Introduction: Endovascular variable aortic control (EVAC) is an automated partial resuscitative endovascular balloon occlusion of the aorta (REBOA) platform designed to mitigate the deleterious effects of complete REBOA. Long-term experiments are needed to assess potential benefits. The feasibility of a 24-hour experiment in a complex large animal trauma model remains unknown.
Materials and methods: Anesthetized swine were subjected to controlled hemorrhage, blunt thoracic trauma, and tibial fractures. Animals were then randomized (N = 3/group) to control (No balloon support), 90 minutes of complete supraceliac REBOA, or 10 minutes of supraceliac REBOA followed by 80 minutes of EVAC. One hundred ten minutes after injury, animals were resuscitated with shed blood, the REBOA catheter was removed. Automated critical care under general anesthesia was maintained for 24 hours.
Results: Animals in the control and EVAC groups survived to the end of the experiment. Animals in the REBOA group survived for 120, 130, and 660 minutes, respectively. Animals in the EVAC group displayed similar mean arterial pressure and plasma lactate concentration as the control group by the end of the experiment. Histologic analysis suggested myocardial injury in the REBOA group when compared with controls.
Conclusions: This study demonstrates the feasibility of intermediate-term experiments in a complex swine model of polytrauma with 90 minutes of REBOA. EVAC may be associated with improved survival at 24 hours when compared with complete REBOA. EVAC resulted in normalized physiology after 24 hours, suggesting that prolonged partial occlusion is possible. Longer studies evaluating partial REBOA strategies are needed.
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