Energy expenditure and substrate utilization in mechanically ventilated children

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.

Methods recently used for the assessment of physical activity in children and adolescents

PURPOSE OF REVIEW

The aim of this review is to summarize recent evidences and advances on the implementation and the use of new tools to assessing physical activity (PA) in children.

RECENT FINDINGS

Technological advances provide, increasingly, new objective methods for the evaluation of PA in children. In addition to accelerometry, there are other objective methods for assessing PA in children such as new wearable monitoring and activity bracelets, smartphone and recording software applications, Global Positioning System or Inertial Sensors Devices.

SUMMARY

Doubly labeled water and calorimetry are reference methods to assessing PA but with limitations of use. Accelerometry is an accurate method for measuring sedentary behavior and PA levels in children. In fact, it is a real alternative reference method for the validation of methods and tools of assessing PA. However, there is still no consensus about the most appropriate approach to analyze the duration and intensity of PA in children. Therefore, the implementation of other alternative objective methods, as well as complementation with PA questionnaires, can provide a more precise evaluation of different patterns and behaviors related with sedentarism and PA.

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.

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.

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.

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.

Effects of Hypercaloric Feeding on Nutrition Status and Carbon Dioxide Production in Patients With Long-Term Mechanical Ventilation

BACKGROUND

To clarify clinical arguments regarding nutrition support in patients with long-term mechanical ventilation, we investigated the effects of hypercaloric feeding on nutrition status and carbon dioxide production.

METHODS

Twenty-eight mechanically ventilated, clinically stable patients with nasogastric tube feeding were recruited and randomly divided into the control and hypercaloric groups, which were provided with 1.2- and 1.8-fold of resting energy expenditure (REE), respectively. The arterial and venous blood samples were collected, the anthropometric measurements were determined, the serum concentrations of nutrition-related proteins were measured, and the parameters on the ventilator and indirect calorimeter were recorded on weeks 0, 2, and 4.

RESULTS

There were no significant changes in anthropometric measurements, blood gas tensions, and REE between the control and hypercaloric groups during the experimental period (mixed model with repeated measures analysis, p < .05). After adjusted for values on week 0 and time, patients with hypercaloric feeding had significantly increased levels in white blood cells, hemoglobin, and hematocrit. However, the control group had significantly decreased and the hypercaloric group had significantly increased serum concentrations of prealbumin and transferrin, rate of carbon dioxide production, and respiratory quotient (RQ) from week 0 to week 4.

CONCLUSION

Our results suggest that 4 weeks of hypercaloric feeding may significantly increase the production of carbon dioxide but may not significantly alter the clinical outcomes in patients with long-term mechanical ventilation. The adverse effects of hypercaloric feeding may easily be overlooked, and the appropriateness of nutrition support should be carefully monitored in patients with mechanical ventilation.

Use of Indirect Calorimetry to Detect Overfeeding in Critically Ill Children: Finding the Appropriate Definition

OBJECTIVES

Overfeeding during critical illness is associated with adverse effects such as metabolic disturbances and increased risk of infection. Because of the lack of sound studies with clinical endpoints, overfeeding is arbitrarily defined as the ratio caloric intake/measured resting energy expenditure (mREE) or alternatively as a comparison of measured respiratory quotient (RQ) to the predicted RQ based on the macronutrient intake (RQmacr). We aimed to compare definitions of overfeeding in critically ill mechanically ventilated children based on mREE, RQ, and caloric intake to find an appropriate definition.

METHODS

Indirect calorimetry measurements were performed in 78 mechanically ventilated children, median age 6.3 months. Enteral and/or parenteral nutrition was provided according to the local guidelines. Definitions used to indicate overfeeding were the ratio caloric intake/mREE of >110% and >120% and by the measured RQ > RQmacr + 0.05.

RESULTS

The proportion of patients identified as overfed varied widely depending on the definition used, ranging from 22% (RQ > RQmacr + 0.05), to 40% and 50% (caloric intake/mREE of >120% and >110%, respectively). Linear regression analysis showed that all patients would be identified as overfed with the definition RQ > RQmacr + 0.05 when the ratio caloric intake/mREE exceeded 165%. Caloric intake was higher in children with a standard deviation-score weight for age <-2.

