Pathologic study of thoracic impact injury involving a relatively static impact pattern.

Fifty-five rabbits were subjected to left thoracic wall lateral blunt impact involving a relatively static impact pattern. The impact velocities ranged from 7.92 m/s to 16.33 m/s and the compression response ranged from 14.08% to 45.84% of the thoracic width. The surviving animals were sacrificed 6 hours after trauma and autopsies were performed. The lung was divided into bronchial and alveolar regions. Injury scores were assigned according to the hemorrhage area and the injury type (e.g., rupture or rib fracture). The results showed that the severity of bronchial injury was greater than alveolar injury when the impact velocity was low. However, alveolar injury was much more severe than bronchial injury at all levels of impact displacement when the impact velocity was high. The ratio of left/right lung injury decreased when the product of impact velocity and compression criterion increased. The latter was also well correlated with the severity of lung and heart injuries. In addition, the severity of rib injury was mainly related to compression response.