Bioimpedance spectroscopy for clinical assessment of fluid distribution and body cell mass.

Body composition assessment has been used to evaluate clinical interventions in research trials, and has the potential to improve patient care in the clinical setting. Body cell mass (BCM) is an important indicator of nutrition status; however, its measurement in the clinic has been limited. BCM can be estimated by the measurement of intracellular water (ICW). The assessment of extracellular water (ECW) is also important because many clinical populations undergo alterations in fluid distribution, particularly individuals with wasting, those receiving dialysis, and obese individuals. Bioimpedance spectroscopy (BIS) is a unique bioimpedance approach that differs in underlying basis from the more readily recognized single-frequency bioelectrical impedance analysis (SF-BIA) in that it does not require the use of statistically derived, population-specific prediction equations. It has the potential advantage of not only measuring total body water (TBW), as does SF-BIA, but also offering the unique capacity to differentiate between ECW and ICW and, thus, to provide an estimate of BCM. This literature review was conducted to compare available BIS devices to multiple dilution for measuring fluid compartments or BCM in a number of populations. Variable results regarding the ability of BIS to measure absolute volumes, as well as the observation of wide limits of variation, make BIS problematic for individual assessment in the clinic, particularly in populations with abnormal fluid distribution or body geometry. BIS has been found to be more accurate for measuring changes in fluid volumes or BCM, particularly in post-surgical and human immunodeficiency virus (HIV)-infected individuals. It is certainly possible that population-specific adjustments may improve the accuracy of BIS for assessing individuals in the clinical setting; however, additional research and development is needed before the method can be accepted for routine clinical use.     

Effect of a moderately hypoenergetic Mediterranean diet and exercise program on body cell mass and cardiovascular risk factors in obese women

OBJECTIVE: To assess the effects of a moderately hypoenergetic Mediterranean diet (MHMD) and exercise program on body cell mass (BCM) and cardiovascular disease risk factors in obese women. SUBJECTS/METHODS: Forty-seven obese women, 39.7+/-13.2 years of age, with a body mass index (BMI)=30.7+/-6.0 kg/m(2), completed the study. The following were measured at baseline, 2 and 4 months: BCM, BCM index (BCMI), body weight, BMI, fat-free mass (FFM), fat mass (FM), total body water (TBW), extracellular water (ECW) and intracellular water (ICW) using bioelectrical impedance analysis; fasting blood glucose (FBG), serum total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C) and triglyceride (TG) concentrations; systolic (SBP) and diastolic (DBP) blood pressure. RESULTS: Body weight, BMI, FM, TC and TG significantly decreased (P<0.001; P<0.002 (TG)) at 2 and 4 months. FFM, TBW, ECW, FBG and DBP significantly decreased at 2 months (P<0.05 (FFM); P<0.001). LDL-C significantly decreased (P<0.001), while HDL-C significantly increased (P<0.002) at 4 months. BCM, BCMI, ICW and SBP remained stable over time. CONCLUSION: BCM was preserved and cardiovascular disease risk factors improved in obese women placed on a MHMD and exercise program for 4 months.     

Improvement of nutritional status as assessed by multifrequency BIA during 15 weeks of refeeding in adolescent girls with anorexia nervosa

In patients with anorexia nervosa (AN), an assessment of changes in body composition and nutritional status is crucial for adequate nutritional management during refeeding therapies. Phase-sensitive multifrequency bioelectrical impedance analysis (BIA) is an inexpensive and noninvasive technique with which to determine nutritional status and body composition. We investigated 21 female adolescents with AN (initial BMI 15.5 +/- 1.1 kg/m(2)) 4 times between wk 3 and 15 of inpatient refeeding and 19 normal-weight, age-matched female controls. From wk 3 to 15, BMI, fat mass, body cell mass (BCM), total body water (TBW), intracellular water (ICW) but not extracellular mass (ECM), and extracellular water (ECW) increased significantly. Reactance (Xc), phase angle (PhA), and the ECM/BCM index as parameters of nutritional status improved significantly in patients and no longer differed from controls in wk 15, although the BMI of patients was significantly lower than those of controls. Changes in the ECM/BCM index were due to accretion of BCM, which was associated with an increase of ICW. Multifrequency phase-sensitive BIA seems to be a promising tool for the assessment of changes in nutritional status and body composition in patients with AN. An individually determined and controlled hyperenergetic diet as part of a multidimensional, interdisciplinary treatment program for eating disorders seems to quickly improve the nutritional status of AN patients.     

