Indirect calorimetry in nutritional therapy. A position paper by the ICALIC study group

A novel prediction equation of resting energy expenditure for Japanese septic patients

Estimating nutrient consumption and administering appropriate nutritional therapy is essential for improving clinical outcomes in critically ill patients. Various equations, such as the Harris-Benedict equation, have been developed to estimate the required calories. Previous equations, however, targeted Westerners, whose physical characteristics are likely different from those of Asians. Hence, it is unclear whether these equations can be used for Asian patients. This study focused specifically on sepsis patients admitted to a single Japanese ICU, and aimed to develop novel equations to estimate their total energy expenditure. A total of 95 sepsis patients were included in this study. We measured resting energy expenditure (REE) by using indirect calorimetry, and created equations to calculate basal metabolic rate (BMR) using height, weight and age as variables. REE was predicted by multiplying BMR by the novel equation with the stress factor of 1.4. The prediction error of our novel equations were smaller than those of other conventional equations. We further confirmed the accuracy of our equations and that they were unaffected by patient age and disease severity by using data obtained from another patient group. The current study suggested that these equations might allow accurate estimation of the total energy expenditure and proper management of nutritional therapy in Asian sepsis patients.

Clinical Nutrition of Critically Ill Patients in the Context of the Latest ESPEN Guidelines

The group of patients most frequently in need of nutritional support are intensive care patients. This year (i.e., 2019), new European Society for Clinical Nutrition and Metabolism (ESPEN) guidelines of clinical nutrition in intensive care were published, updating and gathering current knowledge on the subject of this group of patients. Planning the right nutritional intervention is often a challenging task involving the necessity of the choice of the enteral nutrition (EN) or parenteral nutrition (PN) route of administration, time of initiation, energy demand, amino acid content and demand as well as the use of immunomodulatory nutrition. The aim of this study was to specify and discuss the basic aspects of the clinical nutrition of critically ill patients recommended by ESPEN guidelines. Clinical nutrition in intensive care seems to be the best-studied type of nutritional intervention. However, meta-analyses and clinical studies comparing EN and PN and their impact on the prognosis of the intensive care patients showed ambiguous results. The nutritional interventions, starting with EN, should be initiated within 24-48 h whereas PN, if recommended, should be implemented within 3-7 days. The recommended method of calculation of the energy demand is indirect calorimetry, however, there are also validated equations used worldwide in everyday practice. The recommended protein intake in this group of patients and the results of insufficient or too high supply was addressed. In light of the concept of immunomodulatory nutrition, the use of appropriate amino acid solutions and lipid emulsion that can bring a positive effect on the modulation of the immune response was discussed.

High birthweight was not associated with altered body composition or impaired glucose tolerance in adulthood

AIM

To investigate whether a high birthweight was associated with an increased proportion of body fat or with impaired glucose tolerance in adulthood.

METHODS

Our cohort comprised 27 subjects with birthweights of 4500 g or more, and 27 controls with birthweights within ±1 standard deviation scores, born at Uppsala University Hospital 1975-1979. The subjects were 34-40 years old at the time of study. Anthropometric data was collected, and data on body composition was obtained by air plethysmography and bioimpedance and was estimated with a three-compartment model. Indirect calorimetry, blood sampling for fasting insulin and glucose as well as a 75 g oral glucose tolerance test were also performed. Insulin sensitivity was assessed using homoeostasis model assessment 2 and Matsuda index.

RESULTS

There were no differences in body mass index, body composition or insulin sensitivity between subjects with a high birthweight and controls.

CONCLUSION

In this cohort of adult subjects, although limited in size, those born with a moderately high birthweight did not differ from those with birthweights within ±1 standard deviation scores, regarding body composition or glucose tolerance.

The malnutrition in polytrauma patients (MaPP) study: Research protocol

BACKGROUND

Polytrauma patients are at risk of considerable harm from malnutrition due to the metabolic response to trauma. However, there is little knowledge of (the risk of) malnutrition and its consequences in these patients. Recognition of sub-optimally nourished polytrauma patients and their nutritional needs is crucial to prevent complications and optimize their clinical outcomes.

AIM

The primary objective is to investigate whether polytrauma patients admitted to the Intensive Care Unit (ICU) who have or develop malnutrition have a higher complication rate than patients who are and remain well nourished. Secondary objectives are to determine the prevalence of pre-existent and in-hospital acquired malnutrition in these patients, to assess the association between malnutrition and long-term outcomes, and to determine the association between serum biomarkers (albumin and pre-albumin) and malnutrition.

METHODS

This international observational prospective cohort study will be performed at three Level-1 trauma centers in the United States and two Level-1 centers in the Netherlands. Adult polytrauma patients (Injury Severity Score ≥16) admitted to the ICU of one of the participating centers directly from the Emergency Department are eligible for inclusion. Nutritional status and risk of malnutrition will be assessed using the Subjective Global Assessment (SGA) scale and Nutritional Risk in Critically Ill (NUTRIC) score, respectively. Nutritional intake, biomarkers and complications will be collected daily. Patients will be followed up to one year after discharge for long-term outcomes.

CONCLUSIONS

This international prospective cohort study aims to gain more insight into the effect and consequences of malnutrition in polytrauma patients admitted to the ICU.

Daily systemic energy expenditure in the acute phase of aneurysmal subarachnoid hemorrhage

Background: Patients with subarachnoid hemorrhage often have impaired consciousness and cannot regulate nutritional intakes themselves. Previous studies have demonstrated elevated energy expenditure in the acute phase, but it is not known whether the energy demand is constant during the first week after onset of the disease. In this study, we performed daily measurements of energy expenditure with indirect calorimetry during the first 7 days after aneurysmal subarachnoid hemorrhage in mechanically ventilated patients.Methods: Metabolic measurements were performed daily with indirect calorimetry in 26 patients with aneurysmal subarachnoid hemorrhage. All patients were intubated and mechanically ventilated. The measured value was compared to the predicted values from the Harris-Benedict equation and the Penn State University 1998 equation. Urinary nitrogen excretion was measured daily.Results: There was a significant increase in energy expenditure during days 2-3 compared to days 5-6. The Harris-Benedict equation underestimated metabolic demand. The Penn State 1998 equation was closer to the measured values, but still underestimated caloric need. Urinary nitrogen excretion increased throughout the first week from initially low values.Conclusions: There is a dynamic course in energy expenditure in patients with aneurysmal subarachnoid hemorrhage, with increasing metabolic demand during the first week of the disease. Indirect calorimetry could be used more often to help provide an adequate amount of energy.

Metabolic support in the critically ill: a consensus of 19

Metabolic alterations in the critically ill have been studied for more than a century, but the heterogeneity of the critically ill patient population, the varying duration and severity of the acute phase of illness, and the many confounding factors have hindered progress in the field. These factors may explain why management of metabolic alterations and related conditions in critically ill patients has for many years been guided by recommendations based essentially on expert opinion. Over the last decade, a number of randomized controlled trials have been conducted, providing us with important population-level evidence that refutes several longstanding paradigms. However, between-patient variation means there is still substantial uncertainty when translating population-level evidence to individuals. A cornerstone of metabolic care is nutrition, for which there is a multifold of published guidelines that agree on many issues but disagree on others. Using a series of nine questions, we provide a review of the latest data in this field and a background to promote efforts to address the need for international consistency in recommendations related to the metabolic care of the critically ill patient. Our purpose is not to replace existing guidelines, but to comment on differences and add perspective.

