Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans

Effects of gender-affirming hormone therapy on body fat: a retrospective case‒control study in Chinese transwomen

BACKGROUND

There is insufficient research on how gender-affirming hormone therapy (GAHT) affects body fat modifications in transwomen from China. It is unclear whether hormone therapy affects the prevalence of obesity and blood lipid levels within this population. The current research aimed to assess how GAHT and treatment duration had an impact on the change in and redistribution of body fat in Chinese transwomen.

METHODS

This study included 40 transwomen who had not received GAHT and 59 who had. Body fat, blood lipid, and blood glucose levels were measured. GAHT is mainly a pharmacologic (estrogen and anti-androgen) treatment. The study also stratified participants based on the duration of GAHT to assess its impact on body fat distribution. The duration of GAHT was within one year, one to two years, two to three years, or more than three years.

RESULTS

After receiving GAHT, total body fat increased by 19.65%, and the percentage of body fat increased by 17.63%. The arm, corrected leg, and leg regions showed significant increases in fat content (+ 24.02%, + 50.69%, and + 41.47%, respectively) and percentage (+ 25.19%, + 34.90%, and + 30.39%, respectively). The total visceral fat content decreased (-37.49%). Based on the diagnostic standards for a body mass index ≥ 28 or total body fat percentage ≥ 25% or 30%, the chance of developing obesity did not change significantly. Blood glucose levels significantly increased (+ 12.31%). Total cholesterol levels (-10.45%) decreased significantly. Fat changes in those who received GAHT for one to two years were significantly different from those who did not receive GAHT.

CONCLUSION

After receiving GAHT, total body fat and regional fat increased in Chinese transwomen, and the body fat distribution changed from masculine to feminine, especially during the first two years. However, neither the increase in total body fat percentage nor the decrease in visceral fat content didn't bring about significant changes in the incidence of obesity, nor did triglycerides or low-density lipoprotein-cholesterol.

Development of an Obesity Information Diagnosis Model Reflecting Body Type Information Using 3D Body Information Values

This study uses various body values (length, circumference, and volume) that can be derived from 3D data to determine variables and areas that substantially affect obesity and suggests guidelines for diagnosing obesity that are more elaborate than existing obesity indices. Body data for 170 participants (87 men and 73 women aged 20-30 years) are collected for the chest, abdomen, hips, and arms/legs. A 3D scanner, which can produce accurate body point results, and dual-energy X-ray (DEXA), which can accurately determine the fat percentage, are used to derive fat rates for each body part. The fat percentage and total fat percentage for each body part are used as learning data. For the derived data, the eigenvalue for each body part is derived using a principal component analysis, and the following four clusters are created for each part: underweight, normal, overweight, and obese. A comparison with the obesity index, which diagnoses obesity based on the cluster model, showed that the accuracy of the model proposed in this study is higher at 80%. Therefore, this model can determine the body information necessary for accurate obesity diagnosis and be used to diagnose obesity with greater accuracy than obesity indices without a body fat measurement machine such as DEXA.

Bioelectrical Impedance Changes of the Trunk are Opposite the Limbs Following Acute Hydration Change

This study aimed to evaluate the changes in impedance and estimates of body composition variables obtained from segmental multi-frequency bioelectrical impedance analysis (SMFBIA) following acute hydration change. All participants (N = 11 active adults) had SMFBIA measurements at baseline (euhydration), post-dehydration, and post-hyperhydration in an experimental repeated-measures design. Dehydration and hyperhydration trials were randomized with the opposite treatment given 24 h later. Dehydration was achieved via a heat chamber of 40 °C and 60% relative humidity. Hyperhydration was achieved by drinking lightly-salted water (30 mmol·L^-1 NaCl; 1.76 g NaCl·L^-1) within 30 min. Post-measurements were taken 30 min after each treatment. Despite changes in mass post-dehydration (Δ = -2.0%, p < 0.001) and post-hyperhydration (Δ = 1.2%, p < 0.001), SMFBIA estimates of total body water (TBW) did not change significantly across trials (p = 0.507), leading to significant differences (p < 0.001) in SMFBIA-estimates of body fat percentage across trials. Dehydration resulted in a significant (p < 0.001) 8% decrease in limb impedances at both 20 kHz and 100 kHz. Hyperhydration increased limb impedances only slightly (1.5%, p > 0.05). Impedance changes in the trunk followed an opposite pattern of the limbs. SMFBIA failed to track acute changes in TBW. Divergent impedance changes suggest the trunk is influenced by fluid volume, but the limbs are influenced by ion concentration.

[Methods for assessing the electrophysical properties of body tissues and the possibility of their application in forensic medical practice]

This article provides an overview of some diagnostic methods for indicators and changes in the electrophysical properties of biological tissues. The key principles of assessing the electrical conductivity and resistance of tissues under the influence of alternating and direct current electric charge using standard and modified meters and signal generators, as well as the possibilities of digital improvement of computational models, are considered. Some existing and promising methods are presented that enable to solve important problems of forensic medical practice by registering changes in electrophysical parameters.

Development of muscle mass and body fat reference curves for white male UK firefighters

OBJECTIVE

This study describes the development of the world's first suite of firefighter body composition centile reference curves which can be used as both academic research tools and clinical references, to plot and track individual firefighter skeletal muscle mass (SMM) and fat mass (FM) measurements against the representative reference sample.

METHODS

The body composition of 497 white male London (England) firefighters was measured by anthropometry and bioelectrical impedance analysis. Smoothed centile curves were then generated for skeletal muscle mass index (SMMI), fat mass index (FMI), body fat percentage (BF%) and waist-to-height ratio (WHtR).

RESULTS

Between 48 and 62 years, firefighter SMMI is greater than the UK white male age-matched general population by a mean of 0.35 units, although SMMI declines 0.006 units/years faster in firefighters between these ages. This is estimated to translate to a mean decline of approximately 0.6% of absolute SMM per year. Between 40 and 49 years, firefighter FMI is 0.1 units greater than the UK white male age-matched general population, which becomes identical (7 units) between 50 and 54 years. At the 50th centile, WHtR exceeds 0.5 by 39 years reaching 0.55 at 62 years. This contrasts with FMI which remains stable from 47 years.

CONCLUSION

Firefighters in this study possess greater FM and SMM compared with the UK general population. SMM appears to decline rapidly within older age ranges. These references offer a novel improvement upon the limitations of BMI and BF% for the benefit of an occupational group at elevated risk of cardiovascular disease.

