Nilesh M. Mehta

A.S.P.E.N. Clinical Guidelines: Nutrition Support of the Critically Ill Child

careful selection of the appropriate mode of feeding and monitoring the success of the feeding strategy. The use of specific nutrients, which possess a drug-like effect on the immune or inflammatory state during critical illness, continues to be an exciting area of investigation. The lack of systematic research and clinical trials on various aspects of nutrition support in the PICU is striking and makes it challenging to compile evidence based practice guidelines. There is an urgent need to conduct well-designed, multicenter trials in this area of clinical practice. The extrapolation of data from adult critical care literature is not desirable and many of the interventions proposed in adults will have to undergo systematic examination and careful study in critically ill children prior to their application in this population. In the following sections, we will discuss some of the key aspects of nutrition support therapy in the PICU; examine the literature and provide best practice guidelines based on evidence from PICU patients, where available. While some PICU popu lations include neonates, A.S.P.E.N. Clinical Guidelines for neonates will be published as a separate series.

Nutritional practices and their relationship to clinical outcomes in critically ill children—An international multicenter cohort study*

Objectives:To examine factors influencing the adequacy of energy and protein intake in the pediatric intensive care unit and to describe their relationship to clinical outcomes in mechanically ventilated children. Design, Setting, Patients:We conducted an international prospective cohort study of consecutive children (ages 1 month to 18 yrs) requiring mechanical ventilation longer than 48 hrs in the pediatric intensive care unit. Nutritional practices were recorded during the pediatric intensive care unit stay for a maximum of 10 days, and patients were followed up for 60 days or until hospital discharge. Multivariate analysis, accounting for pediatric intensive care unit clustering and important confounding variables, was used to examine the impact of nutritional variables and pediatric intensive care unit characteristics on 60-day mortality and the prevalence of acquired infections. Main Results:31 pediatric intensive care units in academic hospitals in eight countries participated in this study. Five hundred patients with mean (SD) age 4.5 (5.1) yrs were enrolled and included in the analysis. Mortality at 60 days was 8.4%, and 107 of 500 (22%) patients acquired at least one infection during their pediatric intensive care unit stay. Over 30% of patients had severe malnutrition on admission, with body mass index z-score >2 (13.2%) or <−2 (17.1%) on admission. Mean prescribed goals for daily energy and protein intake were 64 kcals/kg and 1.7 g/kg respectively. Enteral nutrition was used in 67% of the patients and was initiated within 48 hrs of admission in the majority of patients. Enteral nutrition was subsequently interrupted on average for at least 2 days in 357 of 500 (71%) patients. Mean (SD) percentage daily nutritional intake (enteral nutrition) compared to prescribed goals was 38% (34) for energy and 43% (44) for protein. A higher percentage of goal energy intake via enteral nutrition route was significantly associated with lower 60-day mortality (Odds ratio for increasing energy intake from 33.3% to 66.6% is 0.27 [0.11, 0.67], p = .002). Mortality was higher in patients who received parenteral nutrition (odds ratio 2.61 [1.3, 5.3], p = .008). Patients admitted to units that utilized a feeding protocol had a lower prevalence of acquired infections (odds ratio 0.18 [0.05, 0.64], p = .008), and this association was independent of the amount of energy or protein intake. Conclusions:Nutrition delivery is generally inadequate in mechanically ventilated children across the world. Intake of a higher percentage of prescribed dietary energy goal via enteral route was associated with improved 60-day survival; conversely, parenteral nutrition use was associated with higher mortality. Pediatric intensive care units that utilized protocols for the initiation and advancement of enteral nutrient intake had a lower prevalence of acquired infections. Optimizing nutrition therapy is a potential avenue for improving clinical outcomes in critically ill children.