Is resting metabolic rate different between men and women?

A low resting metabolic rate (RMR) has been proposed as a possible cause for the increased body fat commonly seen in women compared with men. Absolute RMR is higher in men, but whether RMR adjusted for lean body mass (LBM) remains higher is unresolved. The objective of the present study was to determine whether RMR adjusted for various body composition factors differed between healthy adult men and women. Thirty men years, BMI and twenty-eight women years, BMI were included in the analyses. RMR was measured by open-circuit indirect calorimetry for 60 min. Extracellular water (ECW) was measured by corrected Br(-) space and total body water (TBW) by 2H dilution. LBM was estimated as TBW/0.732. Intracellular water (ICW) was calculated as TBW-ECW, and body cell mass (BCM) as ICW/0.732. Men were heavier and had higher BMI, LBM, BCM and ECW, but less fat mass. Absolute RMR was higher in men than women v. P<0.0001). This difference became non-significant when RMR was adjusted for LBM by ANCOVA v. P=0.2191), but remained significant when adjusted for BCM v. P=0.0249). Fat mass explained a significant amount of variation in RMR in women (r(2) 0.28, P=0.0038), but not in men (r(2) 0.03, P=0.3301). The relationships between body fat and the various subcompartments of BCM and RMR require further elucidation.     

腹膜透析病人体内水分布与营养状况的关系

目的:了解持续性不卧床腹膜透析(CAPD)病人体内水的分布状况及其与营养之间的关系。方法:用生物电阻抗法对66名无临床水肿表现的CAPD病人进行体内水的测量,分别测出其细胞外液(ECW)、细胞内液(ICW)、总体水(TBW),同时对所有病人进行营养状况的主观综合评价(SGA)。相同年龄段的正常人作为对照。结果:临床无水肿的CAPD病人与相同年龄的正常人相比,体内水的分布存在明显异常,表现为细胞内液显著减少,细胞外液无明显变化,细胞外液与细胞内液之比(E/I)明显增加;当病人存在营养不良时,上述现象表现得更加明显。结论:持续性不卧床式腹膜透析(CAPD)病人体内水的分布是异常的,营养不良可以加重体内水的异常分布。因此,对于临床无明显水肿表现但存在营养不良的CAPD病人不能通过E/I来判断体内是否存在水负荷过多。     

The oral contraceptive containing 30 microg of ethinylestradiol plus 3 mg of drospirenone is able to antagonize the increase of extracellular water occurring in healthy young women during the luteal phase of the menstrual cycle: an observational study

PURPOSE: This nonrandomized study aimed to evaluate body weight and composition during the menstrual cycle and during oral contraception with 30 microg of ethinylestradiol plus 3 mg of drospirenone (EE+DRSP). DESIGN: Multifrequency bioelectrical impedance analysis was carried out in 38 normally cycling women (mean age, 25.5 years) at baseline during the follicular phase (FP) and the luteal phase (LP) of the menstrual cycle and after three and six cycles of EE+DRSP to evaluate total body water (TBW), intracellular water (ICW), extracellular water (ECW), fat mass and fat-free mass. Body weight, waist-to-hip ratio, blood pressure and the plasma concentrations of electrolytes were also determined at each visit. RESULTS: TBW and ECW increased in the LP. During EE+DRSP, TBW and ECW were significantly lower than in the LP but similar to the values measured in the FP. No significant variations in ICW or in the other parameters were observed. CONCLUSION: EE+DRSP maintains the same concentrations in TBW and ECW observed in the FP. This effect is likely due to the antimineralocorticoid activity of DRSP, which counteracts the water retention elicited by estrogen.     