Accuracy of bioelectrical impedance analysis and skinfold thickness in the assessment of body composition in people with chronic spinal cord injury

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

This study: (1) investigated the accuracy of bioelectrical impedance analysis (BIA) and skinfold thickness relative to dual-energy X-ray absorptiometry (DXA) in the assessment of body composition in people with spinal cord injury (SCI), and whether sex and lesion characteristics affect the accuracy, (2) developed new prediction equations to estimate fat free mass (FFM) and percentage fat mass (FM%) in a general SCI population using BIA and skinfolds outcomes.

SETTING

University, the Netherlands.

METHODS

Fifty participants with SCI (19 females; median time since injury: 15 years) were tested by DXA, single-frequency BIA (SF-BIA), segmental multi-frequency BIA (segmental MF-BIA), and anthropometry (height, body mass, calf circumference, and skinfold thickness) during a visit. Personal and lesion characteristics were registered.

RESULTS

Compared to DXA, SF-BIA showed the smallest mean difference in estimating FM%, but with large limits of agreement (mean difference = -2.2%; limits of agreement: -12.8 to 8.3%). BIA and skinfold thickness tended to show a better estimation of FM% in females, participants with tetraplegia, or with motor incomplete injury. New equations for predicting FFM and FM% were developed with good explained variances (FFM: R² = 0.94; FM%: R² = 0.66).

CONCLUSIONS

None of the measurement techniques accurately estimated FM% because of the wide individual variation and, therefore, should be used with caution. The accuracy of the techniques differed in different subgroups. The newly developed equations for predicting FFM and FM% should be cross-validated in future studies.

Segmental body composition estimated by specific BIVA and dual-energy X-ray absorptiometry

AIMS

The aim of this study was to analyse the association between specific bioelectric impedance vector analysis (BIVA) and dual-energy X-ray absorptiometry (DXA) to assess segmental body composition using DXA as the reference technique.

METHODS

The sample comprised 50 young active students who practised or played different sports (25 men, age: 24.37 ± 4.79 y; 25 women, age: 24.32 ± 4.43 y) from the National Institute of Physical Education of Catalonia (INEFC). Anthropometric data (height, weight, arm, waist, and calf circumferences) and bioelectrical measurements (R, ohm; Xc, ohm) were recorded. Body composition was analysed with specific BIVA. DXA was used as the reference method to assess body composition of the whole-body, the trunk, and the limbs. The percentage of fat mass (%FM_DXA) and fat-free mass index (FFMI_DXA = FFM/length²) were calculated. The agreement between specific BIVA and DXA was evaluated by a depth-depth analysis, two-way ANOVA, and Pearson's correlations.

RESULTS

The depth-depth analysis showed a good agreement between DXA and BIVA (F = 14.89, p < 0.001) in both sexes and all body segments. Specific vector length (Zsp; i.e. indicative of %FM) was correlated with %FM_DXA in the whole body and all body segments, and the phase angle was correlated with FFMI_DXA, with he trunk in women as the only exception. Specific BIVA demonstrated to balance the effect of body size on bioelectrical measurements in both whole and segmental approaches.

CONCLUSIONS

Segmental specific BIVA and DXA provided a consistent evaluation of body composition in both sexes, of the whole body and each body segment. The indices %FM and FFMI obtained with DXA were correlated to vector length and phase angle in each segment, respectively. Specific BIVA represents a promising technique for monitoring segmental body composition changes in sport science and clinical applications.

A Novel Radiofrequency Device to Monitor Changes in Pulmonary Fluid in Dialysis Patients

Background and Objectives

Fluid monitoring is an important management strategy in patients with chronic kidney disease (CKD) and heart failure (HF). The µCor™ Heart Failure and Arrhythmia Management System uses a radiofrequency-based thoracic fluid index (TFI) to track pulmonary edema. During hemodialysis, the acute removal of fluid through ultrafiltration offers a model for measuring a patient's fluid status. The objective of the study was to assess the relationship between the device measured TFI and ultrafiltration volume (UFV).

Design Setting Participants and Measurements

Patients undergoing chronic dialysis with and without heart failure were enrolled in the study. The relationship between TFI and UFV in each individual subject was assessed by calculating the Pearson correlation coefficient (r). The average correlation across all subjects was calculated through the use of the Fisher's z transform. Responder analysis was performed to assess the magnitude of change in TFI before and after dialysis.

Results

Twenty subjects were enrolled in the trial. The mean volume of fluid removal was 3.63 L (SD 0.88 L). The mean correlation based on Fisher's transform was 0.95 CI (0.92-0.99). Responder analysis showed that the mean reduction of TFI after dialysis was 5.5% ± 3.8.

Conclusion

The µCor system provides radiofrequency-based measurements of thoracic fluid which correlate well with total body fluid removal in a real-world setting. Fluid management based on the radar-derived TFI may provide benefits to dialysis patients and serves as a potential model for pulmonary edema common to the clinical course of heart failure.

Comparison of Bioelectrical Impedance Analysis and Dual Energy X-ray Absorptiometry for Total and Segmental Bone Mineral Content with a Three-Compartment Model

Modern bioelectrical impedance analysis (BIA) provides a wide range of body composition estimates such as fat mass (FM), lean body mass (LBM), and body water, using specific algorithms. Assuming that the fat free mass (FFM) and LBM can be accurately estimated by the 8-electrode BIA analyzer (BIA_8MF; InBody230, Biospace), the bone mineral content (BMC) may be calculated by subtracting the LBM from the FFM estimates based on the three-compartment (3C) model. In this cross-sectional study, 239 healthy Taiwanese adults (106 male and 133 female) aged 20-45 years were recruited for BIA and dual-energy X-ray absorptiometry (DXA) measurements of the whole body and body segments, with DXA as the reference. The results showed a high correlation between BIA_8MF and DXA in estimating total and segmental LBM, FM and percentage body fat (r = 0.909-0.986, 0.757-0.964, and 0.837-0.936, respectively). For BMC estimates, moderate to high correlations (r = 0.425-0.829) between the two methods were noted. The percentage errors and pure errors for BMC estimates between the methods ranged from 33.9% to 93.0% and from 0.159 kg to 0.969 kg, respectively. This study validated that BIA_8MF can accurately assesses LBM, FM and body fat percentage (BF%). However, the estimation of segmental BMC based on the difference between FFM and LBM in body segments may not be reliable by BIA_8MF.

Reference values for skeletal muscle mass and fat mass measured by bioelectrical impedance in 390 565 UK adults

BACKGROUND

Loss of skeletal muscle mass (SMM) increases the risk of frailty and, together with excess fat mass (FM), is a risk factor for cardio-metabolic disease. However, use of body composition measurements in nutritional surveillance and routine clinical practice is limited by the lack of reference data. Our aim was to produce age-specific and sex-specific reference values for SMM and FM in the White ethnic adult population in the UK. Secondary objectives were to examine the tracking over time using a subsample of the population with repeated measures of body composition and to assess the validity of these reference values in different ethnic subgroups.

