Parenteral nutrition (PN) must be initiated as soon as possible after delivery in very low birth weight (VLBW) preterm infants in order to prevent postnatal growth failure and improve neurodevelopmental outcome. When administered early, high levels of parenteral
amino acids (AA) are well tolerated and prevent negative
nitrogen balance. Although
proteins are the driving force for growth,
protein synthesis is energy-demanding.
Intravenous lipid emulsions (ILE) constitute a good energy source because of their high energy density and provide
essential fatty acids (FA) along with their long-chain
polyunsaturated fatty acid (LC-PUFA) derivatives necessary for central nervous system and
retinal development. Early supply of ILE is not associated with increased morbidity. No significant differences were found between ILE based on
soybean oil only and mixed ILE containing
soybean oil in combination with other fat sources, except for a reduction in the incidence of
sepsis with non-pure soybean ILE, and possibly less PN-associated
liver disease with mixed ILE containing some
fish oil. In preterm infants
glucose homeostasis is still immature in the first days of life and abnormalities of
glucose homeostasis are common. VLBW infants may not tolerate high levels of
glucose infusion without
hyperglycemia. Administering lower levels of
glucose infusion as part of full early PN seems more successful than
insulin at this stage. Postpartum there is a transition period when the water and electrolyte balance may be severely disturbed and should be closely monitored. Avoiding fluid overload is critical for preventing respiratory and other morbidities.