Weight-adjusted resting energy expenditure is not constant in critically ill patients

Muscle protein catabolism and splanchnic arginine consumption drive arginine dysregulation during Pseudomonas Aeruginosa induced early acute sepsis in swine

Human sepsis is characterized by increased protein breakdown and changes in arginine and citrulline metabolism. However, it is unclear whether this is caused by changes in transorgan metabolism. We therefore studied in a Pseudomonas aeruginosa induced pig sepsis model the changes in protein and arginine related metabolism on whole body (Wb) and transorgan level. We studied 22 conscious pigs for 18 hours during sepsis, induced by infusing live bacteria (Pseudomonas aeruginosa) or after placebo infusion (control). We used stable isotope tracers to measure Wb and skeletal muscle protein synthesis and breakdown, as well as Wb, splanchnic, skeletal muscle, hepatic and portal drained viscera (PDV) arginine and citrulline disposal and production rates. During sepsis, arginine Wb production (p=0.0146), skeletal muscle release (p=0.0035) and liver arginine uptake were elevated (p=0.0031). Wb de novo arginine synthesis, citrulline production, and transorgan PDV release of citrulline, glutamine and arginine did not differ between sepsis and controls. However, Wb (p<0.0001) and muscle (p<0.001) protein breakdown were increased, suggesting that the enhanced arginine production is predominantly derived from muscle breakdown in sepsis. In conclusion, live-bacterium sepsis increases muscle arginine release and liver uptake, mirroring previous pig endotoxemia studies. In contrast to observations in humans, acute live-bacterium sepsis in pigs does not change citrulline production or arterial arginine concentration. We therefore conclude that the arginine dysregulation observed in human sepsis is possibly initiated by enhanced protein catabolism and splanchnic arginine catabolism, while decreased arterial arginine concentration and citrulline metabolism may require more time to fully manifest in patients.

A critical view of the use of predictive energy equations for the identification of hypermetabolism in motor neuron disease: A pilot study

BACKGROUND AND AIMS

People living with motor neuron disease (MND) frequently struggle to consume an optimal caloric intake. Often compounded by hypermetabolism, this can lead to dysregulated energy homeostasis, prompting the onset of malnutrition and associated weight loss. This is associated with a poorer prognosis and reduced survival. It is therefore important to establish appropriate nutritional goals to ensure adequate energy intake. This is best done by measuring resting energy expenditure (mREE) using indirect calorimetry. However, indirect calorimetry is not widely available in clinical practice, thus dietitians caring for people living with MND frequently use energy equations to predict resting energy expenditure (pREE) and estimate caloric requirements. Energy prediction equations have previously been shown to underestimate resting energy expenditure in over two-thirds of people living with MND. Hypermetabolism has previously been identified using the metabolic index. The metabolic index is a ratio of mREE to pREE, whereby an increase of mREE by ≥110% indicates hypermetabolism. We aim to critically reflect on the use of the Harris-Benedict (1919) and Henry (2005) energy prediction equations to inform a metabolic index to indicate hypermetabolism in people living with MND.

METHODS

mREE was derived using VO₂ and VCO₂ measurements from a GEMNutrition indirect calorimeter. pREE was estimated by Harris-Benedict (HB) (1919), Henry (2005) and kcal/kg/day predictive energy equations. The REE variation, described as the percentage difference between mREE and pREE, determined the accuracy of pREE ([pREE-mREE]/mREE) x 100), with accuracy defined as ≤ ± 10%. A metabolic index threshold of ≥110% was used to classify hypermetabolism. All resting energy expenditure data are presented as kcal/24hr.

RESULTS

Sixteen people living with MND were included in the analysis. The mean mREE was 1642 kcal/24hr ranging between 1110 and 2015 kcal/24hr. When REE variation was analysed for the entire cohort, the HB, Henry and kcal/kg/day equations all overestimated REE, but remained within the accuracy threshold (mean values were 2.81% for HB, 4.51% for Henry and 8.00% for kcal/kg/day). Conversely, inter-individual REE variation within the cohort revealed HB and Henry equations both inaccurately reflected mREE for 68.7% of participants, with kcal/kg/day inaccurately reflecting 41.7% of participants. Whilst the overall cohort was not classified as hypermetabolic (mean values were 101.04% for HB, 98.62% for Henry and 95.64% for kcal/kg/day), the metabolic index ranges within the cohort were 70.75%-141.58% for HB, 72.82%-127.69% for Henry and 66.09%-131.58% for kcal/kg/day, indicating both over- and under-estimation of REE by these equations. We have shown that pREE correlates with body weight (kg), whereby the lighter the individual, the greater the underprediction of REE. When applied to the metabolic index, this underprediction biases towards the classification of hypermetabolism in lighter individuals.

