DEVELOPMENT OF GRANULOMAS AND VASCULAR FIBROCELLULAR PROLIFERATION IN THE 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 TPN through central venous catheters for 7 weeks. To secure adequate nutrition and gastrointestinal absorbance of nutrients, an additional full oral diet was given to eight of these animals. Fifteen control animals received Ringer solution through central venous catheters in addition to the oral diet. All animals infused with TPN for 7 weeks developed lung granulomas, a finding not observed in control animals. No lung granulomas were seen in three TPN animals sacrificed after 3 to 5 weeks owing to illness. All TPN animals also developed tissue reactions suggesting long-standing lung vascular inflammation. Similar vascular changes were seen in seven control animals that had bacterial infection or endotoxemia. The total amount of neutral fat in lung homogenate tended to increase in animals given TPN, and the linoleic acid content was significantly increased. In conclusion, long-term TPN caused lung granulomas in pigs. Vascular damage seemed to be accelerated by bacterial infection as well as by the TPN. The tissue reactions presumably involved long-term activation of monocytes/macrophages.