Primary fracture immobilization as a method to prevent post-traumatic pulmonary changes- an experimental model.

: Post-traumatic pulmonary insufficiency or "respiratory distress syndrome" (RDS) is one of the most feared complications of severe trauma. The aetiology is probably multifactorial, and is obscure. Although modern treatment has reduced the mortality, there is no certain way of preventing the syndrome. The aim of the investigation was to develop an experimental model on anaesthetized pigs subjected to trauma and folllowed up for 3-4 days, still under anaesthesia, the repeated lung X-rays and post-mortem naked-eye and histological examination of lung tissue. 26 pigs were used. 12 (Group I) were subjected to missile trauma of a limb, with a fracture that was left without immobilization. 10 were treated similarly but with immobilization of the fracture (Group II). Four control animals were prepared and observed under anaesthesia but no trauma was inflicted (Group III). In Group I, all but two developed, 10-70 h after the injury, roentgen and morphological changes identical to those seen in patients with clinically documented RDS. No such changes were seen in the controls or in Group II. With our experimental model it seems possible to induce in experimental animals roentgen and morphological changes corresponding to RDS in man. The method provides new means of studying the mechanisms behind and the effects of different forms of treatment in RDS. The results also support the hypothesis that early immobilization of fractures is an important step in preventing RDS.