Distal pressure monitoring and titration with percent balloon volume: feasible management of partial resuscitative endovascular balloon occlusion of the aorta (P-REBOA).

INTRODUCTION: Resuscitative endovascular balloon occlusion of the aorta (REBOA) increases proximal arterial pressure, but may also induce life-threatening distal ischemia. Partial REBOA (P-REBOA) is thought to mitigate distal ischemia during aortic occlusion. However, feasible indicators of the degree of P-REBOA remain inconsistent. We hypothesised percent balloon volume could be a substitute for pressure measurements of gradients during P- REBOA. This study aimed to compare balloon volume and arterial pressure gradient, and analysed with intra-balloon pressure and balloon shape. METHODS: Proximal (carotid) and distal (femoral) arterial pressures were recorded and a 7-Fr REBOA catheter was placed in four swine. Total REBOA was defined as a cessation of distal pulse pressure and maximum balloon volume was documented. The balloon volume was titrated by 20% increments of maximum capacity to adjust the degree of P-REBOA. The distal/proximal arterial pressure gradient and the intra-balloon pressures were also recorded. The changes in shape and the cross-sectional area of the balloon were evaluated with computed tomography (CT) images. RESULTS: The proximal mean arterial pressure (MAP) plateaued after 60% balloon volume; meanwhile, distal pulse pressure was still left. The balloon pressure was traced with proximal MAP before contact with aortic wall. The balloon shape changed unevenly from "cone" to "spindle" shape, although the balloon cross-sectional area of the mid-segment linearly increased. CONCLUSION: Monitoring distal pressure and titrating percent balloon volume is feasible to manage P-REBOA. In this experiment, 60% balloon volume was enough inflation to elevate central pressure allowing distal perfusion. The intra-balloon pressure was not reliable due to the strong influence of proximal MAP and uneven change of the balloon shape.