DEVELOPMENT OF GRANULOMAS AND VASCULAR FIBROCELLULAR PROLIFERATION INTHE LUNGS OF PIGS RECEIVING LONG-TERM LIPID-BASED PARENTERAL-NUTRITION

The lungs of pigs receiving long-term total parenteral nutrition (TPN) have been studied. A total of 20 pigs were tentatively infused with T PN through central venous catheters for 7 weeks. To secure adequate nu trition and gastrointestinal absorbance of nutrients, an additional fu ll oral diet was given to eight of these animals. Fifteen control anim als received Ringer solution through central venous catheters in addit ion to the oral diet. All animals infused with TPN for 7 weeks develop ed lung granulomas, a finding not observed in control animals. No lung granulomas were seen in three TPN animals sacrificed after 3 to 5 wee ks owing to illness. All TPN animals also developed tissue reactions s uggesting long-standing lung vascular inflammation. Similar vascular c hanges were seen in seven control animals that had bacterial infection or endotoxemia. The total amount of neutral fat in lung homogenate te nded to increase in animals given TPN, and the linoleic acid content w as significantly increased. In conclusion, long-term TPN caused lung g ranulomas in pigs. Vascular damage seemed to be accelerated by bacteri al infection as well as by the TPN. The tissue reactions presumably in volved long-term activation of monocytes/macrophages.