Enteral omega-3 in acute respiratory distress syndrome

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.

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.

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.