Associations between anthropometry, body composition, and body image in athletes: a systematic review.

Introduction: Poor body image is a potent risk factor for disordered eating and eating disorders. Athletes are a population at increased risk for eating disorders despite reports of lower body image concerns compared to non-athletes. Body size and composition may influence an athlete's susceptibility to poor body image. Methods: Five electronic databases (PubMed, Cochrane Library, PsycINFO, Web of Science, SPORTDiscus) were searched to systematically evaluate the literature regarding the association between body measures (i.e., anthropometric and body composition indicators) and body image in athletes. The systematic review was completed following PRISMA guidelines and 27 cross-sectional studies were identified for inclusion and evaluated using the Joanna Briggs Institute Critical Appraisal Checklist for Analytical Cross-Sectional Studies. Results: Studies differed in methodological assessment of anthropometry or body composition (i.e., self-reported versus researcher-measured), methods for evaluating aspects of body image, geographic location, and sport type. Higher body mass index (BMI) or percent body fat (%BF) was significantly associated with greater body dissatisfaction in 16 of 22 studies (72.7%). Positive associations between body measures and aspects of negative body image were most consistently observed among studies that assessed BMI based on self-reported heights and weights, while significant associations between body composition measures (e.g., %BF, fat mass, fat-free mass) were less common. Four of seven studies assessing relationships between BMI and an aspect of positive body image reported significant inverse relationships, while three revealed insignificant associations. Discussion: Overall, higher BMI and body fat were associated with body dissatisfaction among athletes. Future studies are needed to confirm these findings within focused populations and utilizing body composition methods (e.g., bioelectrical impedance techniques). Systematic review registration: https://www.crd.york.ac.uk/prospero/, CRD42023446518.

Malnutrition and pectoralis muscle index in medical intensive care unit patients: A matched cohort study.

BACKGROUND: Muscle assessment is an important component of nutrition assessment. The Global Leadership Initiative on Malnutrition (GLIM) consortium recently underscored the need for more objective muscle assessment methods in clinical settings. Various assessment techniques are available; however, many have limitations in clinical populations. Computed tomography (CT) scans, obtained for diagnostic reasons, could serve multiple purposes, including muscle measurement for nutrition assessment. Although CT scans of the chest are commonly performed clinically, there is little research surrounding the utility of pectoralis muscle measurements in nutrition assessment. The primary aim was to determine whether CT-derived measures of pectoralis major cross-sectional area (PMA) and quality (defined as mean pectoralis major Hounsfield units [PMHU]) could be used to identify malnutrition in patients who are mechanically ventilated in an intensive care unit (ICU). A secondary aim was to evaluate the relationship between these measures and clinical outcomes in this population. METHODS: A retrospective analysis was conducted on 33 pairs of age- and sex-matched adult patients who are being mechanically ventilated in the ICU. Patients were grouped by nutrition status. Analyses were performed to determine differences in PMA and mean PMHU between groups. Associations between muscle and clinical outcomes were also investigated. RESULTS: Compared with nonmalnourished controls, malnourished patients had a significantly lower PMA (P = 0.001) and pectoralis major (PM) index (PMA/height in m2; P = 0.001). No associations were drawn between PM measures and clinical outcomes. CONCLUSION: These findings regarding CT PM measures lay the groundwork for actualizing the GLIM call to action to validate quantitative, objective muscle assessment methods in clinical settings.

The bioelectrical impedance analysis (BIA) international database: aims, scope, and call for data.

BACKGROUND: Bioelectrical impedance analysis (BIA) is a technique widely used for estimating body composition and health-related parameters. The technology is relatively simple, quick, and non-invasive, and is currently used globally in diverse settings, including private clinicians' offices, sports and health clubs, and hospitals, and across a spectrum of age, body weight, and disease states. BIA parameters can be used to estimate body composition (fat, fat-free mass, total-body water and its compartments). Moreover, raw measurements including resistance, reactance, phase angle, and impedance vector length can also be used to track health-related markers, including hydration and malnutrition, and disease-prognostic, athletic and general health status. Body composition shows profound variability in association with age, sex, race and ethnicity, geographic ancestry, lifestyle, and health status. To advance understanding of this variability, we propose to develop a large and diverse multi-country dataset of BIA raw measures and derived body components. The aim of this paper is to describe the 'BIA International Database' project and encourage researchers to join the consortium. METHODS: The Exercise and Health Laboratory of the Faculty of Human Kinetics, University of Lisbon has agreed to host the database using an online portal. At present, the database contains 277,922 measures from individuals ranging from 11 months to 102 years, along with additional data on these participants. CONCLUSION: The BIA International Database represents a key resource for research on body composition.

