The magnitude, phasing, and attenuation of pressure waves in the aorta during abdominal belt laoading

Rupture of the aorta is a leading cause of death after motor vehicle crashes, but the exact mechanisms of this injury remain unidentified. It is well documented that transient pressure waves develop within the aorta during impact loading and this increase in blood pressure has been postulated as a primary or contributory mechanism of aortic rupture. This paper investigates the in situ intra-aortic pressure generated during dynamic belt loading of the abdomen. Ten juvenile swine (average weight 21.4±1.4 kg) were subjected to dynamic belt loading on the abdomen using a customized pneumatic device. Instrumentation included ultra-miniature vascular pressure transducers inserted into the distal (abdominal), thoracic, and proximal (arch) aorta to track the magnitude and propagation of the blood pressure wave generated by the loading. Belt penetration depth and rate, muscle tension, and belt location (upper and lower abdomen) were considered. Belt penetration ranged from 35% to 68% of the unloaded abdominal depth at a peak rate of 3.5 m/s to 7.0 m/s. The average peak pressure measured in the abdominal aorta during belt loading was 847±277 mm Hg. The peak pressure measured in the thoracic aorta was on average the 69% of that in the abdominal aorta, and the peak in the aortic arch was on average 53% of the abdominal aorta. No macroscopic aortic trauma was observed in any subject.