Computed Tomography and Histologic Results in the Early Stages of Endotoxin-Injured Pig Lungs as a Model for Adult Respiratory Distress Syndrome

Abstract

To determine early radiographic changes in diffuse alveolar injury, the authors correlated computed tomography (CT) and histopathology in pigs with recurrent endotoxinemia. Five pigs received recurrent endotoxin over a 17-hour period. Three pigs received physiologic saline and served as controls. Hemodynamic and blood-gas data were analyzed. CT was performed immediately before killing the animals. The lungs were cut into 5-mm-thick slices in the same axis as the CT scans and were investigated by light and electron microscopy. Hemodynamic data, blood-gas analysis, and morphologic changes closely simulated the clinical situation of septic shock in the five pigs that had received endotoxin. Results of histologic examination depicted changes similar to those associated with adult respiratory distress syndrome (ARDS). CT clearly demonstrated both interstitial, and to a minor degree, intra-alveolar lesions in the endotoxin-injected group, which correlated well with dilated lymph vessels, thickened interstitium, and areas of dystelectasis on histologic examination. Although there was a rather uniform clinical picture, CT and histologic findings showed different degrees of involvement. CT clearly depicts changes in endotoxin-injured pig lungs in an early clinical state, which are similar to changes associated with ARDS on histologic examination.