METHODS

We used data from segmental bioelectrical impedance analysis (BIA) in 390 565 participants, aged 40-69 years, in the UK Biobank, and data from dual-energy X-ray absorptiometry from n = 905 participants to validate the BIA measurements. SMM was calculated as the sum of the predicted muscle mass from the limbs. The LMS method was used to produce percentile curves for the SMM index (SMMI = SMM/height² ) and the FM index (FMI = FM/height² ). We investigated the validity of the White ethnic reference values by plotting z-scores (99.7% confidence interval) from Black and Asian groups to check if their confidence interval included zero. Longitudinal trajectories were predicted based on the baseline z-scores and the correlation between repeated measurements at follow-up.

RESULTS

The percentile curves show that SMMI declines in men from the age of 40, whereas in women, SMMI is more stable and decreases only slightly among women in the higher percentiles. FMI increases with age in both men and women. Women have higher FMI and lower SMMI than men in all age groups. The validity of the White-based reference values for non-White ethnic groups is poor. Longitudinal trajectories in body composition in the subsample of participants with a follow-up assessment show regression towards the mean in both men and women, with some evidence of declining SMMI only among men. The predicted 90% limits for the expected 5 year trajectories of SMMI and FMI can be used to identify people with unusual trajectories and in clinical practice to identify and track individuals at risk of excessive loss of SMM.

CONCLUSIONS

These body composition reference values developed from BIA in a middle/older-aged healthy White ethnic population in the UK could be used as a simple assessment tool for nutritional surveillance and to identify individuals with low SMMI or high FMI who may be at increased risk of disease and/or frailty.

Measurement of Fluid Shift in Capd Patients Using Segmental Bioelectrical Impedance Analysis

Objective

To determine, using segmental bioelectrical impedance analysis (BIA), the characteristics of fluid shift of each body segment in continuous ambulatory peritoneal dialysis (CAPD) patients during and after peritoneal dialysis (PD) solution exchange.

Design

Observational study with repeated measurements of bioelectrical impedance, which is inversely related to tissue fluid content.

Patients

Thirteen clinically stable CAPD patients.

Methods

Bioelectrical impedance was measured at frequencies of 5, 50, 250, and 500 kHz in each body segment four times: (1) before and (2) after drainage of dialysate, and (3) at 1 hour and (4) at 2 hours after exchange of new 1.5% dextrose PD solution.

Results

Impedance of both arms was significantly increased at 1 hour post exchange at all frequencies. In the trunk, impedance at all frequencies increased significantly after drainage, decreased significantly at 1 hour post exchange, and then increased again for the next hour without significance. Impedance of both legs showed a decreasing tendency at all frequencies during and after exchange. Net calculated water volume changes between the time before drainage and 2 hours post exchange were –0.5 L in the trunk, –0.25 L in both arms, +0.47 L in both legs, –0.28 L in total. The change in body weight between the time before drainage and 2 hours post exchange was –0.21 kg, on average, and significantly correlated with total net calculated water volume change ( p = 0.009).

Conclusions

Each body segment of the CAPD patient has its own characteristic pattern of fluid shift in response to PD solution exchange or dwell. Segmental BIA may be a useful tool for understanding the physiological changes in fluid shift in CAPD patients.

Bioelectrical Impedance Analysis for Monitoring Fluid and Body Cell Mass Changes in Patients Undergoing Cardiopulmonary Bypass

OBJECTIVE

To evaluate preoperative and postoperative body fluid distribution with a bioelectrical impedance analyzer in patients undergoing cardiopulmonary bypass.

METHODS

Fifteen adult patients undergoing cardiopulmonary bypass were included in this study. Total body fluid changes, basal metabolism rates, body fat masses, lean body masses, and total cell masses were recorded. The patients' values were measured before anesthesia, after anesthesia, after sternotomy, at the 5th, 30th, and 60th minutes of cardiopulmonary bypass, and on the 1st, 3rd, and 5th postoperative days. All values were compared with preoperative values.

RESULTS

Total body fluid changed significantly after cardiopulmonary bypass (P<0.01). Metabolic velocity significantly changed compared to preoperative measurements (P<0.05). Fat mass and lean body mass also changed significantly. Body mass index and phase angle did not change significantly (P>0.05).

CONCLUSION

Changes in body fluids during and after cardiopulmonary bypass are inevitable. The increase in total body weight shows that this fluid load shifts to the extracellular space during bypass and the fluid load in this area passes into the intravascular area in the early postoperative period. This may cause edema and dysfunction in the major organs. Therefore, the fluid balance should be adjusted very carefully, especially during the bypass phase and the early postoperative period.

Assessing the Validity of Bioelectrical Impedance and Skinfold Calipers for Measuring Body Composition in NOLS Backcountry Hikers

INTRODUCTION

The National Outdoor Leadership School (NOLS) conducts backcountry research in an effort to provide the most up-to-date support to its students. Past research efforts have used a variety of body composition measurement tools, including bioelectrical impedance (BIA), skinfold calipers, and air displacement plethysmography (Bod Pod), but these tools are not interchangeable. The purpose of this study was to determine the feasibility and accuracy of the Tanita scale and the Harpenden skinfold calipers for assessing body composition in backcountry hikers.

METHODS

Twenty-two NOLS participants completed a 23-d backpacking trip into the Wind River Range in Wyoming. Pre- and postexpedition anthropometric measures were collected using 3 different body composition measurement tools: Tanita segmental body composition monitor, Harpenden skinfold calipers, and the Bod Pod. For the purposes of this study, the Bod Pod was used as the standard against which other methods were compared.

RESULTS

Participants lost a significant amount of weight and fat during the expedition. Fat-free mass increased by 0.4±1.9 kg, but this did not reach significance. A high degree of reliability was found between skinfold calipers and the Bod Pod and between BIA and the Bod Pod. The BIA measurements significantly underreported body fat percentage when compared to the Bod Pod, whereas the skinfold measurements were not significantly different from the Bod Pod, but measurements were more variable.

CONCLUSIONS

This study shows that the skinfold caliper and the Tanita scale give measurements comparable to the less readily available and more costly Bod Pod measurement in backcountry expedition participants.

