Partial Resuscitative Endovascular Balloon Occlusion of the Aorta (p-REBOA) Minimizes Distal Ischemia While Preserving Central Circulation in a Swine model (Sus scrofa).

Rachel M Russo, MD¹, Christopher Lamb, MD², Lucas P Neff, MD³, Kevin Grayson, DVM, PHD³, Jeremy W Cannon, MD⁴, Timothy K Williams, MD³. ¹UC Davis Department of Surgery, ²East Midlands Deanery, ³David Grant Medical Center, Travis AFB, ⁴San Antonio Military Medicine Consortium

Objectives:  Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used to salvage patients in shock from non-compressible torso hemorrhage. Previous experiments in swine have demonstrated that REBOA increases central blood pressure at the expense distal organ perfusion. Partial REBOA (p-REBOA) may maintain a favorable hemodynamic profile while decreasing tissue ischemia distal to the balloon.  We investigated the hemodynamic and physiologic effects of p-REBOA versus the current complete REBOA (c-REBOA) technique.

Methods:  Yorkshire-cross swine were anesthetized, instrumented, splenectomized, and subjected to 25% total blood volume loss over 20 minutes.  They were then randomized to treatment with either c-REBOA, p-REBOA, or no intervention.  Aortic pressures (proximal and distal to the balloon), visceral arterial pressures, and serum makers of ischemia and inflammation were recorded throughout the experiment.  P-REBOA was achieved by inflating the balloon catheter to generate a 50% pressure gradient across the balloon.  Aortic balloons remained inflated for 90 minutes in the p-REBOA and c-REBOA groups and uninflated in the control group.  Following balloon deflation, the experiment continued for 15 minutes to evaluate the effects of reperfusion.  Necropsy was performed and the end organs were evaluated histologically.

Results: [preliminary results] Compared with no treatment, c-REBOA produced considerable increases in central aortic pressure after hemorrhage but also substantially higher levels of serum lactate, followed by a precipitous drop in blood pressures on balloon deflation.  p-REBOA was achieved by 80-90% aortic occlusion and resulted in hemodynamic effects and a lactate profile similar to that seen in the no-treatment arm. Qualitative histologic analysis of intestinal mucosa revealed early necrosis and disruption of the villi with c-REBOA and normal-appearing villi in the p-REBOA and control group.

Conclusions: This initial investigation indicates that p-REBOA may minimize the systemic physiologic insult and damage to tissues distal to the balloon.  Further work with a model of ongoing hemorrhage is needed to determine if the hemodynamic improvements associated with p-REBOA will translate into a survival benefit in the face of persistent blood loss.