Clinical applications of body composition and functional status tools for nutrition assessment of hospitalized adults: A systematic review.

BACKGROUND: No global consensus exists on diagnostic criteria for malnutrition. Muscular deficits and functional impairments are major components of available malnutrition diagnostic frameworks because these facets of nutrition status significantly impact outcomes. The purpose of this review is to explore which body composition assessment (BCA) and functional status assessment (FSA) tools are being used for nutrition assessment (NA) and monitoring the response to nutrition interventions (RNIs) in adult inpatients. METHODS: A literature search of Embase, Medline (Ovid), Web of Science, and Cochrane Central was performed to identify studies that used BCA and/or FSA tools for NA (along with an accepted NA diagnostic framework) and/or for monitoring RNI in adult inpatients. RESULTS: The search yielded 3667 articles; 94 were included in the review. The number of studies using BCA and/or FSA tools for NA was 47 and also 47 for monitoring RNI. Seventy-nine percent of studies used bioimpedance for BCA, and 97% that included FSA utilized handgrip strength. When compared against sets of diagnostic criteria, many of the BCA and FSA tools showed promising associations with nutrition status. CONCLUSION: Bioimpedance methods are the most widely used bedside BCA tools, and handgrip strength is the most widely used FSA tool; however, these methods are being used with a variety of protocols, algorithms, and interpretation practices in heterogeneous populations. To create a standardized nutrition status assessment process there is a need for validation studies on bedside methods and the development of globally standardized assessment protocols in clinical inpatient settings.

Usability of classic and specific bioelectrical impedance vector analysis in measuring body composition of children.

In this study, we aimed to analyse the relationship between body composition and bioelectrical variables in children and adolescents. The sample was composed of 6801 individuals (4035 males; 2766 females) aged 8-20 years included in the National Health and Nutrition Examination Survey (NHANES) years 1999-2004. Classic and specific bioelectrical impedance vector analysis (BIVA) were applied and compared with dual-energy X-ray absorptiometry (DXA) for the evaluation of fat mass (FM) and fat-free mass (FFM), and bioimpedance spectroscopy (BIS) for the evaluation of intra-cellular water (ICW), extra-cellular water (ECW), and total body water (TBW). Fat-free mass index (FFMI) was calculated. Spearman's correlation, regression, and depth-depth analyses were applied. The evaluation of body composition with BIVA agreed well with that of DXA or BIS, independently of sex, age, and ethnicity: classic BIVA was mostly sensitive to differences in TBW, ECW/ICW, whereas specific BIVA to differences in %FM, FFMI, and ECW/ICW. The depth-depth analysis confirmed the associations of classic BIVA (coeff. 0.500, p < 0.001), and specific BIVA (coeff. 0.512, p < 0.001), also considering the significant effect of age (p < 0.001). In classic BIVA the association was slightly stronger in females (by 0.03, p = 0.042) and among Blacks (0.06, p = 0.002), whereas in specific BIVA it was stronger by 0.06 (p < 0.001) in females and similar among ethnic groups. The combined use of the two BIVA approaches represents a valuable tool for complete evaluation of body composition in growth studies, for the prevention and monitoring of malnutrition, and the monitoring of the performance in young athletes.

Feasibility of bioimpedance spectroscopy and long-term functional assessment in critically ill children.