Assessment of intracellular water by whole body bioelectrical impedance and total body potassium in HIV-positive patients

OBJECTIVE: Bioelectrical impedance analysis (BIA) is widely used as bedside assessment of body composition. Body cell mass (BCM) and intracellular water (ICW) are clinically important body compartments. Estimates of ICW obtained from BIA by different calculation approaches were compared to a reference method in male HIV-infected patients. PATIENTS: Representative subsample of clinically stable HIV-infected outpatients, consisting of 42 men with a body mass index of 22.4 +/- 3.8 kg/m(2)(range, 13-l31 kg/m(2)). METHODS: Total body potassium was assessed in a whole body counter, and compared to 50 kHz monofrequency BIA and multifrequency bioelectrical impedance spectroscopy. Six different prediction equations for ICW from BIA data were applied. Methods were compared by the Bland-Altman method. RESULTS: BIA-derived ICW estimates explained 58% to 73% of the observed variance in ICW (TBK), but limits of confidence were wide (-16.6 to +18.2% for the best method). BIA overestimated low ICW (TBK) and underestimated high ICW (TBK) when normalized for weight or height. Mono- and multifrequency BIA were not different in precision but population-specific equations tended to narrower confidence limits. CONCLUSION: BIA is an unreliable method to estimate ICW in this population, in contrast to the better established estimation of total body water and extracellular water. Potassium depletion in severe malnutrition may contribute to this finding but a major part of the residual between methods remains unexplained.     

Effects of Water Restriction and Water Replenishment on the Content of Body Water with Bioelectrical Impedance among Young Adults in Baoding,China: A Randomized Controlled Trial (RCT)

Insufficient water intake may affect body composition. The purpose of this research was to explore the effects of water restriction and replenishment on body composition and to evaluate the optimum amount of water that improves body composition. A total of 76 young adults aged 18–23 years old (40 males and 36 females) in Baoding, China, were recruited in this randomized controlled trial, with a 100% completion rate. After fasting overnight for 12 h, at 8:00 a.m. of day 2, a baseline test, including anthropometric indices and collection of urine and blood samples, was explored. Participants were then subjected to water restriction for 24 h, and three meals with ≤75% water content were provided. At 8:00 AM of day 3, the same indices were determined as a dehydration test. Then, participants were randomly assigned into four groups: three water replenishment groups (WR groups 1, 2, and 3 given 1000, 500, and 200 mL of purified water, respectively) and one non-replenishment group (NR group, with no water). After 90 min, the same measurements were performed as a rehydration test. Compared with the baseline test, during the dehydration test, the intracellular water to total body water ratio (ICW/TBW) increased; and extracellular water (ECW), ECW/TBW (extracellular water to total body water ratio), and TBW decreased (all p < 0.05). For males, significant differences were found in ECW, ECW/ICW (extracellular water to intracellular water ratio), ICW/TBW, and ECW/TBW (all p < 0.05); for females, significant reductions were found in ICW, ECW, TBW, ECW/ICW, ICW/TBW, and ECW/TBW (all p < 0.05). Furthermore, significant differences were found in ICW, ECW, ICW/TBW, ECW/TBW, ECW/ICW, TBW, and TBW/BW between males and females during the baseline and dehydration test (all p < 0.05). Comparing the dehydration test with the rehydration test, there were significant interactions between time × volume in ICW and TBW (F = 3.002, p = 0.036; F = 2.907, p = 0.040); in males, these were only found in ICW (F = 3.061, p = 0.040); in females, they were found in ICW and TBW (F = 3.002, p = 0.036; F = 2.907, p = 0.040). The ICW levels in WR groups 1 and 2 were all higher than in the NR group (all p < 0.05); the TBW was higher in WR group 1 than in the NR group (p < 0.05). No significant differences were found between WR groups 1 and 2, either in males or in females (all p > 0.05). In the rehydration test, significant differences in body composition were found between males and females among the four groups (all p < 0.05). Water restriction had adverse effects on body composition, and females were more susceptible to water restriction than males. Water replenishment improved the water content of body composition, alleviating the adverse effects of water restriction on ICW and TBW. After water restriction for 36 h, the optimum volume of water to improve body composition among young male adults was 1000 mL, but this was not the case for females.     