CONCLUSIONS

The proportion of mechanically ventilated patients identified as overfed ranged widely depending on the definition applied. These currently used definitions fail to take into account several relevant factors affecting metabolism during critical illness and are therefore not generally applicable to the pediatric intensive care unit population.

Can Vco2-Based Estimates of Resting Energy Expenditure Replace the Need for Indirect Calorimetry in Critically Ill Children?

BACKGROUND

Optimal energy provision, guided by measured resting energy expenditure (REE), is fundamental in the care of critically ill children. REE should be determined by indirect calorimetry (IC), which has limited availability. Recently, a novel equation was developed for estimating REE derived from carbon dioxide production (Vco₂). The aim of this study was to validate the accuracy of this equation in a population of critically ill children following cardiopulmonary bypass (CPB).

METHODS

This is an ancillary study to a larger trial of children undergoing CPB. Respiratory mass spectrometry was used measure oxygen consumption (Vo₂) and Vco₂. REE was then calculated according to the established Weir equation (REE_W) and the modified, Vco₂-based equation (REE_CO2). The agreement between the 2 measurements was assessed using Bland-Altman plots and mixed-model regressions accounting for repeated measures.

RESULTS

Data from 104 patients, which included 575 paired measurements, were included. The agreement between REE_W and REE_CO2 was biased during the 72-hour observation period post CPB, with a mean percentage error between measurements of 11% (±7%). The most important determinant of the bias with the Vco₂-based equation was the respiratory quotient (RQ). The percentage error between REE_W and REE_CO2 dropped to 4.4% (±2.4%) in those with an RQ between 0.8 and 1. The within-subject variability for RQ in this cohort was wide (11%).

CONCLUSIONS

IC remains the most accurate method to determine the REE of critically ill patients. Widespread availability of Vco₂ data renders Vco₂-based approaches to measurement of REE attractive; however, further research is needed to ensure that REE is estimated accurately.

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.

Accuracy of a simplified equation for energy expenditure based on bedside volumetric carbon dioxide elimination measurement--a two-center study

BACKGROUND & AIMS

Accurate assessment of resting energy expenditure (REE) and metabolic state is essential to optimize nutrient intake in critically ill patients. We aimed to examine the accuracy of a simplified equation for predicting REE using carbon dioxide elimination (VCO2) values.

METHODS

We conducted a two-center study of metabolic data from mechanically ventilated children less than 18 years of age. Mean respiratory quotient (RQ) from the derivation set (n = 72 subjects) was used to modify the Weir equation to obtain a simplified equation based on VCO2 measurements alone. This equation was then applied to subjects at the second institution (validation dataset, n = 94) to predict resting energy expenditure. Bland-Altman analysis was used to assess the agreement between measured REE values, and REE estimated by the new equation as well as the Schofield equation. We also examined the accuracy of the new equation in classifying patients according to their metabolic state.

RESULTS

Mean respiratory quotient (± SD) of 0.89 ± 0.09 in the derivation set was used to obtain a simplified equation, REE (kcal/day) = 5.534*VCO2 (L/min)*1440. In relation to the measured REE in the validation set, the mean bias (limits of agreement) for the REE predicted by this equation was -0.65% (-14.4-13.1%); and the overall diagnostic accuracy for classifying subjects as hypometabolic or hypermetabolic was 84%. Mean bias (limits) of agreement between measured and Schofield equation estimated REE was -0.1% (-40.5-40.7%).

CONCLUSIONS

A simplified metabolic equation using VCO2 values was superior to the standard equation in estimating REE, and provided a reasonably accurate metabolic classification in mechanically ventilated children. In the absence of indirect calorimetry, bedside VCO2 monitoring could provide valuable continuous metabolic information to guide optimal nutrient intake.

