The clinical evaluation of the new indirect calorimeter developed by the ICALIC project

Analysis of metabolic alterations as 30 days intensive care mortality predictors for patients undergoing continuous renal replacement therapy

BACKGROUND

Acute kidney injury patients on continuous renal replacement therapy are subjected to alterations in metabolism, which in turn are associated with worse clinical outcome and mortality. The aim of this study is to determine which metabolism indicators can be used as independent predictors of 30 days intensive care unit (ICU) mortality.

METHODS

This was a prospective observational study on critical care patients on renal replacement therapy. Integrated approach of metabolism evaluation was used, combining the energy expenditure measured by indirect calorimetry, bioelectrical impedance provided fat free mass index (FFMI), amino acid and glucose concentrations. ICU mortality was defined as all cause 30 days mortality. Regression analysis was conducted to determine the conventional and metabolism associated predictors of mortality.

RESULTS

The study was conducted between the 2021 March and 2022 October. 60 high mortality risk patients (APACHE II of 22.98 ± 7.87, 97% on vasopressors, 100% on mechanical ventilation) were included during the period of the study. The rate of 30 days ICU mortality was 50% (n = 30). Differences across survivors and non-survivors in metabolic predictors were noted in energy expenditure (kcal/kg/day) (19.79 ± 5.55 vs 10.04 ± 3.97 p = 0.013), amino acid concentrations (mmol/L) (2.40 ± 1.06 vs 1.87 ± 0.90 p = 0.040) and glucose concentrations (mmol/L) (7.89 ± 1.90 vs 10.04 ± 3.97 p = 0.010). No differences were noted in FFMI (23.38 ± 4.25 vs 21.95 ± 3.08 p = 0.158). In the final linear regression analysis model, lower energy expenditure (exp(B) = 0.852 CI95%: 0.741-0.979 p = 0.024) and higher glucose (exp(B) = 1.360 CI95%: 1.013-1.824 p = 0.041) remained as independent predictors of the higher mortality.

CONCLUSION

The results of the study imply strong association between the metabolic alterations and ICU outcome. Our findings suggest that lower systemic amino acid concentration, lower energy expenditure and higher systemic glucose concentration are predictive of 30 days ICU mortality.

The usefulness of a new indirect calorimeter in critically ill adult patients

BACKGROUND & AIMS

The use of indirect calorimetry to determine energy requirements is highly recommended in critically ill patients. To facilitate this a new and easy to use calorimeter (Q-NRG+, Cosmed) was developed. The primary aim of our study was to describe the usefulness of this calorimeter and, secondarily, to investigate the agreement between measured and predicted energy needs in a large cohort of critically ill adult patients.

METHODS

A prospective observational study was conducted among adult mechanically ventilated patients with COVID-19. Indirect calorimetry (Q-NRG+) to measure resting energy expenditure (mREE) was performed in the first week after admission and, wherever possible, repeated weekly. Reasons for not performing indirect calorimetry were reported. Parameters of indirect calorimetry and patient's conditions during the measurements were collected. Measurements were defined as valid if less than 10% overall variation in VO2 and VCO2 and respiratory quotient ranges between 0.67 and 1.1 were observed. mREE was compared with predictive REE (pREE) using standard formulas to explore hypo (<90%)-and hypermetabolism. (>110%). Bland-Altman method and two-way mixed intraclass correlation coefficients (ICC) (single measures) were used to assess the agreement between mREE and pREE.

RESULTS

Indirect calorimetric measurements were performed in 180 of the 432 admitted patients (42%). Of the 276 performed measurements 85% were valid, and of these 90% were used to tailor nutritional therapy. Most patients were male (71%), median age was 62 years [IQR 52; 70]. Logistical issues (absence of measuring staff, no device, no stock of disposables, MRSA isolation) and clinical issues (e.g Fio2>70%, detubated but still in ICU) were the main reasons for not performing indirect calorimetry. The majority of the REE-measurements indicated either hypo- or hypermetabolism (57% week 1 and 56% week 2). The correlation between mREE and pREE was very moderate (ICC = 0.527).

CONCLUSIONS

Although indirect calorimetry was performed in less than half of the patients, it proved to be of value to guide nutritional therapy. We conclude that the technique is easily applicable and expect that its impact can be significantly increased with the resolution of logistical and organizational issues.

How to interpret and apply the results of indirect calorimetry studies: A case-based tutorial

Evidence is growing that the individual adjustment of energy targets guided by indirect calorimetry (IC) can improve outcome. With the development of a new generation of devices that are easier to use and rapid, it appears important to share knowledge and expertise that may be used to individualize nutrition care. Despite the focus of this tutorial being on one contemporary device, the principles of IC apply across existing devices and can assist tailoring the nutrition prescription and in assessing response to nutrition therapy. The present tutorial addresses its clinical application in intubated mechanically ventilated and spontaneously breathing adult patients (canopy), i.e. it covers the range from critical illness to outpatients. The cases that are presented show how the measured energy expenditure (mEE), and the respiratory quotient (RQ), i.e. the ratio of expired CO2 to consumed O2, should be applied in different cases, to adapt and individualize nutrition prescription, as it is a good marker of over- or underfeeding at the different stages of disease. The RQ also informs about the patient's body's capacity to use different substrates: the variations of RQ indicating the metabolic changes revealing insufficient or excessive feeding. The different cases reflect the use of a new generation device as a metabolic monitor that should be combined with other clinical observations and laboratory biomarkers. The tutorial also points to some shortcomings of the method, proposing alternatives.

Predictive Energy Equations Inaccurately Estimate Metabolic Demands of Older Adult Trauma Patients

INTRODUCTION

Suboptimal nutrition promotes unfavorable outcomes in trauma patients, particularly among those aged 60 and over. While many institutions employ predictive energy equations to determine patients' energy requirements, mounting evidence shows these equations inaccurately estimate caloric needs. In this pilot randomized controlled trial, we sought to quantify the discrepancy between predictive equations and indirect calorimetry (IC)-the gold standard for determining energy requirements-in the older adult trauma population.

METHODS

This is a nested cohort study within a pilot randomized control trial in which 32 older adult trauma patients were randomized 3:1 to receive IC-guided nutrition delivery versus standard of care. IC requirements of patients in the intervention arm were compared to Mifflin St. Jeor (MSJ), Harris-Benedict (HB), and the American Society for Parenteral and Enteral Nutrition-Society of Critical Care Medicine (ASPEN-SCCM) predictive energy equations.