Use of bioimpedance spectroscopy to estimate body water distribution in rats fed high dietary sulfur amino acids

The effect of dietary sulfur amino acids on bioelectric properties was studied in rats by using bioimpedance spectroscopy. Weanling rats were assigned to one of 12 groups in a factorially arranged experiment with dietary variables of supplemental sulfur amino acid (none, 10 g DL-methionine/kg or 10 g DL-homocystine/kg), pyridoxine hydrochloride (0 or 7.5 mg/kg) and nickel (0 or 1 mg/kg). After 9 wk of feeding, 20-h urine specimens were collected from food-deprived rats for measurements of creatinine, and then bioimpedance was measured with multifrequency (Hydra ECF/ICF 4200) and single-frequency (RJL Systems model 101) analyzers. Urinary creatinine excretion was measured by intracellular water (ICW), total body solid and urinary volume (R2 = 0.675). Extracellular water (ECW) did not add significantly to the model. Rats fed methionine had significantly lower total body water, ICW and ECW than rats fed no supplemental sulfur amino acid. Rats fed homocystine had significantly lower ECW and a significantly higher ratio of ICW to ECW. Rats fed methionine or homocystine had significantly lower capacitance corrected for body length and ICW than those fed no supplemental sulfur amino acids. These results suggest that dietary homocystine changes the distribution of body water and that sulfur amino acids can affect membrane porosity and/or membrane thickness.     

Gender specific alterations of body composition in patients with inflammatory bowel disease compared with controls.

OBJECTIVE: To assess body hydration and the distribution of the body water compartments in defined populations of patients with inflammatory bowel disease (IBD) compared with those of matched healthy controls. SUBJECTS: Fifty-two patients with IBD at time of diagnosis (20 patients with Crohn's disease (CD-new) and 32 patients with ulcerative colitis (UC-new)), 40 patients with long-standing CD (CD-long) and 2 matched healthy control groups (n = 52 and n = 40) were recruited for the study. METHODS: Total body water (TBW) and extracellular water (ECW) were measured by deuterium oxide and bromide dilution, respectively. Intracellular water (ICW) was calculated as TBW-ECW. In addition, hydration of fat-free mass (FFM) and the ECW:ICW ratio were calculated. FFM, body fat (BF) and % body fat (%BF) were assessed by dual energy X-ray absorptiometry. RESULTS: In female IBD patients, the ECW:ICW ratio was significantly (P < 0.05) higher than in controls (CD-new: 0.89+/-0.11 vs 0.79+/-0.08, P < 0.01; UC-new: 0.85+/-0.15 vs 0.77+/-0.10, P < 0.05; CD-long: 0.86+/-0.14 vs 0.80+/-0.10, P < 0.05). In these female patients, the ICW:FFM ratio was significantly (P < 0.05) lower than in controls. Fluid shifts were especially pronounced in female patients with recently diagnosed CD. In male patients with recently diagnosed UC and in those with long-standing CD, body weight, body mass index, BF and %BF were significantly (P < 0.05) lower than in controls. No differences in body hydration or body water distribution were observed between male patients and controls. CONCLUSIONS: An altered body water distribution and body hydration was observed in female IBD patients, especially in female patients with recently diagnosed CD.     

Effect of an oral contraceptive containing 30 microg ethinylestradiol plus 3 mg drospirenone on body composition of young women affected by premenstrual syndrome with symptoms of water retention

PURPOSE: This study was conducted to evaluate body weight and composition during oral contraception with 30 microg ethinylestradiol plus 3 mg drospirenone (30EE+DRSP) in women affected by premenstrual syndrome (PMS) with somatic symptoms related to water retention. DESIGN: This prospective study was performed using multifrequency bioelectrical impedance analysis in 18 normally cycling PMS patients (mean age, 28.8 years) evaluated at baseline, during the luteal phase of the menstrual cycle and after 3 and 6 cycles of 30EE+DRSP. Total body water (TBW), intracellular water (ICW), extracellular water (ECW), fat mass and fat-free mass were evaluated. Body weight, waist-to-hip ratio and blood pressure were also determined at each visit. Basal values were compared with those measured in 31 healthy females without PMS (controls). RESULTS: PMS patients have higher levels of TBW and ICW than controls. After 6 months of 30EE+DRSP, TBW and ECW were significantly lower than before treatment. No significant variations in ICW or in the other parameters were observed. CONCLUSION: In women with PMS, 30EE+DRSP reduces the concentrations in TBW and ECW. This effect is likely due to the antimineralocorticoid activity of DRSP. Whether these changes may account for the improvement of premenstrual fluid-related symptoms reported with this formulation is discussed.     

