Resting energy expenditure and nitrogen balance in critically ill pediatric patients on mechanical ventilation

Macronutrient and Micronutrient Intake in Children with Lung Disease

This review article aims to summarize the literature findings regarding the role of micronutrients in children with lung disease. The nutritional and respiratory statuses of critically ill children are interrelated, and malnutrition is commonly associated with respiratory failure. The most recent nutrition support guidelines for critically ill children have recommended an adequate macronutrient intake in the first week of admission due to its association with good outcomes. In children with lung disease, it is important not to exceed the proportion of carbohydrates in the diet to avoid increased carbon dioxide production and increased work of breathing, which potentially could delay the weaning of the ventilator. Indirect calorimetry can guide the process of estimating adequate caloric intake and adjusting the proportion of carbohydrates in the diet based on the results of the respiratory quotient. Micronutrients, including vitamins, trace elements, and others, have been shown to play a role in the structure and function of the immune system, antioxidant properties, and the production of antimicrobial proteins supporting the defense mechanisms against infections. Sufficient levels of micronutrients and adequate supplementation have been associated with better outcomes in children with lung diseases, including pneumonia, cystic fibrosis, asthma, bronchiolitis, and acute respiratory failure.

Effect of three enteral diets with different protein contents on protein metabolism in critically ill infants: a randomized controlled trial

INTRODUCTION

The optimal intake to improve protein metabolism without producing adverse effects in seriously ill infants has yet to be established. The aim of our study was to analyse whether an increased protein intake delivered through enteral nutrition would be associated with an improvement in nitrogen balance and serum protein levels in critically ill infants.

METHODS

We conducted a multicentre, prospective randomized controlled trial (December 2016-June 2019). The sample consisted of critically ill infants receiving enteral nutrition assigned randomly to 3 protein content groups: standard diet (1.7 g/dL), protein-enriched diet (2.7 g/dL) and high protein-enriched diet (5.1 g/dL). Blood and urine tests were performed, and we assessed nitrogen balance at baseline and at 3-5 days of the diet. We analysed variations in nitrogen balance and serum protein levels (total protein, albumin, transferrin, prealbumin, and retinol-binding protein) throughout the study period.

RESULTS

Ninety-nine infants (33 per group) completed the study. We did not find any differences were between groups in demographic characteristics, severity scores or prescribed medications, except for corticosteroids, administered in a higher proportion of patients in the third group. We observed significant increases in prealbumin and retinol-binding protein levels in patients receiving the protein-enriched and high protein-enriched diets at 3-5 days compared to baseline. The nitrogen balance increased in all groups, but the differences were not significant in the high protein-enriched group. There were no differences in gastrointestinal tolerance. Patients fed high protein-enriched formula had higher levels of serum urea, with a higher incidence of hyperuraemia in this group.

CONCLUSION

Enteral administration of higher amounts of protein improves serum protein levels in critically ill children. A protein intake of 2.2 g/kg/day is generally safe and well tolerated, whereas an intake of 3.4 g/kg/day may produce hyperuraemia in some patients.

Effectiveness of high versus lower enteral protein intake, considering energy intake, on clinical outcomes in critically ill children: a systematic review protocol

OBJECTIVE

The objective of this review is to evaluate the effectiveness of high versus lower enteral protein intake, considering energy intake, on clinical and nutritional outcomes in critically ill children hospitalized in the pediatric intensive care unit.

INTRODUCTION

Over and undernutrition increases the risk of morbidity and mortality in critically ill children. The impact of high versus lower enteral protein intake on clinical outcomes, considering energy intake, still needs to be investigated in children of different ages.

INCLUSION CRITERIA

This review will consider studies of critically ill children (aged between ≥ 37 wk' gestational age and < 18 y) admitted to the pediatric intensive care unit for a minimum of 48 hours and receiving enteral nutrition. Randomized controlled trials comparing high versus lower enteral protein intake, considering energy intake, will be eligible. Primary outcomes will include clinical and nutritional outcomes, such as length of stay in the pediatric intensive care unit and nitrogen balance.

METHODS

Using the JBI methodology for systematic reviews of effectiveness, we will search for randomized controlled trials published in English, French, Italian, Spanish, and German in electronic databases, including MEDLINE, CINAHL Complete, Embase, and the Cochrane Library, from database inception until the present. We will also search clinical trial registers and, if required, contact authors. Two independent reviewers will screen and select studies for inclusion, data extraction, and assessment of methodological quality. A third reviewer will be consulted if necessary. A statistical meta-analysis will be performed if feasible.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42022315325.

Protein supplementation versus standard feeds in underweight critically ill children: a pilot dual-centre randomised controlled trial protocol

INTRODUCTION

Protein-energy malnutrition, increased catabolism and inadequate nutritional support leads to loss of lean body mass with muscle wasting and delayed recovery in critical illness. However, there remains clinical equipoise regarding the risks and benefits of protein supplementation. This pilot trial will determine the feasibility of performing a larger multicentre trial to determine if a strategy of protein supplementation in critically ill children with body mass index (BMI) z-score ≤-2 is superior to standard enteral nutrition in reducing the length of stay in the paediatric intensive care unit (PICU).

METHODS AND ANALYSIS

This is a randomised controlled trial of 70 children in two PICUs in Singapore. Children with BMI z-score ≤-2 on PICU admission, who are expected to require invasive mechanical ventilation for more than 48 hours, will be randomised (1:1 allocation) to protein supplementation of ≥1.5 g/kg/day in addition to standard nutrition, or standard nutrition alone for 7 days after enrolment or until PICU discharge, whichever is earlier. Feasibility outcomes for the trial include effective screening, satisfactory enrolment rate, timely protocol implementation (within first 72 hours) and protocol adherence. Secondary outcomes include mortality, PICU length of stay, muscle mass, anthropometric measurements and functional outcomes.