Medical Nutrition Therapy in Critically Ill Patients Treated on Intensive and Intermediate Care Units: A Literature Review

Medical nutrition therapy in critically ill patients remains challenging, not only because of the pronounced stress response with a higher risk for complications, but also due to their heterogeneity evolving from different phases of illness. The present review aims to address current knowledge and guidelines in order to summarize how they can be best implemented into daily clinical practice. Further studies are urgently needed to answer such important questions as best timing, route, dose, and composition of medical nutrition therapy for critically ill patients and to determine how to assess and to adapt to patients’ individual needs.

Indirect Calorimetry in Clinical Practice

Indirect calorimetry (IC) is considered as the gold standard to determine energy expenditure, by measuring pulmonary gas exchanges. It is a non-invasive technique that allows clinicians to personalize the prescription of nutrition support to the metabolic needs and promote a better clinical outcome. Recent technical developments allow accurate and easy IC measurements in spontaneously breathing patients as well as in those on mechanical ventilation. The implementation of IC in clinical routine should be promoted in order to optimize the cost–benefit balance of nutrition therapy. This review aims at summarizing the latest innovations of IC as well as the clinical indications, benefits, and limitations.

Energy expenditure in acute pancreatitis evaluated by the Harris-Benedict equation compared with indirect calorimetry

OBJECTIVES

Enteral nutrition (EN) is recommended for severe acute pancreatitis (AP) and for biliary AP if cholecystectomy is delayed. Energy expenditure (EE) is calculated using the Harris-Benedict equation (HBE), but indirect calorimetry (IC) can also be employed. We wished to compare EE evaluated by the HBE equation, modified HBE (mHBE) and IC at study inclusion and 1 month after AP resolution.

METHODS

We undertook a single-center prospective study in Paris, France.

RESULTS

Among 35 patients, 19 had biliary AP and 11 alcoholic-related AP. Eleven cases had severe AP. There was no significant difference between EE calculated by the HBE and that using IC at study inclusion. However, the EE calculated by the mHBE was significantly higher than that calculated using IC. For severe AP, the HBE underestimated EE whereas the mHBE overestimated it. No difference was found based on the cause of AP. There was no difference between methods for EE at 30 days.

CONCLUSIONS

The HBE underestimated EE for severe AP, whereas the mHBE overestimated it. IC seems to be the best means of EE evaluation for AP.

Clinical Nutrition in Critical Care Medicine - Guideline of the German Society for Nutritional Medicine (DGEM)

PURPOSE

Enteral and parenteral nutrition of adult critically ill patients varies in terms of the route of nutrient delivery, the amount and composition of macro- and micronutrients, and the choice of specific, immune-modulating substrates. Variations of clinical nutrition may affect clinical outcomes. The present guideline provides clinicians with updated consensus-based recommendations for clinical nutrition in adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function.

METHODS

The former guidelines of the German Society for Nutritional Medicine (DGEM) were updated according to the current instructions of the Association of the Scientific Medical Societies in Germany (AWMF) valid for a S2k-guideline. According to the S2k-guideline classification, no systematic review of the available evidence was required to make recommendations, which, therefore, do not state evidence- or recommendation grades. Nevertheless, we considered and commented the evidence from randomized-controlled trials, meta-analyses and observational studies with adequate sample size and high methodological quality (until May 2018) as well as from currently valid guidelines of other societies. The liability of each recommendation was described linguistically. Each recommendation was finally validated and consented through a Delphi process.

RESULTS

In the introduction the guideline describes a) the pathophysiological consequences of critical illness possibly affecting metabolism and nutrition of critically ill patients, b) potential definitions for different disease phases during the course of illness, and c) methodological shortcomings of clinical trials on nutrition. Then, we make 69 consented recommendations for essential, practice-relevant elements of clinical nutrition in critically ill patients. Among others, recommendations include the assessment of nutrition status, the indication for clinical nutrition, the timing and route of nutrient delivery, and the amount and composition of substrates (macro- and micronutrients); furthermore, we discuss distinctive aspects of nutrition therapy in obese critically ill patients and those treated with extracorporeal support devices.

CONCLUSION

The current guideline provides clinicians with up-to-date recommendations for enteral and parenteral nutrition of adult critically ill patients who suffer from at least one acute organ dysfunction requiring specific drug therapy and/or a mechanical support device (e.g., mechanical ventilation) to maintain organ function. The period of validity of the guideline is approximately fixed at five years (2018-2023).

Metabolic and Nutritional Characteristics of Long-Stay Critically Ill Patients

Background: insufficient feeding is frequent in the intensive care unit (ICU), which results in poor outcomes. Little is known about the nutrition pattern of patients requiring prolonged ICU stays. The aims of our study are to describe the demographic, metabolic, and nutritional specificities of chronically critically ill (CCI) patients defined by an ICU stay >2 weeks, and to identify an early risk factor. Methods: analysis of consecutive patients prospectively admitted to the CCI program, with the following variables: demographic characteristics, Nutrition Risk Screening (NRS-2002) score, total daily energy from nutritional and non-nutritional sources, protein and glucose intakes, all arterial blood glucose values, length of ICU and hospital stay, and outcome (ICU and 90-day survival). Two phases were considered for the analysis: the first 10 days, and the next 20 days of the ICU stay. Statistics: parametric and non-parametric tests. Results: 150 patients, aged 60 ± 15 years were prospectively included. Median (Q1, Q3) length of ICU stay was 31 (26, 46) days. The mortality was 18% at ICU discharge and 35.3% at 90 days. Non-survivors were older (p = 0.024), tended to have a higher SAPSII score (p = 0.072), with a significantly higher NRS score (p = 0.033). Enteral nutrition predominated, while combined feeding was minimally used. All patients received energy and protein below the ICU’s protocol recommendation. The proportion of days with fasting was 10.8%, being significantly higher in non-survivors (2 versus 3 days; p = 0.038). Higher protein delivery was associated with an increase in prealbumin over time (r² = 0.19, p = 0.027). Conclusions: High NRS scores may identify patients at highest risk of poor outcome when exposed to underfeeding. Further studies are required to evaluate a nutrition strategy for patients with high NRS, addressing combined parenteral nutrition and protein delivery.

Resting Energy Expenditure and Protein Balance in People with Epidermolysis Bullosa

Epidermolysis bullosa (EB) is a group of conditions characterized by severe fragility of the skin that causes recurring blistering. The recessive dystrophic subtype of EB (RDEB) has a strong impact on the nutritional status. We evaluated the resting energy expenditure (REE) and presence of protein catabolism in patients with RDEB. REE was assessed in 10 subjects (7 females; age range 4-33 years) by indirect calorimetry and using a predictive equation. Nitrogen balance was calculated by protein intake and 24 h urinary urea excretion estimations. An assessment of body surface area (BSA) with infected and non-infected skin lesions was applied to the nitrogen balance burn equation that was adapted to EB. The REE values predicted by the equation were consistently lower than the ones measured, except for two subjects. All subjects recorded high protein and energy intake, with protein intake being higher than 4 g protein/kg/day for five subjects. Even so, protein catabolism was observed in six subjects, three of whom had infected wounds. This study raises the hypothesis that the clinical and nutritional risks of people with RDEB are associated with an increased REE and negative nitrogen balance, which reinforces the importance of nutritional support.