Measurement of body water by multifrequency bioelectrical impedance spectroscopy in a multiethnic pediatric population.

BACKGROUND: Bioelectrical impedance spectroscopy (BIS) may provide a noninvasive, rapid method for the assessment of total body water (TBW), extracellular water (ECW), and intracellular water (ICW). Few studies, however, have examined the accuracy of BIS in pediatric populations. OBJECTIVE: Our objective was to evaluate the accuracy of BIS for the measurement of TBW, ECW, and ICW in healthy children. DESIGN: Dual-energy X-ray absorptiometry (DXA), total body potassium (TBK), and BIS measurements were performed in 347 children (202 males and 145 females aged 4-18 y). The reference values for TBW, ECW, and ICW were defined by using a DXA+TBK model. BIS values were evaluated by using the method of Bland and Altman. A randomly selected calibration group (n = 231) was used to derive new BIS constants that were tested in the remaining group (n = 116). RESULTS: BIS values were highly correlated with the reference values (r(2) = 0.94-0.97, P < 0.0001), but differences between the BIS and DXA+TBK models for individuals were significant (P < 0.001). Use of new BIS constants reduced the mean differences between the BIS and DXA+TBK models; the SDs of the mean differences were improved (1.8 L for TBW, 1.4 L for ICW, and 1.0 L for ECW) for the total population. CONCLUSIONS: On a population basis, BIS can be calibrated to replace the DXA+TBK model for the assessment of TBW, ECW, and ICW in healthy children. The accuracy of the BIS measurement in individual children may be refined further by using age- and sex-specific adjustments for the BIS calibration constants.     

Bioelectrical impedance analysis--part I: review of principles and methods

The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant fluid and electrolyte abnormalities, when using appropriate population, age or pathology-specific BIA equations and established procedures. Published BIA equations validated against a reference method in a sufficiently large number of subjects are presented and ranked according to the standard error of the estimate. The determination of changes in body cell mass (BCM), extra cellular (ECW) and intra cellular water (ICW) requires further research using a valid model that guarantees that ECW changes do not corrupt the ICW. The use of segmental-BIA, multifrequency BIA, or bioelectrical spectroscopy in altered hydration states also requires further research. ESPEN guidelines for the clinical use of BIA measurements are described in a paper to appear soon in Clinical Nutrition.     

Severity of human immunodeficiency virus infection is associated with decreased phase angle, fat mass and body cell mass in adults with pulmonary tuberculosis infection in Uganda.

Although coinfection with tuberculosis and human immunodeficiency virus (HIV) is emerging as a major problem in many developing countries, nutritional status has not been well characterized in adults with tuberculosis and HIV infection. We compared nutritional status between 261 HIV-positive and 278 HIV-negative adults with pulmonary tuberculosis in Kampala, Uganda, using anthropometry and bioelectrical impedance analysis. Among 163 HIV-positive and 199 HIV-negative men, intracellular water-to-extracellular water (ICW:ECW) ratio was 1.48 +/- 0.26 and 1.59 +/- 0.48 (P = 0.006) and phase angle was 5.42 +/- 1.05 and 5.76 +/- 1.30 (P = 0.009), respectively. Among 98 HIV-positive and 79 HIV-negative women, ICW:ECW was 1.19 +/- 0.16 and 1.23 +/- 0.15 (P = 0.11) and phase angle was 5.35 +/- 1.27 and 5.43 +/- 0.93 (P = 0.61), respectively. There were no significant differences in BMI, body cell mass, fat mass or fat-free mass between HIV-positive and HIV-negative adults. Among HIV-positive subjects, BMI, ICW:ECW, body cell mass, fat mass and phase angle were significantly lower among those with CD4(+) lymphocytes < or = 200 cells/microL compared with those who had > 200 cells/microL. In sub-Saharan Africa, coinfection with pulmonary tuberculosis and HIV is associated with smaller body cell mass and intracellular water, but not fat-free mass, and by large differences in ICW:ECW and phase angle alpha.     

