To establish a simple and repeatable rat model of pulmonary contusion induced by thoracic trauma.

A total of 40 male SD rats weighing 220-240 g were selected and randomly divided into five groups using a random number table: Group A (control group, impact energy: 0 J), Group B (impact energy: 0.588 J), Group C (impact energy: 0.98 J), Group D (impact energy: 1.176 J), and Group E (200 g, 100 cm, impact energy: 1.96 J). A simple device was made to model the SD rat’s right chest hit by a free fall of a heavy object. The CT imaging of small animals was used to determine the presence of rib fractures and hemopneumothorax. The ratios of pulmonary contusion were calculated to compare the differences in the lung imaging between the groups with different impact energy. HE staining of pathological sections was used to evaluate pulmonary contusion at the microscopic level.

Chest CT showed that there were no obvious fractures in Groups A and B; there were 1 case of single fracture and 1 case of two fractures in Groups C and D; there was no obvious hemopneumothorax in Groups A, B, C, and D. Among the surviving rats in Group E, three had two rib fractures, one had three rib fractures, and one had three or more rib fractures (complicated with a small amount of hemothorax). The ratios of pulmonary contusion were statistically different between the groups. After treatment of lung tissues of pulmonary contusion, HE staining suggested different pathological changes.

An ideal SD rat model of pulmonary contusion is successfully established, and the suitable impact energy is 1.176 J.