CONCLUSION

Whilst predicting resting energy expenditure using the HB, Henry or kcal/kg/day equations accurately reflects derived mREE at group level, these equations are not suitable for informing resting energy expenditure and classification of hypermetabolism when applied to individuals in clinical practice.

Comparison of predictive equations and indirect calorimetry in critical care: Does the accuracy differ by body mass index classification?

BACKGROUND

Nutrition support professionals are tasked with estimating energy requirements for critically ill patients. Estimating energy leads to suboptimal feeding practices and adverse outcomes. Indirect calorimetry (IC) is the gold standard for determining energy expenditure. However, access is limited, so clinicians must rely on predictive equations.

METHODS

A retrospective chart review of critically ill patients who underwent IC in 2019 was conducted. The Mifflin-St Jeor equation (MSJ), Penn State University equation (PSU), and weight-based nomograms were calculated using admission weights. Demographic, anthropometric, and IC data were extracted from the medical record. Data were stratified by body mass index (BMI) classifications, and relationships between estimated energy requirements and IC were compared.

RESULTS

Participants (N = 326) were included. Median age was 59.2 years, and BMI was 30.1. The MSJ and PSU were positively correlated with IC in all BMI classes (all P < 0.001). Median measured energy expenditure was 2004 kcal/day, which was 1.1-fold greater than PSU, 1.2-fold greater than MSJ, and 1.3-fold greater than weight-based nomograms (all P < 0.001).

CONCLUSION

Despite the significant relationships between measured and estimated energy requirements, the significant fold-differences suggest that using predictive equations leads to significant underfeeding, which may result in poor clinical outcomes. Clinicians should rely on IC when available, and increased training in the interpretation of IC is warranted. In the absence of IC, the use of admission weight in weight-based nomograms could serve as a surrogate, as these calculations provided the closest estimate to IC in participants with normal weight and overweight, but not obesity.

How do guideline recommended energy targets compare with measured energy expenditure in critically ill adults with obesity: A systematic literature review

BACKGROUND

Critically ill patients with obesity have unique and complex nutritional needs, with clinical practice guidelines conflicting regarding recommended energy targets. The aim of this systematic review was to 1) describe measured resting energy expenditure (mREE) reported in the literature and; 2) compare mREE to predicted energy targets using the European (ESPEN) and American (ASPEN) guideline recommendations when indirect calorimetry is not available in critically ill patients with obesity.

METHODS

The protocol was registered apriori and literature was searched until 17th March, 2022. Original studies were included if they reported mREE using indirect calorimetry in critically ill patients with obesity (BMI≥30 kg/m²). Group-level mREE data was reported as per the primary publication using mean ± standard deviation or median [interquartile range]. Where individual patient data was available, Bland-Altman analysis was used to assess mean bias (95% limits of agreement) between guideline recommendations and mREE targets (i.e. ASPEN for BMI 30-50, 11-14 kcal/kg actual weight compared to 70% mREE and ESPEN 20-25 kcal/kg adjusted weight compared to 100% mREE). Accuracy was assessed by the percentage (%) of estimates within ±10% of mREE targets.

RESULTS

After searching 8019 articles, 24 studies were included. mREE ranged from 1607 ± 385 to 2919 [2318-3362]kcal and 12-32kcal/actual body weight. For the ASPEN recommendations of 11-14 kcal/kg, a mean bias of -18% (-50% to +13%) and 4% (-36% to +44%) was observed, respectively (n = 104). For the ESPEN recommendations 20-25 kcal/kg, a bias of -22% (-51% to +7%) and -4% (-43% to +34%), was observed, respectively (n = 114). The guideline recommendations were able to accurately predict mREE targets on 30%-39% occasions (11-14 kcal/kg actual) and 15%-45% occasions (20-25 kcal/kg adjusted), for ASPEN and ESPEN recommendations, respectively.

CONCLUSIONS

Measured energy expenditure in critically ill patients with obesity is variable. Energy targets generated using predictive equations recommended in both the ASPEN and ESPEN clinical guidelines have poor agreement with mREE and are frequently not able to accurately predict within ±10% of mREE, most commonly underestimating energy needs.

