Trauma and pulmonary thromboembolism: an experimental study on their correlation.

OBJECTIVE: To investigate the correlation between trauma and pulmonary thromboembolism.
METHODS: Comminuted fractures and extensive soft-tissue contusion at both hind limbs were made by a falling weight from a height in 16 rabbits. Lung perfusion scanning was performed to obtain the radioactivity counts before trauma, at 1 h, 48 h and 96 h after trauma. All the data were divided into 4 groups based on the above 4 time points. The rabbits were sacrificed when positive findings on the pulmonary perfusion scanning appeared. Their lungs were harvested to be paraffin-embedded and stained with hematoxylin-erosin method for histological examination of thromboembolism. The randomized block design ANOVA and the method of least significant difference (LSD) were used for statistical analysis of the radioactivity counts.
RESULTS: The histological findings showed that pulmonary embolism developed in 6 of the 16 rabbits (37.5%). Five of the 6 pulmonary embolism rabbits presented neither clinical symptoms nor positive pulmonary embolism manifestations in the lung perfusion scanning. A significant difference was found in lung perfusion radioactivity between the pre-traumatic, post-traumatic 1h groups and post-traumatic 48 h and 96 h groups(P less than 0.05).
CONCLUSIONS: Fractures of the hind limbs accompanied with extensive soft-tissue contusion may cause pulmonary micro-embolism that is not sensitive to lung perfusion scanning and tends to have no clinical symptoms. Pulmonary embolism development may take more than two days after trauma.