An experimental study on hepatic injury from belt-restraint loading.

The potential for nonpenetrating hepatic injury was investigated by simulated belt-restraint loading to the thoracic and abdominal areas in a supine, rigidly supported, anesthetized beagle. The impact was delivered through a belt interface oriented either transversely or diagonally over the thorax and upper abdomen. Four types of hepatic injury were identified by the following gross characteristics: linear surface laceration, subcapsular hematoma, stellate surface laceration, and hilus laceration. Pressure acting on the organ surface, bending moment acting on the lateral lobes, or shearing stress producing relative displacement between lobes were postulated as major injury-producing mehcanical factors. Approximately 350 kPa of belt pressure or 60% upper abdominal compression at 1.7 m/s was necessary to produce a hepatic surface injury, but the beagle may be predisposed to such injury compared to a human because of increased exposure of its abdomen to the belt webbing. Accordingly, this study does not assess the potential for a belt-induced liver injury to a restrained individual in a rapid-deceleration environment, nor does the study attempt to simualte the performance of any particular current or previous restraint system.