Assessment of Lipid Peroxidation in Newborn Infants and Rabbits by Measurements of Expired Ethane and Pentane: Influence of Parenteral Lipid Infusion*

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Abstract
Peroxidation of the unsaturated fatty acid constituents of tissue is 1 proposed mechanism of in vivo oxidant damage. Products of unsaturated fatty acid peroxidation include the volatile hydrocarbons ethane and pentane. These volatile hydrocarbons are eliminated in expired air and reflect in vivo lipid peroxidation. Newborn infants excrete 16 pmol of ethane per kg body weight per min and 15 pmol of pentane per kg body weight per min. This compares with 1.4 pmol of ethane per kg body weight per min and 1.3 pmol of pentane per kg body weight per min in healthy adult men. Infants receiving total parenteral nutrition including i.v. lipid emulsion excrete more than 100 pmol of pentane per kg body weight per min. Newborn rabbits, delivered at term, also excrete more pentane while receiving lipid emulsion infusion. In the newbron rabbit, the amount of pentane exhaled increases linearly with the dose of lipid emulsion. Blood and tissue thiobarbituric acid reactants are also increased in newborn rabbits after administration of lipid emulsion. Lipid peroxidation is quantitatively greater in infants than in adult humans and can be significantly increased by parenteral administration of lipid emulsion.