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Practical aspects of achieving positive energy balance in low birth weight infants
W C Heird1, C L Jensen, M R Gomez
1Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030.
Insights
Achieving positive energy balance in low birth weight (LBW) infants is crucial. Parenteral nutrition can help overcome feeding intolerance, but essential fatty acid needs require careful consideration for optimal infant development.
Area of Science:
- Neonatal nutrition
- Infant metabolism
- Pediatric intensive care
Background:
- Low birth weight (LBW) infants require precise energy balance for survival and growth.
- Energy expenditure in non-growing LBW infants ranges from 45-55 kcal/kg/day.
- Achieving positive energy balance is essential, but feeding intolerance and necrotizing enterocolitis pose challenges.
Purpose of the Study:
- To review strategies for achieving adequate energy balance in LBW infants.
- To discuss the role of parenteral nutrition in overcoming feeding challenges.
- To highlight the importance of essential fatty acid provision in LBW infants.
Main Methods:
- Review of existing literature on LBW infant nutrition.
- Analysis of energy expenditure and intake requirements.
- Evaluation of parenteral and enteral feeding strategies.
Main Results:
- LBW infants require at least 50 kcal/kg/day for energy equilibrium.
- Parenteral nutrition can provide approximately 40 kcal/kg/day, with potential for increases.
- Essential fatty acid deficiency can develop rapidly, necessitating exogenous intake.
Conclusions:
- Parenteral nutrition is a viable option for supporting energy balance in LBW infants.
- Individualized feeding strategies are necessary, considering infant condition and tolerance.
- Specific fatty acid supplementation may be required for optimal brain development in LBW infants.
Abstract:
For the low birth weight (LBW) infant, energy balance during the first several days of life usually is equated to absorption of sufficient energy to match energy expenditure. Most studies show that energy expenditure of nongrowing LBW infants is 45 to 55 kcal/kg/day. Hence, for energy equilibrium, energy intake minus energy losses (i.e., metabolizable energy intake) must be at least 50 kcal/kg/day. Intakes above this amount result in energy storage or positive energy balance, whereas lesser intakes necessitate mobilization of endogenous energy stores (negative energy balance). Some of the problems of achieving positive energy balance in LBW infants (e.g., feeding intolerance and fear of necrotizing enterocolitis) can be circumvented by use of parenterally delivered nutrients. On balance, virtually all LBW infants will tolerate parenteral amino acid, glucose, and lipid intakes, respectively, of 2, 5, and 1 gm/kg/day or an energy intake of about 40 kcal/kg/day. It usually is possible to increase energy intake of most infants by an additional 10 kcal/kg/day. Whether this is achieved with enterally delivered nutrients or additional parenteral glucose or lipid intake, including the necessary modifications to enhance tolerance (e.g., insulin, 20% vs 10% lipid emulsions, and lipid emulsions containing medium-chain fatty acids), must be decided for each infant based on his or her underlying condition, likelihood of tolerating either substrate, and the impact of intolerance on the underlying condition. The consequences of not providing an essential nutrient during the immediate postnatal period also must be considered. The fact that essential fatty acid deficiency develops more rapidly in infants receiving isocaloric (60 kcal/kg/day) parenteral intakes with versus without amino acids, the likelihood that brain growth continues despite negative energy balance, and the possibility that LBW infants may not be able to desaturate/elongate linoleic and linolenic acids to the more unsaturated, longer-chain fatty acids that are deposited in the developing brain suggest that these infants may require exogenous intakes of specific fatty acids.