Enteral omega-3 in acute respiratory distress syndrome

PURPOSE OF REVIEW: The acute respiratory distress syndrome (ARDS) is a severe illness that is often the cause of death in ICU patients. A safe and effective intervention for this condition is lacking. Fish oil-based enteral nutrition [rich in n-3 polyunsaturated fatty acids (PUFAs) and antioxidants] improved clinical outcomes in a previous trial on ARDS patients but was ineffective, or even harmful in other studies utilizing different fish oil formulae (rich in n-3 PUFAs and arginine) in severely ill ICU patients. Until most recently, consistent evidence that enteral n-3 PUFA is therapeutic in ARDS was lacking. RECENT FINDINGS: In ARDS, an overwhelming inflammatory response damages the endothelial-alveolar units, reducing oxygen diffusion and increasing pulmonary workload. n-3 PUFA targets this inflammatory response. In two recent randomized, controlled studies, the fish oil formula that was previously shown to be effective was administered to patients with ARDS/acute lung injury (in which hypoxia is less severe) and to patients with severe sepsis and hypoxia, respectively. n-3 PUFA feeding improved oxygenation, and a meta-analysis of the three studies demonstrated that enteral fish oil reduces mortality, complications and length of ICU stay. SUMMARY: Enteral administration of fish oil, antioxidants and physiologic amounts of arginine improve oxygenation and clinical outcomes in ICU patients with impaired oxygenation. Whether n-3 PUFA per se produces such benefit is the subject of an ongoing clinical study.