Indirect calorimetry reveals that better monitoring of nutrition therapy in pediatric intensive care is needed

BACKGROUND

Monitoring nutrition therapy is essential in the care of critically ill children, but the risk of nutrition failure seems to remain. The aims of the present study were to examine the prevalence of underfeeding, adequate feeding, and overfeeding in mechanically ventilated children and to identify barriers to the delivery of nutrition support.

MATERIALS AND METHODS

Children aged 0-14 years who fulfilled the criteria for indirect calorimetry were enrolled in this prospective, observational study and were studied for up to 5 consecutive days. Actual energy intake was recorded and compared with the required energy intake (measured energy expenditure plus 10%); energy intake was classified as underfeeding (<90% of required energy intake), adequate feeding (90%-110%), or overfeeding (>110%). The reasons for interruptions to enteral and parenteral nutrition were recorded.

RESULTS

In total, 104 calorimetric measurements for 140 total days were recorded for 30 mechanically ventilated children. Underfeeding, adequate feeding, and overfeeding occurred on 21.2%, 18.3%, and 60.5% of the 104 measurement days, respectively. There was considerable variability in the measured energy expenditure between children (median, 37.2 kcal/kg/d; range, 16.81-66.38 kcal/kg/d), but the variation within each child was small. Respiratory quotient had low sensitivity of 21% and 27% for detecting underfeeding and overfeeding, respectively. Fasting for procedures was the most frequent barrier that led to interrupted nutrition support.

CONCLUSION

The high percentage of children (~61%) who were overfed emphasizes the need to measure energy needs by using indirect calorimetry.

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.

Enteral nutrition in the critically ill child: comparison of standard and protein-enriched diets

OBJECTIVE

To compare a standard diet and a protein-enriched diet in critically ill children.

STUDY DESIGN

In this prospective randomized controlled trial in critically ill children, all patients received enteral nutrition exclusively and were randomly assigned to a standard diet or a protein-enriched diet (1.1 g protein/100 mL of feeding formula). Blood and urine tests, nitrogen balance assessment, and energy expenditure testing by indirect calorimetry were performed before the beginning of the nutrition regimen and at 24 hours, 72 hours, and 5 days after initiation. Demographic data and pediatric mortality risk scores were recorded.

RESULTS

Fifty-one children were randomized, and 41 completed the study. Of these, 21 patients received standard formula and 20 received a protein-enriched formula. There were no between-group differences in terms age, sex, diagnosis, or mortality risk scores. There was a greater positive trend in levels of prealbumin, transferrin, retinol-binding protein, and total protein in the protein-enriched diet group. These differences were significant only for retinol-binding protein. The positive nitrogen balance trend was also higher in the protein-enriched diet group; however, this difference did not reach statistical significance. No adverse effects or hyperproteinemia were detected in the protein-enriched diet group.

CONCLUSIONS

The standard diet provides insufficient protein delivery to critically ill children. Enteral protein supplementation is safe and can improve some biochemical parameters of protein metabolism.

Pathophysiological aspects of hyperglycemia in children with meningococcal sepsis and septic shock: a prospective, observational cohort study

INTRODUCTION

The objective of this study was to investigate the occurrence of hyperglycemia and insulin response in critically ill children with meningococcal disease in the intensive care unit of an academic children's hospital.

METHODS

Seventy-eight children with meningococcal disease were included. The group was classified into shock non-survivors, shock survivors and sepsis survivors. There were no sepsis-only non-survivors. The course of laboratory parameters during 48 hours was assessed. Insulin sensitivity and β-cell function on admission were investigated by relating blood glucose level to insulin level and C-peptide level and by homeostasis model assessment (HOMA) [β-cell function (HOMA-%B) and insulin sensitivity (HOMA-%S)].

RESULTS

On admission, hyperglycemia (glucose >8.3 mmol/l) was present in 33% of the children. Shock and sepsis survivors had higher blood glucose levels compared with shock non-survivors. Blood glucose level on admission correlated positively with plasma insulin, C-peptide, cortisol, age and glucose intake. Multiple regression analysis revealed that both age and plasma insulin on admission were significantly related to blood glucose. On admission, 62% of the hyperglycemic children had overt insulin resistance (glucose >8.3 mmol/l and HOMA-%S <50%); 17% had β-cell dysfunction (glucose >8.3 mmol/l and HOMA-%B <50%) and 21% had both insulin resistance and β-cell dysfunction. Hyperglycemia was present in 11% and 8% of the children at 24 and 48 hours after admission, respectively.

