The Experts below are selected from a list of 53211 Experts worldwide ranked by ideXlab platform
Peter Davies - One of the best experts on this subject based on the ideXlab platform.
-
Body composition reference charts for uk infants and children aged 6 weeks to 5 years based on measurement of Total Body Water by isotope dilution
European Journal of Clinical Nutrition, 2020Co-Authors: Jonathan C K Wells, Peter Davies, Mary Fewtrell, T J ColeAbstract:Until recently, pediatric Body composition reference data were very limited, hindering interpretation of measurements. In the last decade, such data emerged for several techniques for children ≥ 5 years, but equivalent data for younger age groups remain lacking, due to their poor compliance with most techniques. To provide reference data for use in clinical practice and research from 6 weeks to 5 years, that are based on measurements of Total Body Water (TBW) by isotope dilution. The data on anthropometry and TBW were available from studies of 463 infants and children aged 6 weeks to 7 years, conducted between 1988 and 2010. Both breast-fed and formula-fed infants were included. TBW was measured by 2H- or 18O-labeled Water, and converted to fat-free mass (FFM) using published hydration coefficients. Reference charts and SD scores (SDS) were constructed for FFM, fat mass (FM), FFM index and FM index for each sex, using the lambda-mu-sigma method. Both sexes were significantly heavier and longer than UK 1990 reference data (p < 0.01), but did not differ in Body mass index SDS. Breast-fed infants were longer than formula-fed infants but did not differ in Body composition. These reference data will enhance the ability of clinicians to assess and monitor Body composition and FFM/FM accretion in clinical practice in younger age groups. Total Body Water can be measured in most patients, though abnormalities of hydration must be addressed. However, the centiles do not overlap exactly with those published for older age groups, limiting comparability between younger and older children.
-
the use of bioelectrical impedance analysis to estimate Total Body Water in young children with cerebral palsy
Clinical Nutrition, 2013Co-Authors: Kristie L Bell, Roslyn N Boyd, Jacqueline L Walker, Richard D Stevenson, Peter DaviesAbstract:Summary Background & aims Body composition assessment is an essential component of nutritional evaluation in children with cerebral palsy. This study aimed to validate bioelectrical impedance to estimate Total Body Water in young children with cerebral palsy and determine best electrode placement in unilateral impairment. Methods 55 young children with cerebral palsy across all functional ability levels were included. Height/length was measured or estimated from knee height. Total Body Water was estimated using a Bodystat 1500MDD and three equations, and measured using the gold standard, deuterium dilution technique. Comparisons were made using Bland Altman analysis. Results For children with bilateral impairment, the Fjeld equation estimated Total Body Water with the least bias (limits of agreement): 0.0 L (−1.4 L to 1.5 L); the Pencharz equation produced the greatest: 2.7 L (0.6 L–4.8 L). For children with unilateral impairment, differences between measured and estimated Total Body Water were lowest on the unimpaired side using the Fjeld equation 0.1 L (−1.5 L to 1.6 L)) and greatest for the Pencharz equation. Conclusions The ability of bioelectrical impedance to estimate Total Body Water depends on the equation chosen. The Fjeld equation was the most accurate for the group, however, individual results varied by up to 18%. A population specific equation was developed and may enhance the accuracy of estimates. Australian New Zealand Clinical Trials Registry (ANZCTR) number: ACTRN12611000616976.
-
estimation of Total Body Water from foot to foot bioelectrical impedance analysis in patients with cancer cachexia agreement between three prediction methods and deuterium oxide dilution
Journal of Human Nutrition and Dietetics, 2005Co-Authors: Judith Bauer, Sandra Capra, Peter DaviesAbstract:Introduction Bioelectrical impedance analysis (BIA) is a useful bedside measure to estimate Total Body Water (TBW). The aim of this study was to determine the agreement between three equations for the prediction of TBW using BIA against the criterion method, deuterium oxide dilution, in patients with cancer cachexia.
