Biochemical markers in a porcine model of adult respiratory distress syndrome induced by endotoxemia.

To evaluate the influence of a continuous endotoxin infusion on different hematological and biochemical variables which might underlie endotoxin-induced ARDS we investigated 2 groups of pigs, one with and one without endotoxin. Complement activation - both via the classical and alternative pathways -- antithrombin III, (AI-III) factor VIII-related antigen and fibronectin levels could not precisely predict the development of ARDS in the individual animal. It was found, however, that the animals which reacted with a severe endotoxin-induced pulmonary dysfunction (pulmonary responders) had significantly higher levels of complement of both the classical and alternative pathways, greater concentrations of AT-III and factor VIII-related antigen and higher fibronectin levels. These findings might probably be explained by a greater reactivity, i.e. synthesis and release, of these biochemical components in the animals which responded with a severe pulmonary reaction, a phenomenon which probably concealed the consumption. A greater "reactivity" regarding the drop in polymorphonuclear cell count was found in pulmonary responders; a phenomenon which, however, was not compensated for by increased production. A finding of presumably great clinical importance was that animals surviving the observation period had significantly higher levels of fibronectin already at baseline and throughout the observation period.