Clinical issues regarding the use of total nutrient admixtures

The introduction of total nutrient admixtures (TNAs) has offered several clinical advantages. Substituting a portion of the daily dextrose calories with lipids may reduce the incidence of carbohydrate-associated complications (e.g., disturbances in glucose control and immune function). In addition, providing intravenous lipids continuously over 24 hours as a TNA appears to be better utilized by the liver and less likely to interfere with reticuloendothelial system function when compared with conventionally administered, discontinuous lipid infusions. If the peripheral vein is used as a route for parenteral nutrition, the addition of fat to the admixture provides the advantage of enhancing caloric density, while contributing significantly less tonicity than dextrose. Certain pharmaceutical and microbiological issues need to be considered to ensure the intravenous administration of a safe and homogenous dispersion. Attention to established guidelines provided by the lipid manufacturers, as well as careful extrapolation of TNA stability data, will avert the dangers associated with infusion of coalesced lipid particles. This article reviews the evidence supporting the use of lipids as daily caloric sources, with particular emphasis on the role of the total nutrient admixtures as the primary vehicle for administration.