Measurement Of Total Body Water Research Articles

Assessment of the performance of the body mass index in diagnosing obesity in community-dwelling older adults in Latin American and Caribbean countries

BackgroundThe body mass index (BMI) ≥30 kg/m2 is the universally accepted cut-off point for defining obesity; however, its accuracy in classifying obesity in older adults is poorly understood. ObjectivesTo assess the performance of the BMI cut-off point ≥30 kg/m2 in classifying obesity in older adults, using the fat mass index (FMI) and fat mass percentage (FM%) as reference criteria; and to establish region- and sex-specific BMI-based cut-off points to classify obesity in older adults. MethodsThe present study is a secondary analysis derived from a cross-sectional project that included a sample of 1463 older adults from ten Latin American and Caribbean countries. Volunteers underwent total body water measurements using the deuterium dilution technique to determine FMI and FM%. Accuracy of the BMI and derived cutoff points was assessed by the area under the receiver operating characteristic curve (AUC). ResultsThe BMI cut-off point ≥30 kg/m2 had low sensitivity for classifying obesity in these older adults compared to the FMI and FM%. The AUC values for the optimal BMI-derived cut-off points showed an acceptable-to-outstanding discriminatory capacity in diagnosing obesity defined by the FMI. There was also a better balance between sensitivity and specificity than with the values obtained by a BMI ≥30 kg/m2 in older subjects in both regions. ConclusionThe BMI cut-off point ≥30 kg/m2 had poor sensitivity for accurately diagnosing obesity in older adults from two regions. The region- and sex-specific BMI-derived cut-off points for defining obesity using the FMI are more accurate in classifying obesity in older men and women subjects from both regions.

Body composition from birth to 2 years.

Providing all infants with the best start to life is a universal but challenging goal for the global community. Historically, the size and shape of infants, quantified by anthropometry and commencing with birthweight, has been the common yardstick for physical growth and development. Anthropometry has long been considered a proxy for nutritional status during infancy when, under ideal circumstances, changes in size and shape are most rapid. Developed from data collected in the Multicentre Growth Reference Study (MGRS), WHO Child Growth Standards for healthy infants and children have been widely accepted and progressively adopted. In contrast, and somewhat surprisingly, much less is understood about the 'quality' of growth as reflected by body composition during infancy. Recent advances in body composition assessment, including the more widespread use of air displacement plethysmography (ADP) across the first months of life, have contributed to a progressive increase in our knowledge and understanding of growth and development. Along with stable isotope approaches, most commonly the deuterium dilution (DD) technique, the criterion measure of total body water (TBW), our ability to quantify lean and fat tissue using a two-compartment model, has been greatly enhanced. However, until now, global reference charts for the body composition of healthy infants have been lacking. This paper details some of the historical challenges associated with the assessment of body composition across the first two years of life, and references the logical next steps in growth assessments, including reference charts.

Comparison of Bioelectrical Impedance Indices for Skeletal Muscle Mass and Intracellular Water Measurements of Physically Active Young Men and Athletes

