Impact Tolerance and Response of the Human Thorax

At the 1970 SAE International Automobile Safety Conference, the first experimental chest impact results from a new, continuing biomechanics research program were presented and compared with earlier studies performed elsewhere by one of the authors using a different technique. In this paper, additional work from the current program is documented. The general objective remains unchanged: To provide improved quantification of injury tolerance and thoracic mechanical response (force-time, deflection-time, and force-deflection relationships) for blunt sternal impact to the human cadaver. Fourteen additional unembalmed specimens of both sexes (ranging in age from 19-81 years, in weight from 117-180 lb, and in stature from 5 ft 1-1/2 in to 6 ft) have been exposed to midsternal, blunt impacts using a horizontal, elastic-cord propelled striker mass. Impact velocities were higher than those of the previous work, ranging from 14-32 mph. Striker weight varied from 3.6-52 lb, the smaller masses associated with the higher velocities. In all cases the impact was centered over the fourth interspace and delivered through a 6-in diameter, unpadded, flat wooden form with 1/2-in edge radius. In twelve cases the thoracic aorta was liquid pressurized at impact; and in seven cases, intra-aortic and intra-ventricular pressure-time histories were recorded during the impact event. Thoracic autopsies with cardiovascular dissections were performed in all cases; in addition, thorough abdominal explorations were performed in nine.