Parenteral nutrition in the NICU

One of the most important goals in the neonatal intensive care unit (NICU) is to support optimal growth, which in turn supports optimal neurodevelopmental outcomes. When enteral nutrition cannot be utilized or fully utilized, parenteral nutrition is required. In the NICU, pare…nteral nutrition is indicated with prematurity, until enteral feedings can be advanced, and in conditions that prevent or limit the use of enteral nutrition.

Due to immature function and motility of the gastrointestinal (GI) tract, premature infants require total parenteral nutrition (TPN) while enteral feedings are being gradually advanced. Generally, infants born under 32 weeks’ gestation or below 1,800 grams will be started on TPN. In most cases, they’ll be initiated on a starter TPN solution that contains dextrose and protein, may contain calcium, and can be initiated immediately after birth. Lipids are typically administered in combination with the starter TPN.

Other indications for parenteral nutrition

In addition to prematurity, necrotizing enterocolitis (NEC), intestinal perforations, impaired GI motility, and malabsorption are all indications for parenteral nutrition. Conditions that impair GI blood perfusion can lead to an increased risk for NEC, and thus require parenteral nutrition in some cases. Examples include congenital heart disease, patent ductus arteriosus (PDA), hypotension, hypoxic ischemic encephalopathy, and the use of medications that may impair GI perfusion.

Every effort should be made to provide sufficient nutrition to infants, especially preterm infants, as soon as possible after birth. Preterm infants unable to receive a significant amount of enteral nutrition are started on TPN within the first day of life.  Term infants are started on TPN on day of life two or three, if unable to initiate enteral feedings or if advancement is significantly delayed.

Parenteral nutrition access

Access for parenteral nutrition is either peripheral or central. In most cases, very preterm infants will have central umbilical catheters placed shortly after birth.  Umbilical artery catheters are typically used for labs, blood pressure monitoring, and administration of additional fluids. Umbilical venous catheters are commonly used for parenteral nutrition delivery in preterm infants.

If an infant requires TPN for longer than seven days, a peripherally inserted central venous catheter (PICC) will likely be placed.  After about seven days, umbilical catheters can increase the risk for central line-associated bloodstream infections. If an infant has a peripheral IV line, dextrose should be limited to 12.5% and osmolality to 1,000 mOsm/kg.  Some NICUs will limit the amount of calcium provided in the parenteral nutrition solution due to the risk for extravasation and potential subsequent skin injury.

Risks of parenteral nutrition include bloodstream infections, especially with centrally placed IV lines.  If TPN is required long-term, there is a risk for parenteral nutrition-associated liver disease, a complication seen with short bowel syndrome.  Electrolyte abnormalities, fluid overload, and hyperglycemia are additional risks of TPN.

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References:

Groh-Wargo, et al, eds.  Pocket Guide to Neonatal Nutrition. Academy of Nutrition and Dietetics. 2016.

Koletzko B, Proindexter B, Uauy R, eds.  Nutrition Care of Preterm Infants: Scientific Basis and Practical Guidelines. Basel, Switzerland: Karger Publishers; 2014.