BACKGROUND & AIMS: Lean body mass loss due to critical illness in childhood could be detrimental to long term outcomes, including functional status and quality of life. We describe the feasibility of body composition assessment by bioimpedance spectroscopy (BIS) in the pediatric intensive care unit (PICU), and functional status and quality of life assessments up to 6 months following admission in a cohort of mechanically ventilated, critically ill children. METHODS: We conducted a prospective, observational pilot study in a multidisciplinary PICU. Children aged 1 month to 18 years who required mechanical ventilation, with expected stay in the PICU of at least 5 days were included. We examined the feasibility of consenting, enrolling, and completing baseline and 6-month assessments of BIS variables, Functional Status Scale (FSS), and Pediatric Quality of Life (Peds QL), in eligible patients. RESULTS: Of 32 patients approached, 23 (72%) completed baseline assessments [median (IQR) age 3.4 (1.0, 7.8) years, 14 (61%) male]; 6-month assessments were completed in 15 (65%) enrolled patients. Mean (SD) phase angle at study enrollment was 2.95 (0.93) and the impedance ratio was 0.90 (0.03). Phase angle (rs = -0.58, p = 0.03) and impedance ratio (rs = 0.61, p = 0.02) by BIS were significantly correlated with total FSS at PICU discharge. Median total FSS and FSS tech (feeding and respiratory domains of FSS) scores improved from enrollment [16 (13, 26) and 8 (7, 10)] to 6 months [6 (6, 9) and 2 (2, 4), respectively, p < 0.001]. Median Peds QL total, physical summary and psychosocial summary scores were not significantly different between PICU discharge and 6 months after PICU admission. Correlations between the total 6-month FSS and a) phase angle (-0.45, p = 0.197) and b) impedance ratio (0.56, p = 0.096) at PICU discharge were not significant. CONCLUSIONS: We have demonstrated the feasibility of obtaining bedside BIS measurements in the PICU, and functional and quality of life assessments remotely following PICU discharge. Body composition and long-term assessment of functional outcomes and quality of life must be incorporated in nutrition trials in critically ill children.

Doubly labelled water for determining total energy expenditure in adult critically ill and acute care hospitalized inpatients: A scoping review.

BACKGROUND & AIMS: Doubly labelled water (DLW) is considered the reference standard method of measuring total energy expenditure (TEE), but there is limited information on its use in the Intensive Care Unit (ICU) and acute care setting. This scoping review aims to systematically summarize the available literature on TEE measured using DLW in these contexts. METHODS: Four online databases (MEDLINE, Embase, Emcare and CINAHL) were searched up to Dec 12, 2020. Studies in English were included if they measured TEE using DLW in adults in the ICU and/or acute care setting. Key considerations, concerns and practical recommendations were identified and qualitatively synthesized. RESULTS: The search retrieved 7582 studies and nine studies were included; one in the ICU and eight in the acute care setting. TEE was measured over 7-15-days, in predominantly clinically stable patients. DLW measurements were not commenced until four days post admission or surgery in one study and following a 10-14-day stabilization period on parenteral nutrition (PN) in three studies. Variable dosages of isotopes were administered, and several equations used to calculate TEE. Four main considerations were identified with the use of DLW in these settings: variation in background isotopic abundance; excess isotopes leaving body water as carbon dioxide or water; fluctuations in rates of isotope elimination and costs. CONCLUSION: A stabilization period on intravenous fluid and PN regimens is recommended prior to DLW measurement. The DLW technique can be utilized in medically stable ICU and acute care patients, with careful considerations given to protocol design.

Body composition assessment after pediatric liver transplant.

BACKGROUND: Pediatric liver transplantation generally restores metabolic function; yet after transplantation, some children remain malnourished, have increased adiposity, and develop obesity. Measurement of body composition in the assessment of nutrition status could reduce adverse consequences in children. METHODS: Anthropometric measurements, multiple-frequency bioelectrical impedance analysis, air displacement plethysmography, and ultrasound measurements were conducted on children recruited from the liver transplant program at the University of Minnesota Masonic Children's Hospital. A cross-sectional study was conducted to describe the quality of weight gain in post-liver transplant children between the ages of 2 and 17 years using multiple assessment tools (air displacement plethysmography, multiple-frequency bioelectrical impedance analysis, and ultrasound) and to determine whether multiple-frequency bioelectrical impedance analysis and ultrasound accurately describe body composition and quality of weight gain. RESULTS: Mean percent body fat by air displacement plethysmography and multiple-frequency bioelectrical impedance analysis was 18.4% (±3.3) and 19.0% (±3.9), respectively (P > .99). There were insufficient data to examine the relationship between summed muscle and adipose thickness measures by ultrasound and percent body fat determined by air displacement plethysmography or multiple-frequency bioelectrical impedance analysis. CONCLUSION: Percent body fat, fat mass, and fat-free mass measures determined by air displacement plethysmography and multiple-frequency bioelectrical impedance analysis were not statistically different, which suggests the stand-on device used in this study could be a useful body composition assessment tool for the pediatric population.