Increased resting metabolism in neurofibromatosis type 1

BACKGROUND & AIMS

Neurofibromatosis type 1 (NF1) is an autosomal dominant genetic disease that is characterized by neurocutaneous changes with multisystem involvement. A previous study with adults with NF1 revealed that changes in total energy expenditure were related to food consumption and body composition. Resting energy expenditure (REE), a measure of energy that the body expends to maintain vital functions, has not been assessed in NF1 populations. This study aimed to assess REE in individuals with NF1 using indirect calorimetry (IC) and evaluate its correlation with body composition and muscle strength.

METHODS

Twenty-six adults with NF1 (14 men) aged 18-45 years underwent IC for assessing REE, respiratory quotient (RQ), and substrate utilization. Body composition was assessed by dual energy X-ray absorptiometry. Weight, height, and waist circumference (WC) were also measured. Maximum muscular strength (Smax) was measured by handgrip test using a dynamometer. Patients in the NF1 group were compared to 26 healthy controls in the control group, who were matched by sex, age, body mass index (BMI), and physical activity level.

RESULTS

There were no differences in weight, WC, fat mass, and body fat percentage (BFP). Appendicular lean mass (ALM) adjusted by BMI (ALM_BMI) (0.828 ± 0.161 versus 0.743 ± 0.190; P = 0.048) and Smax (37.5 ± 10.6 versus 31.1 ± 12.2; P = 0.035) was lower in the NF1 group than in the control group. No differences in body composition, strength, and anthropometric parameters were observed in men, but women with NF1 presented lower body surface area (BSA), lean body mass (LBM), ALM, ALM_BMI, and Smax. REE adjusted by weight, LBM, or ALM was higher in the NF1 group than in the control group (medians, 21.9 versus 26.3, P = 0.046; 36.5 versus 41.1, P = 0.012; and 82.3 versus 92.4, P = 0.006, respectively), and these differences were observed only among women. RQ was lower in the NF1 group than in the control group (0.9 ± 0.1 versus 0.8 ± 0.1; P = 0.008), revealing that individuals with NF1 oxidized more lipids and fewer carbohydrates than controls. REE correlated negatively with BFP and positively with weight, height, BMI, WC, BSA, LBM, ALM, ALM_BMI, bone mineral content, and Smax.

CONCLUSIONS

Individuals with NF1, particularly women, presented with increased REE (adjusted by weight, LBM, or ALM) and lower RQ compared to healthy controls. These findings were associated with lower ALM_BMI and Smax, possibly indicating premature sarcopenia in this population. Further investigation concerning energy metabolism in NF1 and gender differences may be helpful in explaining underlying mechanisms of these changes.

In vitro validation of indirect calorimetry device developed for the ICALIC project against mass spectrometry

RATIONALE

Accurate evaluation of the energy needs is required to optimize nutrition support of critically ill patients. Recent evaluations of indirect calorimeters revealed significant differences among the devices available on the market. A new indirect calorimeter (Q-NRG^®, Cosmed, Roma, Italy) has been developed by a group of investigators supporting the international calorimetry study initiative (ICALIC) to achieve ultimate accuracy for measuring energy expenditure while being easy to use, and affordable. This study aims to validate the precision and the accuracy of the Q-NRG^® in the in-vitro setting, within the clinically relevant range for adults on mechanical ventilation in the ICU. Mass spectrometry is the reference method for the gas composition analysis to evaluate the analytic performances of the Q-NRG^®.

METHODS

The accuracy and precision of the O₂ and CO₂ measurements by the Q-NRG were evaluated by comparing the measurements of known O₂ and CO₂ gas mixtures with the measurements by the mass spectrometer (Extrel, USA). The accuracy and precision of the Q-NRG^® for measurements of VO₂ (oxygen consumption) and VCO₂ (CO₂ production) at clinically relevant ranges (150, 250 and 400 ml/min STPD) were evaluated by measuring simulated gas exchange under mechanically ventilated setting at different FiO₂ settings (21-80%), in comparison to the reference measurements by the mass spectrometer-based mixing chamber system.

RESULTS

The measurements of gas mixtures of predefined O₂ and CO₂ concentrations by the Q-NRG^® were within 2% accuracy versus the mass spectrometer measurements in Passing Bablok regression analysis. In a mechanically ventilated setting of FiO₂ from 21 up to 70%, the Q-NRG^® measurements of simulated VO₂ and VCO₂ were within 5% difference of the reference mass spectrometer measurements.

CONCLUSION

In vitro evaluation confirms that the accuracy of the Q-NRG^® indirect calorimeter is within 5% at oxygen enrichment to 70%; i.e. maximum expected for clinical use. Further recommendations for the clinical use of the Q-NRG^® by will be released once the ongoing multi-center study is completed.

Associations between nutritional energy delivery, bioimpedance spectroscopy and functional outcomes in survivors of critical illness

BACKGROUND

Patients who survive critical illness frequently develop muscle weakness that can impact on quality of life; nutrition is potentially a modifiable risk factor. The present study aimed to explore the associations between cumulative energy deficits (using indirect calorimetry and estimated requirements), nutritional and functional outcomes.

METHODS

A prospective single-centre observational study of 60 intensive care unit (ICU) patients, who were mechanically ventilated for at least 48 h, was conducted. Cumulative energy deficit was determined from artificial nutrition delivery compared to targets. Measurements included: (i) at recruitment and ICU discharge, weight, fat-free mass (bioimpedance spectroscopy) and malnutrition (Subjective Global Assessment score B/C); (ii) at awakening and ICU discharge, physical function (Physical Function in Intensive Care Test-scored) and muscle strength (Medical Research Council sum-score (MRC-SS). ICU-acquired weakness was defined as a MRC-SS score of less than 48/60.

RESULTS

The median (interquartile range) cumulative energy deficit compared to the estimated targets up to ICU day 12 was 3648 (2514-5650) kcal. Adjusting for body mass index, age and severity of illness, cumulative energy deficit (per 1000 kcal) was independently associated with greater odds of ICU-acquired weakness [odds ratio (OR) = 2.1, 95% confidence interval (CI) = 1.4-3.3, P = 0.001] and malnutrition (OR = 1.9, 95% CI = 1.1-3.2, P = 0.02). In similar multivariable linear models, cumulative energy deficit was associated with reductions in fat-free mass (-1.3 kg; 95% CI = -2.4 to -0.2, P = 0.02) and physical function scores (-0.6 points; 95% CI = -0.9 to -0.3, P = 0.001).

CONCLUSIONS

Cumulative energy deficit from artificial nutrition support was associated with reduced functional outcomes and greater loss of fat-free mass in ventilated ICU patients.

Assessment of resting energy demand and body composition in oncological patients undergoing partial resections of the liver

INTRODUCTION

The metabolism of the body is a complicated process. The most important organ of the organism that affects the intensity of changes is the liver. An effective treatment method of primary and metastatic tumours is a partial resection of the organ. The analysis of changes in the body composition of patients undergoing this type of treatment allows identification of problems coexisting with the underlying disease.

AIM

To evaluate changes in the parameters of body composition and the amount of resting metabolism.

MATERIAL AND METHODS

The study group consisted of 87 patients who underwent resection of changes in the liver or thermoablation of focal lesions during hospitalisation.

RESULTS

Analysis of the data showed that the surgical intervention contributes to a statistically significant (p < 0.05) decrease in the value of the phase angle. A significant increase was noted within the extra cellular water content. The amount of resting metabolism in the postoperative period did not differ significantly; however, there was an upward trend in women and a downward trend in men.

