Use of intravenous fat emulsions in adult critically ill patients: does omega 3 make a difference?

Abstract

Critical illness is a multisystem process that can result in significant morbidity and mortality. In most patients, critical illness is preceded by a physiological deterioration, characterized by a catabolic state and intense metabolic changes, resulting in malnutrition and impaired immune functions.1 Intravenous lipid emulsions (IVLE) constitute the main source of energy and fatty acids (FA) in parenteral nutrition formulations and remain associated with the development of adverse effects. Different types of lipid emulsions (LE) have different effects on blood function tests and metabolic functions including inflammatory and immune response, coagulation and cell signalling. These effects appear to be based on complex modifications in the composition and structure of cell membranes, through eicosanoid and cytokine synthesis and by modulation of gene expression. Proinflammatory properties of omega-6 polyunsaturated fatty acids (PUFA) have been associated with poor clinical outcomes and have led to the development of newer generation IVLE. There is clinical data suggesting that omega-3 PUFA, particularly fish oil, have beneficial effects on the immune system, organ function and improves clinical outcomes in surgical and acute respiratory distress syndrome (ARDS) patients. In addition, there is some promising data on their use in septic patients.^2-4

This literature review focuses on the administration of different lipid emulsions, in particular omega-3 PUFA via the parenteral nutrition route, in critically ill adult patients. The clinical consequences associated with critical illness as well as the administration of different intravenous lipid emulsions are addressed, focusing on how omega-3 PUFA can possibly attenuate inflammation, improve outcomes and reduce complications associated with the administration of parenteral nutrition.