Prevalence and characteristics of starvation-related malnutrition in a mid-Atlantic healthcare system: A cohort study.

BACKGROUND: Malnutrition in the hospital negatively impacts outcomes, including readmissions, mortality, and cost. Starvation-related malnutrition (SRM) is a state of chronic undernutrition with little to no inflammation. Research on SRM within the hospital setting is lacking. Our objective was to determine the prevalence and characteristics of malnutrition within the hospital, focusing on characteristics associated with readmissions in those with SRM. METHODS: We conducted a retrospective cohort study analyzing characteristics of adult in patients with acute disease-related malnutrition (ADM) and chronic disease-related malnutrition (CDM) compared with patients with SRM. Prevalence of all malnutrition types was calculated as the total number of malnourished patients divided by the total number of hospital discharges. Analysis of variance with Tukey post hoc analysis was performed to determine differences between characteristics of patients with SRM and other forms of malnutrition. RESULTS: Total prevalence of malnutrition was 2.8%. Of malnourished patients, 17.6%, 79.9%, and 2.5% had ADM, CDM, and SRM, respectively. Patients with SRM had lower body mass index (BMI) (P < .001) and higher rates of readmission (P = 0.046), infectious disease (P < .001), psychiatric disease (P < .001), and substance abuse (P < .001) than patients with ADM or CDM. Readmitted patients with SRM had lower BMI and higher rates of infection and drug abuse than those without readmission. CONCLUSION: The high incidence of comorbid substance abuse and mental illness in patients with SRM provide important targets for treatment that might reduce readmission and improve outcomes.

Ultrasound measurements of abdominal muscle thickness are associated with postmenstrual age at full oral feedings in preterm infants: A preliminary study.

BACKGROUND: A premature infant's discharge from the neonatal intensive care unit (NICU) is dependent on factors such as respiratory stability, adequate growth, and the ability to consume oral feeds. Once infants have achieved respiratory stability, a tool that can better predict age at discharge is desirable. Thus, we conducted a secondary data analysis to assess the association between ultrasound measurements of abdominal muscle thickness and postmenstrual age (PMA) at full oral feedings. METHODS: Forty-nine (n = 49) healthy, premature infants (mean gestational age = 32 weeks) were recruited from the NICU. Anthropometric measurements and ultrasound measurements of the rectus abdominis were conducted when infants were medically stable. Fat-free mass (FFM) was obtained using air displacement plethysmography. The relationship between ultrasound measurements of muscle thickness and PMA at full oral feedings was assessed using linear regression analysis. The relationship between FFM z-scores and PMA at full oral feedings was also assessed for comparison. RESULTS: When adjusting for gestational age at birth, PMA at measurement, days of positive pressure respiratory support, weight, and length, ultrasound measurements of abdominal muscle thickness were independently, negatively associated with PMA at full oral feedings (ß estimate: -0.71, P = .03). CONCLUSION: Preliminary results suggest infants with greater abdominal muscle thickness may reach full oral feedings at an earlier PMA (nearly 1 week per millimeter). Thus, ultrasound measurements of abdominal muscle thickness may be helpful in assessing readiness for discharge in healthy preterm infants. Further research is needed for development and validation of a prediction equation.

Body Composition Post Pediatric Liver Transplant: Implications and Assessment.

Liver disease has a negative influence on growth and development of children. Measurement of body composition as a component of nutrition status assessment in children before and after transplant would facilitate tailoring of nutrition therapy. A comprehensive literature search on pediatric liver transplant and body composition assessment was performed using a modified systematic approach. This review includes evidence specific to body composition of children undergoing liver transplant and a discussion of relevant body composition assessment methods for this population. Malnutrition is commonly seen in children with liver disease prior to transplant because of the disrupted metabolic pathways from liver dysfunction; however, malnutrition is not consistently diagnosed. Within 1 year of transplant, children tend to quickly recover with weight gain and linear growth. In some children, obesity and sarcopenia have been observed as long-term posttransplant outcomes. Body composition assessment tools have been utilized in diagnosing nutrition status in adults; yet there are limited studies that use these tools in the pediatric liver-transplant population. Technologies available to assess body composition include air displacement plethysmography, dual-energy x-ray absorptiometry, bioimpedance, and ultrasound. Total body potassium has been used for body composition assessment in adults and children post liver transplant; however, this method is not applicable in a clinical setting. We conclude that understanding posttransplant body composition could help clinicians diagnose and treat malnutrition.

