Adult respiratory distress syndrome (ARDS) is the most fatal complication after severe trauma (1,3). ARDS is seen in multiple injured patients with fractures and the risk for ARDS increases with the number of fractures (9). One of the theories concerning the etiology in ARDS is, that tissue thromboplastine from the site of the fracture and surrounding soft tissue activates the coagulation system resulting in pulmonary microembolism (6). Riska (8) has noticed by clinical experience that increased frequency of early fracture stabilization by internal fixation in multiply injured patients has dramatically reduced the frequency of post-traumatic respiratory insufficiency. The aim of the present study was to investigate the effect of primary fracture immobilization on post-traumatic pulmonary changes in pigs. We used a model in which anesthetized pigs can be subjected to trauma and then observed for several days, while still under anesthesia, under careful respiratory and circulatory control, by means of repeated chest x-rays and postmortem macroscopic and microscopic examination of lung tissue.

Twenty-six pigs (Swedish Landrace), weight 17–23 kg were used. Chest x-rays were done in all animals before the experiment excluding those pigs with any pulmonary changes. The pigs were anesthetized with pentobarbital and pethidine, and tracheostomy, carotid artery cateterization and cystostomy were performed.