CONCLUSIONS

Children with meningococcal disease often show hyperglycemia on admission. Both insulin resistance and β-cell dysfunction play a role in the occurrence of hyperglycemia. Normalization of blood glucose levels occurs within 48 hours, typically with normal glucose intake and without insulin treatment.

Relationship between energy expenditure, nutritional status and clinical severity before starting enteral nutrition in critically ill children

The objective of the present study was to investigate the relationship between energy expenditure (EE), biochemical and anthropometric nutritional status and severity scales in critically ill children. We performed a prospective observational study in forty-six critically ill children. The following variables were recorded before starting nutrition: age, sex, diagnosis, weight, height, risk of mortality according to the Paediatric Risk Score of Mortality (PRISM), the Revised Paediatric Index of Mortality (PIM2) and the Paediatric Logistic Organ Dysfunction (PELOD) scales, laboratory parameters (albumin, total proteins, prealbumin, transferrin, retinol-binding protein, cholesterol and TAG, and nitrogen balance) and EE measured by indirect calorimetry. The results showed that there was no relationship between EE and clinical severity evaluated using the PRISM, PIM2 and PELOD scales or with the anthropometric nutritional status or biochemical alterations. Finally, it was concluded that neither nutritional status nor clinical severity is related to EE. Therefore, EE must be measured individually in each critically ill child using indirect calorimetry.

Challenge of predicting resting energy expenditure in children undergoing surgery for congenital heart disease

OBJECTIVES

To determine pre- and postoperative predictors of energy expenditure in children with congenital heart disease requiring open heart surgery; and to compare measured resting energy expenditure with current predictive equations.

DESIGN

Prospective resting energy expenditure data were collected, using indirect calorimetry, for ventilated children admitted consecutively to the pediatric intensive care unit after surgery for congenital heart disease. A 30-min steady-state measurement was performed in suitable patients. Resting energy expenditure was compared to pre- and postoperative clinical variables, and to predicted energy expenditure, using currently used predictive equations.

SETTING

Pediatric intensive care unit at the Royal Brompton Hospital, London.

PATIENTS

Children ventilated in the pediatric intensive care unit post surgery for congenital heart disease.

INTERVENTIONS

Measurement of energy expenditure by indirect calorimetry.

MEASUREMENTS AND MAIN RESULTS

Twenty-one mechanically ventilated children (n = 17 boys, 4 girls) were enrolled in the study. Mean +/- sd measured resting energy expenditure was 67.8 +/- 15.4 kcal/kg/day. Most children had inadequate delivery of nutrients compared with actual requirements. Cardiopulmonary bypass had a significant influence on energy expenditure after surgery; in patients who underwent cardiopulmonary bypass during surgery, mean resting energy expenditure was 73.6 +/- 14.45 kcal/kg/day vs. 58.3 +/- 10.29 kcal/kg/day in patients undergoing nonbypass surgery. Children who were malnourished preoperatively had greater resting energy expenditure postoperatively. There was also a significant difference between measured energy expenditure and the Schofield (p = .006), World Health Organization (p = .002), and pediatric intensive care unit-specific formula (p < .0001). However, energy expenditure or a relative energy deficit in the early postoperative period was not associated with severity or duration of organ dysfunction.

CONCLUSIONS

Poor nutritional status preoperatively and cardiopulmonary bypass were associated with a greater energy expenditure post cardiac surgery. None of the current predictive equations predicted energy requirements within acceptable clinical accuracy.

Can an adequate energy intake be able to reverse the negative nitrogen balance in mechanically ventilated critically ill patients?