Defining Pediatric Malnutrition A Paradigm Shift Toward Etiology-Related Definitions

Lack of a uniform definition is responsible for underrecognition of the prevalence of malnutrition and its impact on outcomes in children. A pediatric malnutrition definitions workgroup reviewed existing pediatric age group English-language literature from 1955 to 2011, for relevant references related to 5 domains of the definition of malnutrition that were a priori identified: anthropometric parameters, growth, chronicity of malnutrition, etiology and pathogenesis, and developmental/ functional outcomes. Based on available evidence and an iterative process to arrive at multidisciplinary consensus in the group, these domains were included in the overall construct of a new definition. Pediatric malnutrition (undernutrition) is defined as an imbalance between nutrient requirements and intake that results in cumulative deficits of energy, protein, or micronutrients that may negatively affect growth, development, and other relevant outcomes. A summary of the literature is presented and a new classification scheme is proposed that incorporates chronicity, etiology, mechanisms of nutrient imbalance, severity of malnutrition, and its impact on outcomes. Based on its etiology, malnutrition is either illness related (secondary to 1 or more diseases/injury) or non-illness related, (caused by environmental/behavioral factors), or both. Future research must focus on the relationship between inflammation and illness-related malnutrition. We anticipate that the definition of malnutrition will continue to evolve with improved understanding of the processes that lead to and complicate the treatment of this condition. A uniform definition should permit future research to focus on the impact of pediatric malnutrition on functional outcomes and help solidify the scientific basis for evidence-based nutrition practices.

Challenges to Optimal Enteral Nutrition in a Multidisciplinary Pediatric Intensive Care Unit

OBJECTIVE To describe nutrient intake in critically ill children, identify risk factors associated with avoidable interruptions to enteral nutrition (EN), and highlight opportunities to improve enteral nutrient delivery in a busy tertiary pediatric intensive care unit (PICU). Design, Setting, and Measurements: Daily nutrient intake and factors responsible for avoidable interruptions to EN were recorded in patients admitted to a 29-bed medical and surgical PICU over 4 weeks. Clinical characteristics, time to reach caloric goal, and parenteral nutrition (PN) use were compared between patients with and without avoidable interruptions to EN. RESULTS Daily record of nutrient intake was obtained in 117 consecutive patients (median age, 7 years). Eighty (68%) patients received EN (20% postpyloric) for a total of 381 EN days (median, 2 days). Median time to EN initiation was less than 1 day. However, EN was subsequently interrupted in 24 (30%) patients at an average of 3.7 +/- 3.1 times per patient (range, 1-13), for a total of 88 episodes accounting for 1,483 hours of EN deprivation in this cohort. Of the 88 episodes of EN interruption, 51 (58%) were deemed as avoidable. Mechanically ventilated subjects were at the highest risk of EN interruptions. Avoidable EN interruption was associated with increased reliance on PN and impaired ability to reach caloric goal. CONCLUSIONS EN interruption is common and frequently avoidable in critically ill children. Knowledge of existing barriers to EN such as those identified in this study will allow appropriate interventions to optimize nutrition provision in the PICU.

Energy imbalance and the risk of overfeeding in critically ill children

Objective: To examine the role of targeted indirect calorimetry in detecting the adequacy of energy intake and the risk of cumulative energy imbalance in a subgroup of critically ill children suspected to have alterations in resting energy expenditure. We examined the accuracy of standard equations used for estimating resting energy expenditure in relation to measured resting energy expenditure in relation to measured resting energy expenditure and cumulative energy balance over 1 week in this cohort. Design: A prospective cohort study. Setting: Pediatric intensive care unit in a tertiary academic center. Interventions: A subgroup of critically ill children in the pediatric intensive care unit was selected using a set of criteria for targeted indirect calorimetry. Measurements: Measured resting energy expenditure from indirect calorimetry and estimated resting energy expenditure from standard equations were obtained. The metabolic state of each patient was assigned as hypermetabolic (measured resting energy expenditure/estimated resting energy expenditure >110%), hypometabolic (measured resting energy expenditure/estimated resting energy expenditure <90%), or normal (measured resting energy expenditure/estimated resting energy expenditure = 90–110%). Clinical variables associated with metabolic state and factors influencing the adequacy of energy intake were examined. Main Results: Children identified by criteria for targeted indirect calorimetry, had a median length of stay of 44 days, a high incidence (72%) of metabolic instability and alterations in resting energy expenditure with a predominance of hypometabolism in those admitted to the medical service. Physicians failed to accurately predict the true metabolic state in a majority (62%) of patients. Standard equations overestimated the energy expenditure and a high incidence of overfeeding (83%) with cumulative energy excess of up to 8000 kcal/week was observed, especially in children <1 yr of age. We did not find a correlation between energy balance and respiratory quotient (RQ) in our study. Conclusions: We detected a high incidence of overfeeding in a subgroup of critically ill children using targeted indirect calorimetry The predominance of hypometabolism, failure of physicians to correctly predict metabolic state, use of stress factors, and inaccuracy of standard equations all contributed to overfeeding in this cohort. Critically ill children, especially those with a longer stay in the PICU, are at a risk of unintended overfeeding with cumulative energy excess.