Nutrition Status and Health-Related Quality of Life Among Outpatients With Advanced Head and Neck Cancer.

This pilot study evaluated nutrition status and health-related quality of life (HRQOL) outcomes among outpatients with head and neck cancer (HNC). Data were collected from 19 patients (18 males, 1 female) during 3 time points: once before chemoradiotherapy (CRT) initiation and 1 and 3 months after CRT. Nutrition status was evaluated using the Scored Patient-Generated Subjective Global Assessment (PG-SGA). Malnutrition was defined as PG-SGA stage B (moderate/suspected malnutrition) or stage C (severely malnourished). HRQOL was assessed through the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30) and its HNC-specific module (QLQ-H&N35). We found that well-nourished patients reported having fewer issues with pain, fatigue, appetite loss, chewing, sticky saliva, coughing, and social eating than those categorized as malnourished (P < .05). The association between the global quality-of-life score and PG-SGA score was statistically significant but weak in strength (r = -0.37, P = .012). Although PG-SGA identified 70% as either moderately or severely malnourished before treatment initiation, the mean body mass index was in the overweight category (29 ± 5 kg/m2 ). Compared with pretreatment, patients reported more severe problems with chewing, swallowing, sticky saliva, dry mouth, speech, social eating, and taste and smell sensations at 1-month follow-up, although issues with dry mouth persisted 3 months post treatment (P = .003). In conclusion, malnourished patients reported having worse HRQOL symptoms compared with well-nourished patients. Routine nutrition and psychosocial assessment through PG-SGA and EORTC tools might help identify patients in need of nutrition and psychosocial care.

Update on body composition tools in clinical settings: computed tomography, ultrasound, and bioimpedance applications for assessment and monitoring.

Patients with acute/critical illness are particularly vulnerable to muscle loss and fluid shifts, which adversely impact clinical outcomes. Assessment of these parameters in hospital settings is often subjective and imprecise, which creates discrepancies in identification and difficulty in assessing longitudinal changes. Body composition (BC) technologies provide objective information about muscle and fluid status that can enhance clinical assessment, and BC variables could be biomarkers for prognosis and targets to monitor intervention. There is growing interest in computed tomography (CT), ultrasound (US), and bioimpedance techniques as bedside assessment tools in clinical populations, and specific muscle measures, whole-body BC estimates, and select BC variables show promise as biomarkers of muscle health, nutrition risk, and fluid status. This brief review highlights work within the past 5 years on the use of BC variables generated from CT, US, and bioimpedance in clinical populations with an emphasis on those with acute/critical illness and a brief discussion of implementation challenges in these populations. Consensus on measurement protocols will facilitate identification of BC targets that best reflect prognosis and outcomes and will ultimately allow clinicians to identify individuals who would benefit most from targeted nutrition and physical therapy interventions and reliably monitor their response to treatment.

Impact of Software Selection and ImageJ Tutorial Corrigendum on Skeletal Muscle Measures at the Third Lumbar Vertebra on Computed Tomography Scans in Clinical Populations.