Validity of multi-frequency bioelectric impedance methods to measure body composition in obese patients: a systematic review

OBJECTIVE

Excessive lean tissue loss following bariatric surgery may pose serious metabolic consequences. Accurate methods to assess body composition following bariatric surgery are required. This review aimed to investigate if multi-frequency bioelectric impedance (MF-BI) is a valid tool to determine body composition in obese patients.

METHODS

MEDLINE, EMBASE, CINAHL and CENTRAL databases were searched until March 2017. Included studies were published in English with obese (body mass index (BMI) ≥ 30 kg/m²) adults measuring body composition with MF-BI methods in comparison with reference methods. Exclusions were pregnancy, animal studies, non-English language studies, single frequency BI. A total of 6395 studies were retrieved.

RESULTS

Sixteen studies were eligible for inclusion. Sample sizes ranged from 15 to 157, with BMI 26-48 kg/m². MF-BI underestimated fat mass (FM) in 11 studies and overestimated fat-free mass (FFM) in nine studies in comparison with reference methods. Correlations of absolute values from MF-BI and reference methods for FM and FFM were high, however, agreement was lower at an individual level. When adjustments for BMI were made to machine algorithms, measurement accuracy improved. Significant heterogeneity was evident among included studies.

CONCLUSIONS

This review found that MF-BI is reliable for use at a group level. Obese-specific adjustment of algorithms for MF-BI machines increases the accuracy of absolute measures of body composition in obese individuals, improving their utility in the clinical setting. Multiple variables contributed a lack of consistency among studies included, highlighting the need for more robust studies that control confounding variables to establish clear validity assessment.

Changes in regional body fat, lean body mass and body shape in trans persons using cross-sex hormonal therapy: results from a multicenter prospective study

OBJECTIVE

Cross-sex hormonal therapy (CHT) in trans persons affects their total body fat and total lean body mass. However, it is unknown how separate body regions are affected and whether these changes alter body shape. Therefore, the aim of this study was to determine the effects on body fat and lean body mass in separate body regions and on body shape after one year of CHT.

DESIGN AND METHODS

In a multicenter prospective study at university hospitals, 179 male-to-female gender dysphoric persons, referred to as transwomen, and 162 female-to-male gender dysphoric persons, referred to as transmen, were included. All underwent whole-body dual-energy X-ray absorptiometry and anthropometric measurements before and after one year of CHT.

RESULTS

In transwomen, increases in body fat ranged from +18% (95% CI: 13%;23%) in the android region to +42% (95% CI: 37%;46%) in the leg region and +34% (95% CI: 29%;38%) in the gynoid region. In transmen, changes in body fat ranged from -16% (95% CI: -19;-14%) in the leg region and -14% in the gynoid region (95% CI: -16%;-12) to no change in the android region (+1%, 95% CI: -3%;5%). Waist-to-hip ratio (WHR) decreased in transwomen (-0.03, 95% CI: -0.04;-0.02) mainly due to an increase in hip circumference (+3.2 cm, 95% CI: 2.3;4.0). Transmen have a decrease in hip circumference (-1.9 cm, 95% CI: -3.1;-0.7) resulting in an increase in WHR (+0.01, 95% CI: 0.00;0.02).

CONCLUSIONS

CHT causes a more feminine body fat distribution and a lower WHR in transwomen and a more masculine body fat distribution with a lower hip circumference in transmen.

Comparative associations between anthropometric and bioelectric impedance analysis derived adiposity measures with blood pressure and hypertension in India: a cross-sectional analysis

Background

The utility of bioelectrical impedance analysis (BIA) derived adiposity measures as compared to anthropometric measures for the assessment of adiposity-related health risk is not clear. We aimed to clarify the relationships of BIA and anthropometric derived adipose measures with blood pressure and hypertension, and to compare the discriminative ability of the respective measures for hypertension.

Methods

We used baseline data collected between 2015 and 2016 from the Indian Study on Health of Adults (ISHA), an ongoing population based cohort study in India (N = 5990; age 30–69 years). We examined and compared the associations and discriminative ability between anthropometric (body mass index, waist circumference, hip circumference, waist-hip ratio, waist-height ratio) and BIA (whole body and trunk fat percentage) derived adiposity measures with blood pressure components (systolic pressure, diastolic pressure, pulse pressure, mean arterial pressure, mid-blood pressure) and hypertension.

Results

Regardless of whether the adiposity measure was derived from BIA or anthropometry, all were strongly and positively associated with blood pressure and hypertension. For both men and women, the magnitude of association of BIA measures with blood pressure and hypertension were comparable to those of anthropometric measures. Further, the ability of BIA derived adiposity measures to distinguish between those with and without hypertension was similar to the discriminative ability of anthropometric measures.

Conclusions

As compared to simple anthropometric measures, BIA derived estimates of adiposity provide no apparent advantage in the assessment of blood pressure and hypertension. The observed similarities between adiposity measures suggest that simple anthropometrics may be sufficient to assess adiposity and adiposity-related risks.

Accuracy and Reliability of Assessing Lateral Compartmental Leg Composition Using Dual-Energy X-ray Absorptiometry

PURPOSE

This study aimed to investigate the accuracy and reliability of a novel dual-energy x-ray absorptiometry (DXA) scanning method in the frontal plane for total, fat, and lean mass quantification of the anterior and posterior upper leg compartments.

METHODS

Twenty-one (11 females; X¯age = 20.3 ± 1.3 yr) college athletes were assessed for total and regional body composition using DXA. The segmentation of anterior/posterior thigh compartments was measured with participants lying on their right and left sides and the scanned leg elevated with two foam pads. Custom regions of interest (ROIs) were created manually with enCore software for each scan using bony landmarks to quantify lean, fat, and total masses. Paired t-tests assessed this novel positioning method's accuracy against standard positioning. Intraclass correlation coefficients and coefficients of variation examined inter- and intrarater reliability for lateral scan measures of total, fat, and lean masses from manually created ROIs.

RESULTS

All mean ± SD differences between frontal and lateral DXA scans of right (R) and left (L) leg total mass (R: 8.42 ± 195.57 g; L: 19.47 ± 131.80 g), fat mass (R: 61.26 ± 215.66 g; L: -5.89 ± 239.97 g), and lean mass (R: -103.00 ± 302.54 g; L: -27.58 ± 288.14 g) were nonsignificant (P value range = 0.15-0.91). Intraclass correlation coefficients were high for all composition measures between and within raters, ranging from 0.983 to 0.999 and from 0.954 to 0.999, respectively, with low variation across measures (all coefficients of variation ≤ 5%).