ETHICS AND DISSEMINATION

The trial protocol was approved by the institutional review board of both participating centres (Singhealth Centralised Institutional Review Board and National Healthcare Group Domain Specific Review Board) under the reference number 2020/2742. Findings of the trial will be disseminated through peer-reviewed journals and scientific conferences.

TRIAL REGISTRATION NUMBER

NCT04565613.

A methodological and clinical approach to measured energy expenditure in the critically ill pediatric patient

The metabolic response to injury and stress is characterized initially by a decreased energy expenditure (Ebb phase) followed by an increased metabolic expenditure (Flow phase). Indirect calorimetry is a methodology utilized to measure energy expenditure and substrate utilization by measuring gas exchange in exhaled air and urinary nitrogen. The use of indirect calorimetry in critically ill patients requires precise equipment to obtain accurate measurements. The most recent guidelines suggested that measured energy expenditure by indirect calorimetry be used to determine energy requirements. This article reviews the methodological and clinical use of indirect calorimetry in critically ill pediatric patients.

Nutritional support for children during critical illness: European Society of Pediatric and Neonatal Intensive Care (ESPNIC) metabolism, endocrine and nutrition section position statement and clinical recommendations

Background

Nutritional support is considered essential for the outcome of paediatric critical illness. There is a lack of methodologically sound trials to provide evidence-based guidelines leading to diverse practices in PICUs worldwide. Acknowledging these limitations, we aimed to summarize the available literature and provide practical guidance for the paediatric critical care clinicians around important clinical questions many of which are not covered by previous guidelines.

Objective

To provide an ESPNIC position statement and make clinical recommendations for the assessment and nutritional support in critically ill infants and children.

Design

The metabolism, endocrine and nutrition (MEN) section of the European Society of Pediatric and Neonatal Intensive Care (ESPNIC) generated 15 clinical questions regarding different aspects of nutrition in critically ill children. After a systematic literature search, the Scottish Intercollegiate Guidelines Network (SIGN) grading system was applied to assess the quality of the evidence, conducting meta-analyses where possible, to generate statements and clinical recommendations, which were then voted on electronically. Strong consensus (> 95% agreement) and consensus (> 75% agreement) on these statements and recommendations was measured through modified Delphi voting rounds.

Results

The final 15 clinical questions generated a total of 7261 abstracts, of which 142 publications were identified relevant to develop 32 recommendations. A strong consensus was reached in 21 (66%) and consensus was reached in 11 (34%) of the recommendations. Only 11 meta-analyses could be performed on 5 questions.

Conclusions

We present a position statement and clinical practice recommendations. The general level of evidence of the available literature was low. We have summarised this and provided a practical guidance for the paediatric critical care clinicians around important clinical questions.

Electronic supplementary material

The online version of this article (10.1007/s00134-019-05922-5) contains supplementary material, which is available to authorized users.

Prealbumin and Retinol Binding Proteins Are Not Usable for Nutrition Follow-Up in Pediatric Intensive Care Units

PURPOSE

Feeding children is a problem in pediatric intensive care units (PICU) and it is difficult to know the correct amount. The purpose of this study is to evaluate if prealbumin or retinol binding proteins (RBP) are effective relative to daily enteral nutrition, without being affected by severity of diseases or infections and can be used to follow up nutritional amount.

METHODS

This is a prospective observational study that includes 81 patients admitted to PICU in Akdeniz University with estimated duration >72 hours, age between 1 month and 8 years. Daily calorie and protein intake were calculated and prealbumin, RBP and C-reactive protein (CRP) levels were measured on the first, third, fifth and seventh mornings.

RESULTS

We find moderate correlation between daily calorie intake and prealbumin levels (r=0.432, p<0.001), RBP levels and daily protein intake (r=0.330, p<0.001). When we investigated the relationship between changes of prealbumin, RBP, CRP, calorie and protein intake during intensive care stay, we found that increase of Prealbumin and RBP levels are explained by decrease of CRP levels (r=-0.546 and -0.645, p<0.001) and not with increase of nourishment.

CONCLUSION

Even adjusted for PRISM3, age and CRP, prealbumin and RBP are correlated with last 24 hours' diet. However, it is not convenient to use as a follow up biomarker because increase of their levels is related with decrease of CRP levels.

Chinese guidelines for the assessment and provision of nutrition support therapy in critically ill children

BACKGROUND

This document represents the first evidence-based guidelines to describe best practices in nutrition therapy in critically ill children (> 1 month and < 18 years), who are expected to require a length of stay more than 2 or 3 days in a Pediatric Intensive Care Unit admitting medical patients domain.

METHODS

A total of 25,673 articles were scanned for relevance. After careful review, 88 studies appeared to answer the pre-identified questions for the guidelines. We used the grading of recommendations, assessment, development and evaluation criteria to adjust the evidence grade based on the quality of design and execution of each study.

RESULTS

The guidelines emphasise the importance of nutritional assessment, particularly the detection of malnourished patients. Indirect calorimetry (IC) is recommended to estimate energy expenditure and there is a creative value in energy expenditure, 50 kcal/kg/day for children aged 1-8 years during acute phase if IC is unfeasible. Enteral nutrition (EN) and early enteral nutrition remain the preferred routes for nutrient delivery. A minimum protein intake of 1.5 g/kg/day is suggested for this patient population. The role of supplemental parenteral nutrition (PN) has been highlighted in patients with low nutritional risk, and a delayed approach appears to be beneficial in this group of patients. Immune-enhancing cannot be currently recommended neither in EN nor PN.