Bioelectrical impedance measurements in patients with gastrointestinal disease: validation of the spectrum approach and a comparison of different methods for screening for nutritional depletion

BACKGROUND: Bioelectrical impedance spectroscopy (BIS) may be of value in identifying patients with nutritional depletion. OBJECTIVE: The primary aim of the study was to assess the validity of BIS in patients with gastrointestinal disease. The secondary aim was to compare different screening methods for identifying nutritionally depleted patients. DESIGN: In 70 patients with gastrointestinal disease, BIS measurements were performed and fluid compartments were calculated from extrapolated resistance (R) values of extracellular (R(ECW)) and intracellular (R(ICW)) water based on mixture equations. Results were compared with total body water and ECW, which were measured by dilution methods. Patients were classified as depleted if their actual fat-free mass (FFM) was <90% of their ideal FFM (iFFM). Different screening approaches for depletion were compared: the impedance vector method and the resistance index (RI) in relation to iFFM (RI/iFFM). RESULTS: Total body water and ICW were largely underestimated (4 L) in the not-depleted patients but not in the depleted patients. In both groups, ECW was slightly overestimated (0.6-0.7 L). The critical frequency was 60% higher and the membrane capacitance was 40% lower in the depleted than in the not-depleted patients. The impedance vector method failed to identify depleted patients, whereas the proposed ratio at R(50) (R measured at 50 kHz) and R(inf) (R at infinite frequency) resulted in comparable sensitivity (86%) and specificity (73-80%). CONCLUSIONS: BIS measures of body fluids are influenced by the presence of depletion, probably because of alterations in the electric properties of the body at the cellular level. However, for screening purposes, the use of the ratio (L(2)/R)/iFFM at R(50) and R(inf) may be of value.     

Assessment of body composition by bioelectrical impedance analysis without the need for measurement of height

Conventional whole-body single frequency bioelectrical impedance analysis (BIA) of body composition typically uses height as a surrogate measure of conductor length. A new method of BIA analysis for the prediction of body cell mass (BCM) and extracellular water (ECW, as % body weight) not using height has been introduced-the Soft Tissue Analyser (STA(TM), Akern Sri, Florence, Italy)-making it ideal for use in subjects where measurement of height is difficult or impossible. The performance of the new analytical method in predicting BCM and ECW in 139 normal control subjects was assessed by comparison with reference data obtained from a four-component (4-C) model of body composition and with predictions obtained from conventional BIA analysis. Both predicted BCM and ECW were strongly (r=0.82, SEE=6.3 kg and 0.89, SEE=1.3 kg respectively) correlated with the corresponding 4-C model measurements although differing significantly from the lines of identity (P<0.0001). Fat-free mass, calculated from STA estimates of BCM and ECW, was better predicted (r=0.91, SEE=5.6 kg). The significant differences in STA-group mean values for BCM and ECW and wide limits of agreement compared with the reference data indicate that the method cannot be used with confidence for prediction of these body compartments despite the obvious advantage of not requiring an accurate measurement of height.     

Bioelectrical impedance analysis-part II: utilization in clinical practice

BIA is easy, non-invasive, relatively inexpensive and can be performed in almost any subject because it is portable. Part II of these ESPEN guidelines reports results for fat-free mass (FFM), body fat (BF), body cell mass (BCM), total body water (TBW), extracellular water (ECW) and intracellular water (ICW) from various studies in healthy and ill subjects. The data suggests that BIA works well in healthy subjects and in patients with stable water and electrolytes balance with a validated BIA equation that is appropriate with regard to age, sex and race. Clinical use of BIA in subjects at extremes of BMI ranges or with abnormal hydration cannot be recommended for routine assessment of patients until further validation has proven for BIA algorithm to be accurate in such conditions. Multi-frequency- and segmental-BIA may have advantages over single-frequency BIA in these conditions, but further validation is necessary. Longitudinal follow-up of body composition by BIA is possible in subjects with BMI 16-34 kg/m(2) without abnormal hydration, but must be interpreted with caution. Further validation of BIA is necessary to understand the mechanisms for the changes observed in acute illness, altered fat/lean mass ratios, extreme heights and body shape abnormalities.     

