Paediatric parenteral nutrition
Adequate nutrition is essential for the survival and growth of infants and children. Growth of the foetus, infant or child, is impaired by nutrient deficiency. The critical period for development is during the first few years of life, and so malnutrition in this period can have a profound effect, with stunting of growth.1 “Catch up” growth may be exhibited when more liberal feeding occurs.2
Neuronal development is maximal during the third trimester of pregnancy and throughout the first two years of life. Even modest energy deprivation during periods of rapid brain growth and differentiation is thought to lead to adverse neuronal development.3
Nutritional requirements differ according to age. Unlike in adults, endogenous nutrient reserves are limited in the young paediatric population and can be rapidly depleted by the metabolic stresses from surgical procedures or disease. Poor nutrition leads to immunosuppression, impaired tissue and muscle function, reduced respiratory and cardiac reserve, and impaired growth.4 Chronically ill paediatric patients with congenital heart defects, or gastrointestinal or respiratory disease, are particularly at risk of malnutrition.
Parenteral nutrition is indicated for infants and children who are unable to tolerate adequate enteral feeding to sustain their nutritional requirements. The therapeutic goal is to maintain nutritional status and achieve balanced somatic growth. Somatic growth spurts occur in early infancy and adolescence. A preterm infant of 1kg has reserves that will sustain it through four days of starvation, whereas a term infant (4kg) has reserves that will sustain it for 30 days.5 Older children do not require parenteral nutrition unless malnutrition is anticipated for more than five or seven days.6
Optimal use of parenteral nutrition has resulted in higher survival of critically ill infants. Also, improvements in techniques for artificial nutrition have led to an improved quality of life for long-term parenteral nutrition patients. Indications for parenteral nutrition are shown in Panel 1, p59.
Energy is required for the maintenance of homeostasis and new tissue synthesis. Energy requirements are increased when the body is under catabolic stress, fever or sepsis, or if there is failure to thrive.7 An adequate energy substrate is necessary to ensure proper utilisation of protein. The principal sources of calories in parenteral nutrition formulations are carbohydrates and lipids. Glucose and lipids are increased in a step-wise approach, as tolerated. For effective nitrogen utilisation, the nitrogen to kcal ratio should be between 150 and 250kcal per gram of nitrogen.3,8-10 If the energy intake is insufficient, the nitrogen is used for calories; with excessive intake, the energy is deposited as fat, which may have long-term consequences.
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Citation: Hospital Pharmacist URI: 10976668
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