CONCLUSION

Overall, the pediatric critically ill population is heterogeneous, and an individualized nutrition support with the aim of improving clinical outcomes is necessary and important.

The science and art of pediatric critical care nutrition

PURPOSE OF REVIEW

Nutritional status and nutrient delivery during critical illness impact clinical outcomes. We have reviewed recent studies that may guide best practices regarding nutrition therapy in critically ill children.

RECENT FINDINGS

Malnutrition is prevalent in the pediatric ICU population, and is associated with worse outcomes. Nutrition support teams, dedicated dietitians, and educational programs facilitate surveillance for existing malnutrition and nutrition risk, but specific tools for the pediatric ICU population are lacking. Estimation of macronutrient requirements is often inaccurate; novel strategies to accurately determine energy expenditure are being explored. Indirect calorimetry remains the reference method for measuring energy expenditure. Enteral nutrition is the preferred route for nutrition in patients with a functioning gut. Early enteral nutrition and delivery of adequate macronutrients, particularly protein, have been associated with improved clinical outcomes. Delivery of enteral nutrition is often interrupted because of fasting around procedures and perceived intolerance. Objective measures for detection and management of intolerance to nutrient intake are required. In low-risk patients who are able to tolerate enteral nutrition, supplemental parenteral nutrition may be delayed during the first week of critical illness.

SUMMARY

Systematic research and consensus-based practices are expected to promote optimal nutritional practices in critically ill children with the potential to improve clinical outcomes.

Diabetes mellitus after injury in burn and non-burned patients: A population based retrospective cohort study

OBJECTIVE

To compare hospitalisations for diabetes mellitus (DM) after injury experienced by burn patients, non-burn trauma patients and people with no record of injury admission, adjusting for socio-demographic, health and injury factors.

METHODS

Linked hospital and death data for a burn patient cohort (n=30,997) in Western Australia during the period 1980-2012 and two age and gender frequency matched comparison cohorts: non-burn trauma patients (n=28,647); non-injured people (n=123,399). The number of DM admissions and length of stay were used as outcome measures. Multivariate negative binomial regression was used to derive adjusted incidence rate ratios and 95% confidence intervals (IRR, 95%CI) for overall post-injury DM admission rates. Multivariate Cox regression models and hazard ratios (HR) were used to examine time to first DM admission and incident admission rates after injury discharge.

RESULTS

The burn cohort (IRR, 95%: 2.21, 1.80-2.72) and other non-burn trauma cohort (IRR, 95%CI: 1.63, 1.24-2.14) experienced significantly higher post-discharge admission rates for DM than non-injured people. Compared with the non-burn trauma cohort, the burn cohort experienced a higher rate of post-discharge DM admissions (IRR, 95%CI: 1.40, 1.07-1.84). First-time DM admissions were significantly higher during first 5-years after-injury for the burn cohort compared with the non-burn trauma cohort (HR, 95%CI: 2.00, 1.31-3.05) and non-injured cohort (HR, 95%CI: 1.96, 1.46-2.64); no difference was found >5years (burn vs. non-burn trauma: HR, 95%CI: 0.88, 0.70-1.12; burn vs non-injured: 95%CI: 1.08 0.82-1.41). No significant difference was found when comparing the non-burn trauma and non-injured cohorts (0-5 years: HR, 95%CI: 1.03, 0.71-1.48; >5years: HR. 95%CI: 1.11, 0.93-1.33).

CONCLUSIONS

Burn and non-burn trauma patients experienced elevated rates of DM admissions after injury compared to the non-injured cohort over the duration of the study. While burn patients were at increased risk of incident DM admissions during the first 5-years after the injury this was not the case for non-burn trauma patients. Sub-group analyses showed elevated risk in both adult and pediatric patients in the burn and non-burn trauma. Detailed clinical data are required to help understand the underlying pathogenic pathways triggered by burn and non-burn trauma. This study identified treatment needs for patients after burn and non-burn trauma for a prolonged period after discharge.

Impact of the structure and dose of protein intake on clinical and metabolic outcomes in critically ill children: A systematic review

OBJECTIVE

The aim of this study was to describe the effects of structure/type and total amount of protein intake on protein balance and clinical outcomes in critically ill children.

METHODS

We conducted a systematic review of relevant literature on Embase, PubMed/Medline, Web of Science, Scopus, and Latin American and Caribbean Health Sciences. A partial gray literature search was undertaken and the reference lists of the selected articles were searched manually. Observational and clinical trials that evaluated the total protein intake, structure of the protein source, or both, in critically ill children were included. Nitrogen balance and clinical outcomes (mortality, length of stay, and duration of mechanical ventilation) were the main outcomes of interest.

RESULTS

We found 18 eligible studies, of which 17 assessed the quantity and one described protein structure in relation to the outcomes. In all, 2118 pediatric critically ill patients <18 y of age were included. The total daily protein intake ranged from 0.67 to 4.7 g/kg. Average daily total protein intake >1.1 g/kg, especially >1.5 g/kg, was associated with positive protein balance and lower mortality.

CONCLUSION

In critically ill children, total daily protein intake >1.1 g/kg was associated with positive effects on clinical outcomes and protein balance. The existing data are not sufficient for determining the optimal structure of protein delivered by enteral route in critically ill children.