BACKGROUND: There is growing interest in computed tomography (CT) measures of skeletal muscle cross-sectional area (CSA) for nutrition assessment. Multiple software programs are available, but little work has been done comparing programs. We aimed to determine if CT-derived measures of skeletal muscle CSA at the level of the L3 are influenced by the software program used. We also demonstrate the importance of the ImageJ corrigendum published in this journal. METHODS: Two software programs, National Institutes of Health ImageJ and Tomovision sliceOmatic, were compared. ImageJ measures were obtained using both the original tutorial and corrigendum instructions. Skeletal muscle CSA at the level of the L3 was measured in advanced heart failure and head and neck cancer populations by 3 different investigators. Intraclass correlation coefficients were used to calculate intrarater and interrater reliability. Bland-Altman analysis was used to assess agreement. RESULTS: Both software programs yielded excellent intrarater and interrater reliability scores (intraclass correlation coefficients, 0.985-1.000). The overall mean difference (ImageJ tutorial with corrigendum - sliceOmatic) for the entire sample (N = 51) was found to be 1.53 cm2 (95% CI, 0.59-2.47 cm2 ). The overall mean difference (ImageJ corrected - original) for the entire sample (N = 51) was found to be -11.35 cm2 (95% CI, -12.75 to -9.95 cm2 ). CONCLUSION: Measures of skeletal muscle CSA at the L3 were found to be ∼1.53 cm2 higher with ImageJ than sliceOmatic. This difference was not found to affect interpretation against a published cut point. The importance of accounting for the ImageJ tutorial corrigendum was shown to be clinically significant when applied to published cut points.

Diagnosing clinical malnutrition: Perspectives from the past and implications for the future.

This review, intended for both researchers and clinicians, provides a history of the definition of clinical malnutrition. Despite global efforts, we remain without one clear, objective, internationally accepted definition; clarity in this regard will ultimately improve our evaluation and monitoring of nutritional status to achieve optimal patient outcomes. In this review we explore the development of the term malnutrition and its diagnosis and application in the setting of acute and chronic disease. We begin in the second century A.D. with the work of the Greek physician Galen who is credited as the first to apply the term marasmus to characterize three categories of malnutrition, which are surprisingly similar to components of current international definitions. We then highlight significant developments over the next 2000 years culminating in our current application of the clinical diagnosis of malnutrition. A perspective on historical practices may inform current efforts toward a global definition and diagnosis of malnutrition.

Malnutrition Identified by the Academy of Nutrition and Dietetics and American Society for Parenteral and Enteral Nutrition Consensus Criteria and Other Bedside Tools Is Highly Prevalent in a Sample of Individuals Undergoing Treatment for Head and Neck Cancer.

BACKGROUND: Using the Academy of Nutrition and Dietetics and American Society for Parenteral and Enteral Nutrition (Academy/ASPEN) Consensus malnutrition definition, we estimated malnutrition prevalence in a sample of individuals with head and neck cancer (HNC) and compared it with the Patient-Generated Subjective Global Assessment (PG-SGA). We also investigated the utility of the 50-kHz phase angle (PA) and 200-kHz/5-kHz impedance ratio (IR) to identify malnutrition. MATERIALS AND METHODS: Nineteen individuals (18 males, 1 female) scheduled to undergo chemoradiotherapy were seen at 5 time points during and up to 3 months after treatment completion. Multiple-frequency bioelectrical impedance analysis, PG-SGA, nutrition-focused physical examination, anthropometry, dietary intake, and handgrip strength data were collected. RESULTS: Using the Consensus, 67% were found to be malnourished before treatment initiation; these criteria diagnosed malnutrition with overall good sensitivity (94%) and moderate specificity (43%) compared with PG-SGA. Over all pooled observations, "malnourished" (by Consensus but not PG-SGA category) had a lower mean PA (5.2 vs 5.9; P = .03) and higher IR (0.82 vs 0.79; P = .03) than "well-nourished" categorizations, although the clinical relevance of these findings is unclear. PA and IR were correlated with higher PG-SGA score (r = -0.35, r = 0.36; P < .01) and handgrip strength (r = 0.48, r = -0.47; P < .01). CONCLUSION: The Academy/ASPEN Consensus and the PG-SGA were in good agreement. It is unclear whether PA and IR can be used as surrogate markers of nutrition status or muscle loss.

Protein in the Hospital: Gaining Perspective and Moving Forward.

Provision of adequate protein is crucial for optimizing outcomes in hospitalized patients. However, the methodologies upon which current recommendations are based have limitations, and little is known about true requirements in any clinical population. In this tutorial, we aim to give clinicians an understanding of how current protein recommendations were developed, an appreciation for the limitations of these recommendations, and an overview of more sophisticated approaches that can be applied to better define protein requirements. A broader perspective of the challenges and opportunities in determining clinical protein requirements can help clinicians think critically about the individualized nutrition care they provide to their patients with the goal of administering adequate protein to optimize outcomes.