-
evaluation of foot to foot bioelectrical impedance analysis for the prediction of Total Body Water in oncology outpatients receiving radiotherapy
European Journal of Clinical Nutrition, 2004Co-Authors: Elisabeth Isenring, Judith Bauer, Sandra Capra, Peter DaviesAbstract:Objective: To investigate the accuracy of Total Body Water (TBW) predicted by foot-to-foot bioelectrical impedance compared with a deuterium oxide dilution technique in oncology outpatients receiving radiotherapy.
-
assessment of foot to foot bioelectrical impedance analysis for the prediction of Total Body Water
European Journal of Clinical Nutrition, 1998Co-Authors: N A Bell, P D Mcclure, Rebecca J Hill, Peter DaviesAbstract:Objective: To investigate the accuracy of foot-to-foot impedance methodology for the prediction of Total Body Water and whether leg length rather than stature should be used in the prediction of Total Body Water. Design: Cross-sectional study using volunteers from the community. Setting: University laboratory. Subjects: 57 subjects (29 male; 28 female) aged 19‐56 y. Interventions: Total Body Water was measured using a deuterium oxide dilution technique. Total Body Water was also predicted using foot-to-foot impedance apparatus (Tanita Inc, Tokyo, Japan, Model TBF 305). Results: Mean values for predicted and measured Total Body Water differed by 0.7 l. However this bias was not constant across all individuals with a progressive underestimation of Total Body Water by foot-to-foot impedance technology as the Water content of the Body increases. Also the use of leg length did not improve the accuracy of the prediction equation. Conclusions: At the population level predictions of Total Body Water obtained from foot-to-foot impedance technology compare well with measured Total Body Water. However the significant correlation between the difference between predicted and measured Total Body Water and the absolute value for Total Body Water is a concern especially if the technology is used for Body composition assessment during a weight loss program. Sponsorship: RJH was in receipt of a Queensland University of Technology Vacation Scholarship. Descriptors: bioelectrical impedance; Total Body Water; Body composition
L C Ward - One of the best experts on this subject based on the ideXlab platform.
-
mean expected error in prediction of Total Body Water a true accuracy comparison between bioimpedance spectroscopy and single frequency regression equations
BioMed Research International, 2015Co-Authors: Fernando Seoane, Shirin Abtahi, Farhad Abtahi, Lars Ellegard, Gudmundur Johannsson, Ingvar Bosaeus, L C WardAbstract:Mean Expected Error in Prediction of Total Body Water. : A True Accuracy Comparison between Bioimpedance Spectroscopy and Single Frequency Regression Equations.
-
comparison of whole Body and segmental bioimpedance methodologies for estimating Total Body Water
Annals of the New York Academy of Sciences, 2006Co-Authors: M Wotton, B J Thomas, B H Cornish, L C WardAbstract:We compared the whole Body (WB) and segmental bioelectrical impedance analysis (BIA) methodologies in a group of healthy adults ( n= 25 ). It has been suggested that the segmental methodology may overcome the difficulty in generating a single algorithm to predict Total Body Water (TBW) in all groups whether healthy or not. We measured TBW, using D2O dilution, and WB and segmental BIA parameters. Cole-Cole analysis was used to determine the impedance at the characteristic frequency (Zc). The correlation between TBW (by D2O dilution) and segmental BIA measures (multiple regression, r= 0.90 , p < 0.001 , SEE = 3.1 L) was not significantly higher than the correlation between TBW (D2O dilution) and WB BIA measures (simple regression, r= 0.85 , p < 0.001 , SEE = 3.6 L). Others have observed this "lack of improvement" in a group of healthy subjects. The true value of the segmental BIA methodology may lie in applications involving groups with altered distributions of segmental and compartmental fluid.
-
improved prediction of extracellular and Total Body Water using impedance loci generated by multiple frequency bioelectrical impedance analysis
Physics in Medicine and Biology, 1993Co-Authors: B H Cornish, B J Thomas, L C WardAbstract:Bioelectrical impedance analysis (BIA) using a frequency of 30 kHz is an established method of predicting Total Body Water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. The paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-Body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. Predictions of extracellular Water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively.
