Underfeeding versus full enteral feeding in critically ill patients with acute respiratory failure: a systematic review with meta-analysis of randomized controlled trials.

Introduction: Although guidelines emphasize that the provision of enteral nutrition (EN) should be as close as the patient's needs, prospective studies question this strategy.
Objective: To compare the effect of two EN strategies (underfeeding versus full-feeding) on ICU and overall mortality (hospital mortality or 60-day mortality) and length of stay (LOS), duration of mechanical ventilation (MV), infectious complications, and gastrointestional tolerability in ICU patients.
Methods: Random effects meta-analysis of randomized controlled trials (RCT). Our search covered MEDLINE, EMBASE, SCOPUS and CENTRAL databases until May 2015. Underfeeding was assigned into to two different groups according to the level of energy intake achieved (moderate feeding 46-72% and trophic feeding 16-25%) for subgroup analysis.
Results: Five RCTs were included among the 904 studies retrieved (n=2432 patients). No difference was found in overall mortality when all five studies were combined. In the subgroup analysis, moderate feeding (three studies) showed lower mortality compared with full-feeding (RR 0.82;95%CI,0.68-0.98;I2 0% p=0.59 for heterogeneity). No differences were found for ICU mortality, ICU and hospital LOS, duration of MV, and infectious complications. Underfeeding showed lower occurrence of GI signs and symptoms except for aspiration and abdominal distention.
Conclusions: This meta-analysis found no differences in ICU and overall mortality, ICU and hospital LOS, duration of MV, and infectious complications between underfeeding and full-feeding. The subgroup analysis showed lower overall mortality among patients receiving moderate underfeeding. This result should be cautiously interpreted due to the limitations of the small number of studies analyzed and their methodology.