Preoperative Pectoralis Muscle Quantity and Attenuation by Computed Tomography Are Novel and Powerful Predictors of Mortality After Left Ventricular Assist Device Implantation.

BACKGROUND: Skeletal muscle mass decreases in end-stage heart failure and is predictive of clinical outcomes in several disease states. Skeletal muscle attenuation and quantity as quantified on preoperative chest computed tomographic scans may be predictive of mortality after continuous flow (CF) left ventricular assist device (LVAD) implantation. METHODS AND RESULTS: A single-center continuous flow-LVAD database (n=354) was used to identify patients with chest computed tomographies performed in the 3 months before LVAD implantation (n=143). Among patients with computed tomography data available, unilateral pectoralis muscle mass indexed to body surface area and attenuation (approximated by mean Hounsfield units [PHUm]) were measured in each patient with a high intrarater and inter-rater reliability (intraclass correlation coefficients 0.98 and 0.97, respectively). Multivariate Cox regression analyses were performed, censoring at cardiac transplantation, to assess the impact of preoperative pectoralis muscle index and pectoralis muscle mean Hounsfield unit on survival after LVAD implantation. Each unit increase in pectoralis muscle index was associated with a 27% reduction in the hazard of death after LVAD (adjusted hazard ratio, 0.73; 95% confidence interval, 0.58-0.92; P=0.007). Each 5-U increase in pectoralis muscle mean Hounsfield unit was associated with a 22% reduction in the hazard of death after LVAD (adjusted hazard ratio, 0.78; 95% confidence interval, 0.68-0.89; P<0.0001). Pectoralis muscle index and pectoralis muscle mean Hounsfield unit outperformed other traditional measures in the data set, including the HeartMate II risk score. CONCLUSIONS: Pectoralis muscle size and attenuation were powerful predictors of outcomes after LVAD implantation in this data set. This one time, repeatable, internal assessment of patient substrate added valuable prognostic information that was not available on standard preoperative testing.

Avaliação de modelos avançados de espectroscopia de bioimpedância para medir a composição do corpo em adultos saudáveis (NHANES 1999-2004) e aqueles que sofrem perda de peso em massa após a cirurgia de bypass gástrico Roux-en-Y / Evaluation of Advanced Bioimpedance Spectroscopy Models for Measuring Body Composition in Healthy Adults (NHANES 19992004) and Those Undergoing Massive Weight Loss Following Roux-en-Y Gastric Bypass Surgery

Introduction: Bioimpedance spectroscopy (BIS) devices utilize biophysical modeling to generate body composition data. The addition of body mass index (BMI) to modified Xitron-Hanai-based mixture equations improved BIS estimates of intracellular water (ICW), particularly at the extremes of BMI. A 3-compartment model for distinguishing excess fluid (ExF) from normally hydrated lean (NHLT) and adipose tissue may further improve BIS estimates. Objective:We aimed to validate a BIS approach based on the Chamney model for determining fat mass (FM) in healthy individuals (NHANES) and for measuring FM changes in individuals undergoing massive weight loss. Methods: Using adult NHANES 1999-2004 (2821 female, 3063 male) and longitudinal pre-topost-RYGB (15F) data, we compared dual-energy-X-ray absorptiometry (DXA) and BIS for FM. We applied BIS adiposity-corrected values to Chamney equations for normally hydrated lean and adipose tissue (NHLT, NHAT) and FM. Method agreement was evaluated by correlations, paired t-tests, root mean square error (RMSE), BlandAltman (B-A) analysis, and concordance correlation coefficients (CCC). Results: Method agreement between BIS and DXAFM was good in healthy adults (r=0.96, CCC=0.93, p<.0001), and pre-to-post-RYGB (r=0.93-0.98, CCC=0.81-0.86, p<.001). Although cross-sectional FM measures differed, FM change measures post-RYGB did not (35.6±8.9 vs. 35.2±9.2 kg, BIS vs. DXA) and agreed well (r=0.84, p<.0001). The 15 subjects with follow-up measurements at 1 year lost 11.5±9.8 kg FFM by DXA, but only 1.3±2.5 kg of NHLT by BIS, suggesting that the FFM loss may have been mostly adipose tissue water. Conclusions: Incorporation of the Chamney model into BIS algorithms is a major conceptual advancement for assessing and monitoring body composition. Its ability to differentiate ICW and extracellular water (ECW) in NHLT and NHAT, as well as excess ECW is promising, and would facilitate lean tissue monitoring in obesity and acute/chronic disease.(AU)