RESULTS

Twenty patients underwent IC to assess measured resting energy expenditure (mREE), yielding a mean (standard deviation) mREE of 23.1 ± 4.8 kcal/kg/d. MSJ and HB gave mean predictive resting energy expenditures of 17.5 ± 2.0 and 18.5 ± 2.0 kcal/kg/d in these patients, demonstrating that IC-derived values were 32.1% and 25.0% higher, respectively. When patients were stratified by body mass index (BMI), MSJ, and HB more severely underestimated caloric requirements in individuals with BMI <30 versus BMI 30-50. While the mean mREE fell within the mean predictive resting energy expenditure range prescribed by ASPEN-SCCM equations (21.4 ± 4.1 to 26.2 ± 4.3 kcal/kg/d), individuals' IC-derived values fell within their personal range in 8 of 20 cases.

CONCLUSIONS

The MSJ and HB predictive energy equations consistently and significantly underpredict metabolic demands of older adult trauma patients compared to IC and perform worse in lower BMI individuals. ASPEN-SCCM equations frequently overpredict or underpredict resting energy expenditure. While these findings should be confirmed in a larger randomized control trial, this study suggests that institutions should prioritize IC to accurately identify the metabolic demands of older trauma patients.

Advances in nutritional metabolic therapy to impede the progression of critical illness

With the advancement of medical care and the continuous improvement of organ support technologies, some critically ill patients survive the acute phase of their illness but still experience persistent organ dysfunction, necessitating long-term reliance on intensive care and organ support, known as chronic critical illness. Chronic critical illness is characterized by prolonged hospital stays, high mortality rates, and significant resource consumption. Patients with chronic critical illness often suffer from malnutrition, compromised immune function, and poor baseline health, which, combined with factors like shock or trauma, can lead to intestinal mucosal damage. Therefore, effective nutritional intervention for patients with chronic critical illness remains a key research focus. Nutritional therapy has emerged as one of the essential components of the overall treatment strategy for chronic critical illness. This paper aims to provide a comprehensive review of the latest research progress in nutritional support therapy for patients with chronic critical illness.

Effects of Energy Delivery Guided by Indirect Calorimetry in Critically Ill Patients: A Systematic Review and Meta-Analysis

BACKGROUND

The utility of using indirect calorimetry (IC) to estimate energy needs and methods for its application to this purpose remain unclear. This systematic review investigated whether using IC to estimate energy expenditure in critically ill patients is more meaningful for improving survival than other estimation methods.

METHODS

Comprehensive searches were conducted in MEDLINE using PubMed, Cochrane Central Register of Controlled Trials, and Igaku-Chuo-Zasshi up to March 2023.

RESULTS

Nine RCTs involving 1178 patients were included in the meta-analysis. The evidence obtained suggested that energy delivery by IC improved short-term mortality (risk ratio, 0.86; 95% confidence interval [CI], 0.70 to 1.06). However, the use of IC did not appear to affect the length of ICU stay (mean difference [MD], 0.86; 95% CI, -0.98 to 2.70) or the duration of mechanical ventilation (MD, 0.66; 95% CI, -0.39 to 1.72). Post hoc analyses using short-term mortality as the outcome found no significant difference by target calories in resting energy expenditure, whereas more frequent IC estimates were associated with lower short-term mortality and were more effective in mechanically ventilated patients.

CONCLUSIONS

This updated meta-analysis revealed that the use of IC may improve short-term mortality in patients with critical illness and did not increase adverse events.

Association of energy delivery with short-term survival in mechanically ventilated critically ill adult patients: a secondary analysis of the NEED trial

BACKGROUND AND AIMS

The optimal energy delivery for mechanically ventilated patients is controversial, particularly during the first week of ICU admission. This study aimed to investigate the association between different caloric adequacy and 28-day mortality in a cohort of critically ill adults on mechanical ventilation.

METHODS

This is a secondary analysis of a multicenter, cluster-randomized controlled trial. Eligible patients were divided into four quartiles (Q1-Q4) according to caloric adequacy calculated by the actual average daily energy delivery during the first seven days of ICU stay divided by energy requirement as a percentage. Cox proportional hazards models were used to examine the impact of different quartiles of caloric adequacy on 28-day mortality in the whole cohort and subgroups with different nutritional risk status at enrollment.

RESULTS

A total of 1587 patients were included in this study, with an overall 28-day mortality of 15.8%. The average caloric adequacy was 26.3 ± 11.9% (Q1), 52.5 ± 5.5% (Q2), 71.7 ± 6.4% (Q3), 107.0 ± 22.2% (Q4), respectively (p < 0.001 among quartiles). Compared with Q1, Q3 was associated with lower mortality in the unadjusted model (hazard ratio [HR] = 0.536; 95% confidence interval [CI], 0.375-0.767; P = 0.001) and adjusted model (adjusted HR = 0.508; 95% CI, 0.339-0.761; P = 0.001). This association remained valid in the subgroup of high nutritional risk patients (unadjusted HR = 0.387; 95% CI, 0.238-0.627; P < 0.001 and adjusted HR = 0.369; 95% CI, 0.216-0.630; P < 0.001, respectively), but not in those with low risk.

CONCLUSIONS

Energy delivery near the 70% energy requirements in the first week of ICU stay was associated with reduced 28-day mortality among mechanically ventilated critically ill patients, especially in patients with high nutrition risk at admission.

Trajectories of resting energy expenditure and performance of predictive equations in children hospitalized with an acute illness and malnutrition: a longitudinal study

There is scarce data on energy expenditure in ill children with different degrees of malnutrition. This study aimed to determine resting energy expenditure (REE) trajectories in hospitalized malnourished children during and after hospitalization. We followed a cohort of children in Bangladesh and Malawi (2-23 months) with: no wasting (NW); moderate wasting (MW), severe wasting (SW), or edematous malnutrition (EM). REE was measured by indirect calorimetry at admission, discharge, 14-and-45-days post-discharge. 125 children (NW, n = 23; MW, n = 29; SW, n = 51; EM, n = 22), median age 9 (IQR 6, 14) months, provided 401 REE measurements. At admission, the REE of children with NW and MW was 67 (95% CI [58, 75]) and 70 (95% CI [63, 76]) kcal/kg/day, respectively, while REE in children with SW was higher, 79 kcal/kg/day (95% CI [74, 84], p = 0.018), than NW. REE in these groups was stable over time. In children with EM, REE increased from admission to discharge (65 kcal/kg/day, 95% CI [56, 73]) to 79 (95% CI [72, 86], p = 0.0014) and was stable hereafter. Predictive equations underestimated REE in 92% of participants at all time points. Recommended feeding targets during the acute phase of illness in severely malnourished children exceeded REE. Acutely ill malnourished children are at risk of being overfed when implementing current international guidelines.

