Determination Of Total Body Water Research Articles

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.

Use of bioelectrical impedance spectroscopy to provide a measure of body composition in sows

The ability to accurately estimate fat mass and fat-free mass (FFM) has the potential to improve the way in which sow body condition can be managed in a breeding herd. Bioelectrical impedance spectroscopy (BIS) has been evaluated as a practical technique for assessment of body composition in several livestock species, but similar work is lacking in sows. Bioelectrical impedance uses population-specific algorithms that require values for the apparent resistivities of body fluids and body proportion factors. This study comprised three major aims: (i) to derive apparent resistivity coefficients for extracellular water (ECW) and intracellular water (ICW) required for validation of BIS predictions of total body water (TBW) in live sows against standard reference tracer dilution methods; (ii) to develop predictions of TBW to body composition prediction algorithms, namely FFM, by developing a body geometry correction factor (Kb) and (iii) to compare the BIS predictions of FFM against existing impedance predictors and published prediction equations for use in sows, based on physical measurements of back-fat depth and BW (P2-based predictors). Whole body impedance measurements and the determination of TBW by deuterium dilution and ECW by bromide dilution were performed on 40 Large White x Landrace sows. Mean apparent resistivity coefficients of body fluids were 431.1 Ω.cm for ECW and 1827.8 Ω.cm for ICW. Using these coefficients, TBW and ECW were over-estimated by 6.5 and 3.3%, respectively, compared to measured reference values, although these differences were not statistically different (P > 0.05). Mean Kb was 1.09 ± 0.14. Fat-free mass predictions were 194.9 kg, which equates to 60.9% of total sow weight, and 183.0 kg for BIS and the deuterium dilution method, respectively. Mean differences between the predicted and measured FFM values ranged from −8.2 to 32.7%, but were not statistically different (P > 0.05). Method validation (leave-one-out procedure) revealed that mean differences between predicted and measured values were not statistically significant (P > 0.05). Of the impedance-based predictors, equivalence testing revealed that BIS displayed the lowest test bias of 11.9 kg (8.2%), although the P2-based prediction equations exhibited the lowest bias and percentage equivalence, with narrow limits of agreement. Results indicate although differences between mean predicted and measured values were not significantly different, relatively wide limits of agreement suggest BIS as an impractical option for assessing body composition in individual sows compared to the use of existing prediction equations based on BW and back fat.

EFFECT OF INGESTION AND EXCRETION OF FLUIDS IN DETERMINING BODY COMPOSITION WITH DEUTERIUM DILUTION METHOD IN SCHOOL CHILDREN

the deuterium dilution technique is a reference method for measuring body composition in children. However, to our knowledge, there is no report on how some of the procedures used affect the measurement of total body water (TBW) and other estimates. to analyze whether considering fluid intake and urine excretion during the test affects the final TBW, fat mass and fat free mass results. ingestion of fluids (100 mL rinse water + orange juice 150 mL) and excretion (urine) were measured in 139 schoolchildren (65 girls) during the determination of TBW. We found significant differences in body composition (p < 0.001), TBW (100-200 mL), FFM and FM (100-300 g) when corrected by volume of fluids ingested and excreted. However, these differences were not considered clinically relevant.

Total Body Water Determination: Have We To Adapt Its Determination To The Patient Clinical Status?

