Omega-6 sparing effects of parenteral lipid emulsions—an updated systematic review and meta-analysis on clinical outcomes in critically ill patients

This systematic review and meta-analysis included 20 trials (n = 1366) in critically ill adults aged 18 years or older admitted to intensive care. It evaluated omega-6 fatty acid-sparing parenteral lipid emulsions versus standard lipid emulsions across mortality, length of stay, mechanical ventilation, and infectious complications, with subgroup analyses for fish oil-containing, Omegaven, stand-alone fish oil, and other lipid-emulsion strategies.

Intravenous omega-6 fatty acid-sparing parenteral lipid emulsions were compared with standard lipid emulsions in critically ill adults receiving parenteral nutrition. The most studied regimens were fish oil-containing formulations, including Omegaven; reported fish oil dosing was 0.1-0.2 g/kg/day IV as part of PN.

Overall, omega-6 fatty acid-sparing parenteral nutrition did not significantly reduce mortality versus control (RR 0.91, 95% CI 0.76 to 1.10; p = 0.34). The clearest benefit was with fish oil-containing PN, which reduced infectious complications (RR 0.65, 95% CI 0.44 to 0.95; p = 0.03) and was associated with shorter hospital stay (WMD -6.88, 95% CI -11.27 to -2.49; p = 0.002). ICU length of stay was not significantly reduced overall (WMD -1.94, 95% CI -4.41 to 0.52; p = 0.12), and duration of mechanical ventilation was also nonsignificant (WMD -0.87, 95% CI -1.82 to 0.07; p = 0.07). Fish oil-containing PN showed a mortality signal at 28 days (RR 0.74, 95% CI 0.54 to 1.01; p = 0.06), and Omegaven was associated with lower mortality (RR 0.68, 95% CI 0.48 to 0.95; p = 0.03).

Findings were heterogeneous across lipid formulations, comparators, and outcomes, with substantial heterogeneity for ICU length of stay (I2 = 83%). Several analyses included relatively small numbers of studies or participants, many effects were borderline or nonsignificant, and detailed age, sex, geographic, and dietary information was not reported.