Translational studies on mechanical hemostasis and coagulopathy in trauma

Sammanfattning: Trauma, in terms of physical injury, is the leading cause of death and disability among children and young adults worldwide. Hemorrhage and coagulation dysfunction are two important causes of preventable deaths after traumatic injuries. Novel methods for management of non-compressible hemorrhage and treatment of trauma induced coagulopathy (TIC) may reduce mortality. In this thesis we investigate two fundamentally different methods for mechanical hemorrhage control after potentially lethal truncal hemorrhage: intravascular occlusion- and external compression of the aorta. The Abdominal Aortic and Junctional Tourniquet® (AAJT) and Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) were initially introduced in military medicine as possible interventions to avoid exsanguination from large vessel injuries. We assessed these interventions during 60 to 240 minutes with the aim to identify specific physiological effects and suggest tolerable application times. The feasibility of a transition between the methods was studied. We investigated the hemodynamic effects of crystalloid- and whole blood transfusion in conjunction with the interventions. Intermittent reperfusion during REBOA, with the aim to decrease organ damage was investigated. We introduced a method for advanced analyzation of viscoelastic tests by principal component analysis to detect TIC. The AAJT and REBOA were both effective to stop hemorrhage distal to the aortic bifurcation and restored critical circulation proximal to the aortic occlusion. Infra-renal REBOA required more crystalloid fluids to restore the circulation than AAJT. Both methods caused ischemic injuries which became significant after 1 hour of infra-renal aortic occlusion. The ischemic injuries were alleviated by intermittent reperfusion during thoracic REBOA application. TIC was detected in pigs by principal component analysis of rotational thromboelastometry, which comprised a new method for possible identification of TIC phenotypes. In conclusion, mechanical hemostasis was effective by both abdominal tourniquet- and intravascular aortic occlusion. We also identified potentially severe complications due to hemodynamic- and metabolic consequences, particularly when application times exceed one hour.