CONCLUSION

The results of this study suggest that DXA measures using lateral subject positioning and custom ROIs to assess upper leg total, fat, and lean masses are accurate and reliable compared with total-body frontal subject positioning. Future studies are needed to determine the clinical usefulness of lateral view measures regarding prevention or rehabilitation of sports- or age-related injury.

A novel approach for acoustic estimation of neck fluid volume between men and women

Obstructive Sleep apnea can be caused by fluid shift from the legs to the neck that narrows the upper airway (UA) and contributes to changes in tracheal sound. Tracheal sound is generated from the turbulent airflow in the pharynx and respiratory airways and it has recently been used to estimate increases in neck fluid volume (NFV). However, tracheal sound is also highly variable among people, especially across the sexes. In this paper, a novel method is proposed to select tracheal sound features towards estimating NFV in men and women separately. To validate this method, it was applied to the tracheal sound data of 28 healthy individuals. Our proposed feature selection algorithm is based on sparse representations and incorporates NFV to maximize the relevance of selected features. This feature selection eliminates the dependence of the previous methods on calibrating the model for every individual. Two models, regression and Kalman filters, are then used to estimate NFV from selected features. Kalman filter obtains the highest performance, estimating NFV with more than 90% accuracy in both men and women. This algorithm can be used to develop non-invasive acoustic technologies to investigate the effects of fluid on UA anatomy in general applications. These results could be used to develop convenient devices to monitor the neck edema and its contribution to sleep apnea severity in fluid retaining patients such as heart or renal failure.

Leg fluid accumulation during prolonged sitting

The accumulation of fluid in the legs due to sedentariness can be a health risk in extreme cases. Negative health impacts associated with leg fluid accumulation include leg edema and risk of blood clots. Furthermore, fluid accumulating in the legs is accompanied by fluid shift into the upper body which is also associated with health risks such as: increased blood pressure when lying down, respiratory problems in people with heart failure, and increased sleep apnea. Understanding the pattern by which fluid accumulates in the legs can aid in the development of devices for reducing leg fluid accumulation. The purpose of this study was to characterize the time course of fluid accumulation over a two-and-half-hour seated period. Non-obese participants with sleep apnea and no other co-morbidities were included in the sample as part of a larger study. Leg fluid was measured continuously using a method of bioelectrical impedance. Participants were first asked to lie supine for 30 minutes as a washout, and then sat with their legs still for two and a half hours. The main finding of this study is that the pattern of leg fluid accumulation differed in the first 45 minutes compared to the latter 105 minutes. In the first 45 minutes, fluid accumulated according to first order exponential function. In the latter period, fluid accumulated according to a linear function. The initial exponential accumulation is likely due to the large increase in capillary pressure caused by rapid blood flow into the legs due to gravity, leading to substantial filtration of blood plasma into the tissue spaces. The latter linear portion likely represents continued slow filtration of fluid out of the vasculature and into the tissue spaces. This is the first study to show that fluid accumulation in the legs is a combination of an exponential and linear functions. The linear increase identifies that there is no foreseeable point in which leg fluid stops accumulating while sitting for prolonged periods.

Total body composition estimated by standing-posture 8-electrode bioelectrical impedance analysis in male wrestlers

Standing-posture 8-electrode bioelectrical impedance analysis is a fast and practical method for evaluating body composition in clinical settings, which can be used to estimate percentage body fat (BF%) and skeletal muscle mass in a subject’s total body and body segments. In this study, dual-energy X-ray absorptiometry (DXA) was used as a reference method for validating the standing 8-electrode bioelectrical impedance analysis device BC-418 (BIA₈, Tanita Corp., Tokyo, Japan). Forty-eight Taiwanese male wrestlers aged from 17.9 to 22.3 years volunteered to participate in this study. The lean soft tissue (LST) and BF% in the total body and body segments were measured in each subject by the BIA₈ and DXA. The correlation coefficients between total body, arm, leg segments impedance index (BI, ht²/Z) and lean soft tissue mass measured from DXA were r = 0.902, 0.453, 0.885, respectively (p < 0.01). In addition, the total body and segmental LST estimated by the BIA₈ were highly correlated with the DXA data (r = 0.936, 0.466, 0.886, p < 0.01). The estimation of total body and segmental BF% measured by BIA₈ and DXA also showed a significant correlation (r > 0.820, p < 0.01). The estimated LST and BF% from BIA₈ in the total body and body segments were highly correlated with the DXA results, which indicated that the standing-posture 8-electrode bioelectrical impedance analysis may be used to derive reference measures of LST and BF% in Taiwanese male wrestlers.

Validity of segmental bioelectrical impedance analysis for estimating fat-free mass in children including overweight individuals

This study examined the validity of segmental bioelectrical impedance (BI) analysis for predicting the fat-free masses (FFMs) of whole-body and body segments in children including overweight individuals. The FFM and impedance (Z) values of arms, trunk, legs, and whole body were determined using a dual-energy X-ray absorptiometry and segmental BI analyses, respectively, in 149 boys and girls aged 6 to 12 years, who were divided into model-development (n = 74), cross-validation (n = 35), and overweight (n = 40) groups. Simple regression analysis was applied to (length)²/Z (BI index) for each of the whole-body and 3 segments to develop the prediction equations of the measured FFM of the related body part. In the model-development group, the BI index of each of the 3 segments and whole body was significantly correlated to the measured FFM (R² = 0.867-0.932, standard error of estimation = 0.18-1.44 kg (5.9%-8.7%)). There was no significant difference between the measured and predicted FFM values without systematic error. The application of each equation derived in the model-development group to the cross-validation and overweight groups did not produce significant differences between the measured and predicted FFM values and systematic errors, with an exception that the arm FFM in the overweight group was overestimated. Segmental bioelectrical impedance analysis is useful for predicting the FFM of each of whole-body and body segments in children including overweight individuals, although the application for estimating arm FFM in overweight individuals requires a certain modification.

Validation study of multi-frequency bioelectrical impedance with dual-energy X-ray absorptiometry among obese patients

BACKGROUND

Body mass index (BMI) is the most common parameter for classifying nutritional status. However, body composition (BC) may vary considerably among individuals with identical BMIs; consequently, we need to assess BC efficiently. Bariatric surgery is the most effective method for treating obesity. To improve quality assessment of postoperative weight loss, it is essential to assess BC. Multi-frequency bioelectrical impedance analysis (BIA) is a practical assessment instrument, though limited when applied among the obese population. Despite dual-energy X-ray absorptiometry (DXA) being the current reference standard, it has physical limitations which restrict its practical application. This study, therefore, sought to correlate the results of BC assessments of same patient population using BIA and DXA.

