Fat emulsion for complete intravenous nutrition.

AN ADEQUATE amount of food is important in order to maintain a patient in the best possible condition to stand such strains as disease or trauma of different kinds (infections, burn, surgery, etc.). If oral feeding is impossible the nutrients have to be given in some other way. The two possibilities available are tube feeding and intravenous nutrition. The intravenous route is employed when tube feeding is impossible. Complete intravenous nutrition means the administration of adequate amounts of all the essential nutrients: protein or amino acids, fats, carbohydrates, electrolytes, vitamins and water. The intravenous supply of water, carbohydrates, electrolytes and vitamins has been employed for many years without difficulty. The supply of protein can be covered by blood, plasma and/or amino acid solutions. To utilize the supplied amino acids in the synthesis of proteins and, concomitantly, to maintain body weight and normal body composition, it is necessary to supply also the other nutrients and calories required. It is difficult or, in many cases, even impossible to give a sufficient amount of calories in the form of amino acids, carbohydrates or alcohol. This is because too large a volume of fluid has to be provided when isotonic solutions are used. When hypertonic solutions are administered, vascular complications such as thrombophlebitis arise, and a hyperosmotic diuresis may also occur. When parenteral nutrition has to be used it is possible to cover the caloric needs by means of fat emulsions given intravenously. The high caloric content of fat emulsion, containing 10-20% of fat, makes it possible to avoid the disadvantages associated with the large volumes or high concentrations required to cover the caloric need by other nutrients. The fat in the emulsion does not change the tonicity of the water phase. It can be infused into peripheral veins without causing vascular complications. The infusions do not produce a diuresis. Further, no losses are observed in the urine or the faeces. It is also possible that the fats in the emulsion contribute to the maintenance of the normal lipid composition of the body. Fat was apparently first administered parenterally in 1869 (Wentzel & Perco, 1869). After comprehensive animal experiments they gave subcutaneous injections of fat to a patient suffering from Pott's disease and in an emaciated condition. Hodder in Toronto used intravenous infusion of milk as a treatment for cholera in 1873 (Hodder, 1873). The first systematic attempts to administer artificial fat emulsion to man were carried out in Japan between 1920 and 1930. In the United States this subject was discussed, but nothing really useful was achieved, however, until 1950. In 1957 clinical and experimental results were published with a fat emulsion which, on administration, caused only a few acute side effects, and which seemed to be of great clinical value (Metabolism, 1957). This fat emulsion, Lipomul, was investigated extensively during the following years. As a result of certain side-effects, however, the manufacture of Lipomul was later discontinued. Several reviews of intravenous fat emulsions have been published (Geyer, 1960; Schuberth & Wretlind, 1961; Schoin & Zeller, 1962; Edgren & Wretlind, 1963; Wretlind, 1964a). Papers dealing with recent experimental and clinical research in the field of intravenous fat emulsions were published in the American Journal of Clinical Nutrition in 1965. A fat emulsion for intravenous nutrition usually contains a vegetable oil in water and one or two emulsifiers to stabilize the emulsion. A large number of fats or triglycerides have been studied during recent years. The five commercial fat emulsions, Infonutrol, Intralipid, Lipofundin, Lipomul and Lipiphysan, contain either cottonseed oil or soybean oil. As emulsifiers, different phosphatides are used. To obtain isotonicity with the blood, the water phase contains glucose, sorbitol or glycerol. The fatty acid compositions of the two oils differ. Soybean oil contains more linoleic acid and less saturated fatty acids than cottonseed oil. Soybean oil also contains linolenic acid, which is not found in cottonseed oil (Edgren & Wretlind, 1963; Rose et al., 1965). This paper will treat mainly of the experiences gained with the soybean oil-egg-yolk phosphatide emulsion. These emulsions contain 100 g or 200 g of fat, 12 g of egg-yolk phosphatides, and 25 g of glycerol per litre. Comparisons will be made between this emulsion and some cottonseed oil emulsions.