Use of
intravenous lipid emulsions in
trauma and
sepsis still remains controversial. In order to examine the impact
lipid emulsions have on host defense against
bacterial infection during
total parenteral nutrition (TPN), 56 male Sprague-Dawley rats underwent jugular cannulation and were randomly divided into three groups, each receiving one of three TPN regimens. All regimens delivered approximately 250 kcal/kg X
body weight/day, of which 12.5 g were as
amino acids. Group 1 received 100% of the nonprotein calories as
glucose (AA + G). Group 2 was given 50% of the nonprotein calories as a longchain
triglyceride emulsion (100% LCT). Group 3 received 50% of nonprotein calories as a mixed
lipid system, composed of medium- and long-chain
triglycerides (75% MCT/25% LCT). After 24 hr on intravenous nutrition, all animals received bilateral septic femur fractures and were continued on TPN for 3 days. On the last day, the level of
bacteremia and the in vivo response to an intravenous challenge of 59Fe-labeled Escherichia coli were examined. Three days following the septic injury, animals given MCT as part of their
lipid calories were not bacteremic, whereas the other groups had greater than 10(2) cfu/ml of blood. Animals receiving TPN with MCT sequestered a greater percentage of exogenously administered bacteria in the liver and sequestered less in the lung compared to animals given 100% LCT (p less than 0.05). From these data, we conclude that
parenteral nutrition formulas where LCT has been partially replaced with MCT may better support host bactericidal capacity than similar regimens comprised of LCT as the sole
lipid source.