CONCLUSIONS

Surgical resection of lesions aimed at extending the survival of patients are performed more and more often, while the consequences of these operations are not sufficiently known. The adverse effect of resection treatments on body composition parameters, mainly imaged by decreasing the phase angle value, should be minimised. Effects on metabolism remain ambiguous because no significant changes have been demonstrated in the postoperative period.

Strategies for optimal calorie administration in critically ill patients

Nutritional therapy is one of the important treatments in critically ill patients. How to estimate calorie consumption and how to determine an optimal calorie dose are clinical questions of great importance. Although indirect calorimetry is the gold standard for assessing energy expenditure, many intensivists are unable to use this technique. Therefore, the use of formulas, such as the Harris-Benedict equation, or the simple predictive value of 25 kcal/kg/day is reasonable. Several studies and guidelines have shown that the strategies for nutritional therapy depend on the nutritional risk of patients. If patients have low nutritional risks, these estimated values should not be adopted in the acute phase. Until the patient’s condition improves, less than 18 kcal/kg/day might be an optimal calorie target. Contrastingly, cumulative negative energy balance can also be harmful to critically ill patients. Thus, it is important to accurately determine the energy requirement and to make the required changes in the administered calorie dose to go from a strategy of “defense” to that of “offense” in a timely manner. In this article, the concepts of optimal calorie administration in critically ill patients were reviewed.

N. G. Malbrain M, Spapen HD. Energy expenditure of patients on ECMO: A prospective pilot study

BACKGROUND

An optimal nutritional approach sustained by convenient monitoring of metabolic status and reliable assessment of energy expenditure (EE) may improve the outcome of critically ill patients on extracorporeal membrane oxygenation (ECMO). We previously demonstrated the feasibility of indirect calorimetry (IC)-the standard of care technique to determine caloric targets-in patients undergoing ECMO. This study aims to compare measured with calculated EE during ECMO treatment. We additionally provide median EE values for use in settings where IC is not available.

METHODS

IC was performed in seven stable ECMO patients. Gas exchange was analyzed at the ventilator, and ECMO side and values were introduced in a modified Weir formula to calculate resting EE. Results were compared with EE calculated with the Harris-Benedict equation and with the 25 kcal/kg/day ESPEN recommendation.

RESULTS

Total median oxygen consumption rate was 196 (Q1-Q3 158-331) mL/min, and total median carbon dioxide production was 150 (Q1-Q3 104-203) mL/min. Clinically relevant differences between calculated and measured EE were observed in all patients. The median EE was 1334 (Q1-Q3 1134-2119) kcal/24 hours or 18 (Q1-Q3 15-27) kcal/kg/day.

CONCLUSION

Compared with measured EE, calculation of EE both over- and underestimated caloric needs during ECMO treatment. Despite a median EE of 21 kcal/kg/day, large variability in metabolic rate was found and demands further investigation.

Energy expenditure and caloric targets during continuous renal replacement therapy under regional citrate anticoagulation. A viewpoint

BACKGROUND

Indirect calorimetry (IC) is the gold standard for measuring energy expenditure in critically ill patients However, continuous renal replacement therapy (CRRT) is a formal contraindication for IC use.

AIMS

To discuss specific issues that hamper or preclude an IC-based assessment of energy expenditure and correct caloric prescription in CRRT-treated patients.

METHODS

Narrative review of current literature.

RESULTS

Several relevant pitfalls for validation of IC during CRRT were identified. First, IC measures CO₂ production (VCO₂) and O₂ consumption to calculate resting energy expenditure (REE) with the Weir equation. VCO₂ measurements are influenced by CRRT because CO₂ is exchanged during the blood purification process. CO₂ exchange also depends on type of pre- and/or postdilution fluid(s). CO₂ dissolves in different forms with dynamic but unpredictable impact on VCO₂. Second, the effect of immunologic activation and heat loss on REE caused by extracorporeal circulation during CRRT is poorly documented. Third, caloric prescription should be adapted to CRRT-induced in- and efflux of different nutrients. Finally, citrate, which is the preferred anticoagulant for CRRT, is a caloric source that may influence IC measurements and REE.

CONCLUSION

Better understanding of CRRT-related processes is needed to assess REE and provide individualized nutritional therapy in this condition.

Are Predictive Energy Expenditure Equations Accurate in Cirrhosis?

Malnutrition is associated with significant morbidity and mortality in cirrhosis. An accurate nutrition prescription is an essential component of care, often estimated using time-efficient predictive equations. Our aim was to compare resting energy expenditure (REE) estimated using predictive equations (predicted REE, pREE) versus REE measured using gold-standard, indirect calorimetry (IC) (measured REE, mREE). We included full-text English language studies in adults with cirrhosis comparing pREE versus mREE. The mean differences across studies were pooled with RevMan 5.3 software. A total of 17 studies (1883 patients) were analyzed. The pooled cohort was comprised of 65% men with a mean age of 53 ± 7 years. Only 45% of predictive equations estimated energy requirements to within 90⁻110% of mREE using IC. Eighty-three percent of predictive equations underestimated and 28% overestimated energy needs by ±10%. When pooled, the mean difference between the mREE and pREE was lowest for the Harris⁻Benedict equation, with an underestimation of 54 (95% CI: 30⁻137) kcal/d. The pooled analysis was associated with significant heterogeneity (I² = 94%). In conclusion, predictive equations calculating REE have limited accuracy in patients with cirrhosis, most commonly underestimating energy requirements and are associated with wide variations in individual comparative data.

Carbohydrate and Lipid Prescription, Administration, and Oxidation in Critically Ill Patients With Acute Kidney Injury: A Post Hoc Analysis

OBJECTIVE

In a prospective multicenter study on adult patients with acute kidney injury (AKI) receiving enteral and/or parenteral nutrition, administered carbohydrates and lipids were compared to the prescribed amounts, as well as to substrate utilization data derived from indirect calorimetry measurements.

METHODS

Resting energy expenditure (REE) was measured by indirect calorimetry. Nitrogen excretion was obtained from the protein catabolic rate calculated from urinary urea nitrogen when available and by urea kinetic-based methods in patients on renal replacement therapy. Fat and carbohydrate oxidations were derived from Frayn formulas.

RESULTS

Ninety-two REE measurements were available in 35 critically ill patients with AKI (16 on renal replacement therapy). The mean lipid oxidation rate was 101 g/24 h (standard deviation [SD] 73.8), whereas prescribed lipids were 67 g/24 h (SD 32; P < .001). Carbohydrate utilization was derived from the same REE measurements yielding a mean carbohydrate oxidation of 105.8 g/24 h (SD 131.8), thus, much lower than the prescribed carbohydrates (186.7 g/24 h; SD 74.3; P < .001). The amount of fat and carbohydrates administered correlated to the prescribed amount (r = 0.896 and r = 0.829, respectively). Further analysis showed that this nutritional pattern was independent from the presence of sepsis.

CONCLUSION

Our study suggests that critically ill patients with AKI do not receive an amount of carbohydrate and lipids adequate to support their needs on the basis of measured substrate utilization data. Thus, current nutritional approach in these patients, based on commercial formulas, should be challenged with measured substrate utilization-guided nutritional support.