-
improved prediction of extracellular and Total Body Water using impedance loci generated by multiple frequency bioelectrical impedance analysis
Physics in Medicine and Biology, 1993Co-Authors: B H Cornish, B J Thomas, L C WardAbstract:Bioelectrical impedance analysis (BIA) using a frequency of 50 kHz is an established method of predicting Total Body Water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. This paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-Body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. The standard error associated with the prediction of TBW (determined by isotope dilution) using Zc was 5.9% compared with a standard error of prediction of 10.1% using the established BIA method at 50 kHz on the same data. Predictions of extracellular Water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively. These results demonstrate a significant (P < 0.01) improvement in the prediction of TBW and ECW using multiple frequency bioelectrical impedance analysis (MFBIA).
-
measurement of extracellular and Total Body Water of rats using multiple frequency bioelectrical impedance analysis
Nutrition Research, 1992Co-Authors: B H Cornish, L C Ward, B J ThomasAbstract:Abstract Multiple frequency bioelectrical impedance analysis (MFBIA) was used to measure whole Body impedance of rats between frequencies from 1 kHz to 100 kHz. The data were analysed, with reference to an equivalent electrical circuit for biological tissue, to estimate Total Body Water (TBW) and extracellular Water (ECW). TBW and ECW were independently determined by isotope dilution and desiccation. Correlation between MFBIA measurements and these alternative techniques were r=0.984 (SEE=6.5%) and r=0.995 (SEE=3.2%) for TBW and ECW respectively. These results establish the validity, accuracy and precision of MFBIA for the assessment of both TBW and ECW.
B J Thomas - One of the best experts on this subject based on the ideXlab platform.
-
comparison of whole Body and segmental bioimpedance methodologies for estimating Total Body Water
Annals of the New York Academy of Sciences, 2006Co-Authors: M Wotton, B J Thomas, B H Cornish, L C WardAbstract:We compared the whole Body (WB) and segmental bioelectrical impedance analysis (BIA) methodologies in a group of healthy adults ( n= 25 ). It has been suggested that the segmental methodology may overcome the difficulty in generating a single algorithm to predict Total Body Water (TBW) in all groups whether healthy or not. We measured TBW, using D2O dilution, and WB and segmental BIA parameters. Cole-Cole analysis was used to determine the impedance at the characteristic frequency (Zc). The correlation between TBW (by D2O dilution) and segmental BIA measures (multiple regression, r= 0.90 , p < 0.001 , SEE = 3.1 L) was not significantly higher than the correlation between TBW (D2O dilution) and WB BIA measures (simple regression, r= 0.85 , p < 0.001 , SEE = 3.6 L). Others have observed this "lack of improvement" in a group of healthy subjects. The true value of the segmental BIA methodology may lie in applications involving groups with altered distributions of segmental and compartmental fluid.
-
improved prediction of extracellular and Total Body Water using impedance loci generated by multiple frequency bioelectrical impedance analysis
Physics in Medicine and Biology, 1993Co-Authors: B H Cornish, B J Thomas, L C WardAbstract:Bioelectrical impedance analysis (BIA) using a frequency of 30 kHz is an established method of predicting Total Body Water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. The paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-Body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. Predictions of extracellular Water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively.
-
improved prediction of extracellular and Total Body Water using impedance loci generated by multiple frequency bioelectrical impedance analysis
Physics in Medicine and Biology, 1993Co-Authors: B H Cornish, B J Thomas, L C WardAbstract:Bioelectrical impedance analysis (BIA) using a frequency of 50 kHz is an established method of predicting Total Body Water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. This paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-Body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. The standard error associated with the prediction of TBW (determined by isotope dilution) using Zc was 5.9% compared with a standard error of prediction of 10.1% using the established BIA method at 50 kHz on the same data. Predictions of extracellular Water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively. These results demonstrate a significant (P < 0.01) improvement in the prediction of TBW and ECW using multiple frequency bioelectrical impedance analysis (MFBIA).
