Parenteral Nutrition in Very Low Birth Weight Preterm Infants.

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.