Nutrition and metabolism in burn patients

Severe burn causes significant metabolic derangements that make nutritional support uniquely important and challenging for burned patients. Burn injury causes a persistent and prolonged hypermetabolic state and increased catabolism that results in increased muscle wasting and cachexia. Metabolic rates of burn patients can surpass twice normal, and failure to fulfill these energy requirements causes impaired wound healing, organ dysfunction, and susceptibility to infection. Adequate assessment and provision of nutritional needs is imperative to care for these patients. There is no consensus regarding the optimal timing, route, amount, and composition of nutritional support for burn patients, but most clinicians advocate for early enteral nutrition with high-carbohydrate formulas.

Nutritional support must be individualized, monitored, and adjusted throughout recovery. Further investigation is needed regarding optimal nutritional support and accurate nutritional endpoints and goals.

Nutritional management in the critically ill child with acute kidney injury: a review

Acute kidney injury (AKI) in critically ill children is frequently a component of the multiple organ failure syndrome. It occurs within the framework of the severe catabolic phase determined by critical illness and is intensified by metabolic derangements. Nutritional support is a must for these children to improve outcomes. Meeting the special nutritional needs of these children often requires nutritional supplementation by either the enteral or the parenteral route. Since critically ill children with AKI comprise a heterogeneous group of subjects with varying nutrient needs, nutritional requirements should be frequently reassessed, individualized and carefully integrated with renal replacement therapy. This article is a state-of-the-art review of nutrition in critically ill children with AKI.

Protein Requirements of the Critically Ill Pediatric Patient

This article includes a review of protein needs in children during health and illness, as well as a detailed discussion of protein metabolism, including nitrogen balance during critical illness, and assessment and prescription/delivery of protein to critically ill children. The determination of protein requirements in children has been difficult and challenging. The protein needs in healthy children should be based on the amount needed to ensure adequate growth during infancy and childhood. Compared with adults, children require a continuous supply of nutrients to maintain growth. The protein requirement is expressed in average requirements and dietary reference intake, which represents values that cover the needs of 97.5% of the population. Critically ill children have an increased protein turnover due to an increase in whole-body protein synthesis and breakdown with protein degradation leading to loss of lean body mass (LBM) and development of growth failure, malnutrition, and worse clinical outcomes. The results of protein balance studies in critically ill children indicate higher protein needs, with infants and younger children requiring higher intakes per body weight compared with older children. Monitoring the side effects of increased protein intake should be performed. Recent studies found a survival benefit in critically ill children who received a higher percentage of prescribed energy and protein goal by the enteral route. Future randomized studies should evaluate the effect of protein dosing in different age groups on patient outcomes, including LBM, muscle structure and function, duration of mechanical ventilation, intensive care unit and hospital length of stay, and mortality.

Nutrition and metabolism in burn patients

Severe burn causes significant metabolic derangements that make nutritional support uniquely important and challenging for burned patients. Burn injury causes a persistent and prolonged hypermetabolic state and increased catabolism that results in increased muscle wasting and cachexia. Metabolic rates of burn patients can surpass twice normal, and failure to fulfill these energy requirements causes impaired wound healing, organ dysfunction, and susceptibility to infection. Adequate assessment and provision of nutritional needs is imperative to care for these patients. There is no consensus regarding the optimal timing, route, amount, and composition of nutritional support for burn patients, but most clinicians advocate for early enteral nutrition with high-carbohydrate formulas. Nutritional support must be individualized, monitored, and adjusted throughout recovery. Further investigation is needed regarding optimal nutritional support and accurate nutritional endpoints and goals.

The metabolic stress response to burn trauma: current understanding and therapies

Major burns provoke a profound stress response, which is unrivalled in terms of its magnitude and duration. Evidence suggests that the pathophysiological stress response to severe burn trauma persists for several years after injury. Thus, there is a pressing need for novel strategies that mitigate this response and restore normal metabolic function in patients with burns. This is the first in a Series of three papers about the care of people with burns. In this paper, we review the current knowledge of the stress response to burn trauma, with a focus on hypermetabolism, muscle wasting, and stress-induced diabetes. We highlight recent developments and important knowledge gaps that need to be pursued to develop novel therapeutic strategies to improve outcomes in burn survivors.

Nutrition in the pediatric population in the intensive care unit

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.

How much protein and energy are needed to equilibrate nitrogen and energy balances in ventilated critically ill children?

BACKGROUND & AIMS

Protein and energy requirements in critically ill children are currently based on insufficient data. Moreover, longitudinal measurements of both total urinary nitrogen (TUN) and resting energy expenditure (REE) are lacking. The aim of this study was to investigate how much protein and energy are needed to equilibrate nitrogen and energy balances in ventilated critically ill children on the basis of daily measurements of TUN, REE and protein and energy intakes. Comparisons were made with the guidelines of the American Society for Parenteral and Enteral Nutrition and the Dietary Reference Intakes.

METHODS

Children with an expected duration of mechanical ventilation ≥72 h were prospectively recruited. TUN was measured by chemiluminescence, and REE was measured by indirect calorimetry. Generalised linear models for longitudinal data were used to study the relation between protein intake and nitrogen balance and to calculate the minimum intake of protein needed to achieve nitrogen equilibrium. A similar approach was used for energy. Results were compared to the recommended values.