Introduction The correct assessment of the total body water (TBW) is a crucial issue of the renal replacement therapy due to it represents the urea distribution volume, used for the determination of the dialysis adequacy Kt/V. Our objective was to study the correlation between the TBW estimated by Watson formula and with BCM-body composition monitor (Fresenius Medical care®). Methods We study all the patients in hemodialysis in the Hospital La Paz Unit and Madrid El Pilar center, before the dialysis treatments. Results Table 1 . Weight ( kg) 70,05±13,12 ICW(l) 16,02±3,73 BMI( kg/ m2) 26,86±9,8 Albumin( g/dl) 3,87±0,48 FM(%) 37,97±10,52 Prealbumin ( g/dl) 28,22±8,18 FFM(%) 43,09±12,54 CRP 11,34±23 ECW(l) 16,8±3,51 TBW w(l) 35,76±6,15 TBW bcm(l) 32,92±7,31 Regarding the nutritional status, a 36.8% patients were undernourished by Chang criteria (19.3% sleigh, 15.8 % moderately and 1.8% severely). A 50.9% were obese by the %MG and a 61.4% had some criteria of muscle atrophy. We analyze the TBW differences by linear regression, adjusted by: BMI R2=0,076 p=0,038, %FFM R2=0,553 p Conclusion There is a good concordance between both methods in the determination of the TBW. The Watson formula overestimates the TBW in patients with high %FM and underestimates in those with high FFM. In the clinical practice, it is necessary to adapt the determination of TBW to the patient situation.

Development of predictive equations for total body water using the deuterium-dilution method as the gold standard in a population of asymptomatic HIV-positive Zulu women in South Africa

Objectives: The study aimed to derive predictive equations for total body water determinations with bioelectrical impedance and anthropometric measurements in a population of asymptomatic human immunodeficiency virus (HIV) -positive Zulu women.Design: Cross-sectional data from within an ongoing prospective study that observed the effect of infant feeding mode on maternal and child health in a cohort of asymptomatic HIV-positive women were used for this objective.Setting: A community health centre in Durban.Subjects: Asymptomatic HIV-infected women who were not eligible for antiretroviral therapy. They were resident in the area and were of Zulu ethnicity.Outcome measures: Development of predictive equations for total body water.Results: Success was achieved in developing predictive equations for total body water using bioelectrical impedance analysis and anthropometric measurements that were specific to the HIV-positive female Zulu population. These equations were developed using the total body water that was obtained from deuterium-dilution method as a gold standard.Conclusion: These predictive equations are likely to be more valid for the HIV-positive female African populations of similar build than the current predictive equations that derive from the Western population.

Assessment of body fat in the pony: Part II. Validation of the deuterium oxide dilution technique for the measurement of body fat

Excessive accumulations or depletions of body fat have been associated with increased morbidity and mortality in horses and ponies. An objective, minimally-invasive method to accurately quantify body fat in living animals is required to aid nutritional management and define welfare/performance limits. To compare deuterium oxide (D(2) O) dilution-derived estimates of total body water (TBW) and body fat with values obtained by 'gold standard' proximate analysis and cadaver dissection. D(2) O dilution offers a valid method for the determination of TBW and body fat in equids. Seven mature (mean ± s.e. 13 ± 3 years, 212 ± 14 kg, body condition scores 1.25-7/9), healthy, Welsh Mountain pony mares, destined for euthanasia (for nonresearch purposes) were used. Blood samples were collected before and 4 h after D(2) O (0.11-0.13 g/kg bwt, 99.8 atom percent excess) administration. Plasma was analysed by gas isotope ratio mass spectrometry following filtration and zinc reduction. After euthanasia, white adipose tissue (WAT) mass was recorded before all body tissues were analysed by proximate chemical analyses. D(2) O-derived estimates of TBW and body fat were strongly associated with proximate analysis- and dissection-derived values (all r(2) >0.97, P≤0.0001). Bland-Altman analyses demonstrated good agreements between methods. D(2) O dilution slightly overestimated TBW (0.79%, limits of agreement (LoA) -3.75-2.17%) and underestimated total body lipid (1.78%, LoA -0.59-4.15%) and dissected WAT (0.72%, LoA -2.77-4.21%). This study provides the first validation of the D(2) O dilution method for the minimally-invasive, accurate, repeatable and objective measurement of body water and fat in living equids.

