Purpose In the past decade blast injuries have become more prevalent. Blast trauma may cause extensive injuries requiring improved early resuscitation and prevention of haemorrhage. Randomized prospective trials are logistically and ethically challenging, and large animal models are important for further research efforts. Few severe blast trauma models have been described, which is why we aimed to establish a comprehensive polytrauma model in accordance with the criteria of the Berlin definition of polytrauma and with a survival time of > 2 h. Multiple blast injuries to the groin and abdomen were combined with hypoperfusion, respiratory and metabolic acidosis, hypoventilation, hypothermia and inflammatory response. The model was compared to lung contusion and haemorrhage. Methods 16 landrace swine (mean weight 60.5 kg) were randomized to "control" (n = 5), "chest trauma/hem" by lung contusion and class II haemorrhage (n = 5), and "blast polytrauma" caused by multiple blast injuries to the groin and abdomen, class II haemorrhage, lipopolysaccharide (LPS) infusion and hypothermia 32 °C (n = 6). Results The blast polytrauma group had an Injury Severity Score of 57 which resulted in haemodynamic shock, hypothermia, respiratory and metabolic acidosis and inflammatory response. The chest trauma/hem group had an Injury Severity Score of 9 and less profound physiologic effects. Physiologic parameters presented a dose-response relationship corresponding to the trauma levels. Conclusion A comprehensive blast polytrauma model fulfilling the Berlin polytrauma criteria, with a high trauma load and a survival time of > 2 h was established. A severe, but consistent, injury profile was accomplished enabling the addition of experimental interventions in future studies, particularly of immediate resuscitation efforts including whole blood administration, trauma packing and haemostasis.

BACKGROUND Uncontrolled bleeding is the leading cause of potentially preventable deaths among trauma patients. Tissue injury and shock result in trauma-induced coagulopathy (TIC). There are still uncertainties regarding detection methods and best practice management for TIC, and a deeper understanding of the pathophysiology requires robust animal models. The applicability of swine in coagulation studies, particularly after trauma has not been sufficiently elucidated. We, therefore, evaluated the swine as a vehicle for TIC research in a selection of trauma modalities. METHODS Twenty-six landrace swine (3 females/23 males) (mean weight, 60.0 kg) were anesthetized and randomized to negative controls, receiving no manipulation (n = 5), positive controls by hemodilution (n = 5), pulmonary contusion without hemorrhage (n = 5), pulmonary contusion with hemorrhage (n = 5), and blast polytrauma with hypothermia, hypoperfusion, hypoventilation, and systemic inflammation (n = 6). A comprehensive coagulation panel was analyzed at baseline, 20 minutes and 120 minutes after trauma. RESULTS PT(INR), aPTT, thrombocytes, and fibrinogen did not change after trauma. D-dimer increased (p < 0.0001), prothrombin decreased (p < 0.05) and aPC decreased (p < 0.01) after polytrauma. PAI-1 decreased after pulmonary contusion with hemorrhage (p < 0.05). Positive controls displayed changes in PT(INR), thrombocytes, fibrinogen, prothrombin, aPC (p < 0.05). Principal Component Analysis of rotational thromboelastometry presented pathologic coagulation profiles in both polytrauma and positive control groups with vectors extending outside the 95% confidence interval, which were not detected in negative controls. CONCLUSION Coagulopathy was induced after severe porcine blast polytrauma, specifically detected in rotational thromboelastometry. A novel method for principal component analysis of viscoelastic tests was introduced which may increase the detection sensitivity and differentiation of TIC phenotypes and should be further investigated in trauma populations.