Growth and clinical outcome in very low birthweight infants after the introduction of a multicomponent lipid emulsion

Abstract

Very low birthweight (VLBW; birthweight <1,500 g) infants are dependent on parenteral nutrition after birth. Conventional intravenous lipid emulsions are associated with inflammatory and metabolic complications which may be harmful to preterm infants. Evidence to support any clinical benefit associated with newer multicomponent emulsions, in particular those enriched with omega-3 fatty acids, remains inconsistent and unsubstantiated in appropriate studies. The aim of this thesis was to determine whether a change from a purely soybean oil-based emulsion (Intralipid) to one containing soy, medium-chain triglycerides, olive oil and fish oil (SMOFlipid) would improve growth and clinical outcomes in VLBW infants born in the neonatal unit at National Women’s Health, Auckland City Hospital. A review of red blood cell transfusions before and after a contemporaneous change to the protocol on commencement of ferrous sulphate supplementation was also conducted. Consecutively-born VLBW infants were identified from a prospectively-maintained database of admissions. Data were collected retrospectively for the first four weeks after birth on nutritional intake, growth parameters, bilirubin concentrations, red blood cell transfusions, and a range of neonatal morbidities. Outcomes were compared between the two lipid cohorts with Student’s t-test or the Wilcoxon Rank Sum test. Data were available for 105 infants who received Intralipid and 102 infants who received SMOFlipid. There was no difference in growth velocity or change in weight, length and head circumference Z-scores between cohorts. Significantly fewer infants in the SMOFlipid cohort developed any retinopathy of prematurity (Intralipid 59% vs. SMOFlipid 39%, p=0.005) or intraventricular haemorrhage (Intralipid 27% vs. SMOFlipid 15%, p=0.03) during their admission. Receiving SMOFlipid was associated with significantly lower mean (p=0.01), minimum (p=0.03) and maximum (p=0.04) total bilirubin concentrations across the first four weeks after birth. SMOFlipid infants received ferrous sulphate supplementation significantly earlier (Intralipid 29 (28–30) days vs. SMOFlipid 18 (15–25) days, p<0.0001) and received one fewer red blood cell transfusions (Intralipid 2 (0–5) vs. SMOFlipid 1 (0–3) transfusions, p=0.02). This was associated with meeting international consensus recommendations for total enteral iron intake 13 days earlier. These data indicate that SMOFlipid may represent a favourable alternative to conventional lipid emulsions in neonatal parenteral nutrition regimens.