Background: Extremity hemorrhage is a contributor to preventable battlefield mortality. The Army has liberalized tourniquet use guidelines in an attempt to prevent these deaths. To evaluate wound hemostatic agents that might allow for early tourniquet removal while maintaining hemorrhage control, a model of lethal extremity hemorrhage in the goat (Capra hircus) was developed and a polymeric dressing agent (BioFoam) tested.
Methods: After administration of a spinal block, animals were placed in lateral recumbancy with a head-up tilt of 6 degrees, 500 mL crystalloid was injected and 600 u/Kg of heparin was administered. After tourniquet application to the thigh, a soft tissue and vascular injury was created by transecting muscles and the femoral artery. The polymeric wound dressing was applied and the tourniquet was released.
Results: In testing, the primary endpoint was mortality within the first hour after tourniquet release. None of the control animals survived the full hour. Two out of five (40%) of the treated animals survived. With survivors' survival time calculated as 60 minutes, survival time was found not to differ between treated (34 +/- 19 minutes) and untreated (29 +/- 18 minutes) animals (p = 0.77).
Conclusion: The physical characteristics of tissue injury, need for anticoagulation, and manipulation of blood pressure are vital factors contributing to the lethality of a large animal fatal extremity hemorrhage model. BioFoam was successful in preventing fatal arterial extremity hemorrhage after the release of an effective tourniquet in some cases. An agent that can reliably allow for safe tourniquet removal and restoration of collateral circulation is a potential solution to tourniquet-associated morbidity in traumatic extremity injury. The model developed will serve as a rigorous test for such agents.