METHODS

This was a cross-sectional validation study with patients invited to undergo a multi-frequency BIA (Inbody 720®) and afterwards a DXA examination Statistical analyses were done using the intraclass correlation coefficient (ICC), paired t-test and the Bland-Altman plot analysis.

RESULTS

A total of 108 patients were randomly selected, with 73 meeting the criteria for study inclusion. Most were female (89%) and had an average BMI of 40.17 ± 4.08 kg/m(2). An almost perfect correlation of fat (kg) and fat-free mass (kg) was found in results from the BIA and DXA examination (ICC = 0.832 and ICC = 0.899, respectively). A substantial correlation was also found between the percentage of body fat (%BF) and the percentage of fat-free mass (%FFM). The comparison made between the BIA and DXA using the t-test showed significant differences between all parameters. The Bland-Altman plot showed that the BIA method tends to underestimate the FM and overestimate the LM measurements when compared with DXA.

CONCLUSION

BIA proved to be a safe alternative for assessing BC in clinically severely obese patients and thus provides a more accessible evaluation tool for this population. But, consideration should be given to the formula added to the BIA measurement, adjusting the values to differences observed in order to reduce errors when compared with the DXA measurements.

Accuracy of segmental bioelectrical impedance analysis for predicting body composition in pre- and postmenopausal women

This study aimed to compare the accuracy for predicting body composition using single-frequent segmental bioelectrical impedance analysis (BIA) between pre- and postmenopausal women. A total f 559 Japanese women aged 30-88yr were divided into 4 groups by questionnaire: natural menopause, pathological menopause, regular menstruation, or irregular menstruation. The measurement values by dual-energy X-ray absorptiometry were used as a reference of the body composition. In terms of the results, regardless of the menopausal status, BIA slightly but significantly overestimated the percentage of body fat (standard error of estimate: 5.3%-6.7%) and the leg lean soft tissue mass (LSTM; 5.1%-6.1%), and underestimated the LSTM in the whole body (6.2%-7.6%) and arm (2.8%-3.7%). The absolute values of the predictive error for leg LSTM were significantly higher in postmenopausal groups than in the premenopausal ones. The corresponding values for the whole body and arm LSTM, and the percentage of body fat were higher in premenopausal groups than in postmenopausal ones. In conclusion, the predictive accuracy of BIA for postmenopausal women is not inferior to that for premenopausal ones, unless we target the leg LSTM.

Association among body composition, muscle performance and functional autonomy in older adults

Introduction Decrease in muscle mass and increase in body fat are important changes that occur with aging. Strength decline and worse resistance to fatigue can lead to a decreased functional autonomy of the elderly. Objective The present study aimed to verify the existence of a relationship between body composition, muscle strength, lower limbs fatigue and functional autonomy in active elderly women. Materials and methods The sample consisted of 29 elderly women with a mean age of 68.2 (± 7.3) years. Body composition was analyzed by total and segmental bioelectrical impedance. Muscle fatigue was assessed using electromyography, through the analysis of median frequency and root mean square during a 60-second sustained isometric knee extension contraction, at 50% of the maximum voluntary isometric contraction. Functional autonomy was assessed by using the Latin American Development Group for Maturity (GDLAM) protocol. Results There were significant correlations between height and strength (r = 0.49), age and lean body mass (r = -0.42), body fat percentage (BF%) and GDLAM tests (r = 0.39-0.41). The lean body mass was positively correlated with strength (r = 0.55), but not with resistance to fatigue. Conclusion The lean body mass of the analyzed sample was found to be associated with the performance on the maximum strength test, but not with the performance on the resistance to fatigue test. This shows that these two parameters (strength and fatigue) are independent of one another. Elderly women with higher BF% showed worse performance on the GDLAM tests. This evidences that individuals with high adiposity levels tend to have a more limited functional autonomy.

Investigating the Dynamics of Supine Fluid Redistribution Within Multiple Body Segments Between Men and Women

While supine, fluid moves from the legs and accumulates in the chest and neck. However, patterns of rostral fluid shift are not clear. Furthermore, real-time measurement of neck fluid volume has not been investigated. The objective of this study was to investigate the dynamics of rostral fluid shift in men and women. We developed a bioelectrical impedance system to measure leg, abdominal, thoracic and neck fluid volumes (LFV, AFV, TFV, NFV) continuously. Forty healthy non-obese adults (20 men) lay supine for 90 min while fluid volumes were measured. After 90 min, a similar volume of fluid shifted out of the legs in both sexes (p = 0.079), but men accumulated more fluid in their thorax (63 ± 6 vs. 44 ± 11 ml, p = 0.016) and neck (17 ± 2 vs. 14 ± 1 ml, p = 0.029) than women. In both sexes, the increase in NFV caused a significant increase in neck circumference, which was greater in men (p = 0.009). Furthermore, 80% of rostral fluid shift would occur in the first 2 h of lying supine. These results suggest that greater fluid shift into the thorax and neck may contribute to the higher prevalence of sleep apnea in men than in women.

Novel equations to predict body fat percentage of Brazilian professional soccer players: A case study

This study analyzed classical and developed novel mathematical models to predict body fat percentage (%BF) in professional soccer players from the South Brazilian region using skinfold thicknesses measurement. Skinfolds of thirty one male professional soccer players (age of 21.48 ± 3.38 years, body mass of 79.05 ± 9.48 kg and height of 181.97 ± 8.11 cm) were introduced into eight mathematical models from the literature for the prediction of %BF; these results were then compared to Dual-energy X-ray Absorptiometry (DXA). The classical equations were able to account from 65% to 79% of the variation of %BF in DXA. Statistical differences between most of the classical equations (seven of the eight classic equations) and DXA were found, rendering their widespread use in this population useless. We developed three new equations for prediction of %BF with skinfolds from: axils, abdomen, thighs and calves. Theses equations accounted for 86.5% of the variation in %BF obtained with DXA.

Factors influencing accuracy and reproducibility of body resistance measurements by foot-to-foot impedancemeters

The electronics of a BodySignal V2 (Tefal, France) foot-to-foot impedancemeter (FFI) was modified to display the foot-to-foot resistance instead of body fat. This device was connected to electrodes of different sizes mounted on a podoscope permitting photographs of subjects feet soles and electrodes in order to calculate the contact area between feet and electrodes. The foot-to-foot resistance was found to decrease when the contact area of feet with current and voltage electrodes increased. It was also sensitive to feet displacement and a backward move of 5 cm increased the mean resistance by 37 Ω. The resistance reproducibility was tested by asking the subject to repeat measurements 10-times by stepping up and down from the podoscope. The mean SD of these tests was 0.88% of mean resistance, but it fell to 0.47% when feet position was guided and to 0.29% with transverse voltage electrodes. For good reproducibility, it is important that voltage electrodes be small and that the scale design facilitates a correct position of heels on these electrodes.

