detrimental effects of this treatment.
Several studies have identified coagulation parameters as reliable predictors of massive transfusion, even very early after trauma. Prothrombin time international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), fibrinogen concentration, and viscoelastic tests such as thrombelastography (TEG) and rotational thrombelastometry (RoTEM) have proved to be of value in predicting massive transfusion when performed in-hospital. PT/INR appears to be slightly more accurate than the other parameters, with a reported sensitivity of 84.8% and an area under the receiver operating curve of 0.87. Comparison studies on PT/INR, aPTT, and viscoelastic assays do suggest that caution should be taken when point-of-care (POC) methods, as opposed to conventional laboratory analyses, are used. Novel techniques for POC measurement of fibrinogen levels are currently being developed, and preclinical data suggest acceptable agreement with conventional methods.
A number of factors should be considered regarding the feasibility of POC tests in the prehospital environment. In addition to environmental factors such as temperature, altitude, and humidity, electromagnetic interference issues and operators' skills must be taken into account. Coagulation parameters appear to be a useful tool in identifying patients with increased risk of massive bleeding at an early stage. Further studies are needed to determine if prehospital intervention based on POC analyses improves outcome.