A bridge from bioimpedance spectroscopy to 50 kHz bioimpedance analysis: application to total body water measurements

This paper presents a method for extrapolating the total body water (TBW) resistance Rt50 from the resistance measured at 50 kHz (R50). A DXA examination and impedance measurements were carried out in a 1st group of 57 healthy volunteers with a Xitron 4200 multifrequency impedancemeter, in order to determine their values of Rt50 by comparison with resistances extrapolated at an infinite frequency by the Xitron (R∞). TBW volumes were calculated using our modified BIS method (Jaffrin et al 2006 Med. Biol. Eng. Comput. 44 873–82) from R∞, Rt50 and from the fat-free mass measured by DXA, assuming a hydration rate of 73.2%. The same protocol and calculations were also carried out on a 2nd group of 21 subjects for independent validation. Data of the 1st group showed that values of Rt50, not significantly different from those of R∞, could be obtained by dividing R50 by 1.231 in men and by 1.224 in women. Applying this method to the 2nd group yielded also values of Rt50 not significantly different from R∞. TBW volumes Vt50 obtained from Rt50 were not significantly different from those of our modified BIS method Vtn, or from TBW volumes obtained from DXA in both groups. A comparison with three BIA methods of TBW determination showed that our new method gave results in better agreement with TBW from DXA and from our modified BIS method.

Metabolic consequences of body size and body composition in hemodialysis patients

Small body mass index is associated with increased mortality in chronic hemodialysis patients. The reasons for this observation are unclear but may be related to body composition. This study aimed to investigate the body composition in chronic hemodialysis patients. The difference between body mass and the sum of muscle, bone, subcutaneous, and visceral adipose tissue masses, measured by whole body magnetic resonance imaging, was defined as the high metabolic rate compartment representing the visceral mass. Protein catabolic rate was calculated from urea kinetics. Forty chronic hemodialysis patients (mean age 54.7 years; 87.5% African Americans; 45% females) were studied. High metabolic rate compartment expressed in percent of body weight was inversely related to body weight (r=-0.475; P=0.002) and body mass index (r=-0.530; P<0.001). In a multiple linear regression model, protein catabolic rate was significantly correlated only with high metabolic rate compartment (r=0.616; P<0.001). Assuming that protein catabolic rate in addition to protein intake reflects urea and uremic toxin generation, it follows that high metabolic rate compartment is the major compartment involved in their generation. Consequently, uremic toxin production rate may be relatively higher in patients with low body weight and low body mass index as compared to their heavier counterparts. The poorer survival observed in smaller dialysis patients may be related to these relative differences.

Total body water measurements using resonant cavity perturbation techniques

A recent paper proposed a novel technique for determining the total body water (TBW) of patients suffering with abnormal hydration levels, using a resonant cavity perturbation method. Current techniques to measure TBW are limited by resolution and technical constraints. However, this new method involves measuring the dielectric properties of the body, by placing a subject in a large cavity resonator and measuring the subsequent change in its resonant frequency, fres and its Q-factor. Utilizing the relationship that water content correlates to these dielectric properties, it has been shown that the measured response of these parameters enables determination of TBW. Results are presented for a preliminary study using data estimated from anthropometric measurements, where volunteers were asked to lie and stand in an electromagnetic screened room, before and after drinking between 1 and 2 l of water, and in some cases, after voiding the bladder. Notable changes in the parameters were observed; fres showed a negative shift and Q was reduced. Preliminary calibration curves using estimated values of water content have been developed from these results, showing that for each subject the measured resonant frequency is a linear function of TBW. Because the gradients of these calibration curves correlate to the mass-to-height-ratio of the volunteers, it has proved that a system in which TBW can be unequivocally obtained is possible. Measured values of TBW have been determined using this new pilot-technique, and the values obtained correlate well with theoretical values of body water (r = 0.87) and resolution is very good (750 ml). The results obtained are measurable, repeatable and statistically significant. This leads to confidence in the integrity of the proposed technique.

Albuterol improves response to levodopa and increases skeletal muscle mass in patients with fluctuating Parkinson disease.

