Nutrition support plays a crucial role in the management of premature neonates. Parenteral nutrition (PN) especially has continued to have an impact on the care of neonates who are unable to ingest sufficient enteral calories and fluids. The use of PN has evolved in the neonatal intensive care unit (NICU) to minimize the metabolic complications that interrupt normal growth. To deliver PN to neonates, those involved in the ordering and delivery of PN need to be educated and trained to ensure safety and standardization.1 This chapter provides a practical overview to provide optimal nutrition support to neonates in the NICU, keeping in mind the particular conditions and physiology of premature neonates.
Parenteral nutrition can be used as the sole source of nutrition and fluids for neonates. There are multiple conditions that can inhibit or limit the use of enteral nutrition. Patients can develop short-bowel syndrome from intestinal atresia, volvulus, or necrotizing enterocolitis. Motility issues can arise from Hirschsprung disease, meconium ileus, ileus as a result of generalized illness, or gastroschisis. Neonates with asphyxia or hypotension with use of vasopressors might not be clinically stable enough for the initiation of enteral nutrition. Preterm neonates on slowly advancing feedings will also require PN supplementation to obtain substantial calories and fluids until goal feedings have been reached. PN or enteral nutrition should be started within 24 hours after birth.2, 3, 4, and 5 More aggressive administration of both glucose and amino acids has led to the use of standard, starter, or “vanilla” total parenteral nutrition (TPN). Many of these solutions come premixed; many institutions still compound the mixture in the hospital pharmacy. These initial solutions usually contain 7.5% to 10% dextrose and 3% amino acids.6 The goal is to have a glucose infusion rate (GIR) of 6–8 mg/kg/min and amino acid administration of 2 to 3 g/kg/day.
Peripheral venous access limits the osmolality of fluids that can be infused through it, which limits dextrose concentration to 12.5%. Increased osmolality that infuses through a peripheral catheter increases the risk of thrombophlebitis, although concomitant infusion of a fat emulsion can reduce venous irritation.7,8 Central venous access, either through an umbilical venous catheter (UVC) or a peripherally inserted central catheter (PICC) is generally needed. Positioning of these catheters must be confirmed with an x-ray showing the tip terminating at the junction of the superior vena cava and right atrium of the heart. Continuous infusion of heparin 0.5 IU/kg/h has been shown to reduce occlusions of PICC lines in neonates and can be added directly to the PN fluid.9,10
PARENTERAL NUTRITION COMPONENTS
There are many factors that can increase the metabolic demands of neonates, including increased heat loss, small for gestational age (SGA), fever, sepsis, respiratory distress, ...