Indirect calorimetry as point of care testing

Determining energy requirement is a fundamental of nutrition support. Indirect calorimetry (IC) has been long recognized as the gold standard for assessing basal or resting energy expenditure (REE). The measurement of REE is recommended particularly in the situation where adjustment of energy provision is critical. The result of the IC measurement can lead to changes in treatment and since the change can be carried out immediately at the bedside, this may be considered as point-of-care testing. Beyond the nutritional aspects, studies of energy expenditure with IC have brought out more understanding of the metabolic changes during the natural course of diseases or conditions as well as those related to the intervention. The literature in various disease states has shown that changes in energy expenditure may reveal hidden metabolic information that might be translated into clinical information and have the potential of being both prognostic indicators and/or treatment targets.

Modification of Nutrition Therapy During Continuous Renal Replacement Therapy in Critically Ill Pediatric Patients: A Narrative Review and Recommendations

Introduction

Nutrition is an important part of treatment in critically ill children. Clinical guidelines for nutrition adaptations during continuous renal replacement therapy (CRRT) are lacking. We collected and evaluated current knowledge on this topic and provide recommendations.

Methods

Questions were produced to guide the literature search in the PubMed database.

Results

Evidence is scarce and extrapolation from adult data was often required. CRRT has a direct and substantial impact on metabolism. Indirect calorimetry is the preferred method to assess resting energy expenditure (REE). Moderate underestimation of REE is common but not clinically relevant. Formula‐based calculation of REE is inaccurate and not validated in critically ill children on CRRT. The nutrition impact of nonintentional calories delivered as citrate, lactate, and glucose during CRRT must be considered. Quantifying nitrogen balance is not feasible during CRRT. Protein delivery should be increased by 25% to compensate for losses in the effluent. Fats are not removed by CRRT and should not be adapted during CRRT. Electrolyte disturbances are frequently present and should be treated accordingly. Vitamins B1, B6, B9, and C are lost in the effluent and should be adapted to the effluent dose. Trace elements, with the exception of selenium, are not cleared in relevant quantities. Manganese accumulation is of concern because of potential neurotoxicity.

Conclusion

Current recommendations regarding nutrition support in pediatric CRRT must be extrapolated from adult studies. Recommendations are provided, based on the weak level of evidence. Additional research on this topic is warranted.

Factors Related to the Assessment of Resting Metabolic Rate in Critically Ill Patients

BACKGROUND

Predicting resting metabolic rate (RMR) in mechanically ventilated, critically ill patients is an important part of the nutrition care in such patients.

METHODS

RMR and associated clinical data from various studies of mechanically ventilated, critically ill patients were combined, and the impact of body size, age, reason for admission, and sedation level were analyzed along with prediction methods of RMR (the American Society for Parenteral and Enteral Nutrition [ASPEN] standards and the Penn State equation).

RESULTS

Among 826 measurements, trauma patients had a higher RMR than surgical and medical patients (2077 ± 290 vs 1987 ± 282 kcal/d; P < .0001). RMR was not different in sedated vs unsedated patients. Wide ranges of weight (27-374 kg) and age (18-95 years) were captured. The relationships between weight and RMR and RMR and age were curvilinear. For weight-based ratio methods of RMR prediction, <50% of predictions were within the range in which they were designed to work. The accuracy of the Penn State equation was better in some weight categories than others. New equations based on a wider range of body weights and ages are presented.

CONCLUSIONS

Curvilinear functions exist for weight and age in relation to RMR, but extraordinary levels of each are required for the curve to become apparent. The ASPEN energy standards (kcal/kg body weight) fail to predict RMR because the relationship is more complex than a simple ratio. The Penn State equations are better able to model these relationships. The new versions of the equation presented here await validation.

ESPEN guideline on clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous guidelines to provide best medical nutritional therapy to critically ill patients have been updated. These guidelines define who are the patients at risk, how to assess nutritional status of an ICU patient, how to define the amount of energy to provide, the route to choose and how to adapt according to various clinical conditions. When to start and how to progress in the administration of adequate provision of nutrients is also described. The best determination of amount and nature of carbohydrates, fat and protein are suggested. Special attention is given to glutamine and omega-3 fatty acids. Particular conditions frequently observed in intensive care such as patients with dysphagia, frail patients, multiple trauma patients, abdominal surgery, sepsis, and obesity are discussed to guide the practitioner toward the best evidence based therapy. Monitoring of this nutritional therapy is discussed in a separate document.

Optimization of Nutrition Therapy with the Use of Calorimetry to Determine and Control Energy Needs in Mechanically Ventilated Critically Ill Patients: The ONCA Study, a Randomized, Prospective Pilot Study

BACKGROUND

Adequate nutrition therapy in critically ill patients poses a challenge because of the variable energy and substrate needs. The objective was to investigate whether nutrition therapy involving indirect calorimetry (IC), instead of equations for assessment of energy needs, could improve the nutrition status of critically ill patients.

METHODS

Forty mechanically ventilated patients were randomized into a group in which energy needs were controlled by calorimetry (IC group) and a group treated with a formula-based approach reflecting standard care (SC group). The primary outcome was change in the phase angle (PhA), a bioelectrical impedance parameter related to nutrition status and prognosis.

RESULTS

The mean IC-based energy requirement was lower than the formula-based estimate (21.1 ± 6.4 versus [vs] 25 kcal/kg/d, P < .01). The IC group reached 98% ± 8% of the energy goal, whereas the SC group reached only 79% ± 29% (P < 0.05), although mean intake was similar in both groups. The protein intake goal was better met in the IC group (91% ± 24%) than the SC group (73% ± 33%). The PhA of the IC group did not change during treatment, whereas that of the SC group tended to decrease by 0.36° ± 0.86° (P = .077). A shorter length of stay in intensive care was observed in the IC than in the SC group (13 ± 8 vs 24 ± 20 days, P < .05).

CONCLUSION

Intensified individual nutrition therapy involving IC appears to be useful for improving nutrition status in critically ill patients.

Indirect calorimetry in critically ill mechanically ventilated patients: Comparison of E-sCOVX with the deltatrac

BACKGROUND & AIMS

Indirect calorimetry is recommended to measure energy expenditure (EE) in critically ill, mechanically ventilated patients. The most validated system, the Deltatrac® (Datex-Ohmeda, Helsinki, Finland) is no longer in production. We tested the agreement of a new breath-by-breath metabolic monitor E-sCOVX® (GE healthcare, Helsinki, Finland), with the Deltatrac. We also compared the performance of the E-sCOVX to commonly used predictive equations.

METHODS

We included mechanically ventilated patients eligible to undergo indirect calorimetry. After a stabilization period, EE was measured simultaneously with the Deltatrac and the E-sCOVX for 2 h. Agreement and precision of the E-sCOVX was tested by determining bias, limits of agreement and agreement rates compared to the Deltatrac. Performance of the E-sCOVX was also compared to four predictive equations: the 25 kcal/kg, Penn State University 2003b, Faisy, and Harris-Benedict equation.

RESULTS

We performed 29 measurements in 16 patients. Mean EE-Deltatrac was 1942 ± 274 kcal/day, and mean EE-E-sCOVX was 2177 ± 319 kcal/day (p < 0.001). E-sCOVX overestimated EE with a bias of 235 ± 149 kcal/day, being 12.1% of EE-Deltatrac. Limits of agreement were -63 to +532 kcal/day. The 10% and 15% agreement rates of EE-E-sCOVX compared to the Deltatrac were 34% and 72% respectively. The bias of E-sCOVX was lower than the bias of the 25 kcal/kg-equation, but higher than bias of the other equations. Agreement rates for E-sCOVX were similar to the equations. The Faisy-equation had the highest 15% agreement rate.

