Body water distribution in severe obesity and its assessment from eight-polar bioelectrical impedance analysis

Pulmonary diffusing capacity for nitric oxide during exercise in morbid obesity

Morbidly obese individuals may have altered pulmonary diffusion during exercise. The purpose of this study was to examine pulmonary diffusing capacity for nitric oxide (DLNO) and carbon monoxide (DLCO) during exercise in these subjects. Ten morbidly obese subjects (age = 38 +/- 9 years, BMI = 47 +/- 7 kg/m(2), peak oxygen consumption or VO(2peak) = 2.4 +/- 0.4 l/min) and nine nonobese controls (age = 41 +/- 9 years, BMI = 23 +/- 2 kg/m(2), VO(2peak) = 2.6 +/- 0.9 l/min) participated in two sessions: the first measured resting O(2) and VO(2peak) for determination of wattage equating to 40, 75, and 90% oxygen uptake reserve (VO(2)R). The second session measured pulmonary diffusion from single-breath maneuvers of 5 s each, as well as heart rate (HR) and VO(2) over three workloads. DLNO, DLCO, and pulmonary capillary blood volume were larger in obese compared to nonobese groups (P <or= 0.06) only when expressed relative to alveolar volume (VA). The slope between VO(2) and all measures of pulmonary diffusion, whether or not expressed to VA, were not different between groups (P > 0.10). The morbidly obese have increased pulmonary diffusion per unit increase in VA compared with nonobese controls which may be due to a lower rise in VA per unit increase in VO(2) in the obese during exercise.

Multifrequency bioelectrical impedance analysis and bioimpedance spectroscopy for monitoring fluid and body cell mass changes after gastric bypass surgery

BACKGROUND & AIMS

There is a growing need for clinically applicable body composition assessment tools for extremely obese individuals. The objective of this research was to evaluate several bioimpedance techniques for monitoring changes in fluid, particularly intracellular water (reflecting body cell mass) after bariatric surgery.

DESIGN

Fifteen extremely obese women (body mass index: 48.9+/-7.0 kg/m(2); age: 48+/-9 years) were assessed before (baseline; T1), and approximately 6 weeks after gastric bypass surgery (T2) by several multifrequency bioelectrical impedance analysis approaches (MFBIA; QuadScan 4000), a bioimpedance spectroscopy device (BIS; Hydra 4200), and multiple dilution.

RESULTS

BIS provided intracellular water estimates that were comparable to criterion, based on mean comparisons, at both time points (T1: criterion: 24.2+/-3.1L, BIS: 24.0+/-3.7 L; T2: criterion: 20.6+/-3.7 L, BIS: 19.7+/-3.2L). MFBIA (with Deurenberg equations) provided comparable measures to criterion only at T2 (criterion: 20.3+/-3.7L, MFBIA: 20.6+/-2.7 L). Both MFBIA (with QuadScan proprietary equations) and BIS produced estimates of intracellular water change that were comparable to dilution. There was substantial variability in individual volume measures.

CONCLUSIONS

Although MFBIA and BIS hold promise as convenient techniques for assessing fluid changes, individual variability in measurements makes them impractical for assessment of extremely obese patients in the clinical setting.

Risk factors for bone mineral density at the calcaneus in 40-59 year-old male workers: a cross-sectional study in Korea

Background

Few epidemiologic studies have attempted to investigate the prevalence and risk factors for osteopenia and osteoporosis in middle-aged Asian men. We performed this study to determine the prevalence and risk factors of osteopenia and osteoporosis in this population.

Methods

This cross-sectional study was conducted from March to July, 2004. The subjects were 2,073 males aged from 40 to 59 years in the KHNP (Korea Hydro & Nuclear Power) workplace-based cohort. Bone mineral density (BMD) was measured by peripheral, dual-energy, X-ray absorptiometry (DXA) at the calcaneus. Anthropometric and lifestyle factors were investigated using a standard, self-reported questionnaire.

Results

BMD was 0.60 ± 0.09 g/cm² (mean ± standard deviation) and was negatively correlated with age (r = -0.18, P < 0.001), but positively correlated with waist-to-hip ratio (WHR; r = 0.15, P < 0.001), body fat (r = 0.10, P < 0.001), BMI (r = 0.35, P < 0.001), height (r = 0.26, P < 0.001), and weight (r = 0.43, P < 0.001).

In multiple linear regression analysis, the independent determinants associated with BMD were increasing age (coefficient = -0.002, P < 0.001), physical activity (≤ 2/week vs. ≥ 3/week; coefficient = 0.017, P < 0.001), WHR (coefficient = -0.796, P < 0.001), body mass index (BMI; coefficient = 0.023, P < 0.001) and smoking status (never vs. ever; coefficient = -0.018, P < 0.001).