Determining energy and protein needs in critically ill pediatric patients: A scoping review

INTRODUCTION

In critically ill pediatric patients, optimal energy and protein intakes are associated with a decreased risk of morbidity and mortality. However, the determination of energy and protein needs is complex. The objective of this scoping review was to understand the extent and type of evidence related to the methods used to determine energy and protein needs in critically ill pediatric patients.

METHODS

An international expert group composed of dietitians, pediatric intensivists, a nurse, and a methodologist conducted the review, based on the Johanna Briggs Institute methodology. Two researchers searched for studies published between 2008 and 2023 in two electronic databases, screened abstracts and relevant full texts for eligibility, and extracted data.

RESULTS

A total of 39 studies were included, mostly conducted in critically ill children undergoing ventilation, to assess the accuracy of predictive equations for estimating resting energy expenditure (REE) (n = 16, 41%) and the impact of clinical factors (n = 22, 56%). They confirmed the risk of underestimation or overestimation of REE when using predictive equations, of which the Schofield equation was the least inaccurate. Apart from weight and age, which were positively correlated with REE, the impact of other factors was not always consistent. No new indirect calorimeter method used to determine protein needs has been validated.

CONCLUSION

This scoping review highlights the need for scientific data on the methods used to measure energy expenditure and determine protein needs in critically ill children. Studies using a reference method are needed to validate an indirect calorimeter.

Implementation of the ESPEN guideline on clinical nutrition in the intensive care unit (ICU): It is time to move forward!: A position paper from the 'nutrition in the ICU' ESPEN special interest group

Nutritional assessment and provision of nutritional therapy are a core part of intensive care unit (ICU) patient treatment. The ESPEN guideline on clinical nutrition in the ICU was published in 2019. However, uncertainty and difficulties remain regarding its full implementation in daily practice. This position paper is intended to help ICU healthcare professionals facilitate the implementation of ESPEN nutrition guidelines to ensure the best care for their patients. We have aimed to emphasize the guideline recommendations that need to be implemented in the ICU, are advised, or are optional, and to give practical directives to improve the guideline recommendations in daily practice. These statements were written by the members of the ICU nutrition ESPEN special interest group (SIG), based on a survey aimed at identifying current practices relating to key issues in ICU nutrition. The ultimate goal is to improve the ICU patients quality of care.

Controlled enteral nutrition in critical care patients - A randomized clinical trial of a novel management system

PURPOSE

Nutritional therapy is essential to ICU care. Successful early enteral feeding is hindered by lack of protocols, gastrointestinal intolerance and feeding interruptions, leading to impaired nutritional intake. smART+ was developed as a nutrition management feeding platform controlling tube positioning, reflux, gastric pressure, and malnutrition. This study evaluated the potential of this new ICU care platform to deliver targeted nutrition and improve ICU outcomes.

METHODS

Critically ill patients ≥18 years-old, mechanically ventilated and enterally fed, were randomized to receive ESPEN-guideline-based nutrition or smART+ -guided nutrition for 2-14 days. Primary endpoint was average deviation from daily targeted nutrition determined via calculation of energy targets per calorimetry. Secondary endpoints included gastric residual volumes, length of stay (LOS) and length of ventilation (LOV).

RESULTS

smART+ achieved a mean deviation from daily targeted nutrition of 10.5% (n = 48) versus 34.3% for control (n = 50), p < 0.0001. LOS and LOV were decreased in the smART+ group versus control (mean LOS: 10.4 days versus 13.7; reduction 3.3 days, adjusted HR 1.71, 95% CI:1.13,2.60, p = 0.012; mean LOV: 9.5 days versus 12.8 days reduction of 3.3 days, adjusted HR 1.64, 95% CI:1.08-2.51, p = 0.021). Feeding goals were met (within ±10%) on 75.7% of days for smART+ versus 23.3% for control (p < 0.001). No treatment-related adverse events occurred in either group. The study was stopped due to success in a planned interim analysis of the first 100 patients.

CONCLUSION

The smART+ Platform improved adherence to feeding goals and reduced LOS and LOV versus standard of care in critically ill patients.

TRIAL REGISTRATION

NCT04098224; registered September 23, 2019.

Two-hour indirect calorimetry measurement as a predictor of 24-hour energy expenditure in critically ill surgical patients: A longitudinal study

BACKGROUND

Measuring energy expenditure (EE) by indirect calorimetry (IC) has become the gold standard tool for critically ill patients to define energy targets and tailor nutrition. Debate remains as to the optimal duration of measurements or the optimal time of day in which to perform IC.

METHODS

In this retrospective longitudinal study, we analyzed results of daily continuous IC in 270 mechanically ventilated, critically ill patients admitted to the surgical intensive care unit in a tertiary medical center and compared measurements performed at different hours of the day.

RESULTS

A total of 51,448 IC hours was recorded, with an average 24-h EE of 1523 ± 443 kcal/day. Night shift (00:00-8:00) was found to have significantly lower EE measurements (mean, 1499 ± 439 kcal/day) than afternoon (16:00-00:00; mean, 1526 ± 435 kcal/day) and morning (8:00-16:00; mean, 1539 ± 462 kcal/day) measurements (P < 0.001 for all). The bi-hourly time frame that most closely resembled the daily mean was 18:00-19:59, with a mean of 1521 ± 433 kcal/day. Daily EE measurements of the continuous IC at days 3-7 of admission showed a trend toward a daily increase in 24-h EE, but the difference was not statistically significant (P = 0.081).

CONCLUSIONS

Periodic measurements of EE can differ slightly when performed at various hours of the day, but the error range is small and may not necessarily have a clinical impact. When continuous IC is not available, a 2-h EE measurement between 18:00 and 19:59 can serve as a reasonable alternative.

Documented nutritional therapy in relation to nutritional guidelines post burn injury - a retrospective observational study

BACKGROUND & AIMS

Intensive nutritional therapy is an essential component of burn care. Regarding post-minor burn injuries, the literature is lacking. The aim of this study was to evaluate documented nutritional therapy in relation to international guidelines after both minor and major burn injuries. The secondary aim of this study was to evaluate the adequacy of energy and protein intake compared to individual nutritional goals post-burn injury.

METHODS

A retrospective observational single-centre study including patients admitted between 2017 and 2019 at a burn centre in Sweden was performed. The patients included in the study were ≥18 years old and in need of hospital care for ≥72 h post-burn injury. Information about patients' demographics, nutritional therapy, and clinical characteristics of burn injury was collected. The patients were divided according to total body surface area burnt (TBSA %) into minor burn injuries (TBSA <20%) and major burn injuries (TBSA ≥20%). Descriptive statistics were used to analyse data. Adherence to guidelines was established by comparing 24 nutritional therapy recommendations to documented treatment. If documented nutritional treatment were in accordance with guidelines, adherence was considered high (≥80%), moderate (60-79.9%) or low (<59.9%).