Sex-Specific Aspects of Skeletal Muscle Metabolism in the Clinical Context of Intensive Care Unit-Acquired Weakness

(1) Background: Female sex is considered a risk factor for Intensive Care Unit-Acquired Weakness (ICUAW). The aim is to investigate sex-specific aspects of skeletal muscle metabolism in the context of ICUAW. (2) Methods: This is a sex-specific sub-analysis from two prospectively conducted trials examining skeletal muscle metabolism and advanced muscle activating measures in critical illness. Muscle strength was assessed by Medical Research Council Score. The insulin sensitivity index was analyzed by hyperinsulinemic-euglycemic (HE) clamp. Muscular metabolites were studied by microdialysis. M. vastus lateralis biopsies were taken. The molecular analysis included protein degradation pathways. Morphology was assessed by myocyte cross-sectional area (MCSA). Multivariable linear regression models for the effect of sex on outcome parameters were performed. (3) Results: n = 83 (♂n = 57, 68.7%; ♀n = 26, 31.3%) ICU patients were included. ICUAW was present in 81.1%♂ and in 82.4%♀ at first awakening (p = 0.911) and in 59.5%♂ and in 70.6%♀ at ICU discharge (p = 0.432). Insulin sensitivity index was reduced more in women than in men (p = 0.026). Sex was significantly associated with insulin sensitivity index and MCSA of Type IIa fibers in the adjusted regression models. (4) Conclusion: This hypothesis-generating analysis suggests that more pronounced impairments in insulin sensitivity and lower MCSA of Type IIa fibers in critically ill women may be relevant for sex differences in ICUAW.

The Effect of High Protein and Mobility-Based Rehabilitation on Clinical Outcomes in Survivors of Critical Illness

BACKGROUND

Protein supplementation and mobility-based rehabilitation programs (MRP) individually improve functional outcomes in survivors of critical illness. We hypothesized that combining MRP therapy with high protein supplementation is associated with greater weaning success from prolonged mechanical ventilation (PMV) and increased discharge home in this population.

METHODS

We conducted a retrospective analysis assessing the effects of an MRP on a cohort of survivors of critical illness. All received usual care (UC) rehabilitation. The MRP group received 3 additional MRP sessions each week for a maximum of 8 weeks. Subjects were prescribed nutrition and classified as receiving high protein (HPRO) or low protein (LPRO), based on a recommended 1.0 g/kg/d, and then the subjects were categorized into 4 groups: MRP+HPRO, MRP+LPRO, UC+HPRO, and UC+LPRO.

RESULTS

A total of 32 subjects were enrolled. The MRP+HPRO group had greater weaning success (90% vs 38%, P = .045) and a higher rate of discharge home (70% vs 13%, P = .037) compared to UC+LPRO group. The MRP+HPRO group had a higher, nonsignificant rate of discharge home compared to the MRP+LPRO (70% vs 20%, P = .10).

CONCLUSIONS

Combining high protein with mobility-based rehabilitation was associated with increased rates of discharge home and ventilator weaning success in survivors of critical illness. Further studies are needed to evaluate the role of combined exercise and nutrition interventions in this population.

Systematic review of factors associated with energy expenditure in the critically ill

BACKGROUND AND AIMS

Indirect calorimetry is the reference standard for energy expenditure measurement. Predictive formulae that replace it are inaccurate. Our aim was to review the patient and clinical factors associated with energy expenditure in critically ill patients.

METHODS

We conducted a systematic review of the literature. Eligible studies were those reporting an evaluation of factors and energy expenditure. Energy expenditure and factor associations with p-values were extracted from each study, and each factor was classified as either significantly, indeterminantly, or not associated with energy expenditure. Regression coefficients were summarized as measures of central tendency and spread. Metanalysis was performed on correlations.

RESULTS

The search strategy yielded 8521 unique articles, 307 underwent full text review, and 103 articles were included. Most studies were in adults. There were 95 factors with 352 evaluations. Minute volume, weight, age, % body surface area burn, sedation, post burn day, and caloric intake were significantly associated with energy expenditure. Heart rate, fraction of inspired oxygen, respiratory rate, respiratory disease diagnosis, positive end expiratory pressure, intensive care unit days, C- reactive protein, and size were not associated with energy expenditure. Multiple factors (n = 37) were identified with an unclear relationship with energy expenditure and require further evaluation.

CONCLUSIONS

An important interval step in the development of accurate formulae for energy expenditure estimation is a better understanding of relationships between patient and clinical factors and energy expenditure. The review highlights the limitations of currently available data, and identifies important factors that are not included in current prediction formulae of the critically ill.

Enteral Nutrition in the Mechanically Ventilated Patient

Mechanically ventilated patients are unable to take food orally and therefore are dependent on enteral nutrition for provision of both energy and protein requirements. Enteral nutrition is supportive therapy and may impact patient outcomes in the intensive care unit. Early enteral nutrition has been shown to decrease complications and hospital length of stay and improve the prognosis at discharge. Nutrition support is unique for patients on mechanical ventilation and, as recently published literature shows, should be tailored to the individuals' underlying pathology. This review will discuss the most current literature and recommendations for enteral nutrition in patients receiving mechanical ventilation.

