Nutrition is an essential component of patient management in the pediatric intensive care unit (PICU). Poor nutrition status accompanies many childhood chronic illnesses. A thorough assessment of the critically ill child is required to inform the plan for nutrition support. Accurate and clinically relevant nutritional assessment, including growth measurements, provides important guidance. Indirect calorimetry provides the most accurate measurement of resting energy expenditure, but is too often unavailable in the PICU. To prevent inappropriate caloric intake, reassessment of the child’s nutrition status is imperative. Enteral nutrition is the recommended route of intake. Human milk is preferred for infants.

Keywords

Nutrition

Critically ill child

Nutritional disorders

Child

Intensive care unit

Key points

Introduction

Nutrition is an essential component of patient management in the pediatric intensive care unit (PICU). Critically ill infants and children have an increase in metabolic needs and lower macronutrient stores inherent in infancy and childhood. In addition, the added nutritional complexities of critical illness make providing adequate nutrition particularly difficult. Undernourished states are a common consequence of disease and its treatment. Although a few recent studies challenge assumptions, the significance of nutrition support for hospitalized patients has been well documented.1–7 Delivery of acceptable nutrient amounts is linked with enhanced clinical outcomes, including improved wound healing and tissue integrity.7–15 Higher calorie and protein intake is associated with positive protein balance in children who are ventilated mechanically.8,16–18 In addition, increased delivery of nutrition is linked to reduced infection rates, length of hospital stay, and mortality, especially when nutrition protocols are in place.1,8,13,15,19

Malnutrition has been reported at admission and during hospitalization in critically ill children since the 1980s.20–27 Two of the first widely disseminated studies were completed by Pollack and colleagues.25,26 These investigators noted a 20% occurrence of chronic and acute malnutrition. A recent study confirmed that rates for suboptimal nutrition remain high in PICUs worldwide.28 This international point prevalence study included 31 intensive care units (ICUs), and found that 30% of all PICU patients demonstrate signs of malnutrition.

The trajectory of critical illness varies and is a multifactorial, heterogeneous disease process. Hypermetabolism leads to a shortfall in energy, and simultaneous changes in micronutrient and macronutrient needs. Body storage sites, especially muscles, are depleted for energy to support the immune system and other key body functions. Despite this catabolism, the contraction of muscle fibers associated with mechanical work is an energy-demanding process. With muscle wasting, respiratory insufficiency may lead to delayed weaning from mechanical ventilation.29 Gastrointestinal (GI) dysfunction is commonly reported in critically ill patients.30,31 The motility of the GI tract diminishes almost immediately, triggered by sympathetic stimulation and the inflammatory response connected to injury.32 Alterations in the GI tract place the patient at risk for systemic infections by translocation of the GI flora into the systemic circulation. Acute lower respiratory infections have been associated with undernutrition and zinc deficiency.33 Malnourished patients often have prolonged hospitalizations and increased hospital costs.22,24,34,35

Poor nutrition status accompanies many chronic childhood diseases. Conditions such as congenital heart disease (CHD), oncologic disorders, significant neurologic dysfunction, and other common chronic conditions contribute to the risk of undernutrition. Infants with CHD have demonstrated the presence of growth failure in all age groups and in all stages of repair.20,36 Patients with CHD have a 3.6 times higher chance of not reaching satisfactory caloric intake when matched against subjects without CHD.20 Factors leading to energy deficiency in children with cancer include insufficient intake, increased metabolic rate, altered physical activity, and inflammation.37 Those children with conditions that include severe motor disability are at higher risk of undernutrition.38 In addition, infants with brainstem injury often have feeding difficulties.39

An imbalance of energy and nutrient equation leads to nutrition related consequences. Children with injury or sepsis or those who are admitted to the ICU in a malnourished state are particularly at risk and require the highest priority. Although the metabolic response in critical illness is unavoidable, provision of adequate calories and protein based on patient size and metabolic needs is crucial.40

Determining nutritional needs

A thorough assessment of the critically ill child is required to inform the plan for nutritional support. The American Society of Parenteral and Enteral Nutrition (ASPEN) nutritional support guidelines for critically ill children recommend that children undergo nutrition screening to identify those with existing malnutrition and those nutritionally at risk.13 The Joint Commission requires assessment of nutritional risk within 24 hours of hospital admission.41 Those not at risk on admission should be regularly rescreened, as significant protein and energy depletion in patients hospitalized for longer than 7 to 10 days has been demonstrated.42 Added risk is also related to the longer duration the patient has been without adequate nutrition. When screening measures identify risk of malnutrition, a formal assessment is warranted.

No sole assessment measure is adequate to provide a complete picture of the nutritional status of sick infants and children. A systematic appraisal of the child’s physical examination findings, a review of relevant diagnostics, and an awareness of the metabolic consequences of the child disease are essential. Clinical and biochemical assessment strategies provide specific information to support nutritional prescription. In addition, an evaluation of energy expenditure can be an important asset in guiding the nutrition plan.

The first step in nutritional risk assessment is a careful history. Accurate and clinically relevant nutritional assessment provides important guidance.32 Historical growth data, hospitalizations, surgical procedures, and acute and chronic conditions, especially those that have GI sequelae and feeding difficulties, are important to note. Because of their effect on intake, identifying prior sensory and fine motor dysfunction and chewing and swallowing difficulties is important. In addition, any recent weight loss or decreases in nutrient intake are key indicators of nutrition risk.

The physical examination is useful in establishing nutrition status. Some of the first visual signs of protein malnutrition are seen in rapidly growing tissues.42,43 Skin is thin, dull, and dry in appearance. Hair is brittle and falls out easily. The abdomen may appear...