BackgroundBioelectrical impedance analysis (BIA) is a minimally invasive, safe, easy, and quick technology used to determine body composition. ObjectivesWe compared the relationship among impedance indices obtained using single-frequency BIA, multi-frequency BIA, bioelectrical impedance spectroscopy (BIS), and skeletal muscle mass (SMM) of physically active young men and athletes using the creatine (methyl-d3) dilution method. We also compared the SMM and intracellular water (ICW) of athletes and active young men measured using a reference stable isotope dilution and BIS method, respectively. MethodsWe analyzed data from 28 men (mean age, 20 ± 2 y) who exercised regularly. Single-frequency BIA at 5 kHz and 50 kHz (R5 and R50), multi-frequency BIA (R250–5), and BIS (RICW) methods of determining the SMM were compared. The deuterium and sodium bromide dilution methods of obtaining the total body water, ICW, and extracellular water measurements were also used, and the results were compared to those acquired using bioimpedance methods. ResultsThe correlation coefficients between SMM and L2/R5, L2/R50, L2/R250–5, and L2/RICW were 0.738, 0.762, 0.790, and 0.790, respectively (P < 0.01). The correlation coefficients between ICW and L2/R5, L2/R50, L2/R250–5, and L2/RICW were 0.660, 0.687, 0.758, and 0.730, respectively (P < 0.001). However, the correlation coefficients of L2/R50, L2/R250–5, and L2/RICW for SMM and ICW were not significantly different. ConclusionsOur findings suggest that single-frequency BIA at L2/R50, multi-frequency BIA, and BIS are valid for assessing the SMM of athletes and active young men. Additionally, we confirmed that the SMM and ICW were correlated with single-frequency BIA, multi-frequency BIA, and BIS. Bioimpedance technologies may be dependable and practical means for assessing SMM and hydration compartment status of active young adult males; however, cross-validation is needed.

Validity of total body water measured by multi-frequency bioelectrical impedance devices in a multi-ethnic sample

Total body water (TBW) is the largest component of fat free mass and therefore is commonly used in multi-compartment body composition models and as a stand-alone method to assess body composition. Previous literature has not validated bioelectrical impedance spectroscopy device estimates of TBW in racial and ethnic minority populations; previous studies have focused on bioelectrical impedance analysis devices that rely on proprietary algorithms and participant characteristics for accuracy. The purpose of this study was to assess the validity of two bioelectrical impedance spectroscopy devices for measures of TBW compared to a deuterium dilution criterion in a multi-ethnic sample. 109 individuals (55% female, Age: 26.6±6.9yrs, BMI: 25.3±4.0kg/m2) identifying as Asian, African American/Black, Caucasian/White, Hispanic, and Multi-racial were enrolled. After a 12h fast, participants provided a saliva sample for the criterion baseline TBW measure and completed two bioelectrical impedance device (BIS, IB) measurements of TBW. Participants then ingested deuterium oxide (D2O). After an equilibration period, participants provided a second saliva sample for analysis of TBW. For the total multi-ethnic sample, BIS estimates demonstrated good to fairly good agreement (Total error [TE]=2.56L, R2=0.951) and IB estimates were excellent to very good (TE=1.95L, R2=0.975). Validity results did not vary meaningfully between race and ethnicity. The results suggest the BIS and IB devices evaluated can produce valid TBW estimates compared to D2O in a multi-ethnic sample. TBW estimates from the IB may have better agreement with D2O compared to the BIS when using the default settings.

Agreement and Precision of Deuterium Dilution for Total Body Water and Multicompartment Body Composition Assessment in Collegiate Athletes

BackgroundDeuterium oxide (D2O) dilution is the criterion method for total body water (TBW) measurement, but results may vary depending on the specimen type, analysis method, and analyzing laboratory. Bioelectrical impedance (BIA) estimates TBW, but results may vary by device make and model. ObjectivesWe investigated the accuracy and precision of TBW estimates and how measurement conditions affected the accuracy of body composition using multicompartment body composition models. MethodsEighty collegiate athletes received duplicate TBW measures acquired from 3 BIA devices (S10, SFB7, and SOZO) and from unique D2O combinations of specimen type (saliva, urine), analysis methodology [Fourier transform infrared spectrophotometry (FTIR), isotope-ratio mass spectrometry (IRMS)], and 3 different laboratories. TBW measures were substituted into 2-compartment (2C) and 5-compartment (5C) body composition models. Criterion measures were compared using Lin’s concordance correlation coefficient cutoff of poor (<0.90), moderate (0.90–0.95), substantial (0.95–0.99), and almost perfect (>0.99). ResultsFifty-one participants (26 female) completed the protocol. Using IRMS saliva as the criterion TBW, all other measures produced a substantial or almost perfect agreement, except for SFB7 (poor) and SOZO (moderate). The 2C body composition measures using D2O and BIA produced poor agreement except for moderate agreement for lab 3 FTIR saliva. The 5C body composition measures using D2O produced a substantial agreement, whereas the BIA device S10 and SOZO had a moderate agreement, while the SFB7 had a poor agreement to the criterion. Test–retest precision varied between techniques from 0.3% to 1.2% for TBW. ConclusionsSmall differences in TBW measurement led to significant differences in 2C models. The 5C models partially mitigate differences seen in 2C models when different TBW measures are used. Interchanging TBW measures in multicompartment models can be problematic and should be performed with these considerations.