Prescribed hypocaloric nutrition support for critically-ill adults

BACKGROUND

There are controversies about the amount of calories and the type of nutritional support that should be given to critically-ill people. Several authors advocate the potential benefits of hypocaloric nutrition support, but the evidence is inconclusive.

OBJECTIVES

To assess the effects of prescribed hypocaloric nutrition support in comparison with standard nutrition support for critically-ill adults SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, Embase and LILACS (from inception to 20 June 2017) with a specific strategy for each database. We also assessed three websites, conference proceedings and reference lists, and contacted leaders in the field and the pharmaceutical industry for undetected/unpublished studies. There was no restriction by date, language or publication status.

SELECTION CRITERIA

We included randomized and quasi-randomized controlled trials comparing hypocaloric nutrition support to normo- or hypercaloric nutrition support or no nutrition support (e.g. fasting) in adults hospitalized in intensive care units (ICUs).

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We meta-analysed data for comparisons in which clinical heterogeneity was low. We conducted prespecified subgroup and sensitivity analyses, and post hoc analyses, including meta-regression. Our primary outcomes were: mortality (death occurred during the ICU and hospital stay, or 28- to 30-day all-cause mortality); length of stay (days stayed in the ICU and in the hospital); and Infectious complications. Secondary outcomes included: length of mechanical ventilation. We assessed the quality of evidence with GRADE.

MAIN RESULTS

We identified 15 trials, with a total of 3129 ICU participants from university-associated hospitals in the USA, Colombia, Saudi Arabia, Canada, Greece, Germany and Iran. There are two ongoing studies. Participants suffered from medical and surgical conditions, with a variety of inclusion criteria. Four studies used parenteral nutrition and nine studies used only enteral nutrition; it was unclear whether the remaining two used parenteral nutrition. Most of them could not achieve the proposed caloric targets, resulting in small differences in the administered calories between intervention and control groups. Most studies were funded by the US government or non-governmental associations, but three studies received funding from industry. Five studies did not specify their funding sources.The included studies suffered from important clinical and statistical heterogeneity. This heterogeneity did not allow us to report pooled estimates of the primary and secondary outcomes, so we have described them narratively.When comparing hypocaloric nutrition support with a control nutrition support, for hospital mortality (9 studies, 1775 participants), the risk ratios ranged from 0.23 to 5.54; for ICU mortality (4 studies, 1291 participants) the risk ratios ranged from 0.81 to 5.54, and for mortality at 30 days (7 studies, 2611 participants) the risk ratios ranged from 0.79 to 3.00. Most of these estimates included the null value. The quality of the evidence was very low due to unclear or high risk of bias, inconsistency and imprecision.Participants who received hypocaloric nutrition support compared to control nutrition support had a range of mean hospital lengths of stay of 15.70 days lower to 10.70 days higher (10 studies, 1677 participants), a range of mean ICU lengths of stay 11.00 days lower to 5.40 days higher (11 studies, 2942 participants) and a range of mean lengths of mechanical ventilation of 13.20 days lower to 8.36 days higher (12 studies, 3000 participants). The quality of the evidence for this outcome was very low due to unclear or high risk of bias in most studies, inconsistency and imprecision.The risk ratios for infectious complications (10 studies, 2804 participants) of each individual study ranged from 0.54 to 2.54. The quality of the evidence for this outcome was very low due to unclear or high risk of bias, inconsistency and imprecisionWe were not able to explain the causes of the observed heterogeneity using subgroup and sensitivity analyses or meta-regression.

AUTHORS' CONCLUSIONS

The included studies had substantial clinical heterogeneity. We found very low-quality evidence about the effects of prescribed hypocaloric nutrition support on mortality in hospital, in the ICU and at 30 days, as well as in length of hospital and ICU stay, infectious complications and the length of mechanical ventilation. For these outcomes there is uncertainty about the effects of prescribed hypocaloric nutrition, since the range of estimates includes both appreciable benefits and harms.Given these limitations, results must be interpreted with caution in the clinical field, considering the unclear balance of the risks and harms of this intervention. Future research addressing the clinical heterogeneity of participants and interventions, study limitations and sample size could clarify the effects of this intervention.