RESULTS

One hundred thirty-four patients were included, 90 patients with minor burn injuries and 44 patients with major burn injuries. Documented adherence to the nutritional guideline was overall low. After minor burn injury, 8% (2/24) of nutritional therapy recommendations had a high adherence (fat intake <35% of total energy intake and enteral nutrition as prioritized feeding route), 17% (4/24) a moderate adherence, and 75% (18/24) a low adherence. In patients treated after a major burn injury, there were two recommendations with documented high adherence (Vitamin C and Zinc); 25% (6/24) had moderate adherence, and 67% (16/24) had low adherence. In addition, quite a large amount of missing data was found. Adequacy of documented nutritional intake, compared to the individual documented goal, was 78% (±23%) for energy and 66% (±22%) for protein after minor burn injury. After major burn injury, the adequacy was 89% (±21%) for energy and 78% (±19%) for protein, respectively.

CONCLUSIONS

This study revealed low adherence to nutritional guidelines in patients treated for minor and major burn injuries. Compared to major burn injuries, lower documented adequacy for both energy and proteins was found in minor burn injuries. Given the disparity between guidelines and documented nutritional therapy, and the lack of specific guidelines for minor burn injuries, there could be a considerable risk of inadequate nutritional therapy post-burn injury.

Personalized nutrition therapy in critical care: 10 expert recommendations

Personalization of ICU nutrition is essential to future of critical care. Recommendations from American/European guidelines and practice suggestions incorporating recent literature are presented. Low-dose enteral nutrition (EN) or parenteral nutrition (PN) can be started within 48 h of admission. While EN is preferred route of delivery, new data highlight PN can be given safely without increased risk; thus, when early EN is not feasible, provision of isocaloric PN is effective and results in similar outcomes. Indirect calorimetry (IC) measurement of energy expenditure (EE) is recommended by both European/American guidelines after stabilization post-ICU admission. Below-measured EE (~ 70%) targets should be used during early phase and increased to match EE later in stay. Low-dose protein delivery can be used early (~ D1-2) (< 0.8 g/kg/d) and progressed to ≥ 1.2 g/kg/d as patients stabilize, with consideration of avoiding higher protein in unstable patients and in acute kidney injury not on CRRT. Intermittent-feeding schedules hold promise for further research. Clinicians must be aware of delivered energy/protein and what percentage of targets delivered nutrition represents. Computerized nutrition monitoring systems/platforms have become widely available. In patients at risk of micronutrient/vitamin losses (i.e., CRRT), evaluation of micronutrient levels should be considered post-ICU days 5-7 with repletion of deficiencies where indicated. In future, we hope use of muscle monitors such as ultrasound, CT scan, and/or BIA will be utilized to assess nutrition risk and monitor response to nutrition. Use of specialized anabolic nutrients such as HMB, creatine, and leucine to improve strength/muscle mass is promising in other populations and deserves future study. In post-ICU setting, continued use of IC measurement and other muscle measures should be considered to guide nutrition. Research on using rehabilitation interventions such as cardiopulmonary exercise testing (CPET) to guide post-ICU exercise/rehabilitation prescription and using anabolic agents such as testosterone/oxandrolone to promote post-ICU recovery is needed.

Energy Expenditure Under General Anesthesia: An Observational Study Using Indirect Calorimetry in Patients Having Noncardiac Surgery

BACKGROUND

Perioperative hemodynamic management aims to optimize organ perfusion pressure and blood flow-assuming this ensures that oxygen delivery meets cellular metabolic needs. Cellular metabolic needs are reflected by energy expenditure. A better understanding of energy expenditure under general anesthesia could help tailor perioperative hemodynamic management to actual demands. We thus sought to assess energy expenditure under general anesthesia. Our primary hypothesis was that energy expenditure under general anesthesia is lower than preoperative awake resting energy expenditure.

METHODS

We conducted an observational study on patients having elective noncardiac surgery at the University Medical Center Hamburg-Eppendorf (Germany) between September 2019 and March 2020. We assessed preoperative awake resting energy expenditure, energy expenditure under general anesthesia, and energy expenditure after surgery using indirect calorimetry. We compared energy expenditure under general anesthesia at incision to preoperative awake resting energy expenditure using a Wilcoxon signed-rank test for paired measurements.

RESULTS

We analyzed 60 patients. Median (95% confidence interval [CI]) preoperative awake resting energy expenditure was 953 (95% CI, 906-962) kcal d -1 m -2 . Median energy expenditure under general anesthesia was 680 (95% CI, 642-711) kcal d -1 m -2 -and thus 263 (95% CI, 223-307) kcal d -1 m -2 or 27% (95% CI, 23%-30%) lower than preoperative awake resting energy expenditure ( P < .001).

CONCLUSIONS

Median energy expenditure under general anesthesia is about one-quarter lower than preoperative awake resting energy expenditure in patients having noncardiac surgery.

Females have a different metabolic response to critical illness, measured by comprehensive amino acid flux analysis

BACKGROUND

The trajectory from healthy to critical illness is influenced by numerous factors, including metabolism, which differs substantially between males and females. Whole body protein breakdown is substantially increased in critically ill patients, but it remains unclear whether there are sex differences that could explain the different health outcomes. Hence, we performed a secondary analysis of a study, where we used a novel pulse isotope method in critically ill and matched healthy males and females.

METHODS

In 51 critically ill ICU patients (26 males, 15 females) and 49 healthy controls (36 males and 27 females), we assessed their general and disease characteristics and collected arterial(ized) blood in the postabsorptive state after pulse administration of 8 ml of a solution containing 18 stable AA tracers. In contrast to the original study, we now fitted the decay curves and calculated non-compartmental whole body amino acid production (WBP) and compartmental measurements of metabolism, including intracellular amino acid production. We measured amino acid enrichments and concentrations by LC-MS/MS and derived statistics using AN(C)OVA.

RESULTS

Critically ill males and females showed an increase in the WBP of many amino acids, including those related to protein breakdown, but females showed greater elevations, or in the event of a reduction, attenuated reductions. Protein breakdown-independent WBP differences remained between males and females, notably increased glutamine and glutamate WBP. Only severely ill females showed a lower increase in WBP of many amino acids in comparison to moderately ill females, suggesting a suppressed metabolism. Compartmental analysis supported the observations.

CONCLUSIONS

The present study shows that females have a different response to critical illness in the production of several amino acids and changes in protein breakdown, observations made possible using our innovative stable tracer pulse approach.

CLINICAL TRIAL REGISTRY

Data are from the baseline measurements of study NCT02770092 (URL: https://clinicaltrials.gov/ct2/show/NCT02770092) and NCT03628365 (URL: https://clinicaltrials.gov/ct2/show/NCT03628365).

