Zeitschriftenartikel: „Body impedance“

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Aliau-Bonet, Carles, und Ramon Pallas-Areny. „A fast method to estimate body capacitance to ground at mid frequencies“. Journal of Electrical Bioimpedance 6, Nr. 1 (08.08.2019): 33–36. http://dx.doi.org/10.5617/jeb.2569.

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Abstract Impedance measurements that involve the human body are affected by the capacitance between the body and earth ground. This paper describes a fast method to estimate that capacitance at 10 kHz, which is valid for impedance analyzers intended to measure ungrounded impedances. The method does not require any external component other than two common capacitors and two conductive electrodes in contact with the body.

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Bracco, David, Daniel Thiébaud, René L. Chioléro, Michel Landry, Peter Burckhardt und Yves Schutz. „Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans“. Journal of Applied Physiology 81, Nr. 6 (01.12.1996): 2580–87. http://dx.doi.org/10.1152/jappl.1996.81.6.2580.

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Bracco, David, Daniel Thiébaud, René L. Chioléro, Michel Landry, Peter Burckhardt, and Yves Schutz.Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans. J. Appl. Physiol. 81(6): 2580–2587, 1996.—The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whole body value (100.5 ± 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual-energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length2/impedance) and FFM ( r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 ± 23 cm for the arm and 193 ± 39 cm for the leg at 50 kHz) but was higher for the trunk (457 ± 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women.

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Mazess, Richard B. „Letters to the Editor“. Journal of Applied Physiology 84, Nr. 1 (01.01.1998): 396–97. http://dx.doi.org/10.1152/jappl.1998.84.1.396.

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The following is the abstract of the article discussed in the subsequent letter: Bracco, David, Daniel Thiébaud, René L. Chioléro, Michel Landry, Peter Burckhardt, and Yves Schutz.Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans. J. Appl. Physiol. 81(6): 2580–2587, 1996.—The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whole body value (100.5 ± 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual-energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length2/impedance) and FFM ( r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 ± 23 cm for the arm and 193 ± 39 cm for the leg at 50 kHz) but was higher for the trunk (457 ± 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women.

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Hutcheson, Lonn, Lonn Hutcheson, Kris E. Berg und Earnest Prentice. „Body Impedance Analysis and Body Water Loss“. Research Quarterly for Exercise and Sport 59, Nr. 4 (Dezember 1988): 359–62. http://dx.doi.org/10.1080/02701367.1988.10609383.

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5

MURAI, Akihiko. „ENV-BODY Impedance: Modeling Impedance between Human Body and Environment and Its Design“. Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec) 2019 (2019): 2P2—H05. http://dx.doi.org/10.1299/jsmermd.2019.2p2-h05.

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6

Smith, DenisN, PeterM J. M. De Vries, PeterM Kouw, CeesG Olthof, Jean-PaulP M. De Vries und AbJ M. Donker. „Bioelectrical impedance and body composition“. Lancet 341, Nr. 8844 (Februar 1993): 569–70. http://dx.doi.org/10.1016/0140-6736(93)90342-e.

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7

BAUMGARTNER, RICHARD N., CAMERON CHUMLEA und ALEX F. ROCHE. „Bioelectric Impedance for Body Composition“. Exercise and Sport Sciences Reviews 18, Nr. 1 (Januar 1990): 193???224. http://dx.doi.org/10.1249/00003677-199001000-00009.

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8

Walker, M., D. Rodham, G. R. Fulcher, B. Clayton, M. Farrer und K. G. M. M. Alberti. „Bioelectrical impedance and body composition“. Lancet 341, Nr. 8842 (Februar 1993): 448. http://dx.doi.org/10.1016/0140-6736(93)93055-6.

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9

Lukaski, Henry C. „Body mass index, bioelectrical impedance, and body composition“. Nutrition 17, Nr. 1 (Januar 2001): 55–56. http://dx.doi.org/10.1016/s0899-9007(00)00499-8.

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10

Wagner, Dale R. „Bioelectrical impedance changes of the trunk are opposite the limbs following acute hydration change“. Journal of Electrical Bioimpedance 13, Nr. 1 (01.01.2022): 25–30. http://dx.doi.org/10.2478/joeb-2022-0005.