Animal studies indicate that beta(2)-adrenergic receptor agonists enhance transport of levodopa across the blood-brain barrier. Preliminary studies showed improved response to levodopa in patients with Parkinson disease (PD) who were given albuterol as adjunctive therapy. Beta(2)-adrenergic agonists may offer additional benefits to PD patients via their skeletal muscle anabolic effects, particularly those who experience decreased muscle strength and weight loss. Nondemented, fluctuating PD patients receiving levodopa but not experiencing severe dyskinesias underwent the following tests at baseline and 14 weeks after treatment with albuterol sulfate (4 mg four times a day, orally): Unified Parkinson's Disease Rating Scale motor, tapping, and stand-walk-sit tests every 30 minutes between 8 am and 5 pm; body composition analyses using whole-body plethysmography and computed tomography of the thigh; muscle strength tests; and the Parkinson's Disease Questionnaire (PDQ-39). Results were analyzed using paired t-tests (2 tailed), repeated-measures analysis of variance, and the Wilcoxon signed-rank test. Seven of 8 enrolled patients completed the study; 1 patient withdrew because of headache and anxiety. The area under the curve for all-day UPDRS motor scores improved by 9.8 +/- 9.1% (mean +/- standard deviation; P < 0.05) and tapping improved by 7.6 +/- 8.1% (P < 0.05). The effect was more pronounced when only the response to the first levodopa dose (area under the curve, 8-11 am) was analyzed: 13.0 +/- 9.8% and 9.8 +/- 9.6% respectively. Thigh muscle cross-sectional area increased significantly as measured by computed tomography (5.3 +/- 3.2%, P < 0.01), as did fat-free mass by whole-body plethysmography combined with total-body water determination (9.5 +/- 2.9%, P < 0.05). There was no significant improvement in the stand-walk-sit test, muscle strength tests, other UPDRS sections, daily OFF time, or PDQ-39. Four patients were rated as having a mild global improvement (+1 point) on a -3 to +3-point scale, and 3 of them chose to continue albuterol beyond the termination of the study. The mean heart rate increased from 78.3 +/- 9.3 beats/minute to 85.6 +/- 8.7 beats/minute (P < 0.05). No laboratory abnormalities or electrocardiographic changes were induced by albuterol in any subject. This open-label pilot study suggests that albuterol increases muscle mass and improves the therapeutic response to levodopa in patients with fluctuating PD. A double-blind, placebo-controlled study is needed to confirm the effects and safety profile of beta(2)-agonists in PD.

Simultaneous Determination of Total Body Water and Plasma Volume in Conscious Dogs by the Indicator Dilution Principle

Simultaneous Determination of Total Body Water and Plasma Volume in Conscious Dogs by the Indicator Dilution Principle

Urea volume of distribution exceeds total body water in patients with acute renal failure

An accurate estimate of volume of distribution of urea (Vurea) is critically important to guide the prescription of therapy and the quantification of delivered dialysis dose in patients with chronic and acute renal failure (ARF). While Vurea has been shown to be substantially the same as total body water (TBW) in other patient populations, this relationship has not been adequately studied in detail in ARF patients. To evaluate this question, we undertook a systematic study of these parameters in a cohort of 28 patients with ARF to analyze methods of estimating Vurea and TBW using blood-based kinetic data, anthropometric data and bioelectrical impedance analysis (BIA). The results show that Vurea estimated by double-pool Kt/V (67.9 +/- 19.2 L) and by equilibrated Kt/V (61.2 +/- 13.6 L) were statistically significantly higher than Vurea determined by single-pool Kt/V (55.3 +/- 12.9 L; difference of 16% and 11%, respectively). Determination of TBW by anthropometric measurements (Watson, 42.5 +/- 7.0 L; Hume-Weyer, 43.6 +/- 7.1 L; Chertow, 46.8 +/- 8.1 L) yielded significantly lower measures compared to TBW determined by physiological formulae and by BIA (51.1 +/- 11.6 L and 51.1 +/- 13.3 L, respectively). Most importantly, all measures of Vurea by blood-based kinetics exceeded TBW measurements by any method (7% to 50% difference). Our results suggest that in terms of useful guidelines to prescribe a specific dose of dialysis in patients with acute renal failure, estimates of TBW cannot be used as a surrogate for Vurea in determining dialysis adequacy.