PURPOSE

Adequate energy provision and nitrogen losses prevention of critically ill patients are essentials for treatment and recovery. The aims of this study were to evaluate energy expenditure (EE) and nitrogen balance (NB) of critically ill patients, to classify adequacy of energy intake (EI), and to verify adequacy of EI capacity to reverse the negative NB.

METHODS

Seventeen patients from an intensive care unit were evaluated within a 24-hour period. Indirect calorimetry was performed to calculate patient's EE and Kjeldhal for urinary nitrogen analysis. The total EI and protein intake were calculated from the standard parenteral and enteral nutrition infused. Underfeeding was characterized as EI 90% or less and overfeeding as 110% or greater of EE. The adequacy of the EI (EI EE(-1) × 100) and the NB were estimated and associated with each other by Spearman coefficient.

RESULTS

The mean EE was 1515 ± 268 kcal d(-1), and most of the patients (11/14) presented a negative NB (-8.2 ± 4.7 g.d(-1)). A high rate (53%) of inadequate energy intake was found, and a positive correlation between EI EE(-1) and NB was observed (r = 0.670; P = .007).

CONCLUSION

The results show a high rate of inadequate EI and negative NB, and equilibrium between EI and EE may improve NB. Indirect calorimetry can be used to adjust the energy requirements in the critically ill patients.

Critically ill infants benefit from early administration of protein and energy-enriched formula: a randomized controlled trial

BACKGROUND & AIMS

Nutritional support improves outcome in critically ill infants but is impeded by fluid restriction, gastric intolerance and feeding interruptions. Protein and energy-enriched infant formulas may help to achieve nutritional targets earlier during admission and promote anabolism.

METHODS

Randomized controlled design. Infants with respiratory failure due to RSV-bronchiolitis received a protein and energy-enriched formula (PE-formula, n=8) or a standard formula (S-formula, n=10) during 5 days after admission.

PRIMARY OUTCOME

nutrient delivery, energy and nitrogen balance and plasma amino acid concentrations. Secondary outcome: tolerance and safety.

RESULTS

Nutrient intakes were higher in PE fed infants and met population reference intake (PRI) on day 3-5 whilst in S-fed infants PRI was met on day 5 only. Cumulative nitrogen balance (cNB) and energy balance (cEB) were higher in PE-infants compared to S-infants (cNB: 866+/-113 vs. 296+/-71 mg/kg; cEB: 151+/-31 and 26+/-17 kcal/kg, both P<0.01). Essential amino acid levels were higher in PE-infants but within reference limits whereas below these limits in S-infants. Both formulas were well tolerated.

CONCLUSIONS

Early administration of a protein and energy-enriched formula in critically ill infants is well tolerated, promotes a more adequate nutrient intake and improves energy and nitrogen balance without adverse effects.

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.

Causes and consequences of inadequate substrate supply to pediatric ICU patients

PURPOSE OF REVIEW

The prevalence of malnutrition among children admitted to a pediatric intensive care unit is still high. Assessment of nutrient supply is essential in the care of critically ill children because inadequate nutrition can increase morbidity and mortality. This review covers the causes and consequences of inadequate nutrient supply to critically ill children.

RECENT FINDINGS

A major factor contributing to the cause of inadequate nutrient supply is the difficulty in estimating nutritional needs of the individual child. Reasonable values for energy expenditure can be derived from prediction formulae but measuring energy expenditure by indirect calorimetry is useful in selected cases. Furthermore, under-prescription and inadequate delivery of nutrients caused by fluid volume restriction, procedural interruptions or cessation because of gastrointestinal intolerance or mechanical problems cause additional nutritional deficits. As routine nutritional assessment is lacking in many pediatric intensive care units, the ability to monitor the adequacy of nutritional support is poor.

SUMMARY

In the majority of children admitted to a pediatric intensive care unit, nutritional problems--both underfeeding and overfeeding--occur during admission due to poor estimation of nutritional needs, under-prescribing and problems in the delivery of the nutrients. Recommendations are made in order to prevent inadequate nutritional supply and its potentially harmful consequences in critically ill children.

