Development of a Novel Epidural Hemorrhage Model in Swine

Traumatic brain injury is a major public health concern. Among patients with severe traumatic brain injury, epidural hemorrhage is known to swiftly lead to brain herniation and death unless there is emergent neurosurgical intervention. However, immediate neurosurgeon availability is frequently a problem outside of level I trauma centers. In this context, the authors desired to test a novel device for the emergent management of life-threatening epidural hemorrhage. A review of existing animal models determined that all were inadequate for this purpose, as they were found to be either inappropriate or obsolete. Here, we describe the development of a new epidural hemorrhage model in swine (Sus scrofa, 18-26 kg) ideal for translational device testing.

Vascular access was achieved using an ultrasound-guided percutaneous Seldinger catheter-over-wire technique with 5 Fr catheters placed in the bilateral carotid arteries, for continuous blood pressure and to allow for withdrawal of blood for creation of epidural hemorrhage. To simulate an actively bleeding and life-threatening epidural hemorrhage, unadulterated autologous blood was infused from the vascular access point into the epidural space. To be useful for this application and clinical scenario, brain death needed to occur after the planned intervention time but before the end of the protocol period (if no intervention took place). An iterative approach to model development determined that this could be achieved with an initial infusion rate of 1.0 mL/min, slowed to 0.5 mL/min after the first 10 minutes, paired with an intervention time at 15 minutes. All experiments were performed at Oregon Health & Science University, an Association for Assessment and Accreditation of Laboratory Animal Care accredited facility. Oregon Health & Science University's Institutional Animal Care and Use Committee, as well as the United States Army Animal Care and Use Review Office, reviewed and approved this protocol before the initiation of experiments (respectively, protocol numbers IP00002901 and 18116010.e001).

The final developed model allows for the infusion of a known volume of autologous, unadulterated blood directly into the epidural space, without the use of a balloon or other restricting membranes, and is rapidly fatal in the absence of intervention.

This animal model is the first to mirror the expected clinical course of epidural hemorrhage in a physiologically relevant manner, while allowing translational testing of emergency devices. This model successfully allowed the initial testing of a novel interventional device for the emergent management of epidural hemorrhage that was designed for use in the absence of traditional neurosurgical capabilities.