Total-body-water measurement with 18O-labeled water in short-bowel patients with an ileostomy

The aim of this study was to evaluate the use of H 2 18O for total-body-water (TBW) determination in patients with short bowel because ileostomy losses of labeled water can falsify TBW. Thirteen adult short-bowel patients were studied after an overnight fast. Saliva, blood, urine and ileostomy output were collected before and 30, 60, 90, 120, 240, and 360 min after oral ingestion of 0.88 g/kg of 2.5% H 2 18O to measure 18O abundance by isotope-ratio mass spectrometry. TBW was calculated from the dilution of the isotopic water in saliva and plasma. The quantity of labeled water lost in the ileostomy was calculated from the isotopic enrichment of the ileostomy output from T0 to T360. The values obtained from saliva or plasma with (corrected) and without (uncorrected) considering H 2 18O lost in the ileostomy output were compared with a paired t test. Agreement was evaluated using the Bland-Altman method. From T0 to T360, the ileostomy output and the percentage of lost labeled water were 490 ± 314 mL and 6.38 ± 8.52%, respectively. TBW calculated from plasma or saliva isotopic enrichment was different, and a significant difference was also observed between corrected and uncorrected TBW values (saliva: uncorrected TBW = 32.35 ± 7.52 L, corrected TBW = 30.29 ± 6.09 L; plasma; uncorrected TBW = 30.80 ± 7.29 L, corrected TBW = 28.79 ± 5.79 L). The agreement between the values obtained from the two dilution spaces or between the two calculation methods was poor. Because of the large discrepancies between calculation methods, determination of TBW from oral ingestion of 18O-labeled water in patients with short bowel should be calculated only from plasma 18O space dilution and should consider ileostomy losses.

Plasma sample preparation by ultrafiltration for total body water determination.

Measurement of total body water (TBW) content is of importance because TBW can be significantly altered during disease conditions, especially in diseases where the patient can be “waterlogged.”1 This increase in TBW content can result in drug dosing errors and other complications.2,3 Among the available methods of TBW estimation, the isotope dilution technique is considered to be the “gold standard.” However, these techniques require significant expertise and have relatively long and time-consuming preparatory phases, which reduce their efficiency and clinical use. Therefore, our aim was to develop a new and more efficient technique to prepare human plasma samples containing deuterium oxide (D2O) for Fourier Transform InfraRed (FTIR) analysis for TBW determination. This technique needed to efficient to enable TBW determination on a large scale and as quickly as possible.

Dual-energy X-ray absorptiometry for body composition estimation in Chinese women

To determine whether dual-energy X-ray absorptiometry (DXA) is a valid method for body composition assessment of obese and non-obese subjects. Cross-sectional study. Chinese women living in Hong Kong; 66 of 91 subjects had body mass index (BMI) of >25 kg/m2. Anthropometrics, including body weight, body height, waist and hip girth. Percentage body fat (%BF) and fat-free mass (FFM) from DXA (Hologic 2000 plus, Enhanced Array Whole Body Version 5.63) were compared with that based on a tracer dose of deuterium oxide for the determination of total body water (TBW). In both obese and non-obese subjects, FFMDXA was similar to FFMTBW. The Bland and Altman-type analysis indicated that comparable between-methods differences (mean bias) and limits of agreement were obtained in obese and non-obese subjects for FFM (0.4, between -4.4 and 5.2 kg vs 0.5, between -3.1 and 4.1 kg) and %BF (-0.6, between -7.6 and 6.4% vs -1.2, between -8.6 and 6.2%). The %BF bias was independent of age, BMI, hip circumference, and waist-to-hip ratio, but correlated with waist girth (r=0.24, P=0. 021). The sources of bias are methodological and anthropometric in nature. The between-methods differences, however, are small and clinically insignificant. DXA is a valid method for assessing the body composition of obese patients. This study was supported by a HKU-CRCG grant.

