Intravenous lipid emulsions (IVLEs) is a core component of parenteral nutrition (PN) for
providing calories and essential fatty acids. Until recently, Intralipid was the only
available IVLE in North America. For a long time now, the use of Intralipid has been
described to be associated with the development of BPD. Lack of sufficient lipid clearance in
premature infants, augmented oxidative stress, deficiency of anti-inflammatory agents, and
elevated pulmonary artery pressure have all shown to be potential causes for lung injury
during the use of Intralipid.
Intralipid, made mainly of soybean oil, contains high amounts of n6-LCPUFA and low amounts of
n3-LCPUFA. This results in prostaglandin synthesis favoring pro-inflammatory products and
amplified oxidative stress. Current evidence indicates that well-balanced fatty acid supply
is a crucial factor to reduce inflammation and oxidative stress. The concern about unbalanced
n6:n3 ratio has led to the development of novel IVLEs, like SMOFlipid. SMOFlipid is composed
of a mixture of soybean oil (30%), medium-chain triglycerides (MCT) (30%), olive oil (25%)
and fish oil (15%). The combination of soybean oil and fish oil allows delivering balanced
LCPUFA with n6:n3 ratio of 2.5:1 and provides sufficient amounts of the preformed n3-LCPUFA.
Interventions that improve n3-LCPUFA status have been shown to reduce pulmonary inflammation
in animal models.
In humans, a study on extremely preterm infants has revealed a rapid decline in the n3-LCPUFA
in the first week of life despite the use of Intralipid. Early restoration of an adequate
ratio of LCPUFA to inhibit inflammation has gained interest in recent years. In an
observational study by Skouroliakou et al., very low birth weight infants receiving SMOFlipid
within 48 hours of birth and for at least 7 days had a lower incidence of BPD compared to the
Intralipid control group. A recent systematic review and meta-analysis of 8 randomized
control trials (7 compared SMOFlipid to Intralipid) was conducted to evaluate safety and
efficacy of fish oil-enriched IVLEs in preterm infants. Infants who received fish
oil-enriched IVLEs had significantly higher RBC membrane DHA and EPA. The meta-analysis
showed no difference in all-cause mortality and overall complication rate in 238 infants
receiving fish oil-enriched IVLEs. However, all the studies included in this meta-analysis
were small. Furthermore, the studies focused mainly on laboratory findings, and did not aim
to study effect on inflammation, oxidative stress or clinical outcomes. Studies from
critically ill adults in intensive care units exhibited a reduction in the duration of
hospitalization and ventilator days, a risk factor for lung injury, when using n3-LCPUFA
enriched IVLEs.