-
measurement of extracellular and Total Body Water of rats using multiple frequency bioelectrical impedance analysis
Nutrition Research, 1992Co-Authors: B H Cornish, L C Ward, B J ThomasAbstract:Abstract Multiple frequency bioelectrical impedance analysis (MFBIA) was used to measure whole Body impedance of rats between frequencies from 1 kHz to 100 kHz. The data were analysed, with reference to an equivalent electrical circuit for biological tissue, to estimate Total Body Water (TBW) and extracellular Water (ECW). TBW and ECW were independently determined by isotope dilution and desiccation. Correlation between MFBIA measurements and these alternative techniques were r=0.984 (SEE=6.5%) and r=0.995 (SEE=3.2%) for TBW and ECW respectively. These results establish the validity, accuracy and precision of MFBIA for the assessment of both TBW and ECW.
B H Cornish - One of the best experts on this subject based on the ideXlab platform.
-
comparison of whole Body and segmental bioimpedance methodologies for estimating Total Body Water
Annals of the New York Academy of Sciences, 2006Co-Authors: M Wotton, B J Thomas, B H Cornish, L C WardAbstract:We compared the whole Body (WB) and segmental bioelectrical impedance analysis (BIA) methodologies in a group of healthy adults ( n= 25 ). It has been suggested that the segmental methodology may overcome the difficulty in generating a single algorithm to predict Total Body Water (TBW) in all groups whether healthy or not. We measured TBW, using D2O dilution, and WB and segmental BIA parameters. Cole-Cole analysis was used to determine the impedance at the characteristic frequency (Zc). The correlation between TBW (by D2O dilution) and segmental BIA measures (multiple regression, r= 0.90 , p < 0.001 , SEE = 3.1 L) was not significantly higher than the correlation between TBW (D2O dilution) and WB BIA measures (simple regression, r= 0.85 , p < 0.001 , SEE = 3.6 L). Others have observed this "lack of improvement" in a group of healthy subjects. The true value of the segmental BIA methodology may lie in applications involving groups with altered distributions of segmental and compartmental fluid.
-
improved prediction of extracellular and Total Body Water using impedance loci generated by multiple frequency bioelectrical impedance analysis
Physics in Medicine and Biology, 1993Co-Authors: B H Cornish, B J Thomas, L C WardAbstract:Bioelectrical impedance analysis (BIA) using a frequency of 30 kHz is an established method of predicting Total Body Water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. The paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-Body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. Predictions of extracellular Water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively.
-
improved prediction of extracellular and Total Body Water using impedance loci generated by multiple frequency bioelectrical impedance analysis
Physics in Medicine and Biology, 1993Co-Authors: B H Cornish, B J Thomas, L C WardAbstract:Bioelectrical impedance analysis (BIA) using a frequency of 50 kHz is an established method of predicting Total Body Water (TBW). However, very little research has been performed to determine whether 50 kHz is the optimum frequency for the prediction of TBW from impedance measurements. This paper analyses a mathematical expression describing the equivalent electrical circuit for biological tissue, and derives a graphical representation of the resistive and reactive components. The nature of the resulting impedance locus was used in the analysis of measured whole-Body impedance of 42 rats over a range of frequencies to determine the impedance at the characteristic frequency, Zc, and also the impedance at zero frequency, R0. The standard error associated with the prediction of TBW (determined by isotope dilution) using Zc was 5.9% compared with a standard error of prediction of 10.1% using the established BIA method at 50 kHz on the same data. Predictions of extracellular Water (ECW) using the impedance at zero frequency, R0, yielded a standard error of 3.2% compared with standard errors of 4.8% and 4.2% using single frequency BIA measurements at 5 kHz and 1 kHz, respectively. These results demonstrate a significant (P < 0.01) improvement in the prediction of TBW and ECW using multiple frequency bioelectrical impedance analysis (MFBIA).