The management of perioperative nutrition in patients with end stage liver disease undergoing liver transplantation

Malnutrition is found in almost 100% of patients with end stage liver disease (ESLD) awaiting transplantation and malnutrition before transplantation leads to higher rates of post-transplant complications and worse graft survival outcomes. Reasons for protein energy malnutrition include several metabolic alterations such as inadequate intake, malabsorption, and overloaded expenditure. And also, stress from surgery, gastrointestinal reperfusion injury, immunosuppressive therapy and corticosteriods use lead to delayed bowl function recovery and disorder of nutrients absorption. In the pretransplant phase, nutritional goals include optimization of nutritional status and treatment of nutrition-related symptoms induced by hepatic decompensation. During the acute post-transplant phase, adequate nutrition is required to help support metabolic demands, replenish lost stores, prevent infection, arrive at a new immunologic balance, and promote overall recovery. In a word, it is extremely important to identify and correct nutritional deficiencies in this population and provide an adequate nutritional support during all phases of liver transplantation (LT). This study review focuses on prevalence, nutrition support, evaluation, and management of perioperative nutrition disorder in patients with ESLD undergoing LT.

Malnutrition at the time of surgery affects negatively the clinical outcome of critically ill patients with gastrointestinal cancer

Introduction:

Malnutrition is a frequent concomitant of surgical illness, especially in gastrointestinal cancer surgery. The aim of the study was to assess the prevalence of malnutrition in the GI cancer patients and its relation with clinical outcome. We also examined associations between the energy balance and clinical outcomes in these patients.

Methods:

Prospective study on 694 surgical patients treated in the ICU of the UHC of Tirana. Patients were divided into well-nourished and malnourished groups according to their nutritional status. Multiple regression analysis was used to analyze the effect of malnutrition and cumulated energy balance on clinical outcome.

Results:

The prevalence of pre-operative malnutrition was 65.3% for all surgical patients and 84.9% for gastrointestinal cancer patients. Malnutrition, as analyzed by a multivariate logistic regression model, is an independent risk factor for higher complications, infections, and mortality, longer stay in the ventilator and ICU. Also this model showed that cumulated energy balance correlated with infections, and mortality and was independently associated with the length ventilator and ICU stay.

Conclusion:

This study shows that malnutrition is a significant problem in surgical patients, especially in patients with gastrointestinal cancer. Malnutrition and cumulated energy deficit in gastro-intestinal surgery patients with malignancy is an independent risk factor on increased post-operative morbidity and mortality.

Nutritional care of the obese adult burn patient: a U.K. Survey and literature review

Obesity is an emerging healthcare problem and affects an increasing number of burn patients worldwide. An email survey questionnaire was constructed and distributed among the 16 U.K. burn services providing adult inpatient facilities to investigate nutritional practices in obese thermally injured patients. Responses received from all dieticians invited to participate in the study were analyzed, and a relevant literature review of key aspects of nutritional care is presented. The majority of services believe that obese patients warrant a different nutritional approach with specific emphasis to avoid overfeeding. The most common algebraic formulae used to calculate calorific requirements include the Schofield, Henry, and modified Penn State equations. Indirect calorimetry despite being considered the "criterion standard" tool to calculate energy requirements is not currently used by any of the U.K. burn services. Gastric/enteral nutrition is initiated within 24 hours of admission in the services surveyed, and a variety of different practices were noted in terms of fasting protocols before procedures requiring general anesthesia/sedation. Hypocaloric regimens for obese patients are not supported by the majority of U.K. facilities, given the limited evidence base supporting their use. The results of this survey outline the wide diversity of dietetic practices adopted in the care of obese burn patients and reveal the need for further study to determine optimal nutritional strategies.

Gender-specific differences in energy metabolism during the initial phase of critical illness

BACKGROUND/OBJECTIVES

Women and men differ in substrate and energy metabolism. Such differences may affect energy requirements during the acute phase of critical illness.

SUBJECTS/METHODS

Data of 155 critically ill medical patients were reviewed for this study. Indirect calorimetry in each patient was performed within the first 72 h following admission to the medical intensive care unit after an overnight fast.

RESULTS

In overweight (body mass index (BMI) ≥25 kg/m(2)) but not in normal-weight patients, resting energy expenditure (REE) adjusted for body weight (REEaBW) differed significantly between women and men (17.2 (interquartile range (IQR) 15.2-20.7) vs 20.9 (IQR 17.9-23.4) kcal/kg/day, P<0.01). Similarly, REE adjusted for ideal body weight (REEaIBW) was significantly lower in women compared with men (25.5 (IQR 22.6-28.1) vs 28.0 (IQR 25.2-30.0) kcal/kg/day, P<0.05). In overweight patients, gender was identified as an independent predictor of REEaBW in the multivariate regression model (r=-2.57 (95% CI -4.57 to -0.57); P<0.05), even after adjustment for age, simplified acute physiology score (SAPS II), body temperature, body weight and height.

CONCLUSIONS

REEaBW decreases with increasing body mass in both sexes. This relationship differs between women and men. Overweight critically ill women show significantly lower REEaBW and REEaIBW, respectively, compared with men. These findings could affect the current practice of nutritional support during the early phase of critical illness.