A whole-body model to distinguish excess fluid from the hydration of major body tissues

BACKGROUND: Excess fluid (ExF) accumulates in the body in many conditions. Currently, there is no consensus regarding methods that adequately distinguish ExF from fat-free mass. OBJECTIVE: The aim was to develop a model to determine fixed hydration constants of primary body tissues enabling ExF to be calculated from whole-body measurements of weight, intracellular water (ICWWB), and extracellular water (ECWWB). DESIGN: Total body water (TBW) and ECWWB were determined in 104 healthy subjects by using deuterium and NaBr dilution techniques, respectively. Body fat was estimated by using a reference 4-component model, dual-energy X-ray absorptiometry, and air-displacement plethysmography. The model considered 3 compartments: normally hydrated lean tissue (NH_LT), normally hydrated adipose tissue (NH_AT), and ExF. Hydration fractions (HF) of NH_LT and NH_AT were obtained assuming zero ExF within the diverse healthy population studied. RESULTS: The HF of NH_LT mass was 0.703 +/- 0.009 with an ECW component of 0.266 +/- 0.007. The HF of NH_AT mass was 0.197 +/- 0.042 with an ECW component of 0.127 +/- 0.015. The ratio of ECW to ICW in NH_LT was 0.63 compared with 1.88 in NH_AT. ExF can be estimated with a precision of 0.5 kg. CONCLUSIONS: To calculate ExF over a wide range of body compositions, it is important that the model takes into account the different ratios of ECW to ICW in NH_LT and NH_AT. This eliminates the need for adult age and sex inputs into the model presented. Quantification of ExF will be beneficial in the guidance of treatment strategies to control ExF in the clinical setting.     

腹部手术后体液含量与分布的变化及其影响因素

目的 :观察腹部手术后体液含量与分布变化,探讨其变化规律和影响因素。方法 :选择2016年3至6月入住我科的61例病人,利用人体成分分析仪,检测病人术前1天和术后第1、3、5、7天细胞内液(ICW)、细胞外液(ECW)、总体液(TBW)的含量,并依据年龄、性别、手术种类、手术时间、液体净入量分组,分析影响病人体液变化的因素。结果 :与术前1天相比,术后第1天病人ICW、ECW、TBW明显增加(P0.05),且以ECW增加为主,并于术后第3至7天降至术前水平。不同种类手术病人术后第1天体液净增加量不同,女性较男性体液增加多,并且术后第1天体液净增加量与手术时间、液体净入量呈正相关。结论 :腹部手术后早期病人存在体液潴留现象,以ECW潴留为主;手术时间延长、液体净入量增加是术后病人体液潴留的主要影响因素。     

The effects of creatine and whey protein supplementation on body composition in men aged 48 to 72 years during resistance training

Objectives: Creatine and whey protein are supplements believed to have an ergogenic effect. Very little is known regarding the effects of these dietary supplements in older men. The purpose of this study was to determine the effect of creatine and whey protein supplements, consumed independently and in combination, on total and regional body composition in middle-aged men during a resistance-training program.Design, Setting,Participants: Forty-two men were randomly assigned to four groups to receive supplements according to a double-blind protocol. Groups consumed their supplements three times per week immediately following their resistance training sessions. The groups were: 1) placebo (480 ml of Gatorade®); 2) creatine (480 ml of Gatorade® plus 5 grams of creatine); 3) whey protein (480 ml of Gatorade® plus 35 grams of whey protein powder); and 4) whey protein/creatine (480 ml of Gatorade® plus 5 grams of creatine and 35 grams of whey protein powder). All groups participated in resistance training 3 times per week for 14 weeks.Measurements: At the beginning and end of the study, total and regional measures of body composition (DXA) and total (TBW), intracellular (ICW), and extracellular (ECW) body water (Multifrequency BIA) were measured and 3-day diet records were completed.Results: There were significant training effects for regional arm fat (decrease), regional arm bone free-fat free mass (BF-FFM-increase), total body BF-FFM (increase), ICW (increase), and ECW (increase) but no significant group effects and only one significant group by training interaction (ECW). There were no significant changes for total calorie, carbohydrate, fat or protein intake for any of the groups from prestudy to post-study testing.Conclusion: The results from this study suggest that supplementation with creatine, whey protein, or a combination of creatine and whey protein, when combined with resistance training in middle-aged men, have no added benefit to changes that occur to body composition due to resistance training alone.