The theory and fundamentals of bioimpedance analysis in clinical status monitoring and diagnosis of diseases

Bioimpedance analysis is a noninvasive, low cost and a commonly used approach for body composition measurements and assessment of clinical condition. There are a variety of methods applied for interpretation of measured bioimpedance data and a wide range of utilizations of bioimpedance in body composition estimation and evaluation of clinical status. This paper reviews the main concepts of bioimpedance measurement techniques including the frequency based, the allocation based, bioimpedance vector analysis and the real time bioimpedance analysis systems. Commonly used prediction equations for body composition assessment and influence of anthropometric measurements, gender, ethnic groups, postures, measurements protocols and electrode artifacts in estimated values are also discussed. In addition, this paper also contributes to the deliberations of bioimpedance analysis assessment of abnormal loss in lean body mass and unbalanced shift in body fluids and to the summary of diagnostic usage in different kinds of conditions such as cardiac, pulmonary, renal, and neural and infection diseases.

Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA), electrical impedance spectroscopy (EIS), electrical impedance plethysmography (IPG), impedance cardiography (ICG), and electrical impedance tomography (EIT) have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends.

The study of anthropometric estimates in the visceral fat of healthy individuals

Background

Abdominal visceral fat affects the metabolic processes, and is an important risk factor for morbidity and mortality. The purpose of the study was to develop a quick and accurate estimate in the visceral fat area (VFA) of the L4-L5 vertebrae using anthropometric predictor variables that can be measured conveniently.

Methods

A total of 227 individuals participated in this study and were further divided into a Modeling group (MG) and a Validation group (VG). Anthropometrics measurements (height, weight, waist circumference, hip circumference, age, and subcutaneous fat thickness) and VFA_CT were measured using computer assisted tomography for all participants. Multivariate linear regression analysis was applied to the MG to construct a VFA estimator using anthropometric predictor variables and to evaluate its performance using the VG.

Results

The estimate equation obtained from the MG were VFA_ANT = -144.66 + 1.84X₁ + 1.35X₂ + 0.52X₃ (r = 0.92, SEE =14.58 cm², P < 0.001, n = 152). The X₁, X₂, and X₃ variables in the equation were denoted as waist circumference (WC), age, and abdomen subcutaneous fat thickness (AS). In addition, the correlation between VFA_ANT and VFA_CT showed a high correlation (r = 0.92).

Conclusion

A rapid and accurate VFA estimation can be achieved by using only age, WC, and AS. The approach in the present study provides an easy and reliable estimate that can be applied widely in health and epidemiology studies.

Inter-electrode tissue resistance is not affected by tissue oedema when electrically stimulating the lower limb of sepsis patients

ICU patients typically are given large amounts of fluid and often develop oedema. The purpose of this study was to evaluate whether the oedema would change inter-electrode resistance and, thus, require a different approach to using non-invasive electrical stimulation of nerves to assess muscle force. Inter-electrode tissue resistance in the lower leg was measured by applying a 300 µs constant current pulse and measuring the current through and voltage across the stimulating electrodes. The protocol was administered to nine ICU patients with oedema, eight surgical patients without oedema and eight healthy controls. No significant difference in inter-electrode resistance was found between the three groups. For all groups, resistance decreased as stimulation current increased. In conclusion, inter-electrode resistance in ICU patients with severe oedema is the same as the resistance in regular surgical patients and healthy controls. This means that non-invasive nerve stimulation devices do not need to be designed to accommodate different resistances when used with oedema patients; however, surface stimulation does require higher current levels with oedema patients because of the increased distance between the skin surface and the targeted nerve or muscle.

Muscle performance, body fat, pain and function in the elderly with arthritis

Objective:

To correlate muscule performance, body composition, pain and joint function in elderly people with gonarthrosis.

Method:

21 elderly patients were submitted to bioelectrical impedance analysis, dynamometry associated with electromyographic (EMG) evaluation of isometric knee extension, in addition to pain assessment by the Numeric Pain Intensity Scale and function assessment, by the Western Ontario and McMaster Universities (WOMAC) Osteoarthritis (OA) questionnaire. Correlations were checked by the Pearson's correlation coefficient.

Results:

The sample characteristics were mean age 67.36 ± 4.21 years old, body fat percentage 40.57±6.15%, total WOMAC score 43.27 ± 16.32%, and maximum strength 19.95 ± 6.99 kgF. Pain during movement showed a statistical association with WOMAC physical activity domain (r = 0.47) and its general score (r = 0.51); pain intensity at night presented association with WOMAC stiffness domain (r = 0.55), in addition to the negative correlation with the slope values of the Medium Frequency of the EMG signal (r = - 0.57).

Conclusion:

pain intensity is correlated to functional incapacity in elderly people with knee OA and to a greater expression of fatigue in EMG signal. Levels of Evidence III, Study of non consecutive patients

Muscle strength and its relationship with skeletal muscle mass indices as determined by segmental bio-impedance analysis

PURPOSE

Despite increasing interest in bio-impedance analysis (BIA) for estimation of segmental skeletal muscle mass (SMM), published results have not been entirely convincing. Furthermore, a better understanding of the relationship between muscle strength and SMM will be useful in interpreting outcomes of physical/training interventions particularly in groups with diverse body sizes (e.g. men vs women). This study aimed to measure SMM in the upper body (upper extremity and torso), to determine its correlation with muscle strength and to examine the effects of gender on muscle strength-muscle mass relationship.

METHODS

Segmental (upper extremity and torso) SMM and muscle strength in five distinct shoulder planes (forward flexion, abduction in scapular plane, abduction in coronal plane, internal and external rotation) were measured in 45 healthy participants (22 males, 23 females) with mean age 30.3 years. Statistical analysis included independent t tests, Pearson correlation, and multiple regression analysis.

RESULTS

Men and women differed significantly in body mass (BMI: 25.9 ± 4.3 vs 23 ± 3.6) and SMM (p < 0.01). A strong relationship correlation was found between the five shoulder strength measurements and upper extremity SMM (r = 0.66-0.80, p < 0.01), which was not affected by gender. There was a significant gender difference (p < 0.01) in absolute shoulder strength, but not after normalisation to the SMM.

CONCLUSION

BIA-estimated SMM of upper extremity and torso was highly correlated with upper extremity (shoulder) strength independent of gender. SMM may, therefore, be useful for the normalisation of muscle strength allowing size-independent comparisons of muscle strength in individuals with diverse physical characteristics.