CONCLUSION

The E-sCOVX metabolic monitor is not accurate in estimating EE in critically ill mechanically ventilated patients when compared to the Deltatrac, the present reference method. The E-sCOVX overestimates EE with a bias and precision that are clinically unacceptable.

Innovations in energy expenditure assessment

PURPOSE OF REVIEW

Optimal nutritional therapy has been associated with better clinical outcomes and requires providing energy as closed as possible to measured energy expenditure. We reviewed the current innovations in energy expenditure assessment in humans, focusing on indirect calorimetry and other new alternative methods.

RECENT FINDINGS

Although considered the reference method to measure energy expenditure, the use of indirect calorimetry is currently limited by the lack of an adequate device. However, recent technical developments may allow a broader use of indirect calorimetry for in-patients and out-patients. An ongoing international academic initiative to develop a new indirect calorimeter aimed to provide innovative and affordable technical solutions for many of the current limitations of indirect calorimetry. New alternative methods to indirect calorimetry, including CO2 measurements in mechanically ventilated patients, isotopic approaches and accelerometry-based fitness equipments, show promises but have been either poorly studied and/or are not accurate compared to indirect calorimetry. Therefore, to date, energy expenditure measured by indirect calorimetry remains the gold standard to guide nutritional therapy.

SUMMARY

Some new innovative methods are demonstrating promises in energy expenditure assessment, but still need to be validated. There is an ongoing need for easy-to-use, accurate and affordable indirect calorimeter for daily use in in-patients and out-patients.

Feeding mitochondria: Potential role of nutritional components to improve critical illness convalescence

Persistent physical impairment is frequently encountered after critical illness. Recent data point towards mitochondrial dysfunction as an important determinant of this phenomenon. This narrative review provides a comprehensive overview of the present knowledge of mitochondrial function during and after critical illness and the role and potential therapeutic applications of specific micronutrients to restore mitochondrial function. Increased lactate levels and decreased mitochondrial ATP-production are common findings during critical illness and considered to be associated with decreased activity of muscle mitochondrial complexes in the electron transfer system. Adequate nutrient levels are essential for mitochondrial function as several specific micronutrients play crucial roles in energy metabolism and ATP-production. We have addressed the role of B vitamins, ascorbic acid, α-tocopherol, selenium, zinc, coenzyme Q10, caffeine, melatonin, carnitine, nitrate, lipoic acid and taurine in mitochondrial function. B vitamins and lipoic acid are essential in the tricarboxylic acid cycle, while selenium, α-tocopherol, Coenzyme Q10, caffeine, and melatonin are suggested to boost the electron transfer system function. Carnitine is essential for fatty acid beta-oxidation. Selenium is involved in mitochondrial biogenesis. Notwithstanding the documented importance of several nutritional components for optimal mitochondrial function, at present, there are no studies providing directions for optimal requirements during or after critical illness although deficiencies of these specific micronutrients involved in mitochondrial metabolism are common. Considering the interplay between these specific micronutrients, future research should pay more attention to their combined supply to provide guidance for use in clinical practise. REVISION NUMBER: YCLNU-D-17-01092R2.

Parenteral nutrition in the ICU: Lessons learned over the past few years

Since the early 1990s enteral nutrition (EN) has been considered the optimal route of feeding rather than parenteral nutrition (PN), which was considered harmful in critically ill patients with intense inflammation. The aim of this review was to summarize recent developments and progress in PN, which have changed the view on this feeding technique. PubMed and personal databases were searched for studies and reviews reporting historical development of PN, and for clinical trials conducted after 2010 investigating PN in critical illness, comparing it to EN or not. Trials from the past decade have explored modalities and timing of artificial feeding. Trials based on equation-estimated energy targets and applying an early full feeding strategy have generally had negative results in terms of complications (infections, prolonged ventilation, and intestinal complications with EN). The few trials that based their targets on measured energy targets have achieved reduction of complications regardless of the route. Opposing enteral and parenteral feeding is no longer rational in the critical care setting. A pragmatic and reasonable approach offers better options for the individual patient. Although PN is simpler to deliver than EN, its metabolic consequences are more complicated to handle. A combination of both techniques may be a more reasonable approach in the sickest patients.

Feasibility of Exercise Testing in Patients Who Are Critically Ill: A Prospective, Observational Multicenter Study

OBJECTIVE

To evaluate the feasibility and safety of exercise testing and to describe the physiological response to exercise of patients in the Intensive Care Unit (ICU).

DESIGN

A prospective observational multicenter study.

SETTING

Two mixed medical-surgical ICUs.

PARTICIPANTS

Patients (N=37; with no primary neurological disorders, 59% men; median age 50y; ICU length of stay 14.5d; Acute Physiology and Chronic Health Evaluation IV 73.0) who had been mechanically ventilated for more than 48 hours and were hemodynamically stable enough to perform physical exercise.

INTERVENTIONS

A passive or active incremental exercise test, depending on muscle strength, on a bed-based cycle ergometer.

MAIN OUTCOME MEASURES

Feasibility and safety were evaluated based on protocol adherence and adverse events. Physiological responses to exercise quantified as changes in respiratory frequency (RF), oxygen uptake (Vo₂), carbon dioxide output (Vco₂), respiratory exchange ratio (RER), and blood lactate.

RESULTS

Thirty-seven patients of whom 18 were mechanically ventilated underwent the exercise test. The active incremental test was performed by 28, and the passive test by 9 participants. Thirty-three (89%) accomplished the test according to the protocol and 1 moderate severe adverse event (bradycardia; heart rate 44) occurred shortly after the test. RF, Vo₂, Vco₂, and lactate increased significantly, whereas RER did not change during the active incremental exercise test. No changes were observed during the passive exercise test.

CONCLUSIONS

It is safe and feasible to perform exercise testing on a bed-based cycle ergometer in patients who are critically ill and a physiological response could be measured. Future research should investigate the clinical value of exercise testing in daily ICU practice and whether exercise capacity and its limiting factors could be determined by incremental exercise testing.

Nutritional practices and adequacy in children supported on extracorporeal membrane oxygenation

BACKGROUND AND AIMS

Use of extracorporeal membrane oxygenation (ECMO) in children is increasing. Yet, little is known about optimal nutritional practices in these children. We aim to describe the nutritional adequacy, factors associated with enteral nutrition, and the association between nutritional adequacy and mortality in children supported on ECMO.

METHODS

We conducted a retrospective review of all children (1 month-18 years) requiring ECMO between 2010 and 2016. Data on enteral and parenteral energy and protein intake in the first 7 days of ECMO were collected. Adequacy of nutrition intake was defined as total intake vs. total requirements, expressed as a percentage.

RESULTS

51 patients were included, of which 43 (84.3%) were supported on veno-arterial ECMO. Median ECMO duration was 8.6 days [interquartile range (IQR) 6.1-16.2]. Overall energy and protein adequacy across the first 7 days of ECMO were 48.3% (IQR 28.0-67.4) and 44.8% (IQR 26.9-67.0) respectively. Parenteral nutrition provided majority of calories [median 88.0% (IQR 62.9-100)] and protein [median 91.0% (IQR 62.3-100)] intake. Enteral nutrition (EN) was initiated in 33 (64.7%) patients. Time to EN initiation, vasoactive-inotropic score just before ECMO initiation, veno-arterial ECMO mode and continuous renal replacement therapy in the first week of ECMO were factors associated with EN energy adequacy. Hospital mortality rate was 55% (28/51). Compared to survivors, non-survivors had lower adequacy of EN energy intake [0.5% (IQR 0-4.4) vs. 11.8% (IQR 0-24.5), p = 0.034]. After correcting for ECMO duration, need for continuous renal replacement therapy and number of vasoactive drugs required on ECMO, greater EN energy adequacy remained associated with lower risk of mortality [adjusted odds ratio 0.93 (95% confidence interval: 0.86-0.99), p = 0.048].

