Respiratory Metabolism in Infancy and in Childhood

Abstract

The parenteral administration of fat as a potential source of energy has long appealed to clinical investigators. Evidence of the availability to the organism of fat so administered has for the most part been adduced by indirect methods of approach. Such studies include : chemical analyses of the blood ; chemical and histologic examination of the sites of injection, regional lymph nodes and various viscera following parenteral administration of fat ; studies of nitrogen balance ; studies of absorption and excretion of fat-soluble drugs and dyes ; observations on the utilization of fat-soluble vitamins, and finally clinical records of the response of malnourished persons to repeated injections of fat. The results secured from these indirect lines of investigation are far from conclusive, but they suggest that some preparations may be utilized by the organism under certain conditions. The literature covering these studies, which has accumulated since the experiments of von Leube 1 in 1895, was summarized by Koehne and Mendel in 1929.2 Direct evidence of the utilization of parenterally administered fat entails measurements of the respiratory exchange in an effort to demon¬ strate its effect on the respiratory quotient and its specific dynamic action. Murlin and Riche 3 injected 100 cc. of a 3 per cent emulsion of lard intravenously into two dogs and in one of them observed a maximal depression of the respiratory quotient from 0.85 to 0.73 with a concomitant rise in heat production of 7 per cent in the second to the fourth hour following injection.