RESULTS

Based on 402 measurements performed in 74 children (median age: 21 months), the mean TUN was high at 0.20 (95% CI: 0.20, 0.22) g/kg/d and the REE was 55 (95% CI: 54, 57) kcal/kg/d. Nitrogen and energy balances were achieved with 1.5 (95% CI: 1.4, 1.6) g/kg/d of protein and 58 (95% CI: 53, 63) kcal/kg/d for the entire group, but there were differences among children of different ages. Children required more protein and less energy than the Dietary Reference Intakes.

CONCLUSIONS

In critically ill children, TUN was elevated and REE was reduced during the entire period of mechanical ventilation. Minimum intakes of 1.5 g/kg/d of protein and 58 kcal/kg/d can equilibrate nitrogen and energy balances in children up to 4 years old. Older children require more protein.

Systematic review of the influence of energy and protein intake on protein balance in critically ill children

OBJECTIVE

To examine the influence of protein and energy intakes on protein balance in children receiving mechanical ventilation in the pediatric intensive care unit.

STUDY DESIGN

We hypothesized that higher energy and protein intakes are correlated with positive protein balance. We performed a systematic literature search to identify studies reporting protein balance in children requiring mechanical ventilation. Factors contributing to protein balance, including protein and energy intake, age, illness severity, study design, and feeding routes, were analyzed using a qualitative approach.

RESULTS

Nine studies met the entry criteria and were included in the final analysis. Positive nitrogen balance was reported in 6 of the studies, with a wide range of associated energy and protein intakes. Measures of central tendency for daily energy and protein intakes were significantly correlated with positive protein balance. A minimum intake of 57 kcal/kg/day and 1.5 g protein/kg/day were required to achieve positive protein balance.

CONCLUSION

We found a correlation between higher energy and protein intakes and achievement of positive protein balance in children receiving mechanical ventilation in the pediatric intensive care unit. However, there is a paucity of interventional studies, and a variety of protocols have been used to determine nitrogen balance. Larger clinical trials with uniform methodology are needed to further examine the effect of energy and protein intake on protein balance, lean body mass, and clinical outcomes in children on mechanical ventilation.

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.

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.

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 children's 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.

The respiratory quotient has little value in evaluating the state of feeding in burn patients

The respiratory quotient (RQ) is frequently used to predict over or under feeding in burn patients. The purpose of our study was to evaluate the usefulness of RQ obtained from indirect calorimetry to assess feeding adequacy in pediatric burn Intensive Care Unit patients. We evaluated pediatric patients who received enteral nutrition by continuous duodenal tube feeding at a calculated goal rate in the burn intensive care unit from January 2003 to March 2006. RQ lower than 0.85 indicated underfeeding and RQ greater than 1.0 indicated overfeeding. Actual energy intake was recorded and compared with the energy intake divided by measured resting energy expenditure. Underfeeding was defined as a nutritional regimen providing <90% of caloric requirement; appropriate feeding was provision of within +/-10% of caloric requirements and overfeeding was provision of >110% of caloric requirements. On the basis of regression analysis, there was no relationship between energy intake divided by measured resting energy expenditure and RQ (R2 = 0.0059). There was also no relationship between measured RQ and the degree of feeding (N = 222). RQ <0.85 as an indicator of underfeeding had a low sensitivity of 40% and specificity of 77%. RQ >1.0 as an indicator of overfeeding had a poor sensitivity of 23% and a specificity of 85%. The RQ, used in isolation, is a poor method to assess over or underfeeding. Future prospective studies are needed to determine the optimal methodology for the assessment of nutritional needs in children with burn injury.

[Evaluation of energy expenditure in children. Physiological and clinical implications and measurement methods]

The present article reviews the importance of the study of energy metabolism and its methods of assessment in children. Classically, energy requirements have been assessed by predictive equations based on anthropometric data. However, there are several physiologic and pathogenic states that may cause discrepancies between estimated and real values and consequently direct measurements of energy expenditure should be used. The gold standard to assess total energy expenditure during prolonged periods is the doubly labeled water method, which is mainly used for research studies. The best approach for resting energy expenditure determination in the clinical setting is indirect calorimetry. However, this method does not provide data on energy consumption under free-living conditions and its use in some critical care patients is restricted by technical limitations. Several other approaches to assess activity have been developed, based on heart rate, body temperature measurements, motion sensors and combined methods.

Insulin therapy in the pediatric intensive care unit

BACKGROUND & AIMS

Hyperglycemia is a major risk factor for increased morbidity and mortality in the intensive care unit. Insulin therapy has emerged in adult intensive care units and several pediatric studies are currently being conducted. This review discusses hyperglycemia and the effects of insulin on metabolic and non-metabolic pathways, with a focus on pediatric critical illness.

METHODS

A PubMed search was performed by using the following keywords and limits (("hyperglycemia"[MeSH terms] or ("insulin resistance"[MeSH major topic]) and ("critical care"[MeSH terms] or "critical illness"[MeSH terms])) in different combinations with ("metabolism"[MeSH terms] or "metabolic networks and pathways"[MeSH terms]) and ("outcome"[all fields]) and ("infant"[MeSH terms] or "child"[MeSH terms] or "adolescent"[MeSH terms]). Quality assessment of selected studies included clinical pertinence, publication in peer-reviewed journals, objectivity of measurements and techniques used to minimize bias. Reference lists of such studies were included.

RESULTS

The magnitude and duration of hyperglycemia are associated with increased morbidity and mortality in the pediatric intensive care unit (PICU), but prospective, randomized controlled studies with insulin therapy have not been published yet. Evidence concerning the mechanism and the effect of insulin on glucose and lipid metabolism in pediatric critical illness is scarce. More is known about the positive effect on protein homeostasis, especially in severely burned children. The effect in septic children is less clear and seems age dependent. Some non-metabolic properties of insulin such as the modulation of inflammation, endothelial dysfunction and coagulopathy have not been fully investigated in children.