-
measurement of extracellular and Total Body Water of rats using multiple frequency bioelectrical impedance analysis
Nutrition Research, 1992Co-Authors: B H Cornish, L C Ward, B J ThomasAbstract:Abstract Multiple frequency bioelectrical impedance analysis (MFBIA) was used to measure whole Body impedance of rats between frequencies from 1 kHz to 100 kHz. The data were analysed, with reference to an equivalent electrical circuit for biological tissue, to estimate Total Body Water (TBW) and extracellular Water (ECW). TBW and ECW were independently determined by isotope dilution and desiccation. Correlation between MFBIA measurements and these alternative techniques were r=0.984 (SEE=6.5%) and r=0.995 (SEE=3.2%) for TBW and ECW respectively. These results establish the validity, accuracy and precision of MFBIA for the assessment of both TBW and ECW.
W J Hannan - One of the best experts on this subject based on the ideXlab platform.
-
comparison of bio impedance spectroscopy and multi frequency bio impedance analysis for the assessment of extracellular and Total Body Water in surgical patients
Clinical Science, 1995Co-Authors: W J Hannan, S J Cowen, Kenneth C H Fearon, C E Plester, A DebeauAbstract:1. Measurements of extracellular and Total Body Water provide useful information on the nutritional status of surgical patients and may be estimated from whole-Body bio-impedance measurements at different frequencies. 2. Resistance and reactance were measured at 50 frequencies from 5kHz to 1MHz in 29 surgical patients (17 males, 12 females) with a wide range of extracellular to Total Body Water ratios. 3. A fit to the spectrum of reactance versus resistance data gave predicted resistances at frequencies zero and infinity. Values of extracellular and Total Body Water determined by this bio-impedance spectroscopy technique were regressed against values obtained from radioisotope dilution. The standard errors of the estimate were 1.8931 and 3.2591 respectively. 4. Resistance indices (height2/resistance) at selected frequencies gave the highest correlations with extracellular and Total Body Water at 5kHz and 200kHz respectively, and prediction equations derived from multiple stepwise regressions also showed these to be the optimum frequencies. The standard errors of the estimate for this multi-frequency bio-impedance analysis method were 1.9371 and 2.6061 for extracellular and Total Body Water respectively. 5. To assess the ability of the two methods to measure changes in extracellular and Total Body Water, reproducibility was assessed from repeat measurements 10 min apart in a subgroup of 15 patients. Bio-impedance spectroscopy gave mean coefficients of variation for extracellular and Total Body Water of 0.9% and 3.0% respectively. For multi-frequency bio-impedance analysis the corresponding coefficients of variation were 0.9% and 0.6%. 6. It is concluded that a simple impedance analyser operating at only two frequencies compares favourably with the more complex spectroscopy technique for the determination of extracellular and Total Body Water in surgical patients.
-
evaluation of multi frequency bio impedance analysis for the assessment of extracellular and Total Body Water in surgical patients
Clinical Science, 1994Co-Authors: W J Hannan, S J Cowen, Kenneth C H Fearon, C E Plester, J S Falconer, R A RichardsonAbstract:1. Multi-frequency bio-impedance analysis has been used to estimate extracellular and Total Body Water in a heterogeneous group of 43 surgical patients (23 males, 20 females). 2. Radioisotope-dilution methods were used for the measurement of extracellular and Total Body Water. 3. Resistance and reactance were measured between wrist and ankle at frequencies from 5 kHz to 1 MHz. 4. Extracellular and Total Body Water were estimated by multiple stepwise regression using the radioisotope values as the dependent variables. The parameters included in the regression were: resistance and reactance at each frequency, Body habitus parameters, plasma albumin and plasma sodium. 5. The standard errors of the estimates between the measured and estimated values were 1.73 litres (coefficient of variation 9.6%) and 2.17 litres (coefficient of variation 6.0%) for extracellular and Total Body Water, respectively. 6. These errors represent a useful improvement relative to those obtained from anthropometric estimates. However, the improvements relative to the use of a single frequency (50 kHz) are not clinically significant.