Comparison of resting energy expenditure measured with metabolic cart and calculated with predictive formulas in critically ill patients on mechanical ventilation

INTRODUCTION

The purpose was to compare the resting energy expenditure (REE) measured with the Q-NRG™+ metabolic-cart (MREE) with REE predicted by equations (the Harris-Benedict formula and an equation developed in ward, REE-HB and REE-W, respectively). We also aimed to assess the agreement of the measurements of oxygen consumption (V̇O₂) and carbon dioxide production (V̇CO₂) at different inspired fractions of oxygen (FiO₂).

METHODS

27 mechanically ventilated ICU patients were enrolled. V̇O₂ and V̇CO₂ were measured by Q-NRG™+ during breathing 40% and 60% FiO₂. MREE was compared with REE-W and REE-HB normalized for body weight.

RESULTS

V̇O₂ was 233.0 (95.2) ml/min and 217.5 (89.8) ml/min at FiO₂ 40% and 60%, respectively (NS). V̇CO₂ was 199.0 (91.7) ml/min at FiO₂ 40%, and 197.5 (85.5) ml/min at FiO₂ 60% (NS). The REE estimated from the equations was significantly different from the MREE. The best agreement was found for the Harris-Benedict equation without correction for stress-factors. Harris-Benedict equation corrected overestimates REE.

CONCLUSIONS

This new metabolic cart Q-NRG™+ provides a concordance of values for V̇O₂ and V̇CO₂ when measured at different FiO₂, and is a reliable tool for estimating energy expenditure and assessing the nutritional needs of the patient. This study demonstrates that the estimation of REE using predictive formulas does not allow accurate calculation of metabolic demands in ventilated intensive care patient. However, predictive equations allow for a rapid assessment of REE and calculation of the amount of energy derived from different substrates.

Nutrition after severe burn injury

PURPOSE OF REVIEW

Severe burn injury causes significant metabolic changes and demands that make nutritional support particularly important. Feeding the severe burn patient is a real challenge in regard to the specific needs and the clinical constraints. This review aims to challenge the existing recommendations in the light of the few recently published data on nutritional support in burn patients.

RECENT FINDINGS

Some key macro- and micro-nutrients have been recently studied in severe burn patients. Repletion, complementation or supplementation of omega-3 fatty acids, vitamin C, vitamin D, antioxidant micronutrients may be promising from a physiologic perspective, but evidence of benefits on hard outcomes is still weak due to the studies' design. On the contrary, the anticipated positive effects of glutamine on the time to discharge, mortality and bacteremias have been disproved in the largest randomized controlled trial investigating glutamine supplementation in burns. An individualized approach in term of nutrients quantity and quality may proof highly valuable and needs to be validated in adequate trials. The combination of nutrition and physical exercises is another studied strategy that could improve muscle outcomes.

SUMMARY

Due to the low number of clinical trials focused on severe burn injury, most often including limited number of patients, developing new evidence-based guidelines is challenging. More high-quality trials are needed to improve the existing recommendations in the very next future.

Neuromuscular blockade administration is associated with altered energy expenditure in critically ill intubated patients with COVID-19

BACKGROUND & AIMS

ESPEN guidelines advocate that energy needs of critically ill patients with COVID 19 should be assessed using indirect calorimetry, if safely available. This study described energy needs of intubated patients with COVID-19 and explores whether neuromuscular blockade administration (NMBAs) is associated with altered energy expenditure.

METHODS

Resting energy expenditure (REE) and respiratory exchange rate (RER) evaluated among critically ill intubated COVID-19 patients until 28th day of intensive care unit stay (ICU-S) by indirect calorimetry. Paralysed patients were defined as those with drug induced paralysis using cicatracurium, for at least 3 days during their ICU-S.

RESULTS

34 adult COVID 19 patients (59.8% male, 35.2% obese) requiring mechanical ventilation were assessed prospectively. REE measurements suggest a gradual increase of energy needs post 3rd day of ICU-S in both patients without obesity (non ob) ((from 17.8 kcal/kgr up to 29.3 kcal/kgr actual body weight (AcBW) during 28th day of ICU-S, p = 0.011)) and patients with obesity (ob) ((from 18.1 kcal/kgr up to 30.1 kcal/kgr adjusted body weight (AjBW) during 28th day of ICU-S, p = 0.021)). NMBAs use was accompanied by a significant drop in REE, especially during first 7 days of hospitalization, both in non ob (22.9 vs 17.9 kcal/kgr AcBW, p = 0.014) and ob patients (22.5 vs 19.5 kcal/kgr ABW, p = 0.027).

CONCLUSION

We identified the energy needs of COVID-19 intubated patients and highlighted a significant increase beyond the 1st week in the ICU. Administration of NMBAs should be considered, as it may impact resting energy expenditure.

Measured Energy Expenditure Using Indirect Calorimetry in Post-Intensive Care Unit Hospitalized Survivors: A Comparison with Predictive Equations

Actual energy needs after a stay in intensive care units (ICUs) are unknown. The aims of this observational study were to measure the energy expenditure (mEE) of ICU survivors during their post-ICU hospitalization period, and to compare this to the estimations of predictive equations (eEE). Survivors of an ICU stay ≥ 7 days were enrolled in the general ward during the first 7 days after ICU discharge. EE was measured using the Q-NRG calorimeter in canopy mode. This measure was compared to the estimated EE using the Harris−Benedict (HB) equation multiplied by a 1.3 stress factor, the Penn−State (PS) equation or the 30 kcal weight-based (WB) equation. A total of 55 adults were included (67.3% male, age 60 (52−67) y, body mass index 26.1 (22.2−29.7) kg/m2). Indirect calorimetry was performed 4 (3−6) d after an ICU stay of 12 (7−16) d. The mEE was 1682 (1328−1975) kcal/d, corresponding to 22.9 (19.1−24.2) kcal/kg/day. The eEE values derived using HB and WB equations were significantly higher than mEE: 3048 (1805−3332) and 2220 (1890−2640) kcal/d, respectively (both p < 0.001). There was no significant difference between mEE and eEE using the PS equation: 1589 (1443−1809) kcal/d (p = 0.145). The PS equation tended to underestimate mEE with a bias of −61.88 kcal and a wide 95% limit of agreement (−717.8 to 594 kcal). Using the PS equation, agreement within 15% of the mEE was found in 32/55 (58.2%) of the patients. In the present cohort of patients who survived a prolonged ICU stay, mEE was around 22−23 kcal/kg/day. In this post-ICU hospitalization context, none of the tested equations were accurate in predicting the EE measured by indirect calorimetry.

