Background: Noncompressible hemorrhage from central vascular injuries remains the leading cause of preventable death in modern combat. This report introduces a large animal model of noncompressible torso hemorrhage, which permits assessment of the various approaches to this problem.
Methods: Yorkshire swine were anesthetized and monitoring devices for central aortic pressure, carotid flow, and intracerebral and transcutaneous brain oximetry were applied. Class IV hemorrhagic shock was induced through an iliac arterial injury and animals were subjected to different vascular control methods including thoracic aortic clamping, supraceliac aortic clamping, direct vascular control, and proximal endovascular balloon occlusion. After vascular control, the injury was shunted, and damage control resuscitation was continued. Serum markers, intravenous fluid volumes, and vasopressor requirements were tracked over a subsequent resuscitation period. Postmortem tissue analysis was performed to compare levels of acute ischemic injury between groups.
Results: The protocol for animal preparation, hemorrhage volume, open surgical technique, and posthemorrhage resuscitation was developed using four animals. The endovascular approach was developed using two additional animals. After model development, treatment animals subsequently underwent noncompressible hemorrhage with thoracic aortic clamping, supraceliac aortic clamping, direct vascular control, and endovascular aortic occlusion. Premature death occurred in one animal in the direct vascular control group.
Conclusion: This study presents a large animal model of class IV hemorrhagic shock from noncompressible hemorrhage, which permits comparison of various vascular control methods to address this challenging problem. Future studies using this model as the standard will allow further development of strategies for the management of noncompressible hemorrhage.