Estimation of fluid status using three multifrequency bioimpedance methods in hemodialysis patients.

Segmental eight-point bioimpedance has been increasingly used in practice. However, whether changes in bioimpedance analysis components before and after hemodialysis (HD) using this technique in a standing position is comparable to traditional whole-body wrist-to-ankle method is still unclear. We aimed to investigate the differences between two eight-point devices (InBody 770 and Seca mBCA 514) and one wrist-to-ankle (Hydra 4200) in HD patients and healthy subjects in a standing position. Thirteen HD patients were studied pre- and post-HD, and 12 healthy subjects once. Four measurements were performed in the following order: InBody; Seca; Hydra; and InBody again. Electrical equivalent models by each bioimpedance method and the fluid volume estimates by each device were also compared. Overall, total body water (TBW) was not different between the three devices, but InBody showed lower extracellular water (ECW) and higher intracellular water (ICW) compared to the other two devices. When intradialytic weight loss was used as a surrogate for changes in ECW (∆ECW) and changes in TBW (∆TBW), ∆ECW was underestimated by Hydra (-0.79 ± 0.89 L, p < 0.01), InBody (-1.44 ± 0.65 L, p < 0.0001), and Seca (-0.32 ± 1.34, n.s.). ∆TBW was underestimated by Hydra (-1.14 ± 2.81 L, n.s.) and InBody (-0.52 ± 0.85 L, p < 0.05) but overestimated by Seca (+0.93 ± 3.55 L, n.s.). Although segmental eight-point bioimpedance techniques provided comparable TBW measurements not affected by standing over a period of 10-15 min, the ECW/TBW ratio appeared to be significantly lower in InBody compared with Seca and Hydra. Results from our study showed lack of agreement between different bioimpedance devices; direct comparison of ECW, ICW, and ECW/TBW between different devices should be avoided and clinicians should use the same device to track the fluid status in their HD population in a longitudinal direction.

Accuracy of body composition measurement techniques across the age span.

This study investigated the acceptable accuracy of common body composition techniques compared with the reference 4-compartment (4C-R) model, which has not been investigated in a sample with diverse characteristics, including age and sex. Techniques included components of the 4C-R model [dual-energy X-ray absorptiometry, air displacement plethysmography, deuterium dilution (DD)] and surrogate compartment models, which utilised bioelectrical impedance spectroscopy (BIS) rather than DD. Men and women (sex = 1:1, 18-85 years, n = 90) completed body composition testing under best-practice guidance. For measurement of individuals, only the reference 3-compartment (3C-R) equation met acceptable error limits (<5% error among individuals) within the a priori cut-point (80%) for fat-free mass (FFM; CV = 0.52%) and fat mass (FM; CV = 1.61%). However, all investigated techniques reached equivalency to the 4C-R model for FFM on average (CV = 0.52-4.31%), but for FM only the 3C and 4C equations that included quantification of total body water (TBW) by DD or BIS reached equivalency overall (CV = 1.61-6.68%). Sex and age minimally influenced accuracy. Only the 3C-R or 4C-R equations are supported for acceptable individual accuracy for both FFM and FM. For group estimates any investigated technique could be used with acceptable accuracy for FFM; however, for FM, inclusion of TBW measurement within a compartment model is necessary. Novelty: Only the referent 3C and 4C models (including deuterium dilution) provide accurate body composition results that are acceptable for measurement of individuals in the general population. For group estimates of lean mass in the general population, compartments models that include TBW must be used for accurate measurement.

