Effect of omega-3 fatty acids on the clinical outcomes of mechanically ventilated critically ill patients: a systematic review

Abstract

Introduction: Mechanical ventilation (MV) is a life-saving strategy associated with serious complications. Early weaning is required to prevent ventilator-associated events (VAE). Previous studies have shown that omega-3 fatty acids (n-3 FA) could reduce the number of days that a critically ill patient is on MV. Many of the conditions indicating the need for MV, as well as some of the complications of prolonged MV, have a strong inflammatory component which could be ameliorated by the anti-inflammatory properties of n-3 FA. Through these mechanisms, the production of anti-inflammatory cytokines is favoured and can contribute to decreased inflammation, which, in turn, may result in improved oxygenation and, ultimately, earlier weaning from MV. This systematic review therefore aimed to critically review published data to determine the effectiveness of n-3 FA on length of ventilation (LOV) as well as other clinical outcomes. Methods: Electronic searches of MedLine, Scopus, EBSCOhost and ScienceDirect were conducted from 2000 to 2017 in accordance with the PRISMA method. Randomised clinical trials (RCTs) comparing fish oil supplementation in critically ill, mechanically ventilated patients via either the enteral or parenteral route were included. Data were pooled and analysed according to the route of feeding. Heterogeneity was assessed visually and by the Chi2 test with a p-value of less than 0.1 considered significant. This was further quantified by the I2 test. Results: A total of eight enteral RCTs (n=1032) and four parenteral RCTs (n=411) met the inclusion criteria for this systematic review. Following statistical analysis, no significant differences were found with regards to LOV in patients receiving parenteral n-3 FA at day 4 (p=0.51, I2=0%) or day 7 (p=0.54, I2=0%). There were also no significant differences regarding LOV in patients receiving enteral n-3 FA (p=0.68, I2=61%). Analysis of available data of PF ratio, intensive care unit length of stay (ICU LOS) and mortality also did not indicate any significant differences in either groups receiving enteral or parenteral n-3 FA when compared to the control groups. The overall risk of bias of the included RCTs was high and the overall quality, as assessed according to GRADE, was very low. Conclusion: From the available evidence it appears that supplementation with either parenteral or enteral n-3-containing products has no effect on LOV, the ratio of partial pressure of arterial oxygen to the fraction of inspired oxygen (PF ratio) or mortality outcomes in mechanically ventilated critically ill patients. More high quality, large-scale RCTs, that adequately addressed the issues surrounding risk of bias, are required in order to verify the results of previous studies and provide more reliable evidence that can be translated into practice guidelines.