CONCLUSIONS

Nutritional adequacy, especially that of EN, remains low in children supported on ECMO. EN energy adequacy was found to be associated with lower mortality. Further studies on nutritional adequacy in pediatric ECMO, as well as strategies to optimize EN in these children, are warranted.

Predictive equations versus measured energy expenditure by indirect calorimetry: A retrospective validation

BACKGROUND & AIMS

Measuring resting energy expenditure (REE) via indirect calorimetry (IC) in intensive care unit (ICU) patient is the gold standard recommended by guidelines. However technical difficulties hinder its use and predictive equations are largely used instead. We sought to validate commonly used equations using a large cohort of patients.

METHODS

Patients hospitalized from 2003 to 2015 in a 16-bed ICU at a university-affiliated, tertiary care hospital who had IC measurement to assess caloric targets were included. Data was drawn from a computerized system and included REE and other variables required by equations. Measurements were restricted to 5 REE per patient to avoid bias. Equation performance was assessed by comparing means, standard deviations, correlation, concordance and agreement, which was defined as a measurement within 85-115% of measured REE. A total of 8 equations were examined.

RESULTS

A total of 3573 REE measurements in 1440 patients were included. Mean patient age was 58 years and 65% were male. A total of 562 (39%) patients had >2 REE measurements. Standard deviation of REE ranged from 430 to 570 kcal. The Faisy equation had the least mean difference (90 Kcal); Harris-Benedict had the highest correlation (52%) and agreement (50%) and Jolliet the highest concordance (62%). Agreement within 10% of caloric needs was met only in a third of patients.

CONCLUSIONS

Predictive equations have low performance when compared to REE in ICU patients. We therefore suggest that predictive equations cannot wholly replace indirect calorimetry for the accurate estimation of REE in this population.

Does the use of indirect calorimetry change outcome in the ICU? Yes it does

PURPOSE OF REVIEW

To review the recent findings on metabolic monitoring and possible beneficial effects of an adequate nutrition therapy, based on indirect calorimetry as the golden standard to predict energy expenditure.

RECENT FINDINGS

in the last decades, major steps are taken in the field of metabolism and nutrition, evolving from nutrition as a baseline support to a therapeutic intervention. The aspect of energy expenditure is of cardinal importance, and technical possibilities have impressively improved: from the first 'calorimetre' in 1789 to the new generation, clinical applicable indirect calorimeters and the high accuracy and easy use model reaching high technology readiness level [Oshima et al. (2017). Clin Nutr 36:651]. Several recent studies provide information on the technique of metabolic monitoring itself and the positive effects of implementation of the tool in a high-end nutritional care plan [Oshima et al. (2017). Clin Nutr 36:651]. The combination of correct energy provision and protein prescription has shown benefits, and mortality of ICU patients is related to the amount of energy provided [Zusman et al. (2016). Crit Care 20:367]. The use of a monitor per se will not change outcome. Optimal dosing of artificial nutrition can be achieved by the use of a parameter acquired by a measurement instead of by inaccurate equations. In the era of precision medicine, this approach has shown positive effects on outcome. Moreover, above all, the concept of metabolic monitoring of the critically ill is just an issue of common sense.

SUMMARY

Metabolic monitoring by indirect calorimetry is achieving a level in which it can be implemented in critical care practice. Evidence is available to prove that by guiding your nutritional therapy by measured values, it will change outcome of critically ill patients.

Modeling a Predictive Energy Equation Specific for Maintenance Hemodialysis

BACKGROUND

Hypermetabolism is theorized in patients diagnosed with chronic kidney disease who are receiving maintenance hemodialysis (MHD). We aimed to distinguish key disease-specific determinants of resting energy expenditure to create a predictive energy equation that more precisely establishes energy needs with the intent of preventing protein-energy wasting.

MATERIALS AND METHODS

For this 3-year multisite cross-sectional study (N = 116), eligible participants were diagnosed with chronic kidney disease and were receiving MHD for at least 3 months. Predictors for the model included weight, sex, age, C-reactive protein (CRP), glycosylated hemoglobin, and serum creatinine. The outcome variable was measured resting energy expenditure (mREE). Regression modeling was used to generate predictive formulas and Bland-Altman analyses to evaluate accuracy.

RESULTS

The majority were male (60.3%), black (81.0%), and non-Hispanic (76.7%), and 23% were ≥65 years old. After screening for multicollinearity, the best predictive model of mREE (R2 = 0.67) included weight, age, sex, and CRP. Two alternative models with acceptable predictability (R2 = 0.66) were derived with glycosylated hemoglobin or serum creatinine. Based on Bland-Altman analyses, the maintenance hemodialysis equation that included CRP had the best precision, with the highest proportion of participants' predicted energy expenditure classified as accurate (61.2%) and with the lowest number of individuals with underestimation or overestimation.

CONCLUSIONS

This study confirms disease-specific factors as key determinants of mREE in patients on MHD and provides a preliminary predictive energy equation. Further prospective research is necessary to test the reliability and validity of this equation across diverse populations of patients who are receiving MHD.

Evaluation of a short protocol for indirect calorimetry in females with eating disorders and healthy controls

BACKGROUND AND AIMS

To enable clinicians to identify the clinical picture and treatment progress and to adjust eating plans according to personal energy needs, it is important to know the patient's correct resting metabolic rate (RMR). Indirect calorimetry (IC) is the preferred method for assessment of RMR, but long duration of measurement increases the load on the patients, and reduces the effectiveness in clinical and scientific settings. Further; not all patients reach a valid RMR according to the suggested best practice protocol, with 5 min of steady state (SS) where respiratory gas volume exchange varies less than 10%. The aim of this study was to evaluate the possibility for an abbreviated RMR protocol and SS criterion.

METHODS

Forty two women diagnosed with bulimia nervosa or binge eating disorder (eating disorder group, ED), originally recruited for an outpatient treatment study, and 26 age and gender matched healthy controls (HC) were studied during a single, prolonged IC measurement. Participants rested for 10 min in supine position wearing a two-way breathing facemask, before a continuous measurement period of 20 min. Results from a standard 5 min SS criterion was compared to an abbreviated 3 min SS criterion. Both SS-criteria were evaluated through three different SS protocols (<10% variation in respiratory gas exchange), being: 1) measurement during the first 3 or 5 min, 2) measurement after discarding the first 5 min, and 3) the lowest identified RMR during the 20 min of measurement.

