Metabolism of Infants and Children

Abstract

Despite advances in the field of nutrition, prevalence of malnutrition remains strikingly high in hospitalized patients particularly those with protracted illness. Appropriate nutritional intervention following any metabolic stress is predicated upon an understanding of the profound, yet predictable, alteration in metabolism. The primary aim of these interventions is to augment the short-term benefits of the pediatric metabolic response to insult or injury while minimizing any long-term consequences. The metabolic state following insult or injury progresses through two predictable stages: an initial hypometabolic “ebb phase,” followed quickly by a prolonged increase in overall metabolic rate called the “flow phase.” Quantification of energy requirements is an important first step in the design of appropriate nutritional strategies, as dietary regimens that both underestimate and overestimate energy needs are associated with injurious consequences. Pediatric patients additionally have several key differences as compared to adults in terms of available metabolic reserves, baseline energy, and substrate requirements. The metabolic stress response leads to enhanced protein, glucose, and lipid turn over to provide energy and substrate needed for healing and recovery. This enhanced substrate turnover is beneficial in the short-term, but the consequences of sustained catabolism may be quite rapidly deleterious in children. While this substrate breakdown cannot be completely reversed, knowledge of the key differences in the pediatric metabolic stress response can help design nutritional regimens, which can mitigate the deleterious effects associated with sustained catabolism to a large extent by appropriate provision of energy and nutritional substrates.