Introdução: Os dispositivos de espectroscopia de bioimpedância (DEB) utilizam modelagem biofísica para gerar dados de composição corporal. A adição do índice de massa corporal (IMC) às equações de mistura modificadas com Xitron-Hanai modificadas melhorou as estimativas de DEB de água intracelular (AI), particularmente nos casos extremos do IMC. Um modelo de 3 compartimentos para distinguir o excesso de fluido (ExF) de magro normalmente hidratado (NHLT) e tecido adiposo pode ainda melhorar as estimativas do DEB. Objetivo: Pretendemos validar uma abordagem do DEB com base no modelo de Chamney para determinar a massa de gordura (MG) em indivíduos saudáveis (NHANES) e para medir mudanças de MG em indivíduos submetidos à perda de peso maciça. Método: Usando o NHANES adulto 1999-2004 (2821 mulheres, 3063 homens) e dados longitudinais pré-pós-RYGB (15 F), comparamos a absorção de raios-X de dupla energia (DXA) e DEB para MG. Aplicamos os valores corrigidos de adiposidade do BIS às equações de Chamney para tecidos magros e adiposos normalmente hidratados (NHLT, NHAT) e FM. O acordo de método foi avaliado por correlações, testes t pareados, erro quadrado médio (EQM), análise Bland-Altman (B-A) e coeficientes de correlação de concordância (CCC). Resultados: O acordo de método entre DEB e DXA MG foi bom em adultos saudáveis (r=0,96, CCC=0,93, p<.0001) e pré-pós-RYGB (r=0,93-0,98, CCC=0,81-0,86, p<0,001). Embora as medidas de MG transversais diferissem, as medidas de mudança de MG pós-RYGB não (35,6±8,9 vs. 35,2±9,2 kg, DEBvs. DXA) e concordaram bem (r=0,84, p<.0001). Os 15 sujeitos com medidas de seguimento ao 1 ano perderam 11,5±9,8 kg FFM por DXA, mas apenas 1,3±2,5 kg de NHLT pelo DEB, sugerindo que a perda de FFM pode ter sido principalmente água do tecido adiposo. Conclusões: A incorporação do modelo de Chamney em algoritmos DEB é um grande avanço conceitual para avaliar e monitorar a composição corporal. A sua capacidade de diferenciar AI e água extracelular (AE) no NHLT e NHAT, bem como o excesso de AE é promissor e facilitará a monitorização do tecido magro na obesidade e doença aguda/crônica.(AU)

Evaluation of Lean Body Weight Equation by Dual-Energy X-Ray Absorptiometry Measures.

BACKGROUND: When managing patients with disorders that require clinical intervention, a practical assessment of body habitus is valued. The Duffull-Green lean body weight (LBW) equation was derived and validated in adults across a wide body mass index (BMI) range. Whether this predictive equation will perform well in patients at BMI extremes or perform better than a widely used empiric "ideal" body weight (IBW) equation is unknown. MATERIALS AND METHODS: Calculated LBW and calculated IBW were each compared with the dual-energy x-ray absorptiometry (DXA)-derived lean body mass (LBM) by simple linear regression. A mixed model was used to determine how well the LBW equation performed over time in patients with more than 1 DXA measurement. RESULTS: At time 0, 32 patients were 18-67 years old, and all were obese (BMI: 36-65 kg/m2), while the remaining 7 had parenteral nutrition-dependent intestinal failure (BMI: 17-25 kg/m2). A subset of patients underwent bariatric surgery after time 0 (BMI at follow-up: 22-49 kg/m2). The LBW equation was a predictor of LBM ( R2 = 0.67, P < .0001), while the IBW equation was not ( R2 = 0.04, P = .25). The LBW equation remained a predictor of LBM over time ( P < .0001) without significant interaction by number of months since time 0. CONCLUSION: The Duffull-Green LBW equation successfully predicted lean body mass in a patient population with a wide range of BMIs at both a single point in time and after considerable weight loss. In the clinical setting, an equation that performs well in various disease states and body sizes is advantageous.