C69 Determination of total body water and extracellular water compartment

C69 Determination of total body water and extracellular water compartment

Percentage body fat determination in hemodialysis and peritoneal dialysis patients: A comparison

Objective: To evaluate percentage body fat in hemodialysis (HD) and peritoneal dialysis (PD) patients. Design: A prospective study of 20 HD patients and 20 PD patients. Setting: Sol Goldman Renal Therapy Center, Lenox Hill Hospital, New York, NY; Baumritter Kidney Center Albert Einstein College of Medicine, Bronx, NY; Body Composition Unit, St Luke's Roosevelt Hospital, Columbia University, New York, NY. Patients: Twenty HD (10 men, 10 women) patients, mean age 41.8 ± 2.4 years and 20 PD (12 men, 8 women) patients, mean age 48.6 years ± 3.0 years. Intervention: This is a noninterventional study. Patients signed consent to undergo dual-energy x-ray absorptiometry, total body potassium counting bioelectrical impedance analysis, total body water determination, and anthropmetric evaluation. Main outcome measures: Present and compare percentage body fat between HD and PD patients as determined by the methods used. Results: Percentage fat is not different between HD and PD patients. Differences in absolute values of percent fat between techniques exist. Conclusion: HD patients and PD patients may be evaluated by the methods of body composition used. Percentage body fat will vary among techniques; therefore the same method should be used to follow a patient over time.

Determination of total body water by multifrequency bio-electric impedance: development of several models.

Multifrequency bio-electronic impedance analysis (MF BIA) measurements are taken from a heterogeneous group of patients, varying in size between obese and slim. The measuring system uses four electrodes: two current and two potential electrodes. Three new models are developed to calculate total body water (TBW) from the BIA data, and the resulting TBW values are compared with TBW determined by D2O dilution. The results demonstrate that the most simple model provides the best TBW values. For individual patients, TBW can be determined by means of bioimpedance measurement with an accuracy of 3 litres. In the most simple model (model 1), the body is electrically represented by a cylinder, and corrections are made for the amount of fat. This is an extension of the model used by Xitron. In the more advanced models (2 and 3), the body is represented by a cylinder for the trunk, and truncated cones represent the arms and legs. In model 2, delta TBW amounts to 3 litres. It is shown that the resistance of the trunk is proportional to the square root of the length. In model 3, it is assumed that subcutaneous fat is a poor conductor of electric current. An equation is developed that describes the partition of subcutaneous fat, and the fat layer is then removed from the cones representing arms and legs and from the cylinder that models the trunk.

Determination of total body water by IVNAA and 40K counting in young normal and growth hormone deficient adults

Determination of total body water by IVNAA and 40K counting in young normal and growth hormone deficient adults

Evaluating Volume Status in Hemodialysis Patients

Accurate determination of the volume and distribution of body fluids in end stage renal disease patients will permit improved assessment of dry weight and strategies for optimal fluid removal. Certain biochemical markers and anatomical measures have been proposed as markers of dry weight, but these markers primarily reflect the volume of the intravascular compartment and may not reflect total body volume status. Noninvasive determination of total body water and extracellular fluid volumes using bioimpedance analyses has also been proposed for assessment of dry weight, but such determinations do not yet have sufficient accuracy for routine use. Several devices have been recently developed for continuously monitoring changes in blood volume on-line during routine hemodialysis. Such blood volume monitors cannot be used to determine dry weight directly; however, continuous monitoring of blood volume can be used to detect fluid overload because intradialytic changes in blood volume are small in hemodialysis patients who are overhydrated. Furthermore, continuous monitoring of blood volume can be used to predict symptoms resulting from intradialytic hypovolemia. The combined use of blood volume monitoring and time-dependent ultrafiltration and dialysate sodium profiles will be used increasingly in the future to assist in the prevention of hypotension and symptoms that result from intradialytic hypovolemia, especially when automated systems for controlling intradialytic blood volume are individualized and shown to be safe and effective.