Agreement Between A 2-Dimensional Digital Image-Based 3-Compartment Body Composition Model and Dual Energy X-Ray Absorptiometry for The Estimation of Relative Adiposity

The purpose of this study was to compare relative adiposity (%Fat) derived from a 2-dimensional image-based 3-component (3C) model (%Fat3C-IMAGE) and dual-energy X-ray absorptiometry (DXA) (%FatDXA) against a 5-component (5C) laboratory criterion (%Fat5C). 57 participants were included (63.2% male, 84.2% White/Caucasian, 22.5±4.7 yrs., 23.9±2.8 kg/m2). For each participant, body mass and standing height were measured to the nearest 0.1 kg and 0.1 cm, respectively. A digital image of each participant was taken using a 9.7 inch, 16g iPad Air 2 and analyzed using a commercially available application (version 1.1.2, made Health and Fitness, USA) for the estimation of body volume (BV) and inclusion in %Fat3C-IMAGE . %Fat3C-IMAGE and %Fat5C included measures of total body water derived from bioimpedance spectroscopy. The criterion %Fat5C included BV estimates derived from underwater weighing and bone mineral content measures via DXA. %FatDXA estimates were calculated from a whole-body DXA scan. A standardized mean effect size (ES) assessed the magnitude of differences between models with values of 0.2, 0.5, and 0.8 for small, moderate, and large differences, respectively. Data are presented as mean ± standard deviation. A strong correlation (r = 0.94, p <.001) and small mean difference (ES = 0.24, p <.001) was observed between %Fat3C-IMAGE (19.20±5.80) and %Fat5C (17.69±6.20) whereas a strong correlation (r = 0.87, p <.001) and moderate-large mean difference (ES = 0.70, p <.001) was observed between %FatDXA (22.01±6.81) and %Fat5C. Furthermore, %Fat3C-IMAGE (SEE = 2.20 %Fat, TE= 2.6) exhibited smaller SEE and TE than %FatDXA (SEE = 3.14 %Fat, TE = 5.5). The 3C image-based model performed slightly better in our sample of young adults than the DXA 3C model. Thus, the 2D image analysis program provides an accurate and non-invasive estimate of %Fat within a 3C model in young adults. Compared to DXA, the 3C image-based model allows for a more cost-effective and portable method of body composition assessment, potentially increasing accessibility to multi-component methods.

What Total Body Water Measurement Should Be Used for Prescribing the Dialysis Dose in Low-Flow Home Daily Dialysis?

Introduction: In low-flow home daily dialysis (HDD), the dialysis dose is evaluated from the total body water (TBW). TBW can be estimated by anthropometric methods or bioimpedance spectroscopy. Methods: A multicentric cross-sectional study of patients in HDD for >3 months was conducted to assess the correlation and the difference between the anthropometric estimate of TBW (Watson-TBW) and the bioimpedance estimate (BIS-TBW) and to analyse the impact on the dialysate volume prescribed. Results: Forty patients from 10 centres were included. The median BIS-TBW and Watson-TBW were 35.1 (29.1–41.4 L) and 36.9 (32–42.4 L), respectively. The 2 methods had a good correlation (r = 0.87, p < 0.05). However, Bland-Altman analysis showed an overestimation of TBW with Watson’s formula, with a bias of 2.77 L. For 4, 5, or 6 sessions per week, the use of Watson-TBW increases the dialysate prescription per week by 100 L, 45 L, or 10 L, respectively, over our entire cohort. There is no increase in the volume of dialysate prescribed with the 7 sessions per week schedule. Conclusion: BIS-TBW and Watson-TBW estimation have a good correlation; however, Watson’s equation overestimates TBW. This overestimation is negligible for a prescription frequency of >5 sessions per week.

