Intravenous fat emulsions in nutritional support

Intravenous fat emulsions are now used routinely in parenteral nutrition regimens. However, intravenous fat emulsions have a number of toxic effects when given in a conventional manner (ie, as a 6- to 8-hour infusion). Among these effects are impairment of neutrophil and reticuloendothelial function and increased risk of infection; these problems may be avoided by using lower lipid infusion rates. Similarly, defective platelet function has been shown to be associated with intravenous fat emulsions, also apparently avoidable with lower infusion rates. High rates of lipid infusion have been implicated as a cause of hypoxia and increased pulmonary artery pressure, an effect probably mediated by prostaglandins. It is not known whether this effect is dose related. Hypercholesterolemia may also occur as a consequence of intravenous fat emulsion administration, but there is no evidence that it imposes an atherogenic risk. Although much remains to be learned about intravenous fat emulsions and their complications, the available evidence does permit some tentative recommendations for their use. In general, infusion rates should not exceed 0.03 to 0.05 g · kg^-1 · h^-1. In most cases, continuous around-the-clock infusion is required in order to deliver adequate calories at these rates.