Management of prolonged post-operative ileus: evidence-based recommendations

BACKGROUND

Prolonged post-operative ileus (PPOI) occurs in up to 25% of patients following major elective abdominal surgery. It is associated with a higher risk of developing post-operative complications, prolongs hospital stay and confers a significant financial load on health-care institutions. Literature outlining best-practice management strategies for PPOI is nebulous. The aim of this text was to review the literature and provide concise evidence-based recommendations for its management.

METHODS

A literature search through the Ovid MEDLINE, EMBASE, Google Scholar and Cochrane databases was performed from inception to July 2012 using a combination of keywords and MeSH terms. Review of the literature was followed by synthesis of concise recommendations for management accompanied by Strength of Recommendation Taxonomy (either A, B or C).

RESULTS

Recommendations for management include regular evaluation and correction of electrolytes (B); review of analgesic prescription with weaning of narcotics and substitution with regular paracetamol, regular non-steroidal anti-inflammatory drugs if not contraindicated, and regular or as-required Tramadol (A); nasogastric decompression for those with nausea or vomiting as prominent features (C); isotonic dextrose-saline crystalloid maintenance fluids administered within a restrictive regimen (B); balanced isotonic crystalloid replacement fluids containing supplemental potassium, in equivalent volume to losses (C); regular ambulation (C); parenteral nutrition if unable to tolerate an adequate oral intake for more than 7 days post-operatively (A) and exclusion of precipitating pathology or alternate diagnoses if clinically suspected (C).

CONCLUSIONS

Recommendations have a variable and frequently inconsistent evidence base. Further research is required to validate many of the outlined recommendations and to investigate novel interventions that may be used to shorten duration of PPOI.

Comparison of five equations for estimating resting energy expenditure in Chinese young, normal weight healthy adults

BACKGROUND

Most resting energy expenditure (REE) predictive equations for adults were derived from research conducted in western populations; whether they can also be used in Chinese young people is still unclear. Therefore, we conducted this study to determine the best REE predictive equation in Chinese normal weight young adults.

METHODS

Forty-three (21 male, 22 female) healthy college students between the age of 18 and 25 years were recruited. REE was measured by the indirect calorimetry (IC) method. Harris-Benedict, World Health Organization (WHO), Owen, Mifflin and Liu's equations were used to predictREE (REEe). REEe that was within 10% of measured REE (REEm) was defined as accurate. Student's t test, Wilcoxon Signed Ranks Test, McNemar Test and the Bland-Altman method were used for data analysis.

RESULTS

REEm was significantly lower (P < 0.05 or P < 0.01) than REEe from equations, except for Liu's, Liu's-s, Owen, Owen-s and Mifflin in men and Liu's and Owen in women. REEe calculated by ideal body weight was significantly higher than REEe calculated by current body weight ( P < 0.01), the only exception being Harris-Benedict equation in men. Bland-Altman analysis showed that the Owen equation with current body weight generated the least bias. The biases of REEe from Owen with ideal body weight and Mifflin with both current and ideal weights were also lower.

CONCLUSIONS

Liu's, Owen, and Mifflin equations are appropriate for the prediction of REE in young Chinese adults. However, the use of ideal body weight did not increase the accuracy of REEe.

Ghrelin, appetite and critical illness

PURPOSE OF REVIEW

Recovery and rehabilitation after critical illness is a vital part of intensive care management. The role of feeding and nutritional intervention is the subject of many recent studies. The gastric hormone ghrelin has effects on appetite and food intake and on immunomodulatory functions. Here we review the interactions between critical illness, appetite regulation, nutrition and ghrelin.

RECENT FINDINGS

Critical illness results in significant loss of lean body mass; strategies to prevent this have so far proven unsuccessful. Ghrelin has been shown to reduce catabolic protein loss in animal models of critical illness and improve body composition in chronic cachectic illnesses in humans.

SUMMARY

Enhancing recovery from critical illness will improve both short-term and long-term outcomes. Ghrelin may offer an important means of improving appetite, muscle mass and rehabilitation in the period after critical illness, although studies are needed to see whether this potential is realized.

Metabolic support of the obese intensive care unit patient: a current perspective

PURPOSE OF REVIEW

Obesity is a widespread condition associated with a variety of mechanical, metabolic, and physiologic changes that affect both health outcomes and delivery of care. Nutrition support is a key element of management during critical illness known to improve outcomes favorably, but is likewise complicated in the presence of obesity. This review serves to discuss the challenges unique to management of critically ill obese patients and an evidence-based approach to nutrition support in this patient population.