Nutritional Assessment and Enteral Support of Critically Ill Children

Critical care nurses play an important role in feeding of critically ill children. Many procedures and caregiving interventions, such as placement of feeding tubes, registration of gastric retention, observation and care of the mouth, and administration of nutrition (enteral or parenteral), are within the nursing domain. This article discusses nutritional assessment techniques and enteral nutrition in critically ill children.

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.

C-Reactive protein-determined injury severity: length of stay predictor in surgical infants

BACKGROUND/PURPOSE

Serum C-reactive protein (CRP) levels reflect the severity of the metabolic response to injury in critically ill children. During this period, caloric overfeeding can increase complications and delay recovery. The authors hypothesized that by avoiding excessive caloric delivery, the effect of injury severity would be the major factor determining clinical outcome.

METHODS

Twenty-eight surgical infants who had indirect calorimetry measurements while in the Neonatal Intensive Care Unit between August 2000 and January 2002 were studied. Serum CRP concentrations, mean energy expenditure (MEE), respiratory quotient (RQ), length of hospital stay (LOS), and caloric intake (I) at the time of indirect calorimetry were recorded. Data were analyzed using the Pearson product-moment correlation.

RESULTS

Peak serum CRP was significantly correlated to LOS in all patients (r = 0.79, P < .0001). When net caloric balance (I-MEE) did not exceed 5 kcal/kg/d (n = 9), peak serum CRP was correlated positively with RQ (r = 0.66, P = .05). When I-MEE exceeded 5 kcal/kg/d (n = 19), the positive correlation of serum CRP with RQ was diminished (r = 0.23, P = .33).

CONCLUSIONS

CRP-measured injury severity is a major determinant of clinical outcome in surgical infants. In addition, overfeeding causes additional RQ elevation.

The pragmatics of feeding the pediatric patient with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) represents the ultimate pulmonary response to a wide range of injuries, from septicemia to trauma. Optimal nutrition is vital to enhancing oxygen delivery, supporting adequate cardiac contractility and respiratory musculature, eliminating fluid and electrolyte imbalances, and supporting the proinflammatory response. Research is providing a better understanding of nutrients that specifically address the complex physiologic changes in ARDS. This article highlights the pathophysiology of ARDS as it relates to nutrition, relevant nutritional assessment, and important enteral and parenteral considerations for the pediatric patient who has ARDS.

Nutrition and the critically ill horse

A nutritional plan should be incorporated into every treatment plan of the critically ill patient. Weight loss and cachexia are the result of prevalence of catabolic processes over anabolic processes in addition to absolute or relative increased demands and decreased food intake.

Influence of an aggressive early enteral nutrition protocol on nitrogen balance in critically ill children

The objective was to determine stress related factors and nutritional indices affecting the nitrogen balance (NB) and the creatinine height index (CHI) in critically ill children on early enteral nutrition (EEN). Seventy-one consecutively enrolled critically ill children aged 2 to 204 months, requiring prolonged mechanical ventilation, were studied. All patients were on early intragastric nutrition (Nutrison Pediatric or Standard) from day 1 (energy intake equal to 1/2, 1, 5/4, 6/4 and 6/4 of the predicted basal metabolic rate on days 1-5, respectively). Nitrogen balance and CHI changes determined efficacy. Study patients had severe depletion of somatic protein status on stress day 1 (CHI <60%) but they reached the normal range of somatic protein status at the end of the EEN, on post-stress day 5 (CHI >80%, p <.004). On day 1, none of the patients had positive NB but after 5 days of EEN, 44 (62%) had positive NB and only 27 (38%) had negative NB (p <.0001). Multivariate stepwise regression analysis showed that only the difference of daily given-recommended dietary allowances protein and the total repleted energy were positively correlated (r(2) =.47, p <.001 and r(2) = 34, p =.003, respectively) and multiple organ system failure negatively correlated with the NB (r(2) = -.24, p <.03) on the 5th day of the EEN protocol. Our data suggest that achievement of positive protein and energy balance in relation to the basic metabolic rate using an aggressive EEN protocol improves NB during the acute phase of stress in 2/3 of critically ill children.

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.

