N. C. Wang1, P. E. Rabban1, X. Yan2, R. L. Goulson1, B. A. Derstine1, G. L. Su1, H. Lee2, J. L. Eliason1, S. C. Wang1 1University Of Michigan,Surgery,Ann Arbor, MI, USA 2University Of Michigan,Electrical Engineering & Computer Science,Ann Arbor, MI, USA
Introduction: Non-compressible torso hemorrhage is a major cause of mortality in battlefield as well as civilian trauma settings. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been pioneered by the military to stabilize patients. This technique is starting to be used in civilian trauma settings for the management of torso hemorrhage. To support the design of catheter enhancements and inform medical personnel of optimal balloon placement without fluoroscopy, a broad survey of the variation of aortic geometry is needed.
Methods: This study measured aortic geometry using the computed tomography (CT) scans of 1769 trauma patients between the ages of 18-50. A custom set of MATLAB algorithms was used to semi-automatically process the aorta for each scans. The centerline and radii of the aorta were measured for these scans from the femoral artery at the level of each femoral head, through the bifurcation, and up into the aortic arch. Additionally vascular landmarks were placed including the aortic bifurcation (AoBi), kidney, celiac, SMA, and left subclavian branches. These landmarks define the aortic zones, zone I (left subclavian to celiac), zone II (celiac to lowest renal artery), and zone III (renal artery to AoBi)
Results: Within our population, the median length (interquartile range in parentheses) of zone I was 223.7 mm (210-237 mm). Zone III was a significantly smaller region, with a length of 87.0 mm (76-96 mm). The distance from the left femoral artery at the femoral head to the AoBi was 195.8 mm (186-206 mm) in men, and 193.0 mm (184-202 mm) in women, with the distance from the right femoral artery to the AoBi being slightly longer than the left at 200.7 mm (191-210 mm) in men and 198.6 mm (189-208 mm) in women.
The median luminal diameters of the left and right femoral artery were 6.07 mm (5-7 mm) and 6.11 (5-7 mm) respectively. Aortic diameter was largest near the left subclavian, 20.5 mm (19-22 mm). The diameter decreased down the aorta to 18.6 mm (17-21 mm) at the celiac branch, 16.7 mm (15-19 mm) at the lowest renal artery, and 14.3 mm (13-16 mm) at the aortic bifurcation.
Conclusion: Overall, there is significant variation within the population in terms of vascular anatomy. As REBOA is being advocated for use in zone III, to control lower abdominal hemorrhage, it’s important to understand the size and lengths of the vasculature to ensure safe placement within the intended zone. Current catheters range in size up to 14 Fr (4.6 mm), increasing risk of damage to small femoral arteries; recent experience in a Japanese civilian population reported a high incidence of flow occlusion to the lower extremity. The current report may aid in the development and clinical application of novel endovascular devices.