Conclusion

We suggest that BMD of the calcaneus is correlated negatively with exposure to smoke and increased WHR, but positively with regular exercise and increased BMI.

Cross-validation of bioelectrical impedance analysis for the assessment of body composition in a representative sample of 6- to 13-year-old children

BACKGROUND/OBJECTIVES

(1) To cross-validate tetra- (4-BIA) and octopolar (8-BIA) bioelectrical impedance analysis vs dual-energy X-ray absorptiometry (DXA) for the assessment of total and appendicular body composition and (2) to evaluate the accuracy of external 4-BIA algorithms for the prediction of total body composition, in a representative sample of Swiss children.

SUBJECTS/METHODS

A representative sample of 333 Swiss children aged 6-13 years from the Kinder-Sportstudie (KISS) (ISRCTN15360785). Whole-body fat-free mass (FFM) and appendicular lean tissue mass were measured with DXA. Body resistance (R) was measured at 50 kHz with 4-BIA and segmental body resistance at 5, 50, 250 and 500 kHz with 8-BIA. The resistance index (RI) was calculated as height(2)/R. Selection of predictors (gender, age, weight, RI4 and RI8) for BIA algorithms was performed using bootstrapped stepwise linear regression on 1000 samples. We calculated 95% confidence intervals (CI) of regression coefficients and measures of model fit using bootstrap analysis. Limits of agreement were used as measures of interchangeability of BIA with DXA.

RESULTS

8-BIA was more accurate than 4-BIA for the assessment of FFM (root mean square error (RMSE)=0.90 (95% CI 0.82-0.98) vs 1.12 kg (1.01-1.24); limits of agreement 1.80 to -1.80 kg vs 2.24 to -2.24 kg). 8-BIA also gave accurate estimates of appendicular body composition, with RMSE < or = 0.10 kg for arms and < or = 0.24 kg for legs. All external 4-BIA algorithms performed poorly with substantial negative proportional bias (r> or = 0.48, P<0.001).

CONCLUSIONS

In a representative sample of young Swiss children (1) 8-BIA was superior to 4-BIA for the prediction of FFM, (2) external 4-BIA algorithms gave biased predictions of FFM and (3) 8-BIA was an accurate predictor of segmental body composition.

Ability of new octapolar bioimpedance spectroscopy analyzers to predict 4-component-model percentage body fat in Hispanic, black, and white adults

BACKGROUND

New, vertical, 8-electrode bioimpedance spectroscopy (BIS) analyzers provide detailed body-composition and nutritional information within 2 min. This is the first report on BIS's accuracy in predicting relative fatness [percentage body fat (%BF)] in a heterogeneous sample according to a multicomponent model criterion.

OBJECTIVE

We compared %BF measurements from 2 BIS devices with those from a multicomponent model in a sample of Hispanic, black, and white adults.

DESIGN

Equal numbers of apparently healthy men and women (n = 75 of each) from each racial-ethnic group, diverse in body mass index and age, volunteered. Reference %BF (%BF(4C)) was computed by using a 4-component (4C) model with total bone mineral content obtained from dual-energy X-ray absorptiometry, body density from underwater weighing with measured residual lung volume, and total body water from traditional BIS. Estimations from InBody 720 (%BF(720)) and InBody 320 (%BF(320)) BIS analyzers were validated against %BF(4C).

RESULTS

The %BF(720) (r = 0.85, SEE = 5.19%BF) and %BF(320) (r = 0.84, SEE = 5.17%BF) correlations were significant (P < 0.05) in the men; main effects were nonsignificant. Correlations for %BF(720) (r = 0.88, SEE = 4.85%BF) and %BF(320) (r = 0.89, SEE = 4.82%BF) also were significant in the women (P < 0.05); there was a main effect for method but not race-ethnicity. There were no sex-specific overestimations or underestimations at the extremes of the distributions.

CONCLUSIONS

BIS estimates of %BF(4C) were well correlated in men and women. There were no significant methodologic differences in the men. The %BF(4C) was significantly underestimated by %BF(720) and %BF(320) in the women.

Effects of functional electrical stimulation on peak torque and body composition in patients with incomplete spinal cord injury

The aim of this study was to investigate the change in body composition, leg girths, and muscle strength of patients with incomplete spinal cord injury (SCI) after functional electrical stimulation cycling exercises (FESCE). Eighteen subjects with incomplete SCI were recruited. Each patient received FESCE three times per week for 8 weeks. Body composition, thigh and calf girths of bilateral legs, muscle strength of bilateral knee flexors and extensors were measured before and after 4 and 8 weeks of FESCE. A significant increase in bilateral thigh girth after 4 weeks of FESCE and significant increase in muscular peak torque of knee flexion and extension were found after 8 weeks of training. Besides, lean body mass increased significantly after complete treatment. FESCE can increase the thigh girth and muscular peak torque of patients with incomplete spinal cord injury.