RESULTS

About 50% of the participants reached an early SS in both the defined SS minute criteria. Participants reaching a valid SS throughout the 20 min of measurement increased from ∼90% to 100% with an abbreviated 3 min SS. With a 5 min SS criterion, the median (range) RMR for the 3 protocols were 1639.9 (1239.2), 1508.8 (1457.6) and 1500.6 (1328.8) respectively for the ED group, and 1702.2 (1239.4), 1608.4 (1076.4) and 1594.8 (1029.2) respectively for the HC group, (p > 0.05 for all between-group analysis). With a 3 min SS criterion, the median (range) RMR were 1533.6 (1298.2), 1461.2 (1406.1), and 1395.8 (1447.3) respectively for the ED group and 1681.7 (1332.4), 1613.7 (1266.0) and 1523.1 (1050.3), respectively for the HC group, (p > 0.05 for all between-group analysis). Lowest measured RMR was different compared to the other two SS protocols in both the ED- and the HC group, and for both the 5 min- and the 3 min SS criteria, respectively (p < 0.04). Furthermore, a SS of 3 min resulted in lower RMR compared to 5 min SS (p < 0.00) and an increased number of participants classified as hypo-metabolic (RMRmeasured/RMRcalculated < 0.9).

CONCLUSIONS

An abbreviated measurement protocol to identify the lowest RMR using IC was not successful. Abbreviating the SS criteria from 5 to 3 min, resulted in a lower RMR, hence encouraging further examination of the validity of shorter SS criterion than practiced today. Registered in Clinical Trials by id-number NCT02079935, and approved by the Norwegian Regional Committee for Medical and Health Research Ethics with id-number 2013/1871. The trial in which control persons were recruited, is approved by the Norwegian Regional Committees for Medical and Health Research Ethics with the id-number 2016/1718, and prospectively registered in Clinical Trials with the id-number NCT03007459.

Systemic metabolism and energy consumption after microsurgical clipping and endovascular coiling for aneurysmal subarachnoid hemorrhage

BACKGROUND

The postoperative metabolic states of subarachnoid hemorrhage (SAH) patients were investigated using indirect calorimetry (IDC) and various nutritional evaluations to establish any difference in perioperative metabolic and nutritional states between microsurgical and endovascular treatment.

METHODS

This study included 30 acute aneurysmal SAH patients with ruptured intracranial aneurysms treated by surgical clipping (n = 16) or coil embolization (n = 14) at a single institute. The resting energy expenditure (REE) and respiratory quotient were measured using IDC on days 1, 4, 7, 10, 14, and 17-21 after the operation. Various blood tests, including C-reactive protein (CRP) and prealbumin, were evaluated on the same days.

RESULTS

The clipping group showed a significant increase in REE/basal energy expenditure (BEE) compared with the coiling group on days 1 and 4 (p = 0.04 and 0.03, respectively). No significant differences were found on days 7, 10, 14, and 17-21. The mean REE/BEE on days 1-14 and 1-21 showed no significant differences between the groups with repeated measures analysis of variance. The clipping group showed a significant decrease of prealbumin on day 4 and significant increase in CRP on days 1, 4, and 7.

CONCLUSIONS

The clipping group was in the hypermetabolic state compared with the coiling group during the very early postoperative period. However, the difference associated with the treatment modality was relatively small compared to the effects of the SAH and of the sequelae.

Early or Late Feeding after ICU Admission?

The feeding of critically ill patients has recently become a controversial issue, as several studies have provided unexpected and contradictory results. Earlier beliefs regarding energy requirements in critical illness-especially during the initial phase-have been challenged. In the current review, we summarize existing evidence about fasting and the impact of early vs. late feeding on the sick organism's responses. The most important points are the non-nutritional advantages of using the intestine, and recognition that early endogenous energy production as an important player in the response must be integrated in the nutrient prescription. There is as of yet no bedside tool to monitor dynamics in metabolism and the magnitude of the endogenous energy production. Hence, an early "full-feeding strategy" exposes patients to involuntary overfeeding, due to the absence of an objective measure enabling the adjustment of the nutritional therapy. Suggestions for future research and clinical practice are proposed.

The role of nutritional support in the physical and functional recovery of critically ill patients: a narrative review

The lack of benefit from randomised controlled trials has resulted in significant controversy regarding the role of nutrition during critical illness in terms of long-term recovery and outcome. Although methodological caveats with a failure to adequately appreciate biological mechanisms may explain these disappointing results, it must be acknowledged that nutritional support during early critical illness, when considered alone, may have limited long-term functional impact.This narrative review focuses specifically on recent clinical trials and evaluates the impact of nutrition during critical illness on long-term physical and functional recovery.Specific focus on the trial design and methodological limitations has been considered in detail. Limitations include delivery of caloric and protein targets, patient heterogeneity, short duration of intervention, inappropriate clinical outcomes and a disregard for baseline nutritional status and nutritional intake in the post-ICU period.With survivorship at the forefront of critical care research, it is imperative that nutrition studies carefully consider biological mechanisms and trial design because these factors can strongly influence outcomes, in particular long-term physical and functional outcome. Failure to do so may lead to inconclusive clinical trials and consequent rejection of the potentially beneficial effects of nutrition interventions during critical illness.

Energy and Protein in Critically Ill Patients with AKI: A Prospective, Multicenter Observational Study Using Indirect Calorimetry and Protein Catabolic Rate

The optimal nutritional support in Acute Kidney Injury (AKI) still remains an open issue. The present study was aimed at evaluating the validity of conventional predictive formulas for the calculation of both energy expenditure and protein needs in critically ill patients with AKI. A prospective, multicenter, observational study was conducted on adult patients hospitalized with AKI in three different intensive care units (ICU). Nutrient needs were estimated by different methods: the Guidelines of the European Society of Parenteral and Enteral Nutrition (ESPEN) for both calories and proteins, the Harris-Benedict equation, the Penn-State and Faisy-Fagon equations for energy. Actual energy and protein needs were repeatedly measured by indirect calorimetry (IC) and protein catabolic rate (PCR) until oral nutrition start, hospital discharge or renal function recovery. Forty-two patients with AKI were enrolled, with 130 IC and 123 PCR measurements obtained over 654 days of artificial nutrition. No predictive formula was precise enough, and Bland-Altman plots wide limits of agreement for all equations highlight the potential to under- or overfeed individual patients. Conventional predictive formulas may frequently lead to incorrect energy and protein need estimation. In critically ill patients with AKI an increased risk for under- or overfeeding is likely when nutrient needs are estimated instead of measured.

The intensive care medicine research agenda in nutrition and metabolism

Purpose

The objectives of this review are to summarize the current practices and major recent advances in critical care nutrition and metabolism, review common beliefs that have been contradicted by recent trials, highlight key remaining areas of uncertainty, and suggest recommendations for the top 10 studies/trials to be done in the next 10 years.

Methods

Recent literature was reviewed and developments and knowledge gaps were summarized. The panel identified candidate topics for future trials in critical care nutrition and metabolism. Then, members of the panel rated each one of the topics using a grading system (0–4). Potential studies were ranked on the basis of average score.

Results

Recent randomized controlled trials (RCTs) have challenged several concepts, including the notion that energy expenditure must be met universally in all critically ill patients during the acute phase of critical illness, the routine monitoring of gastric residual volume, and the value of immune-modulating nutrition. The optimal protein dose combined with standardized active and passive mobilization during the acute phase and post-acute phase of critical illness were the top ranked studies for the next 10 years. Nutritional assessment, nutritional strategies in critically obese patients, and the effects of continuous versus intermittent enteral nutrition were also among the highest-ranking studies.

Conclusions

Priorities for clinical research in the field of nutritional management of critically ill patients were suggested, with the prospect that different nutritional interventions targeted to the appropriate patient population will be examined for their effect on facilitating recovery and improving survival in adequately powered and properly designed studies, probably in conjunction with physical activity.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-017-4711-6) contains supplementary material, which is available to authorized users.