Omega-3 polyunsaturated fatty acids in critically ill patients with acute respiratory distress syndrome: A systematic review and meta-analysis

•Omega-3 polyunsaturated fatty acids have been administered to ARDS patients, mostly by enteral route with contradictory results.•Enteral immunomodulatory diets with fish oils may be associated with an improvement in early and late PaO2-to-FiO2 ratio in ARDS, although a clinical and statistically significant heterogeneity exists.•The treatment effect seems to be greatest in those trials published before 2011 that provided an immunomodulatory formula with fish oils administered as a continuous infusion.•Further well-powered clinical trials aimed at evaluating whether modulating pathophysiology of ARDS patients with omega-3 could improve morbidity and mortality are warranted. Acute respiratory distress syndrome (ARDS) is characterized by an acute inflammatory response in the lung parenchyma leading to severe hypoxemia. Because of its anti-inflammatory and immunomodulatory properties, omega-3 polyunsaturated fatty acids (ω-3 PUFA) have been administered to ARDS patients, mostly by the enteral route, as immune-enhancing diets with eicosapentaenoic acid, γ-linolenic acid, and antioxidants. However, clinical benefits of ω-3 PUFAs in ARDS patients remain unclear because clinical trials have found conflicting results. Considering the most recent randomized controlled trials (RCTs) and recent change in administration strategies, the aim of this updated systematic review and meta-analysis was to evaluate clinical benefits of ω-3 PUFA administration on gas exchange and clinical outcomes in ARDS patients. We searched for RCTs conducted in intensive care unit (ICU) patients with ARDS comparing the administration of ω-3 PUFAs to placebo. The outcomes assessed were PaO2-to-FiO2 ratio evaluated early (3–4 d) and later (7–8 d), mortality, ICU and hospital length of stay (LOS), length of mechanical ventilation (MV), and infectious complications. Two independent reviewers assessed eligibility, risk of bias, and abstracted data. Data were pooled using a random effect model to estimate the relative risk or weighted mean difference (WMD). Twelve RCTs (n = 1280 patients) met our inclusion criteria. Omega-3 PUFAs administration was associated with a significant improvement in early PaO2-to-FiO2 ratio (WMD = 49.33; 95% confidence interval [CI] 20.88–77.78; P = 0.0007; I2 = 69%), which persisted at days 7 to 8 (WMD = 27.87; 95% CI 0.75–54.99; P = 0.04; I2 = 57%). There was a trend in those receiving ω-3 PUFA toward reduced ICU LOS (P = 0.08) and duration of MV (P = 0.06), whereas m