Accuracy of specific BIVA for the assessment of body composition in the United States population

Background

Bioelectrical impedance vector analysis (BIVA) is a technique for the assessment of hydration and nutritional status, used in the clinical practice. Specific BIVA is an analytical variant, recently proposed for the Italian elderly population, that adjusts bioelectrical values for body geometry.

Objective

Evaluating the accuracy of specific BIVA in the adult U.S. population, compared to the ‘classic’ BIVA procedure, using DXA as the reference technique, in order to obtain an interpretative model of body composition.

Design

A cross-sectional sample of 1590 adult individuals (836 men and 754 women, 21–49 years old) derived from the NHANES 2003–2004 was considered. Classic and specific BIVA were applied. The sensitivity and specificity in recognizing individuals below the 5^th and above the 95^th percentiles of percent fat (FM_DXA%) and extracellular/intracellular water (ECW/ICW) ratio were evaluated by receiver operating characteristic (ROC) curves. Classic and specific BIVA results were compared by a probit multiple-regression.

Results

Specific BIVA was significantly more accurate than classic BIVA in evaluating FM_DXA% (ROC areas: 0.84–0.92 and 0.49–0.61 respectively; p = 0.002). The evaluation of ECW/ICW was accurate (ROC areas between 0.83 and 0.96) and similarly performed by the two procedures (p = 0.829). The accuracy of specific BIVA was similar in the two sexes (p = 0.144) and in FM_DXA% and ECW/ICW (p = 0.869).

Conclusions

Specific BIVA showed to be an accurate technique. The tolerance ellipses of specific BIVA can be used for evaluating FM% and ECW/ICW in the U.S. adult population.

Efficacy of specific bioelectrical impedance vector analysis (BIVA) for assessing body composition in the elderly

OBJECTIVES

This study aimed to ascertain the efficacy of bioelectrical impedance vector analysis (BIVA) in assessing body composition in the elderly by comparing findings with the results of dual-energy X-ray absorptiometry (DXA), and to test an analytical variant of the method (specific BIVA).

DESIGN

Cross-sectional study.

PARTICIPANTS

The sample comprised 207 free-living elderly individuals (75 men and 132 women) aged 65 to 93 years.

MEASUREMENTS

Anthropometric and bioelectrical measurements were taken according to standard criteria. BIVA was applied using the 'classic' procedure and correcting bioelectrical values for body geometry to obtain an estimate of the whole-body impedivity. DXA was used as a reference body composition assessment method. BIVA (classic and specific values) and DXA findings were compared using Student's t and Hotelling's T2 tests, and Pearson's correlation coefficient.

RESULTS

In both sexes, BIVA distinguished between individuals with different amounts of fat and fat-free mass (lean mass including bone mineral content), according to DXA, but not between those with different proportions of fat mass (FM%). Specific bioelectrical values detected changes in body composition.

CONCLUSION

BIVA should be used with caution for evaluating body composition in the elderly. Specific bioelectrical values proved effective, showing promise as a methodological variant of BIVA, suitable for identifying age-related changes in body fatness.

Late evening snack: exploiting a period of anabolic opportunity in cirrhosis

BACKGROUND AND AIM

Cirrhosis is a state of accelerated starvation with impaired protein synthesis. Increased rate of gluconeogenesis and alterations in skeletal muscle signaling pathways result in anabolic resistance and consequent loss of muscle mass or sarcopenia in cirrhosis. Late evening snack (LES) is an intervention to reduce the postabsorptive (fasting) phase with the potential to improve substrate utilization and reverse sarcopenia. Published reports were evaluated to examine the effect of LES on regulation of substrate utilization (short-term studies) and nutritional outcomes (long-term studies).

METHODS

PubMed, EMBASE, Google scholar and OVID databases were searched. All studies published on LES in cirrhosis were included. Studies that included few (n < 3) subjects and patients with hepatocellular carcinoma were excluded.

RESULTS

Late evening snack decreased lipid oxidation and improved nitrogen balance, irrespective of the composition or type of formulation used. Daytime isocaloric isonitrogenous snacks did not have the metabolic or clinical benefit of LES. LES decreased skeletal muscle proteolysis. No studies have examined its effect on muscle protein synthesis. There was inconsistent translation into an increase in lean body or skeletal muscle mass. Improved quality of life occurs but decreased mortality or need for transplantation has not been reported. The optimal composition of LES has not been defined, but based on mechanistic considerations, a branched chain supplemented LES holds most promise.

CONCLUSIONS

Late evening snack holds the most promise as an intervention to reverse anabolic resistance and sarcopenia of cirrhosis with improved quality of life in patients with cirrhosis. Long term benefit and improved survival need critical evaluation.

Estimation of normal hydration in dialysis patients using whole body and calf bioimpedance analysis

Prescription of an appropriate dialysis target weight (dry weight) requires accurate evaluation of the degree of hydration. The aim of this study was to investigate whether a state of normal hydration (DW(cBIS)) as defined by calf bioimpedance spectroscopy (cBIS) and conventional whole body bioimpedance spectroscopy (wBIS) could be characterized in hemodialysis (HD) patients and normal subjects (NS). wBIS and cBIS were performed in 62 NS (33 m/29 f) and 30 HD patients (16 m/14 f) pre- and post-dialysis treatments to measure extracellular resistance and fluid volume (ECV) by the whole body and calf bioimpedance methods. Normalized calf resistivity (ρ(N)(,5)) was defined as resistivity at 5 kHz divided by the body mass index. The ratio of wECV to total body water (wECV/TBW) was calculated. Measurements were made at baseline (BL) and at DW(cBIS) following the progressive reduction of post-HD weight over successive dialysis treatments until the curve of calf extracellular resistance is flattened (stabilization) and the ρ(N)(,5) was in the range of NS. Blood pressures were measured pre- and post-HD treatment. ρ(N)(,5) in males and females differed significantly in NS. In patients, ρ(N)(,5) notably increased with progressive decrease in body weight, and systolic blood pressure significantly decreased pre- and post-HD between BL and DW(cBIS) respectively. Although wECV/TBW decreased between BL and DW(cBIS), the percentage of change in wECV/TBW was significantly less than that in ρ(N)(,5) (-5.21 ± 3.2% versus 28 ± 27%, p < 0.001). This establishes the use of ρ(N)(,5) as a new comparator allowing a clinician to incrementally monitor removal of extracellular fluid from patients over the course of dialysis treatments. The conventional whole body technique using wECV/TBW was less sensitive than the use of ρ(N)(,5) to measure differences in body hydration between BL and DW(cBIS).