In a recent study, Casaer and colleagues compared early versus late parenteral nutrition (PN) in critically ill adult patients. The authors randomized 4,640 patients admitted to one of seven participating intensive care units (ICUs) to either early (within 48h after ICU admission) or late PN (by the eighth ICU day). The results of this study were remarkable. Despite the fact that there was no impact on ICU or 90-day mortality, patients in the late PN group had a shorter ICU and hospital length of stay, fewer infections, and were associated with lower overall healthcare cost.
The study has several limitations, one of which is the exclusion of malnourished patients (i.e. body mass index <17) and the fact that half of the patients included were either extubated on day 2 or day 4 which raises some questions about the indication for PN in these patients. In addition, patients in the early PN group received a 20% glucose solution compared to those in the late PN group where they received only 5% glucose solution. This could explain the reason why patients in the early PN group had higher rates of infections and overall worse outcomes. Finally, systematic bias may have been introduced due to the lack of blinding.
The question that currently exists—can PN be further delayed?
Casaer MP, Mesotten D, Hermans G, et al. Early versus late parenteral nutrition in critically ill adults. N Engl J Med 2011;365:506-517.