Purpose of review
Controversies about the adequate amount of energy to deliver to critically ill patients are still going on, trying to find if hypocaloric or normocaloric regimen is beneficial in this population. Our purpose is to review recent publications using or not indirect calorimetry
Numerous studies have compared hypocaloric to normocaloric regimen using predictive equations. However, these equations have been demonstrated to be inaccurate in most of the cases. Some recent PRCT using indirect calorimetry
are finding some advantages to isocalorie regimens, but others not. Timing of the nutrition respecting or not the early substrate endogenous production, use of an adequate amount of protein, respect of the daily variability of needs may explain the divergent results observed.
Summary Indirect calorimetry
should be used to define the energy expenditure of the patient and to determine its requirements. More studies comparing isocalorie to hypocalorie regimens with fixed protein intake are necessary to confirm the observational and some of the PRCT-positive studies.