Finding the Right Balance: Partial REBOA in a Swine Model of Uncontrolled Vascular Injury

Abstract

Introduction: We have previously shown that pREBOA deployment in the thoracic aorta is safe for 2-4 hours, but it is unclear whether the distal blood flow following partial aortic occlusion would lead to ongoing hemorrhage. The objective of this study was to evaluate the hemostatic efficacy of pREBOA in a model of uncontrolled vascular injury. Methods: Female Yorkshire swine (n=10, 40-45kg) were anesthetized and instrumented. A through-and-through injury was created in the common iliac artery. The animals were randomized to: 1) pREBOA-PRO™ deployment after 3 minutes, and 2) control. Both groups were given normal saline resuscitation for hypotension. The pREBOA was adjusted to partial occlusion [distal mean arterial pressure (MAP) of 30mmHg], and then left without titration for 2 hours. Then, fresh frozen plasma was transfused and vessel repaired. The balloon was deflated and animals were monitored for 2 hours. In the critical care period, 2 liters of normal saline was infused, norepinephrine was given for MAP≤55, and electrolytes/acidosis were corrected. Organs were examined for gross and histological evidence of ischemic injuries. The primary endpoint was post-inflation blood loss. Results: All the pREBOA animals survived until the end, whereas control animals had a mean survival time of 38.2 minutes (p<0.05). The pREBOA group showed significantly less bleeding after balloon deployment (93.8 vs 1980.0 ml, p<0.05), and had appropriate lactate clearance, with minimal histologic distal organ ischemia. Conclusion: Partial aortic occlusion with the newly designed balloon can achieve the desired balance between effective hemorrhage control and adequate distal flow, without a need for ongoing balloon titration.