Malnutrition, nutritional indices, and early enteral feeding in critically ill children

We measured the incidences of protein and fat depletions and the frequencies of acute and chronic protein-energy malnutrition during stress states in children and investigated the influence of early enteral feeding on nutrition indices and acute-phase proteins. Seventy-one, consecutively enrolled, critically ill children received early enteral feeding (energy intakes equal to 0.50, 1, 1.25, 1.5, and 1.5 of the predicted basal metabolic rates on days 1 through 5, respectively) through nasogastric tubes. On the first day of the study, 16.7% of the patients already were depleted of protein and 31% of fat stores. Overall, 16.9% were at risk for chronic protein-energy malnutrition and 21.1% for acute protein-energy malnutrition, whereas 4.2% and 5.6% already had chronic and acute, respectively protein-energy malnutrition. Only 22.7% of patients without protein deficiencies versus 37% of those at risk or already deficient developed multiple-organ system failure. Transferrin and prealbumin levels improved at the end of the period of early enteral feeding (187 +/- 6.6 versus 233 +/- 7 mg/dL, P < 0.0001; 15.1 +/- 2 versus 21.9 +/- 2.9 mg/dL, P < 0.0001; respectively); survivors had higher prealbumin levels than non-survivors (22.3 versus 15.5 mg/dL). With logistic regression analysis, only repleted energy, not anthropometric or nutrition indices, was independently associated with survival (P = 0.05). These results reinforce the observation that critically ill children are at risk for fat or protein depletion and development of malnutrition, which is associated with increased morbidity and mortality. We conclude that early enteral nutrition improves nutrition indices and outcomes.

Accuracy of an indirect calorimeter for mechanically ventilated infants and children: the influence of low rates of gas exchange and varying FIO2

OBJECTIVE

To test the accuracy and validity of the Deltatrac II MBM-200 metabolic monitor for use in mechanically ventilated infants and children in the pediatric intensive care unit.

DESIGN

Laboratory validation of an indirect calorimeter with a ventilated lung model. The influence of low tidal volumes and low levels of oxygen consumption (V(O2)) and carbon dioxide production (V(CO2)) in combination with different levels of inspired oxygen concentrations (F(IO2)) was investigated.

SETTING

University research laboratory.

SUBJECTS

Low tidal volumes were provided with two intermittent flow types of ventilators, a Servo 300 and a Servo 900C.

INTERVENTIONS

A butane flame with a V(O2) approximating 20 mL/min and 40 mL/min was ventilated. To investigate the effect of different levels of F(IO2) on the accuracy of V(O2), V(CO2), and respiratory quotient (RQ), measurements were performed at F(IO2) target values of 0.25, 0.40, and 0.60.

MEASUREMENTS AND MAIN RESULTS

No significant differences were found between the ventilators regarding V(O2), V(CO2), and RQ measurements. The mean deviation of V(O2) increased significantly with increasing F(IO2) to -7.98% with a V(O2) of 21.0 mL/min and to -8.46% with a V(O2) of 38.9 mL/min (F(IO2), 0.558) with a variability (2 SD) of +/- 4.86% and +/- 6.82%, respectively. The mean deviation and variability of V(CO2) in all tests remained within 8%. The mean deviation of RQ increased significantly with increasing F(IO2) to 5.5% with a V(O2) of 21.0 mL/min and to 5.69% with a V(O2) of 38.9 mL/min (F(IO2), 0.558) with a variability (2 SD) of +/- 5.62% and +/- 5.76%, respectively. The minute to minute delivered F(IO2) fluctuated significantly when increasing the level of F(IO2).

CONCLUSIONS

The Deltatrac II MBM-200 metabolic monitor appears accurate for low levels of V(O2) and V(CO2) during mechanical ventilation with F(IO2) levels up to 0.390. With increasing F(IO2) to 0.558, the increase in deviation of V(O2) for single measurements can be of clinical relevance for mechanically ventilated infants and children. The increased fluctuation of delivered F(IO2) on higher levels of F(IO2) is likely the cause of the inaccuracy.