CONCLUSION

Future studies on the effect of insulin on morbidity and mortality as well as on the mechanisms through which insulin exerts these effects are necessary in critically ill children. We propose these studies to be conducted under standardized conditions including precise definitions of hyperglycemia and rates of glucose intake.

[Energy expenditure in critically ill children: correlation with clinical characteristics, caloric intake, and predictive equations]

OBJECTIVE

To study energy expenditure (EE) in critically ill infants and children and its correlation with clinical characteristics, treatment, nutrition, caloric intake, and predicted energy expenditure calculated through theoretical formulas.

PATIENTS AND METHODS

A prospective observational study was conducted in critically ill infants and children. Indirect calorimetry measurements were performed using the calorimetry module of the S5 Datex monitor. Data on mechanical ventilation, nutrition, and caloric intake were registered. Theoretical equations of energy requirement (WHO/FAO, Harris-Benedict, Caldwell-Kennedy, Maffeis, Fleisch, Kleiber and Hunter) were calculated. The statistical analysis was performed using the SPSS 12.0 package.

RESULTS

Sixty-eight EE determinations were performed in 43 critically ill infants and children aged between 10 days and 15 years old. Measured EE was 58.4 (18.4) kcal/kg/day, with wide individual variability. EE was significantly lower in infants and children who had undergone cardiac surgery than in the remainder. No correlation was found between EE and mechanical ventilation parameters, vasoactive drugs, sedatives, or muscle relaxants. A correlation was found between caloric intake and EE. In a high percentage of patients, predictive equations did not accurately estimate EE. The respiratory quotient was not useful to diagnose overfeeding or underfeeding.

CONCLUSIONS

Wide individual variability in EE was found in critically ill infants and children. Predictive equations did not accurately estimate EE. Indirect calorimetry measured by a specific module is a simple method that could allow generalized use of EE measurement in critically ill pediatric patients undergoing mechanical ventilation.

Controlled study of enteral arginine supplementation in burned children: impact on immunologic and metabolic status

OBJECTIVE

We compared the effects of an arginine-supplemented diet with those of an isocaloric isonitrogenous diet on immune and metabolic response of children with burns.

METHODS

This was a double-blind, randomized, placebo-controlled trial in a burn treatment center of a pediatric hospital in Santiago, Chile. All children (1-5 y of age) admitted within 48 h of a moderate to deep burn injury covering 10% to 40% of total body surface area were evaluated. Twenty-eight children met the criteria and were randomly assigned to receive an arginine-supplemented diet (AG; n = 14) or an isocaloric isonitrogenous diet (CG; control, n = 14) for 14 d. Samples were collected at admission (baseline) and on days 7 and 14 for lymphoproliferative response to mitogens, plasma interleukins (interleukin-1, interleukin-6, tumor necrosis factor-alpha), plasma arginine and ornithine levels, serum C-reactive protein, prealbumin, albumin, glucose, and total urinary nitrogen.

RESULTS

The AG enhanced lymphoproliferative responses (analysis of variance, P < 0.05), which were 72% of normal at baseline in both groups; by day 7 responses increased to 144% in the AG group and decreased to 56% in the CG group; both groups returned to normal by day 14. Baseline interleukin-6 was significantly increased in all children. There were no differences in plasma concentrations of interleukin-1, interleukin-6, tumor necrosis factor-alpha, C-reactive protein, prealbumin, albumin, or glucose between the AG and CG groups. On day 7 plasma ornithine levels increased significantly in the AG versus CG group (P < 0.05); arginine levels showed no change.

CONCLUSIONS

An exclusively AG improves mitogen-stimulated lymphocyte proliferation in burned children. The benefits of arginine for the immune system do not appear to be related to a metabolic response. The biological significance of this finding remains to be determined.

Energy expenditure and balance following pediatric intensive care unit admission: a longitudinal study of critically ill children

OBJECTIVE

Longitudinal comparison of prescribed energy, actually administered energy, and energy expenditure (EE) predicted by Schofield's equations to actual EE, as determined by daily indirect calorimetry measurements in critically ill children during the first 7 days following admission.

DESIGN

Observational study.

SETTING

Pediatric intensive care unit, high and medium care wards, in a university hospital.

PATIENTS

Forty-six mechanically ventilated and spontaneously breathing infants and children (0-18 yrs) who were admitted with sepsis or following major abdominal or thoracic surgery or trauma.

INTERVENTIONS

Daily indirect calorimetry measurements and assessment of energy balance.

MEASUREMENTS AND MAIN RESULTS

Energy balance studies were performed for a total of 298 admission days in 13 sepsis, 27 surgery, and 6 trauma patients. Indirect calorimetry measurements were performed on 89% of the days. Mean measured EE was 44.6 +/- 15 kcal/kg.d and equaled predicted EE (44.2 +/- 12 kcal/kg.d; p = .56). Measured EE did not change over time, neither overall nor in diagnostic subgroups. Overall, median (range) administered energy was 31.1 (0-119) kcal/kg.d, which was significantly lower than measured EE (p < .001) and predicted EE (p < .001). Patients were underfed on 60% of days and overfed on 28% of days. Administered energy rose significantly in the course of admission, independently of diagnostic category, and did not differ from prescribed energy (p = .42). Energy intake was significantly higher in sepsis patients than in surgery and trauma patients during the whole course of the study (p < .01). The cumulative energy balance was positive only in sepsis patients. The administration of parenteral feeding was the single significant factor determining energy intake in mixed-effect modeling.

