Requerimientos de energia

Seminars in Fetal & Neonatal Medicine (2007) 12, 2e10 a v a i l a b l e a t w w w. s c i e n c e d i r e c t . c o m

j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / s i n y

Energy requirements
Christian V. Hulzebos*, Pieter J.J. Sauer
Department of Pediatrics, Division of Neonatology, Beatrix Children’s Hospital, University Medical Center Groningen,Hanzeplein 1, 9713 GZ Groningen, The Netherlands

KEYWORDS
Energy balance; Energy expenditure; Extremely low birth-weight infants; Fetal origins of adult diseases; Growth; Outcome

Summary The determination of the appropriate energy and nutritional requirements of a newborn infant requires a clear goal of the energy and other compounds to be administered, valid methods to measure energy balance andbody composition, and knowledge of the neonatal metabolic capacities. Providing an appropriate amount of energy to newborn infants remains a challenge considering the great number of newborn infants who suffer in-hospital growth retardation. The energy requirements of a newborn infant are influenced by several factors e basal metabolism, growth, energy expenditure, and energy losses e which changecontinuously during development. Calculating the energy requirements of preterm infants is subject to error if general recommendations are applied without recognition of the large variation in factors that influence, for example, energy expenditure. Therefore, energy recommendations should be individualized and preferably based on measurements of energy expenditure. In particular, extremely lowbirth-weight and very low birth-weight infants are prone to develop negative energy and nutrient balances, due to low energy intake, low energy reserves and high energy demands. Early energy accretion is not only essential for growth but also influences neurodevelopmental outcome and physical health in the long term, thereby underlining the importance of adequate neonatal nutrition. ª 2006 Elsevier Ltd.All rights reserved.

Introduction
The main goal of fetal and neonatal energy accretion is to achieve growth and progression of development so as to preserve longevity in good health. However, optimal postnatal growth has been poorly defined and is still under debate. To date, the gold standard by which the efficacy of the ex utero growth rate of preterm infants is evaluated

* Correspondingauthor. Tel.: þ31 50 361 9719; fax: þ31 50 361 1704. E-mail address: c.hulzebos@bkk.umcg.nl (C.V. Hulzebos).

refers to the growth rate in utero. It can be argued that this is not a realistic reference standard for the growth rate ex utero. Intrauterine exposure to specific hormones and growth factors is not the same as exposure in the extrauterine environment, and fetal physiology clearly differsfrom neonatal physiology. Moreover, fetal growth varies from population to population and is affected by many factors, e.g. genetic constitution, race, maternal nutritional status, maternal parity, and fetal gender. Currently used postnatal growth curves are mostly based on cross-sectional data of heterogenetic populations and are therefore of limited use for a prospective evaluation of postnatalgrowth of an individual newborn infant.

1744-165X/$ - see front matter ª 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.siny.2006.10.008

Energy requirements The energy balance is reflected by an equation relating energy (E) intake and energy expenditure: E intake À E lossZE expenditure þ E stored Energy expenditure is the sum of energy required for maintenance, growth,thermoregulation, and activity. Energy loss represents the amount of energy lost via intestines or kidneys (approximately 10%). Although seeming to be a rather simple mathematical equation, measuring energy balance remains a laborious procedure, challenged by potential inaccurate calculations of energy intake and the well-known theoretical and practical limitations of the methods used to determine energy...