Usefulness of foot-to-foot bioimpedance analysis for assessing volume status in chronic hemodialysis patients at the Aristide Le Dantec University Hospital (Senegal)

Introduction: Determination of dry weight is one of the daily goals to achieve in hemodialysis. The aim of this study was to validate the use of bioelectrical impedance analysis (BIA) in estimation of dry weight in a population of Senegalese chronic hemodialysis patients. Patients and methods: A 9-week cross-sectional study was carried out at the hemodialysis unit of Aristide Le Dantec University Hospital. Adult patients with no previous hospital history were included. The total body water (TBW) was measured with a single frequency bioelectric impedance foot-to-foot analyzer, before and after six successive hemodialysis sessions. These results were compared with those from clinical measurements with the Watson equation using a Student’s t-test and Bland-Altman analysis. Results: 264 measurements were made in 22 patients (46.6 years, 54.5% men, 92.3 months on dialysis, 62.7 kg mean dry weight). A significant reduction in weight (ΔWeight = 2.0 ± 1.1 kg; p &lt; 0.0001) and in TBW measured by the BIA (ΔTBWBIA = 3.3 ± 1.0 liters; p &lt; 0.0001)) or calculated by Watson’s equation (ΔTBWWatson = 0.5 ± 0.2 liter; p = 0.0001) was observed. There was a strong linear correlation and agreement between the 2 TBW measurements in pre-dialysis. In post-dialysis the concordance diagram indicated a bias = –2.2 and wide agreement limits. Conclusion: The BIA allows reproducible and reliable measurements and a fair estimate of the TBW in pre-dialysis.

The intracellular fluid compartment is smaller than commonly believed when measured by whole-body bioimpedance.

To report our data on the total body water (TBW), intracellular volume (ICV), extracellular volume (ECV), and fat-free mass (FFM) from studies using whole-body bioimpedance (BIA) with the aim of contrasting them to commonly cited reference values. Data were retrospectively retrieved from three single-center studies of adult healthy male volunteers and one study of women scheduled for abdominal hysterectomy where multifrequency BIA had been applied to obtain measurements of TBW, ICV, ECV, and FFM. Based on measurements performed in 44 males, the TBW, ICV, ECV, and FFM represented 49.1 (4.9)%, 23.32 (3.1)%, 25.8 (2.2)%, and 67.4 (7.4)% of the BW, respectively (mean, SD). In 15 females, these volumes were 40.4 (4.5)%, 18.0 (2.1)%, 22.4 (2.6)%, and 55.6 (6.1)% per kg BW, respectively. The deviation of these measurements from the reference values increased linearly with body weight and age. Body fluid volumes indicated by BIA showed that TBW amounted to 80% of the reference volume, which is 60% per kg BW in adult males. The ratio between the ICV and the ECV was approximately 1:1, while this ratio is traditionally reported to be 2:1.

Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy for the Quantitative Analysis of Deuterium in Plasma: Application to Total Body Water Determination in Humans and Other Animals.

Conventional methods for measuring the concentration of deuterium in body fluids are by either isotope ratio mass spectrometry or Fourier transform infrared transmission (FT-IR) spectroscopy. The latter method is often preferred as it is less expensive and time consuming; however, having a lower sensitivity means a larger sample volume is required. This study investigated an alternative FT-IR spectroscopic method, attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR), which has the potential to provide shorter analysis times while requiring smaller sample volumes. Deuterium was assayed using ATR FT-IR in plasma in the concentration range 0.5 to 2.5 mg mL-1, typical of those observed in tracer dilution measurements of total body water. Minimal sample preparation was required and analysis time was substantially decreased compared to transmission FT-IR. Samples were analyzed with high precision (coefficient of variation (CV) < 0.5%). Precision of assay was maintained when assaying plasma volumes of only 10 µL. The application of the method to the determination of total body water in humans and animals (horses) was demonstrated. A rapid and simple method for the measurement of deuterium in plasma is described that only requires very small sample volumes, rendering the method suitable for use in pediatrics where blood sampling is required to be kept to a minimum.