Adequacy of Nutritional Intakes during the Year after Critical Illness: An Observational Study in a Post-ICU Follow-Up Clinic

Whether nutritional intakes in critically ill survivors after hospital discharge are adequate is unknown. The aims of this observational study were to describe the energy and protein intakes in ICU survivors attending a follow-up clinic compared to empirical targets and to explore differences in outcomes according to intake adequacy. All adult survivors who attended the follow-up clinic at 1, 3 and 12 months (M1, M3, M12) after a stay in our intensive care unit (ICU) ≥ 7 days were recruited. Average energy and protein intakes over the 7 days before the face-to-face consultation were quantified by a dietician using food anamnesis. Self-reported intakes were compared empirically to targets for healthy people (FAO/WHO/UNU equations), for critically ill patients (25 kcal/kg/day and 1.3 g protein/kg/day). They were also compared to targets that are supposed to fit post-ICU patients (35 kcal/kg/day and 1.5 g protein/kg/day). Blood prealbumin level and handgrip strength were also measured at each timepoint. A total of 206 patients were analyzed (49, 97 and 60 at the M1, M3 and M12, respectively). At M1, M3 and M12, energy intakes were 73.2 [63.3–86.3]%, 79.3 [69.3–89.3]% and 82.7 [70.6–93.7]% of healthy targets (p = 0.074), respectively. Protein intakes were below 0.8 g/kg/day in 18/49 (36.7%), 25/97 (25.8%) and 8/60 (13.3%) of the patients at M1, M3 and M12, respectively (p = 0.018), and the protein intakes were 67.9 [46.5–95.8]%, 68.5 [48.8–99.3]% and 71.7 [44.9–95.1]% of the post-ICU targets (p = 0.138), respectively. Prealbumin concentrations and handgrip strength were similar in patients with either inadequate energy intakes or inadequate protein intakes, respectively. In our post-ICU cohort, up to one year after discharge, energy and protein intakes were below the targets that are supposed to fit ICU survivors in recovery phase.

Effect of Whey Proteins on Malnutrition and Extubating Time of Critically Ill COVID-19 Patients

The novel SARS-CoV-2 virus has led to a severe pandemic, starting from early 2020. Intensive care (ICU) management of the COVID-19 disease is difficult with high morbidity and mortality. Early nutritional support, especially with whey protein, seems to be crucial in this medical case. Thus, we aimed to assess the effects of an adequate nutritional protocol rich in whey protein on nutritional and inflammatory status, extubating time, and mortality of critically ill COVID-19 patients (CICP). Methods: A prospective single-center exploratory observational study was undertaken on 32 consecutive CICP admitted to the ICU of Santa Maria Hospital, Terni, Italy, and treated with whey protein-enriched formula. Patients’ demographics, nutritional status, indexes of inflammation, daily pre-albumin serum levels, duration of mechanical ventilation, and mortality were recorded. Results: Thirty-two patients were enrolled. Ninety-five percent of them showed a gradual reduction in C-reactive protein (CRP) values and increase in pre-albumin levels after the whey protein-enriched formula. Prealbumin levels were not correlated with a better nutritional status but with a shorter extubating time and better survival. Conclusions: An adequate administration of whey protein during COVID-19 patients’ ICU stays can provide fast achievement of protein targets, reducing the duration of mechanical ventilation, and improving inflammatory status and ICU survival. Further prospective and large-scale, controlled studies are needed to confirm these results.

Specific nutritional and metabolic characteristics of COVID‐19 persistent critically ill patients

Background

Little is known about metabolic and nutrition characteristics of patients with coronavirus disease 2019 (COVID‐19) and persistent critical illness. We aimed to compare those characteristics in patients with PCI and COVID‐19 and patients without COVID‐19 infection (non‐CO)—primarily, their energy balance.

Methods

This is a prospective observational study including two consecutive cohorts, defined as needing intubation for >10 days. We collected demographic data, severity scores, nutrition variables, length of stay, and mortality.

Results

Altogether, 104 patients (52 per group) were included (59 ± 14 years old [mean ± SD], 75% men) between July 2019 and May 2020. SAPSII, Nutrition Risk Screening (NRS) score, proportion of obese patients, duration of intubation (18.2 ± 11.7 days), and mortality rates were similar. Patients with COVID‐19 (vs non‐CO) had lower SOFA scores (P = 0.013) and more frequently needed prone position (P < 0.0001) and neuromuscular blockade (P < 0.0001): lengths of ICU (P = 0.03) and hospital stays were shorter (P < 0.0001). Prescribed energy targets were below those of the ICU protocol. The energy balance of patients with COVID‐19 was significantly more negative after day 10. Enteral nutrition (EN) started earlier (P < 0.0001). During the first 10 days, COVID‐19 patients received more lipid (propofol sedation) and less protein. Higher admission C‐reactive protein (P = 0.002) decreased faster (P < 0.001). Whereas intestinal function was characterized by constipation in both groups during the first 10 days, diarrhea was less common in patients with COVID‐19 thereafter.

Conclusion

Compared with non‐CO patients, COVID‐19 patients were not more obese, had lower SOFA scores, and were fed more rapidly with EN, because of a more normal gastrointestinal function possibly due to fewer non–respiratory organ failures: their energy balances were more negative after the first 10 days. Propofol sedation reduced protein delivery.

When is parenteral nutrition indicated?

The indications and contraindications of parenteral nutrition (PN) are discussed in view of recent clinical findings. For decades, PN has been restricted to patients unable to tolerate enteral nutrition (EN) intake owing to the perceived risk of severe side-effects. The evolution of the PN substrate composition and delivery of nutrition via all-in-one bags has dramatically improved the application prospects of PN. Recent studies show similar complication rates of nutrition therapy administered through enteral and intravenous routes. Therefore, indications of PN have, based on evidence, extended beyond complete gastrointestinal (GI) failure to include conditions such as insufficient EN generating persistent negative energy balance and insufficient protein intakes, malabsorption, or specific needs that are impossible to cover with EN feeds.

Prolonged progressive hypermetabolism during COVID-19 hospitalization undetected by common predictive energy equations

Background & aims

Indirect calorimetry (IC) is the gold-standard for determining measured resting energy expenditure (mREE) in critical illness. When IC is not available, predicted resting energy expenditure (pREE) equations are commonly utilized, which often inaccurately predict metabolic demands leading to over- or under-feeding. This study aims to longitudinally assess mREE via IC in critically ill patients with SARS-CoV-2 (COVID-19) infection throughout the entirety of, often prolonged, intensive care unit (ICU) stays and compare mREE to commonly utilized pREE equations.

