Assessment of Blood Flow Patterns Distal to Aortic Occlusion Using CT in Patients with Resuscitative Endovascular Balloon Occlusion of the Aorta.

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is used to decrease hemorrhage below the level of aortic occlusion (AO); however, the amount of collateral blood flow below the level of occlusion is unknown. Our aim was to investigate blood flow patterns during complete AO in patients who underwent CT scan after REBOA.

Study Design: Between February 2013 and January 2017, patients who received REBOA and underwent CT scan with intravenous contrast during full AO were included. Patients were excluded if they had a CT scan performed with the balloon partially or fully deflated.

Results: Nine patients (8 men) were included; all had blunt trauma. Mean Injury Severity Score (±SD) was 48 ± 8 and mean age was 45 ± 19 years. Four had supra-celiac AO, and 5 had infra-renal AO. Arterial contrast enhancement was noted below the level of AO in all patients, and distal to REBOA sheath placement in 5. Collateralization from arteries above and below the AO was identified in all patients. Contrast extravasation distal to AO was identified in 4 patients, and hematomas in 8. Distal vascular enhancement patterns varied by level of AO and contrast administration site.

Conclusions: Aortic occlusion appears to dramatically decrease, but does not completely impede, distal perfusion during REBOA due to multiple pathways of collateralization. Active extravasation and hematomas can still be detected in the setting of full AO, with purposefully timed contrast and image acquisition. Blood flow persists below the level of both the AO and in-dwelling sheath. Dynamic flow studies are needed to determine the contribution of AO and sheath placement to distal tissue ischemia.