RECENT FINDINGS

High-protein, hypocaloric feeding has emerged as a nutrition support strategy capable of reducing hyperglycemia and protein catabolism, while promoting favorable changes in body composition and fluid mobilization. Recent data have shown a protective effect of mild-moderate obesity (BMI 30-39.9 kg/m2), with improved morbidity and mortality outcomes in this subgroup. Therefore, it is unclear whether hypocaloric feeding represents an inferior approach in this subgroup in which weight maintenance may be preferable.

SUMMARY

There are many obstacles that limit provision of nutrition support in the obese ICU patient. Calculating energy needs accurately is extremely problematic due to a lack of reliable prediction equations and a wide variability in body composition among the obese patients. Further research is needed to determine a better approach to estimating energy needs in this population, in addition to validating hypocaloric feeding as the standard approach to nutrition support in the obese patients.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSION

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

ESPEN Guidelines on Parenteral Nutrition: surgery

In modern surgical practice it is advisable to manage patients within an enhanced recovery protocol and thereby have them eating normal food within 1-3 days. Consequently, there is little room for routine perioperative artificial nutrition. Only a minority of patients may benefit from such therapy. These are predominantly patients who are at risk of developing complications after surgery. The main goals of perioperative nutritional support are to minimize negative protein balance by avoiding starvation, with the purpose of maintaining muscle, immune, and cognitive function and to enhance postoperative recovery. Several studies have demonstrated that 7-10 days of preoperative parenteral nutrition improves postoperative outcome in patients with severe undernutrition who cannot be adequately orally or enterally fed. Conversely, its use in well-nourished or mildly undernourished patients is associated with either no benefit or with increased morbidity. Postoperative parenteral nutrition is recommended in patients who cannot meet their caloric requirements within 7-10 days orally or enterally. In patients who require postoperative artificial nutrition, enteral feeding or a combination of enteral and supplementary parenteral feeding is the first choice. The main consideration when administering fat and carbohydrates in parenteral nutrition is not to overfeed the patient. The commonly used formula of 25 kcal/kg ideal body weight furnishes an approximate estimate of daily energy expenditure and requirements. Under conditions of severe stress requirements may approach 30 kcal/kg ideal body weights. In those patients who are unable to be fed via the enteral route after surgery, and in whom total or near total parenteral nutrition is required, a full range of vitamins and trace elements should be supplemented on a daily basis.

Cigarette smoking significantly increases basal metabolic rate in patients with rheumatoid arthritis

OBJECTIVE

Basal metabolic rate (BMR) is the most important indicator of human metabolism and its abnormalities have been linked to undesirable health outcomes. Cigarette smoking associates with increased BMR in healthy individuals; it is also related with worse disease outcomes in patients with rheumatoid arthritis(RA), in whom BMR is high due to hypercatabolism caused by systemic inflammation. We aimed to investigate whether smokers with RA demonstrated higher BMR levels than their non-smoking counterparts.

METHODS

A total of 53 patients with RA (36 female, 17 male, 20 current smokers) were assessed for: BMR(indirect calorimetry), anthropometrical data, fat-free mass (bioelectrical impedance), physical function (health assessment questionnaire; HAQ) and disease activity(disease activity score DAS28 and C reactive protein).

RESULTS

RA smokers and non-smokers were not significantly different for age, height, weight, body mass index and fat-free mass. Compared to non-smokers,smokers with RA demonstrated significantly higher BMR (mean (SD) 1513.9 (263.3) vs 1718.1 (209.2) kcal/day; p,0.001) and worse HAQ (1.0 (0.8) vs 1.7 (0.8); p=0.01). The BMR difference was significantly predicted by the interaction smoking/gender (p=0.04). BMR was incrementally higher in light, moderate and heavy smokers (p=0.018), and correlated with the daily number of cigarettes smoked (r=0.68, p=0.04).

CONCLUSION

Current cigarette smoking further increases BMR in patients with RA and has a negative impact on patients self-reported functional status. Education regarding smoking cessation is needed for the RA population.

Controversies in the determination of energy requirements

To avoid any negative outcomes associated with under- or overfeeding it is essential to estimate nutrient requirements before commencing nutrition support. The energy requirements of an individual vary with current and past nutritional status, clinical condition, physical activity and the goals and likely duration of treatment. The evidence-base for prediction methods in current use, however, is poor and the equations are thus open to misinterpretation. In addition, most methods require an accurate measurement of current weight, which is problematic in some clinical situations. The estimation of energy requirements is so challenging in some conditions, e.g. critical illness, obesity and liver disease, that it is recommended that expenditure be measured on an individual basis by indirect calorimetry. Not only is this technique relatively expensive, but in the clinical setting there are several obstacles that may complicate, and thus affect the accuracy of, any such measurements. A review of relevant disease-specific literature may assist in the determination of energy requirements for some patient groups, but the energy requirements for a number of clinical conditions have yet to be established. Regardless of the method used, estimated energy requirements should be interpreted with care and only used as a starting point. Practitioners should regularly review the patient and reassess requirements to take account of any major changes in clinical condition, nutritional status, activity level and goals of treatment. There is a need for large randomised controlled trials that compare the effects of different levels of feeding on clinical outcomes in different disease states and care settings.