Total Body and Extracellular Water Measures Are Unrelated to Cramp Sensitivity in Euhydrated Cramp-Prone Individuals.

Earp, JE, Stearns, RL, Agostinucci, J, Lepley, AS, and Ward-Ritacco, CL. Total body and extracellular water measures are unrelated to cramp sensitivity in euhydrated cramp-prone individuals. J Strength Cond Res 36(9): 2653-2656, 2022-Spectral bioelectrical impedance analysis (BIA) is a valid and noninvasive tool for measuring total body water (TBW), intracellular water (ICW), and extracellular water (ECW). As altered hydration and electrolyte imbalance have been proposed as one of 2 etiologies for exercise-associated muscle cramps (EAMC), the purpose of this study was to determine if distribution of body water is related to cramp sensitivity in similarly hydrated cramp-prone individuals. To this end, 11 euhydrated subjects who regularly experience EAMC had their relative TBW, ICW, and ECW assessed using 8-pole spectral BIA. Subjects' cramp sensitivity was then assessed by electrically stimulating the tibial nerve at increasing frequencies until a muscle cramp occurred, allowing for the determination of the threshold frequency (TF) at which the cramp occurred. It was observed that TF was not significantly related to TBW ( r = 0.087, p = 0.368), ICW ( r = 0.105, p = 0.338), ECW ( r = 0.087, p = 0.368), or ECW:TBW ( r = 0.147, p = 0.280). As cramp etiology is poorly understood, these results add to a growing body of literature questioning the role of hydration and electrolyte imbalance in EAMC. Although fluid distribution may be unrelated to TF in those who commonly experience EAMC, additional research is needed to compare those who commonly experience cramps (athletes as well as individuals with specific neuropathies or pharmacologically induced cramps) with those who do not experience cramps and to determine if acute shifts in body water compartmentalization are related to changes in cramp sensitivity.

Quantification of body fluid compartmentalization by combined time-domain nuclear magnetic resonance and bioimpedance spectroscopy.

The measurement of fluid compartmentalization, or the distribution of fluid volume between extracellular (ECF) and intracellular (ICF) spaces, historically requires complicated, burdensome, and often terminal methodologies that do not permit repeated or longitudinal experiments. New technologies including time-domain nuclear magnetic resonance (TD-NMR)-based methods allow for highly accurate measurements of total body water (TBW) within minutes in a noninvasive manner, but do not permit dissection of ECF versus ICF reservoirs. In contrast, methods such as bioimpedance spectroscopy (BIS) allow dissection of ECF versus ICF reservoirs but are hampered by dependence on many nuanced details in data collection that undermine confidence in experimental results. Here, we present a novel combinatorial use of these two technologies (NMR/BIS) to improve the accuracy of BIS-based assessments of ECF and ICF, while maintaining the advantages of these minimally invasive methods. Briefly, mice undergo TD-NMR and BIS-based measures, and then fat masses as derived by TD-NMR are used to correct BIS outputs. Mice of the C57BL/6J background were studied using NMR/BIS methods to assess the effects of acute furosemide injection and diet-induced obesity on fluid compartmentalization, and to examine the influence of sex, body mass and composition, and diet on TBW, ECF, and ICF. We discovered that in mice, sex and body size/composition have substantial and interactive effects on fluid compartmentalization. We propose that the combinatorial use of NMR/BIS methods will enable a revisioning of the types of longitudinal, kinetic studies that can be performed to understand the impact of various interventions on body fluid homeostasis.

