Extending REBOA: Endovascular Variable Aortic Control (EVAC) in a Lethal Model of Hemorrhagic Shock.

Background: The duration of use and efficacy of Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is limited by distal ischemia. We developed a hybrid endovascular-extracorporeal circuit variable aortic control (VAC) device to extend REBOA duration in a lethal model of hemorrhagic shock to serve as an experimental surrogate to further development of endovascular variable aortic control (EVAC) technologies. Methods: Nine Yorkshire-cross swine were anesthetized, instrumented, splenectomized, and subjected to 30% liver amputation. Following a short period of uncontrolled hemorrhage, REBOA was instituted for 20 minutes. Automated variable occlusion in response to changes in proximal mean arterial pressure was applied for the remaining 70 minutes of the intervention phase using the automated extracorporeal circuit. Damage control surgery and whole blood resuscitation then occurred and the animals were monitored for a total of 6 hours. Results: Seven animals survived the initial surgical preparation. After 20 minutes of complete REBOA, regulated flow was initiated through the extracorporeal circuit to simulate VAC and provide perfusion to distal tissue beds during the 90-minute intervention phase. Two animals required circuit occlusion for salvage, while five animals tolerated sustained, escalating restoration of distal blood flow prior to surgical hemorrhage control. Animals tolerating distal flow had preserved renal function, maintained proximal blood pressure, and rapidly weaned from complete REBOA. Conclusion: We combined a novel automated, extracorporeal circuit with complete REBOA to achieve endovascular variable aortic control in a swine model of uncontrolled hemorrhage. Our approach regulated proximal aortic pressure, alleviated supra-normal values above the balloon, and provided controlled distal aortic perfusion that reduced ischemia without inducing intolerable bleeding. This experimental model serves as a temporary surrogate to guide future EVAC catheter designs that may provide transformational approaches to hemorrhagic shock. (C) 2016 Lippincott Williams & Wilkins, Inc.

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