Hypocaloric feeding: pros and cons

PURPOSE OF REVIEW

Since the 1980s, hypocaloric feeding has been regularly proposed in the critically ill, although there is no clear definition available, nor evidence-based strategy to support it. We aim to define hypocaloric feeding based on indirect calorimetric data and to discuss patient-relevant clinical outcomes resulting from hypocaloric feeding.

RECENT FINDINGS

Overfeeding and underfeeding both have proven deleterious effects and should be avoided, which requires determination of the patient's total energy requirement. Indirect calorimetry appears as the only precise method to determine such requirements in clinical settings. We define hypocaloric feeding as the delivery of 0.5-0.9 times the resting energy expenditure, isocaloric feeding as 1.1-1.3 times the resting energy expenditure, whereas hypercaloric feeding delivers more than 1.5 times the resting energy expenditure. Whether the patients are lean or obese, all the available predictive equations of energy requirements are grossly inaccurate in more than 30% of cases.

SUMMARY

There is growing evidence that negative energy balances are associated with poor intensive-care-unit and hospital outcome. Using an evidence-based approach, hypocaloric feeding in the critically ill cannot be supported either. Whether the cutoff of tolerance for introducing feeding is 24 h or more is not yet defined and still awaits a prospective trial.

Poor agreement between continuous measurements of energy expenditure and routinely used prediction equations in intensive care unit patients

BACKGROUND & AIMS

A wide variation in 24h energy expenditure has been demonstrated previously in intensive care unit (ICU) patients. The accuracy of equations used to predict energy expenditure in critically ill patients is frequently compared with single or short-duration indirect calorimetry measurements, which may not represent the total energy expenditure (TEE) of these patients. To take into account this variability in energy expenditure, estimates have been compared with continuous indirect calorimetry measurements.

METHODS

Continuous (24h/day for 5 days) indirect calorimetry measurements were made in patients requiring mechanical ventilation for 5 days. The Harris-Benedict, Schofield and Ireton-Jones equations and the American College of Chest Physicians recommendation of 25 kcal/kg/day were used to estimate energy requirements.

RESULTS

A total of 192 days of measurements, in 27 patients, were available for comparison with the different equations. Agreement between the equations and measured values was poor. The Harris-Benedict, Schofield and ACCP equations provided more estimates (66%, 66% and 65%, respectively) within 80% and 110% of TEE values. However, each of these equations would have resulted in clinically significant underfeeding (<80% of TEE) in 16%, 15% and 22% of patients, respectively, and overfeeding (>110% of TEE) in 18%, 19% and 13% of patients, respectively.

CONCLUSIONS

Limits of agreement between the different equations and TEE values were unacceptably wide. Prediction equations may result in significant under or overfeeding in the clinical setting.

Severity of insulin resistance in critically ill medical patients

Critical illness is characterized by a hypermetabolic state associated with increased mortality, which is partly ascribed to the occurrence of hyperglycemia caused by enhanced endogenous glucose production and insulin resistance (IR). Insulin resistance is well described in patients after surgery and trauma. However, it is less clearly quantified in critically ill medical patients. In this clinical cohort study, IR (M value) was quantified in 40 critically ill medical patients and 25 matched, healthy controls by isoglycemic hyperinsulinemic clamps after an overnight fast on the day after admission to a medical intensive care unit. Energy and substrate metabolism were measured by using indirect calorimetry in the patients before and during the clamp. The severity of illness was assessed by the acute physiology and chronic health evaluation (APACHE) III score. M values of critically ill medical patients were significantly lower compared with healthy controls (2.29 +/- 1.0 and 7.6 +/- 2.9 mg/kg per minute, respectively; P < .001) and were closely related to APACHE III scores (r = -0.43, P < .01), body mass index (r = -0.41, P < .01), and resting energy expenditure (r = 0.40, P < .05). The M value was not associated with age, basal glucose concentrations, and respiratory quotient, and it did not differ among patients with various admission diagnoses. In conclusion, insulin sensitivity was found to be reduced by 70% in critically ill medical patients. The severity of IR was associated with the severity of illness, body mass index, and resting energy expenditure, but not with substrate oxidation rates. In addition, the severity of IR did not vary among patients with different admission diagnoses.