OBJECTIVETo investigate the correlation between trauma and pulmonary thromboembolism.

METHODSComminuted 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.

RESULTSThe 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).

CONCLUSIONSFractures 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.