Bacteriology of the closed duodenal loop model of acute pancreatitis and ultrastructural changes induced in the lungs.

Injection of infected human bile into a closed duodenal loop in the rat consistently produces lethal pancreatitis with severe pulmonary damage. Lung abnormalities, resembling the human adult respiratory distress syndrome (ARDS) are frequently seen in this model and are usually ascribed to the pancreatitis. Similar pulmonary problems are seen in the human form of acute pancreatitis. Recently, it has been suggested, that the lung changes in the experimental animal are more likely to be due to bacteremia than to the pancreatitis. The aim of this study was to determine whether bacteremia occurred in this model, and if so, to determine whether bacteremia alone, in the absence of pancreatitis could produce this lung damage. A group of rats underwent induction of acute pancreatitis by a closed duodenal loop method and were compared to two groups comprising a closed small bowel loop bile infusion preparation, isolated from the pancreas, and a control group of rats undergoing a "sham" gastrotomy. Both pancreatitis and closed small bowel groups of animals were found to be bacteremic when sacrificed at 6 hr. The lungs from the animals with pancreatitis were significantly heavier than those in the other groups and scanning electron micrographs of the lungs in pancreatitis showed gross abnormalities, with marked increases in the alveolar wall thickness. The lungs in the closed small bowel loop preparation were indistinguishable from a control sham gastrotomy group of non-bacteremic rats. These results indicate that although the closed duodenal loop model of pancreatitis produces bacteremia, pancreatitis is necessary for development of pulmonary abnormalities.