Methods

This single-center prospective cohort study of 38 mechanically ventilated COVID-19 patients from April 1, 2020 to February 1, 2021. The Q-NRG® Metabolic Monitor was used to obtain IC data. The Harris-Benedict (HB), Mifflin St-Jeor (MSJ), Penn State University (PSU), and weight-based equations from the American Society of Parenteral and Enteral Nutrition – Society of Critical Care Medicine (ASPEN-SCCM) Clinical Guidelines were utilized to assess the accuracy of common pREE equations and their ability to predict hypo/hypermetabolism in COVID-19 ICU patients.

Results

The IC measures collected revealed a relatively normometabolic or minimally hypermetabolic mREE at 21.3 kcal/kg/d or 110% of predicted by the HB equation over the first week of mechanical ventilation (MV). This progressed to significant and uniquely prolonged hypermetabolism over successive weeks to 28.1 kcal/kg/d or 143% of HB predicted by MV week 3, with hypermetabolism persisting to MV week 7. Obese individuals displayed a more truncated response with significantly lower mREE versus non-obese patients in MV week 1 (19.5 ± 1.0 kcal/kg/d vs 25.1 ± 1.8 kcal/kg/d, respectively; p < 0.01), with little change in weeks 2–3 (19.5 ± 1.5 kcal/kg/d vs 28.0 ± 2.0 kcal/kg/d; p < 0.01). Both ASPEN-SCCM upper range and PSU pREE equations provided close approximations of mREE yet, like all pREE equations, occasionally over- and under-predicted energy needs and typically did not predict late hypermetabolism.

Conclusions

Study results show a truly unique metabolic response in COVID-19 ICU patients, characterized by significant and prolonged, progressive hypermetabolism peaking at 3 weeks’ post-intubation, persisting for up to 7 weeks in ICU. This pattern was more clearly demonstrated in non-obese versus obese patients. This response is unique and distinct from any previously described model of ICU stress response in its prolonged hypermetabolic nature. This data reaffirms the need for routine, longitudinal IC measures to provide accurate energy targets in COVID-19 ICU patients. The PSU and ASPEN-SCCM equations appear to yield the most reasonable estimation to IC-derived mREE in COVID-19 ICU patients, yet still often over-/under-predict energy needs. These findings provide a practical guide for caloric prescription in COVID-19 ICU patients in the absence of IC.

Indirect calorimetry in critical illness: a new standard of care?

PURPOSE OF REVIEW

Review recent literature on the role of indirect calorimetry in critical care nutrition management.

RECENT FINDINGS

Critical illness demands objective, targeted nutritional therapy to prevent adverse effects of underfeeding/over feeding. Thus, all recent societal guidelines recommend indirect calorimetry use to determine energy needs. Very recently, indirect calorimetry technology has finally evolved to allow for accurate, simple, and routine utilization in a wider range of ICU patients. Recent data continues to confirm poor correlation between measured and equation-predicted energy expenditure emphasizing need for indirect calorimetry to be standard of care. This may be particularly true in COVID-19, where significant progressive hypermetabolism and variability in energy expenditure has been shown. Metabolic physiology can change frequently during ICU stay in response to changes in clinical condition or care. Thus, repeated longitudinal indirect calorimetry measures are needed throughout ICU stay to optimize care, with initial data showing improved clinical outcomes when indirect calorimetry targets are utilized.

SUMMARY

Personalized ICU care demands objective data to guide therapy. This includes use of indirect calorimetry to determine energy expenditure and guide ICU nutrition therapy. Long-awaited new innovations in indirect calorimetry technology should finally lead to indirect calorimetry to becoming a fundamental component of modern ICU standard of care and clinical research moving forward.

Overcoming challenges to enteral nutrition delivery in critical care

PURPOSE OF REVIEW

Existing data and all ICU nutrition guidelines emphasize enteral nutrition (EN) represents a primary therapy leading to both nutritional and non-nutritional benefits. Unfortunately, iatrogenic malnutrition and underfeeding is virtually ubiquitous in ICUs worldwide for prolonged periods post-ICU admission. Overcoming essential challenges to EN delivery requires addressing a range of real, and frequently propagated myths regarding EN delivery.

RECENT FINDINGS

Key recent data addresses perceived challenges to EN including: Adequately resuscitated patients on vasopressors can and likely should receive trophic early EN and this was recently associated with reduced mortality; Patients paralyzed with neuromuscular blocking agents can and should receive early EN as this was recently associated with reduced mortality/hospital length of stay; Proned patients can safely receive EN; All ICU nutrition delivery, including EN, should be objectively guided by indirect calorimetry (IC) measures. This is now possible with the new availability of a next-generation IC device.

SUMMARY

It is the essential implementation of this new evidence occurs to overcome real and perceived EN challenges. This data should lead to increased standardization/protocolization of ICU nutrition therapy to ensure personalized nutrition care delivering the right nutrition dose, in the right patient, at the right time to optimize clinical outcome.

Point-Counterpoint: Indirect Calorimetry Is not Necessary for Optimal Nutrition Therapy in Critical Illness

Clinicians have widely recognized that indirect calorimetry (IC) is the "gold standard" for measuring energy expenditure (EE) and thus would intuitively anticipate that its use would be needed to provide optimal nutrition support in critical illness. Recent studies in the literature as well as dramatic changes in clinical practice over the past decade, though, would suggest that such a precise measure by IC to set energy goals is not required to maximize clinical benefit from early feeding in the intensive care unit (ICU). Results from randomized controlled trials evaluating permissive underfeeding, use of supplemental parenteral nutrition to achieve tight calorie control, and caloric density of formulas to increase energy delivery have provided an important perspective on 3 pertinent issues. First, a simple weight-based predictive equation (25 kcal/kg/day) provides a clinically useful approximation of EE. Second, a precise measure of EE by IC does not appear to improve outcomes compared with use of this less accurate estimation of energy requirements. And third, providing some percentage of requirements (50%-80%), achieves similar clinical benefit to full feeding (100%) in the early phases of critical illness. The value from IC use lies in the determination of caloric requirements in conditions for which weight-based equations are rendered inaccurate (anasarca, amputation, severe obesity) or the clinical state is markedly altered (such as the prolonged hyperinflammatory state of coronavirus disease 2019 [COVID-19]). In most other circumstances, routine use of IC would not be expected to change clinical outcomes from early nutrition therapy in the ICU.