Birth size, adult body composition and muscle strength in later life

OBJECTIVE

Low birth weight has been linked to lower lean body mass and abdominal obesity later in life, whereas high birth weight has been suggested to predict later obesity as indicated by high body mass index (BMI). We examined how birth weight was related to adult body size, body composition and grip strength.

DESIGN/SUBJECTS

Cross-sectional study on 928 men and 1075 women born in 1934-1944, with measurements at birth recorded.

MEASUREMENTS

Height, weight, waist and hip circumference and isometric grip strength were measured. Lean and fat body mass were estimated by bioelectrical impedance with an eight-polar tactile electrode system.

RESULTS

A 1 kg increase in birth weight corresponded in men to a 4.1 kg (95% CI: 3.1, 5.1) and in women to a 2.9 kg (2.1, 3.6) increase in adult lean mass. This association remained significant after adjustment for age, adult body size, physical activity, smoking status, social class and maternal size. Grip strength was positively related to birth weight through its association with lean mass. The positive association of birth weight with adult BMI was explained by its association with lean mass. Low birth weight was related to higher body fat percentage only after adjustment for adult BMI. Abdominal obesity was not predicted by low birth weight.

CONCLUSIONS

Low birth weight is associated with lower lean mass in adult life and thus contributes to the risk of relative sarcopenia and the related functional inability at the other end of the lifespan. At a given level of adult BMI, low birth weight predicts higher body fat percentage.

Waist-to-Hip Ratio Is Associated With Pulmonary Gas Exchange in the Morbidly Obese

BACKGROUND

Morbidly obese individuals (ie, body mass index [BMI], > or = 40 kg/m2) may have a pulmonary gas exchange impairment due to the large fat mass surrounding their abdomen.

PURPOSES

To examine the effect of the waist-to-hip (W/H) ratio on pulmonary gas exchange in the morbidly obese.

METHODS

Twenty-five morbidly obese individuals (mean [+/- SD] age, 39 +/- 10 years; mean BMI, 49 +/- 7 kg/m2; mean body fat, 50 +/- 6%; mean waist circumference, 135 +/- 15 cm; mean W/H ratio, 0.97 +/- 0.11) scheduled for bariatric surgery were recruited. Arterial blood was sampled in duplicate after 5 min of rest sitting upright.

RESULTS

The mean PaO2 at rest was 88 +/- 7 mm Hg (range, 72 to 108 mm Hg), the alveolar-arterial oxygen pressure difference (P[A-a]O2) was 19 +/- 9 mm Hg (range, 1 to 37 mm Hg), and the PacO2 was 38 +/- 3 mm Hg (range, 32 to 44 mm Hg). Linear regression showed that 32% and 36%, respectively, of the variance in the P(A-a)O2 and PaO2 were explained by the W/H ratio (p < 0.004 for both). As well, 20% of the variance in PacO2 was explained by the W/H ratio (p = 0.02). Men had larger W/H ratios (p < 0.01) and poorer gas exchange (p = 0.06) compared to women (mean difference: PaO2, -7 mm Hg; P[A-a]O2, 6 mm Hg).

CONCLUSION

Morbidly obese men showed a trend to have poorer pulmonary gas exchange compared to morbidly obese women, and a significant part of the blood gas status in these patients is associated with the W/H ratio.

Accuracy of eight-polar bioelectrical impedance analysis for the assessment of total and appendicular body composition in peritoneal dialysis patients

OBJECTIVE

To establish the accuracy of bioelectrical impedance analysis (BIA) for the assessment of total and appendicular body composition in peritoneal dialysis (PD) patients.

DESIGN

Cross-sectional study.

SETTING

University Nephrology Clinic.

SUBJECTS

In all, 20 PD patients and 77 healthy controls matched for gender, age and body mass index.

METHODS

Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by dual-energy X-ray absorptiometry. Resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz. Whole-body resistance was calculated as the sum of R of arms, trunk and legs. The resistance index (RI) was calculated as the ratio between squared height and whole-body or segmental R.

RESULTS

RI at 500 kHz was the best predictor of FFM, LTM(arm) and LTM(leg) in both PD patients and controls. Equations developed on controls overestimated FFM and LTM(arm) and underestimated LTM(leg) when applied to PD patients. Specific equations were thus developed for PD patients. Using these equations, the percent root mean-squared errors of the estimate for PD patients vs controls were 5 vs 6% for FFM, 8 vs 8% for LTM(arm) and 7 vs 8% for LTM(leg).

CONCLUSION

Eight-polar BIA offers accurate estimates of total and appendicular body composition in PD patients, provided that population-specific equations are used.