Cumulative Energy Imbalance in the Pediatric Intensive Care Unit: Role of Targeted Indirect Calorimetry

INTRODUCTION Failure to accurately estimate energy requirements may result in underfeeding or overfeeding. In this study, a dedicated multidisciplinary nutrition team measured energy expenditure in critically ill children. METHODS Steady-state indirect calorimetry was used to obtain measured resting energy expenditure, which was compared with equation-estimated energy expenditure and the total energy intake for each subject. The childrens metabolic status was examined in relation to standard clinical characteristics. RESULTS Sixteen measurements were performed in 14 patients admitted to the multidisciplinary pediatric intensive care unit over a period of 12 months. Mean age of subjects in this cohort was 11.2 years (range 1.6 months to 32 years) and included 7 males and 7 postoperative patients. Altered metabolism was detected in 13 of 14 subjects and in 15 of 16 (94%) measurements. There was no correlation between the metabolic status of subjects and their clinical characteristics. Average daily energy balance was 200 kcal/d (range -518 to +859 kcal/d). Agreement between measured resting energy expenditure and equation-estimated energy expenditure was poor, with mean bias of 72.3 +/- 446 kcal/d (limits of agreement -801.9 to + 946.5 kcal/d). CONCLUSIONS A disparity was observed between equation-estimated energy expenditure, measured resting energy expenditure, and total energy intake, with a high incidence of underfeeding or overfeeding. A wide range of metabolic alterations were recorded, which could not be accurately predicted using standard clinical characteristics. Targeted indirect calorimetry on high-risk patients selected by a dedicated nutrition team may prevent cumulative excesses and deficits in energy balance.

Nutritional Deficiencies During Critical Illness

A significant proportion of critically ill children admitted to the pediatric intensive care unit (PICU) present with nutritional deficiencies. Malnourished hospitalized patients have a higher rate of complications, increased mortality, longer length of hospital stay, and increased hospital costs. Critical illness may further contribute to nutritional deteriorate with poor outcomes. Younger age, longer duration of PICU stay, congenital heart disease, burn injury, and need for mechanical ventilation support are some of the factors that are associated with worse nutritional deficiencies. Failure to estimate energy requirements accurately, barriers to bedside delivery of nutrients, and reluctance to perform regular nutritional assessments are responsible for the persistence and delayed detection of malnutrition in this cohort.