Comprehensive metabolic amino acid flux analysis in critically ill patients

Amino acid (AA) metabolism is severely disturbed in critically ill ICU patients. To be able to make a more scientifically based decision on the type of protein or AA nutrition to deliver in ICU patients, comprehensive AA phenotyping with measurements of plasma concentrations and whole body production (WBP) is needed. Therefore, we studied ICU patients and matched control subjects using a novel pulse isotope method to obtain in-depth metabolic analysis. In 51 critically ill ICU patients (SOFA~6.6) and 49 healthy controls, we measured REE and body composition/phase-angle using BIA. In the postabsorptive state, we collected arterial (ized) blood for CRP and AA. Then, we administered an 8 mL solution containing 18 stable AA tracers as a pulse and calculated WBP. Enrichments: LC-MS/MS and statistics: t-test, ANCOVA. Compared to healthy, critically ill ICU patients had lower phase-angle (p < 0.00001), and higher CRP (p < 0.0001). Most AA concentrations were lower in ICU patients (p < 0.0001), except tau-methylhistidine and phenylalanine. WBP of most AA were significantly (p < 0.0001) higher with increases in glutamate (160%), glutamine (46%), and essential AA. Remarkably, net protein breakdown was lower. There were only weak relationships between AA concentrations and WBP. Critically ill ICU patients (SOFA 8-16) had lower values for phase angle (p = 0.0005) and small reductions of most plasma AA concentrations, but higher tau-methylhistidine (p = 0.0223) and hydroxyproline (p = 0.0028). Remarkably, the WBP of glutamate and glutamine were lower (p < 0.05), as was their clearance, but WBP of tau-methylhistidine (p = 0.0215) and hydroxyproline (p = 0.0028) were higher. Our study in critically ill ICU patients shows that comprehensive metabolic phenotyping was able to reveal severe disturbances in specific AA pathways, in a disease severity dependent way. This information may guide improving nutritional compositions to improve the health of the critically ill patient. CLINICAL TRIAL REGISTRY: Data are from the baseline measurements of study NCT02770092 (URL: https://clinicaltrials.gov/ct2/show/NCT02770092) and NCT03628365 (URL: https://clinicaltrials.gov/ct2/show/NCT03628365).

Point-Counterpoint: Indirect Calorimetry Is Essential for Optimal Nutrition Therapy in the Intensive Care Unit

Iatrogenic malnutrition and underfeeding are ubiquitous in intensive care units (ICUs) worldwide for prolonged periods after ICU admission. A major driver leading to the lack of emphasis on timely ICU nutrition delivery is lack of objective data to guide nutrition care. If we are to ultimately overcome current fundamental challenges to effective ICU nutrition delivery, we must all adopt routine objective, longitudinal measurement of energy targets via indirect calorimetry (IC). Key evidence supporting the routine use of IC in the ICU includes (1) universal societal ICU nutrition guidelines recommending IC to determine energy requirements; (2) data showing predictive equations or body weight calculations that are consistently inaccurate and correlate poorly with measured energy expenditure, ultimately leading to routine overfeeding and underfeeding, which are both associated with poor ICU outcomes; (3) recent development and worldwide availability of a new validated, accurate, easy-to-use IC device; and (4) recent data in ICU patients with coronavirus disease 2019 (COVID-19) showing progressive hypermetabolism throughout ICU stay, emphasizing the inaccuracy of predictive equations and marked day-to-day variability in nutrition needs. Thus, given the availability of a new validated IC device, these findings emphasize that routine longitudinal IC measures should be considered the new standard of care for ICU and post-ICU nutrition delivery. As we would not deliver vasopressors without accurate blood pressure measurements, the ICU community is only likely to embrace an increased focus on the importance of early nutrition delivery when we can consistently provide objective IC measures to ensure personalized nutrition care delivers the right nutrition dose, in the right patient, at the right time to optimize clinical outcomes.

Energy expenditure and indirect calorimetry in critical illness and convalescence: current evidence and practical considerations

The use of indirect calorimetry is strongly recommended to guide nutrition therapy in critically ill patients, preventing the detrimental effects of under- and overfeeding. However, the course of energy expenditure is complex, and clinical studies on indirect calorimetry during critical illness and convalescence are scarce. Energy expenditure is influenced by many individual and iatrogenic factors and different metabolic phases of critical illness and convalescence. In the first days, energy production from endogenous sources appears to be increased due to a catabolic state and is likely near-sufficient to meet energy requirements. Full nutrition support in this phase may lead to overfeeding as exogenous nutrition cannot abolish this endogenous energy production, and mitochondria are unable to process the excess substrate. However, energy expenditure is reported to increase hereafter and is still shown to be elevated 3 weeks after ICU admission, when endogenous energy production is reduced, and exogenous nutrition support is indispensable. Indirect calorimetry is the gold standard for bedside calculation of energy expenditure. However, the superiority of IC-guided nutritional therapy has not yet been unequivocally proven in clinical trials and many practical aspects and pitfalls should be taken into account when measuring energy expenditure in critically ill patients. Furthermore, the contribution of endogenously produced energy cannot be measured. Nevertheless, routine use of indirect calorimetry to aid personalized nutrition has strong potential to improve nutritional status and consequently, the long-term outcome of critically ill patients.

Oral Nutrition during and after Critical Illness: SPICES for Quality of Care!

Malnutrition is associated to poor outcomes in critically ill patients. Oral nutrition is the route of feeding in less than half of the patients during the intensive care unit (ICU) stay and in the majority of ICU survivors. There are growing data indicating that insufficient and/or inadequate intakes in macronutrients and micronutrients are prevalent within these populations. The present narrative review focuses on barriers to food intakes and considers the different points that should be addressed in order to optimize oral intakes, both during and after ICU stay. They are gathered in the SPICES concept, which should help ICU teams improve the quality of nutrition care following 5 themes: swallowing disorders screening and management, patient global status overview, involvement of dieticians and nutritionists, clinical evaluation of nutritional intakes and outcomes, and finally, supplementation in macro-or micronutrients.

Assessment of energy expenditure: are calories measured differently for different diets?

PURPOSE OF REVIEW

The prevalence and burden of obesity has reached alarming levels. The assessment of human energy expenditure enables the identification of obesity-prone and obesity-resistant individuals and helps to explain the short and long-term success of weight loss treatments. In this review, we describe the state-of-the-art methods used in the assessment of human energy expenditure and the impact of dietary intake on the interpretation of the data.

RECENT FINDINGS

The reference techniques to assess energy expenditure in humans have not significantly changed during the last century. Today, indirect calorimetry, either using a metabolic chamber or a metabolic cart, is the favored method to assess human energy expenditure and is the only method enabling the assessment of macronutrient oxidation. The doubly labeled water method however provides accurate assessment of human energy expenditure under free living conditions.

SUMMARY

Although energy expenditure and macronutrient oxidation can be assessed by simple calculations from oxygen consumption and carbon dioxide production, these calculations can provide erroneous results or require corrections and/or more complex interpretation when several biochemical pathways are simultaneously engaged. Such physiological mechanisms are often elicited by dietary interventions including, among other, gluconeogenesis, lipogenesis, ketogenesis, alcohol oxidation and under or overfeeding.