Validity Of Body Composition Measures By Inbody 770 Bioelectrical Impedance Analyzer

PURPOSE: To test the validity of InBody 770 bioimpedance analyzer (IB770) against isotope dilution (D2O) for total body water (TBW) and against DXA for percent body fat (PBF). METHODS: Fifty-eight apparently healthy women (mean age 21.2 ±2.6 years, BMI 26.7 ±6.3) visited the Exercise Science Physiology Laboratory at KSU after an overnight fast. Subjects were given a 10g deuterium oxide solution (Cambridge Laboratories) to drink within 5 minutes and were asked to remain still in a reclining chair for 4 hours before providing a urine sample. Subjects were assessed via DXA for PBF and IB770 for both TBW and PBF. Frozen urine samples were shipped to an external laboratory for TBW assessment by mass spectroscopy. One extreme outlier was excluded from analysis due to probable D2O measurement error. Correlation analyses were used to assess the validity of TBW and PBF measures from IB770 compared to those from D20 and DXA. RESULTS: TBW estimates from IB770 were similar to those from D20 (32.6 ±5.9 vs. 32.3 ±6.0, respectively). PBF estimates from IB770 were also consistent with those from DXA (35.1 ±9.1 vs. 35.8 ±8.5, respectively). T-tests indicated that there were no significant differences among these measures (p>0.05 for both). IB770 measures for TBW and PBF were strongly correlated with D20 (r=.976, p<0.001) and DXA (r=.961, p<0.001), respectively. CONCLUSIONS: These data suggest that IB770 is a valid method for estimating TBW and PBF and may be appropriate for use as an alternative to D20 and DXA in a young female population.

The impact of total body water on breath alcohol calculations.

SummaryDue to a legislative amendment in Austria to determine breath alcohol (BrAC) instead of blood alcohol (BAC) in connection with traffic offences, many results of blood alcohol calculations were simply converted using distinct conversion factors. In Austria, the transformation of BAC to BrAC was carried out by using a factor of 1:2000, which, however, is commonly known to be too low. Noticing the great demand for a calculation method that is not exclusively based on blood alcohol, a formula for calculating breath alcohol based on blood alcohol was published in 1989, but in which the body surface area (BSA) was considered the most important influencing variable. In order to refine this new method, a liquor intake experiment was conducted combined with measurements of total body water (TBW) as an additional variable, using hand to foot bioelectrical impedance assessment (BIA). The test group comprised 37 men and 40 women to evaluate the accuracy of TBW and BSA as an individual parameter for alcohol concentration. The correlation coefficient of BrAC with TBW was constantly higher than with BSA (maximum = 0.921 at 1 h and 45 min after cessation of alcohol intake). These results are valid for both men and women as well as in a gender independent calculation. Hence, for an accurate back calculation of BrAC adjusted values of eliminations rates had to be found. This study describes mean elimination rates of BrAC for both men (0.065 ± 0.011 mg/L h−1) and women (0.074 ± 0.017 mg/L h−1). As previously shown women displayed a significantly higher elimination rate than men (p = 0.006).

Hemodialysis patients with less extracellular water overload and smaller cardiac atrial chamber sizes are at greater risk of a fall in blood pressure during dialysis.