CONCLUSIONS

Measured EE was stable and not significantly different from predicted values over the course of hospitalization. Underfeeding was frequently present and mainly due to prescription and administration of energy amounts inferior to measured EE values in enterally fed patients.

Adequate feeding and the usefulness of the respiratory quotient in critically ill children

OBJECTIVE

We determined incidences of underfeeding and overfeeding in children who were admitted to a multidisciplinary tertiary pediatric intensive care and evaluated the usefulness of the respiratory quotient (RQ) obtained from indirect calorimetry to assess feeding adequacy.

METHODS

Children 18 y and younger who fulfilled the criteria for indirect calorimetry entered our prospective, observational study and were studied until day 14. Actual energy intake was recorded, compared with required energy intake (measured energy expenditure plus 10%), and classified as underfeeding (<90% of required), adequate feeding (90% to 110% of required), or overfeeding (>110% of required). We also evaluated the adequacy of a measured RQ lower than 0.85 to identify underfeeding, and an RQ higher than 1.0 to identify overfeeding.

RESULTS

Ninety-eight children underwent 195 calorimetric measurements. Underfeeding, adequate feeding, and overfeeding occurred on 21%, 10%, and 69% of days, respectively. An RQ lower than 0.85 to identify underfeeding showed low sensitivity (63%), high specificity (89%), and high negative predictive value (90%). An RQ higher than 1.0 to indicate overfeeding showed poor sensitivity (21%), but a high specificity (97%) and a high positive predictive value (93%). Food composition, notably high-carbohydrate intake, was responsible for an RQ exceeding 1.0 in the overfed group.

CONCLUSION

Children admitted to the intensive care unit receive adequate feeding on only 10% of measurement days during the first 2 wk of admission. The usefulness of RQ to monitor feeding adequacy is limited to identifying (carbohydrate) overfeeding and excluding underfeeding.

Predicted versus measured energy expenditure by continuous, online indirect calorimetry in ventilated, critically ill children during the early postinjury period

OBJECTIVE

Compare the energy expenditure, predicted by anthropometric equations, with that measured by continuous on-line indirect calorimetry in ventilated, critically ill children during the early postinjury period.

DESIGN

Prospective, clinical study.

SETTING

Pediatric intensive care unit of a pediatric university hospital.

PATIENTS

A total of 43 ventilated, critically ill children during the first 6 hrs after injury.

INTERVENTIONS

An indirect calorimeter was used to continuously measure the energy expenditure for 24 hrs.

MEASUREMENTS AND MAIN RESULTS

Clinical data collected were age, gender, actual and ideal weight, height, and body surface. Nutritional status was assessed by Waterlow and Shukla Index. Severity of illness was determined by Pediatric Risk of Mortality, Physiologic Stability Index, and Therapeutic Intervention Scoring System. Energy expenditure was measured (MEE) by continuous on-line indirect calorimetry for 24 hrs. Predicted Energy Expenditure (PEE) was calculated using the Harris-Benedict, Caldwell-Kennedy, Schofield, Food and Agriculture/World Health Organization/United Nation Union, Maffeis, Fleisch, Kleiber, Dreyer, and Hunter equations, using the actual and ideal weight. MEE and PEE were compared using paired Student's t-test, linear correlation (r), intraclass correlation coefficient (pI), and the Bland-Altman method. Mean MEE resulted in 674 +/- 384 kcal/day. Most of the predictive equations overestimated MEE in ventilated, critically ill children during the early postinjury period. MEE and PEE differed significantly (p<.05) except when the Caldwell-Kennedy and the Fleisch equations were used. r2 ranged from 0.78 to 0.81 (p<.05), and pI was excellent (>.75) for the Caldwell-Kennedy, Schofield, Food and Agriculture/World Health Organization/United Nation Union, Fleisch, and Kleiber equations. The Bland-Altman method showed poor accuracy; the Caldwell-Kennedy equation was the best predictor of energy expenditure (bias, 38 kcal/day; precision, +/- 179 kcal/day). The accuracy in the medical group was higher (pI range,.71-.94) than in surgical patients (pI range,.18-.75).

CONCLUSIONS

Predictive equations do not accurately predict energy expenditure in ventilated, critically ill children during the early postinjury period; if available, indirect calorimetry must be performed.

Dead space ventilation in critically ill children with lung injury

STUDY OBJECTIVE

In children with acute lung injury, there is an increase in minute ventilation (E) and inefficient gas exchange due to a high level of physiologic dead space ventilation (VD/VT). Mechanical ventilation with positive end-expiratory pressure, when used in critically ill patients to correct hypoxemia, may contribute to increased VD/VT. The purpose of this study was to measure metabolic parameters and VD/VT in critically ill children.

DESIGN

A cross-sectional study.

SETTING

Pediatric ICU of a university hospital.

PATIENTS

A total of 45 mechanically intubated children (mean age, 5.5 years).

INTERVENTIONS

Indirect calorimetry was used to measure metabolic parameters. VD/VT parameters were calculated using the modified Bohr-Enghoff equation. ARDS was defined based on criteria by The American-European Consensus Conference.