Adequate enteral protein intake is inversely associated with 60-d mortality in critically ill children: a multicenter, prospective, cohort study

BACKGROUND The impact of protein intake on outcomes in pediatric critical illness is unclear. OBJECTIVE We examined the association between protein intake and 60-d mortality in mechanically ventilated children. DESIGN In a prospective, multicenter, cohort study that included 59 pediatric intensive care units (PICUs) from 15 countries, we enrolled consecutive children (age: 1 mo to 18 y) who were mechanically ventilated for ≥48 h. We recorded the daily and cumulative mean adequacies of energy and protein delivery as a percentage of the prescribed daily goal during the PICU stay ≤10 d. We examined the association of the adequacy of protein delivery with 60-d mortality and determined variables that predicted protein intake adequacy. RESULTS We enrolled 1245 subjects (44% female) with a median age of 1.7 y (IQR: 0.4, 7.0 y). A total of 985 subjects received enteral nutrition, 354 (36%) of whom received enteral nutrition via the postpyloric route. Mean ± SD prescribed energy and protein goals were 69 ± 28 kcal/kg per day and 1.9 ± 0.7 g/kg per day, respectively. The mean delivery of enteral energy and protein was 36 ± 35% and 37 ± 38%, respectively, of the prescribed goal. The adequacy of enteral protein intake was significantly associated with 60-d mortality (P < 0.001) after adjustment for disease severity, site, PICU days, and energy intake. In relation to mean enteral protein intake <20%, intake ≥60% of the prescribed goal was associated with an OR of 0.14 (95% CI: 0.04, 0.52; P = 0.003) for 60-d mortality. Early initiation, postpyloric route, shorter interruptions, larger PICU size, and a dedicated dietitian in the PICU were associated with higher enteral protein delivery. CONCLUSIONS Delivery of >60% of the prescribed protein intake is associated with lower odds of mortality in mechanically ventilated children. Optimal prescription and modifiable practices at the bedside might enhance enteral protein delivery in the PICU with a potential for improved outcomes. This trial was registered at clinicaltrials.gov as NCT02354521.

Approach to Enteral Feeding in the PICU

The pediatric intensive care unit (PICU) environment poses unique challenges to achieving enteral nutrition (EN) goals for the critically ill child. Nutrition support in the PICU is often in conflict with the complexity of care provided to acutely ill children. A significant proportion of eligible patients do not receive optimal enteral nutrition for avoidable reasons. Early institution of EN is recommended and the gastric route is preferred because of ease of administration and reduced costs compared with the transpyloric route. In patients with poor gastric emptying or in cases where a trial of gastric feeding has failed, transpyloric or postpyloric feeding may be used to decrease the risk of aspiration and to improve enteral feed tolerance. However, there is no evidence of benefit for routine use of small bowel feeding in all patients admitted to the PICU. The placement of blind nasoenteric feeding tubes can be technically challenging, is not without complications, and requires local expertise and experience for successful placement and maintenance. A protocolized approach to selecting the optimal route and advancing enteral feedings may optimize EN delivery. Institutional practice guidelines based on consensus, available evidence, and national guidelines may decrease time to reaching caloric goal, improve protein balance, and potentially affect clinical outcomes. The rationale and challenges to the delivery and maintenance of optimal EN, and strategies to achieve optimal EN during critical illness, are discussed.

Severe weight loss and hypermetabolic paroxysmal dysautonomia following hypoxic ischemic brain injury: the role of indirect calorimetry in the intensive care unit.

A 14-year-old girl with hypoxic ischemic brain injury developed multiple paroxysms (storms) of dysautonomia. She had a dramatic weight loss of 20 kg over 8 weeks. Resting energy expenditure measured by indirect calorimetry during an autonomic storm was 309% of predicted resting energy expenditure, indicating extreme hypermetabolism. Energy intake and expenditure calculations showed cumulative energy deficits during the period of weight loss. The frequency of her hypermetabolic events increased daily energy needs that were unmatched by her intake, which was calculated from standard equations. Weight stabilized soon after nutrient intake was titrated to account for her heightened energy expenditure. This case illustrates an important nutrition complication of dysautonomic storms in children with brain injury. Regular weight checks during the intensive care course allow detection of weight loss from underfeeding. Measurement of energy needs is prudent when weight loss is unexplained or increased energy expenditure is suspected. In hospitalized patients with metabolic fluctuations, accurate measurement of energy requirements by indirect calorimetry allows serial monitoring of energy balance and may guide nutrition intake to prevent cumulative energy deficits.