Intradialytic hypotension is the most common complication of hemodialysis (HD) treatments. Excessive ultrafiltration results in reduced cardiac preload. We aimed to determine whether a fall in systolic blood pressure during HD was greater in patients starting HD with (a) less overhydration measured by extracellular water (ECW) and (b) lower cardiac preload by cardiac magnetic resonance imaging (MRI). Pre-HD measurements of ECW and total body water (TBW) were performed using multifrequency bioimpedance (MFBIA). Cardiac chamber sizes and functions were determined by MRI. Twenty-six patients, 18 males (69.2%), 11 (42.3%) with diabetes, mean age 63.9 ± 15.9 years were studied. Systolic blood pressure (SBP) fell in 15 (57.7%) patients, and either did not change or increased in 9. There was no difference in demographics between groups. Patients with a fall in SBP had lower pre-HD ECW/TBW (0.400 ± 0.018 vs 0.418 ± 0.021), indexed right ventricular end-diastolic volume (81.2 ± 37.6 vs 100.8 ± 33.7 mL/m2 ), and indexed left atrial size (13.7 ± 3.9 vs 18.3 ± 5.0 mL/m2 ), all P < .05, respectively. There were univariate correlations between the change in SBP and pre-HD ECW/TBW for the trunk (r = .50, P = .009) and indexed left atrial volume (r = .54, P = .005). A fall in blood pressure occurred more commonly in patients starting HD with lower overhydration as measured by bioimpedance, and those with smaller cardiac chamber sizes. Patients with the lowest ECW/TBW and smallest cardiac chamber sizes had the greatest falls in SBP. This study reinforces the importance of determining physiological target weights and avoiding inappropriately low target weights for HD patients.

Relationships Between Measurements of Body Fat in Thoroughbred Horses

Equine obesity is increasing in prevalence, and weight loss diets are frequently recommended for these horses. However, there are also management situations in which horses are deemed to be too thin. To monitor the efficacy of weight change programs, estimates of body fat are often made. There are several systems available to estimate body fat, and there are benefits and challenges to using each method. The objective of this study was to compare four different methods of estimating body fat in Thoroughbred horses. In 14 mature Thoroughbred horses, relationships among body condition score (BCS), morphometric measurements, ultrasonic measures of subcutaneous fat depots, and estimation of total body fat (BFD) via measurement of total body water through deuterium oxide dilution were evaluated. Body condition scores ranged from 4.5 to 6.5 on a 9-point scale. Body condition score, heart girth-to-body weight ratio, and BFD were all positively correlated with each other (P < .05). Subcutaneous fat depth at the tailhead tended to be positively related to BFD when only horses with BCS ≥ 5 were included (P = .0680). These data suggest that BCS remains a simple means of monitoring adiposity in mature horses in moderate condition. Tailhead fat depots may become useful for monitoring changes in body fat in Thoroughbreds with a BCS above 5, although more work with animals of higher adiposity is required and at different times of year.

Skin tissue dielectric constant in women with high body fat content.

Skin tissue dielectric constant (TDC) measurements at a frequency of 300MHz are used to assess skin properties in many conditions. Impacts of patient obesity on these values are unknown, and its quantitative assessment was the goal of this research. Women in a weight loss program (N=32) had TDC measured on forearm, biceps, neck, jowl, and submental regions along with measurements of total body fat (TBF), water (TBW), intracellular water (ICW), and extracellular water (ECW) via multi-frequency bioimpedance. Group age (mean±SD) was 40.0±11.6years (20-70years) with body mass index (BMI) of 31.8±6.7Kg/m2 (23.0-49.9Kg/m2 ). For analysis, subjects were divided into those with BMI<30Kg/m2 (subgroup A, n=16) vs ≥30Kg/m2 (subgroup B, n=16). Tissue dielectric constant at forearm and biceps decreased significantly (P<.001) with increasing depth from 0.5 to 1.5 to 2.5mm but TDC values and their inter-side ratios did not differ between subgroups A and B at any measured site. Although correlations between TBW, ECW, and ICW were significant (P<.001), there was no dependence of TDC values on any of these parameters. Previously unknown TDC values for obese persons are provided and based on subgroup analyses suggest that skin TDC values in overweight and obese persons are not confounded by variables such as TBW and TBF. Further, since inter-side ratios and their SD's yielded thresholds for forearm and biceps similar to those established for women with normal BMI, use of these clinical inter-arm TDC ratios now is extended to include a wider BMI range.

Agreement between Deuterium Oxide and Bioimpedance Spectroscopy Measures of Total Body Water

Agreement between Deuterium Oxide and Bioimpedance Spectroscopy Measures of Total Body Water