MEASUREMENTS AND RESULTS

The group mean (+/- SD) ventilatory equivalent for oxygen (VeqO(2)) and ventilatory equivalent for carbon dioxide (VeqCO(2)) were 2.9 +/- 1 and 3.3 +/- 1 L per 100 mL, respectively. The group mean VD/VT was 0.48 +/- 0.2. When compared to non-ARDS patients (33 patients), the patients with ARDS (12 patients) had a significantly higher VeqO(2) (3.3 +/- 1 vs 2.8 +/- 1 L per 100 mL, respectively; p < 0.05), a significantly higher VeqCO(2) (3.7 +/- 1 L/100 vs 3.1 +/- 1 L per 100 mL, respectively; p < 0.05), and a significantly higher VD/VT (0.62 +/- 0.14 vs 0.43 +/- 0.15, respectively; p < 0.0005).

CONCLUSIONS

Critically ill children with ARDS have increased VD/VT. Increased VD/VT was the main cause of the excess of E demand in these patients. Increased metabolic demands, as shown by the VeqO(2), VeqCO(2), and ventilatory support, are the major determinants of E requirements in children with ARDS.

Nutritional support in the critically ill child

The nutritional management of a critically ill child is not a glamorous subject and seldom receives the attention that it merits despite increasing evidence that appropriate goal-oriented nutritional support is associated with improved outcome. Current nutritional management is based on rapidly emerging knowledge on the very special nutritional requirements related to the "vastly different metabolic and physiologic characteristics of the hypermetabolic and stressed" critically ill child. There has been significant changes in traditional practice particularly in the area of calorie delivery, amount of macronutrients and route of nutrient delivery in the critically ill child. The critically ill child presents with "greatly disordered nutrient metabolism" and successful nutritional support involves an initial "hypocaloric regime" with a precise mix of carbohydrates, proteins and lipids which need periodic review as the child improves. The therapeutic benefits of minimal enteral feeding (MEF) have been clearly established--MEF being associated with diminished morbidity, infection rates as well as reduced ICU and hospital stays. Immune enhancement has also been shown to be of some benefit in the critically ill but the subject needs further study.

Energy metabolism, nitrogen balance, and substrate utilization in critically ill children

BACKGROUND

Critically ill patients are characterized by a hypermetabolic state, a catabolic response, higher nutritional needs, and a decreased capacity for utilization of parenteral substrate.

OBJECTIVE

We sought to analyze the relation between a patient's metabolic state and their nutritional intake, substrate utilization, and nitrogen balance (NB) in mechanically ventilated, critically ill children receiving parenteral nutrition.

DESIGN

This was a cross-sectional study in which resting energy expenditure (REE) and NB were measured and substrate utilization and the metabolic index (MI) ratio (REE/expected energy requirements) were calculated.

RESULTS

Thirty-three children (mean age: 5 y) participated. Their average REE was 0.23 +/- 0.10 MJ x kg(-1) x d(-1) and their average MI was 1.2 +/- 0.5. Mean energy intake, protein intake, and NB were 0.25 +/- 0.14 MJ x kg(-1) x d(-1), 2.1 +/- 1 g x kg(-1) x d(-1), and -89 +/- 166 mg x kg(-1) x d(-1), respectively. Patients with an MI >1.1 (n = 19) had a higher fat oxidation than did patients with an MI <1.1 (n = 14; P < 0.05). Patients with lipogenesis (n = 13) had a higher carbohydrate intake than did patients without lipogenesis (n = 20; P < 0.05). Patients with a positive NB (n = 12) had a higher protein intake than did patients with a negative NB (n = 21; P < 0.001) and lower protein oxidation (P < 0.01).

CONCLUSIONS

Critically ill children are hypermetabolic and in negative NB. In this population, fat is used preferentially for oxidation and carbohydrate is utilized poorly. A high carbohydrate intake was associated with lipogenesis and less fat oxidation, a negative NB was associated with high oxidation rates for protein, and a high protein intake was associated with a positive NB.

Energy expenditure in 100 ventilated, critically ill children: improving the accuracy of predictive equations

OBJECTIVE

The purpose of this study was to evaluate current methods of predicting energy requirements and to develop and validate new equations derived from energy expenditure measurements of ventilated, critically ill children.

DESIGN

Prospective, observational, sequential study.

SETTING

Pediatric intensive care unit.

PATIENTS

A total of 100 ventilated, critically ill children who fit the criteria of energy expenditure measurement. Additional patients (n = 25) were included in the validation study.

INTERVENTION

An indirect calorimeter was used to measure energy expenditure for a period of 30 mins.

MEASUREMENTS AND MAIN RESULTS

The mean measured energy expenditure was 185+/-51 kJ/kg per day. Predicted energy expenditure from standard equations was compared with measured energy expenditure by using the Bland and Altman "methods comparison procedure," and poor precision and accuracy were observed. Patient variables were collected at the time of measurement, and multiple regression analysis was performed to determine the independent contribution of each variable to measure energy expenditure. New predictive equations were formulated and validated with additional energy expenditure measurements. Patient variables that did not correlate significantly with energy expenditure were gender, Pediatric Risk of Mortality score, and commencement of nutritional support. An equation was derived from patient variables (age, weight, weight for age Z score, body temperature, number of days after intensive care admission, and primary reason for admission) that correlated significantly (r2 = .898) with measured energy expenditure. A second, simplified equation (energy expenditure kJ/day = ¿17 x age [months]¿ + ¿48 x weight [kg]¿ + ¿292 x body temperature degrees C¿ - 9,677) was produced (r2 = .867). Validation found no significant difference between measured and predicted energy expenditure by the new equations; however, the equations did not predict accurately for patients <2 months of age.

CONCLUSION

The new equations provide a more accurate alternative to current predictive methods in assessing energy requirements of ventilated, critically ill children.