This study aims to analyse the effect of two total parenteral nutrition diets with lipid emulsions of different compositions on the incidence of nosocomial infection in critical patients. One diet will contain an MCT/LCT emulsion concentrated to 20% (50:50 ratio) and the other will comprise an MCT/LCT/fish oil emulsion (50:40:10 ratio). The secondary objective of this study is to analyse mortality in hospital and up to 6 months of discharge.