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Abstract This study aimed to evaluate the changes in impedance and estimates of body composition variables obtained from segmental multi-frequency bioelectrical impedance analysis (SMFBIA) following acute hydration change. All participants (N = 11 active adults) had SMFBIA measurements at baseline (euhydration), post-dehydration, and post-hyperhydration in an experimental repeated-measures design. Dehydration and hyperhydration trials were randomized with the opposite treatment given 24 h later. Dehydration was achieved via a heat chamber of 40 °C and 60% relative humidity. Hyperhydration was achieved by drinking lightly-salted water (30 mmol·L-1 NaCl; 1.76 g NaCl·L-1) within 30 min. Post-measurements were taken 30 min after each treatment. Despite changes in mass post-dehydration (Δ = -2.0%, p < 0.001) and post-hyperhydration (Δ = 1.2%, p < 0.001), SMFBIA estimates of total body water (TBW) did not change significantly across trials (p = 0.507), leading to significant differences (p < 0.001) in SMFBIA-estimates of body fat percentage across trials. Dehydration resulted in a significant (p < 0.001) 8% decrease in limb impedances at both 20 kHz and 100 kHz. Hyperhydration increased limb impedances only slightly (1.5%, p > 0.05). Impedance changes in the trunk followed an opposite pattern of the limbs. SMFBIA failed to track acute changes in TBW. Divergent impedance changes suggest the trunk is influenced by fluid volume, but the limbs are influenced by ion concentration.

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Nie, Yafei, Jie Wang, Chengshi Zheng, Jian Xu, Xiaodong Li, Yu Wang, Bo Zhong, Juanjuan Cai und Jinqiu Sang. „Measurement and modeling of the mechanical impedance of human mastoid and condyle“. Journal of the Acoustical Society of America 151, Nr. 3 (März 2022): 1434–48. http://dx.doi.org/10.1121/10.0009618.

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Bone conduction devices are used in audiometric tests, hearing rehabilitation, and communication systems. The mechanical impedance of the stimulated skull location affects the performance of the bone conduction devices. In the present study, the mechanical impedances of the mastoid and condyle were measured in 100 Chinese subjects aged from 22 to 67 years. The results show that the mastoid and condyle impedances within the same subject differ significantly and the impedance differences between subjects at the same stimulation position are mainly below the resonance frequency. The mechanical impedance of the mastoid is significantly influenced by age, and not related to gender or body mass index (BMI). While the mechanical impedance of the condyle is significantly affected by BMI, followed by gender, and not related to age. There are some differences in mastoid impedance between the Chinese and Western subjects. An analogy model predicts that the difference in mechanical impedance between the mastoid and condyle leads to a significant difference in the output force of the bone conduction devices. The results can be used to develop improved condyle and mastoid stimulators for the Chinese.

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Bournas, Panagiota, Timothy Wolowiec, Courtney Burland, Sara Trefil, Vasilios Bournas und Regina Schurman. „Is Lower-Body Bioelectrical Impedance Comparable to Whole-Body Bioelectrical Impedance in High School Students?“ Medicine & Science in Sports & Exercise 43, Suppl 1 (Mai 2011): 439. http://dx.doi.org/10.1249/01.mss.0000401211.08758.f8.

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13

De Lorenzo, A., R. P. Sorge, N. Candeloro, C. Di Campli, G. Sesti und R. Lauro. „New insights into body composition assessment in obese women“. Canadian Journal of Physiology and Pharmacology 77, Nr. 1 (01.01.1999): 17–21. http://dx.doi.org/10.1139/y98-133.

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During treatment of patients with non-insulin-dependent diabetes mellitus, there may be marked body weight loss. Therefore, body composition should be monitored to check for a decrease in fat mass alone, without an excessive decrease of both fat-free mass and total body water. Accordingly, it is useful to monitor the hydration of these patients. One method that allows us to check the status of body hydration is the multifrequency bioelectric impedance analysis (MFBIA). It makes use of formulas that estimate total body water on the basis of the concept that the human body may be approximated to a cylinder of length equal to body height. In normal subjects body water estimates are sufficiently accurate, but in obese subjects the true hydration status may be overestimated. In this report, we describe the accuracy of mathematical models previously described in the literature, and correct for the overestimation of total body water in obese subjects by means of a new equation based on a new model. The coefficients for each model have been recalculated by the weighing of our sample in order to test the accuracy of estimates obtained with the equations. This new model includes both body volume and two impedances at appropriate frequencies useful for identifying two terms strictly related to extra- and intra-cellular water. The new formulas do not include body weight, but they include the body volume, a parameter more closely related to the biophysical reference model. Fifty-five overweight females, body mass index ranging from 26.8 to 50.2 kg/m2, were enrolled in the study. The proposed equations, taking advantage of two impedance values at appropriate frequencies, better predict total body water in obese women. This was particularly evident when the results obtained with the multifrequency bioelectric impedance analysis and deuterium isotopic oxide dilution method were compared. Although this last method is considered the "gold standard," it is not suitable for use in routine clinical practice. In conclusion, evaluation of total body composition by means of bioelectric impedance analysis might be included in programs for the prevention of non-insulin-dependent diabetes and for monitoring weight loss during overt pathology.Key words: body composition, bioelectrical impedance, obesity, diabetes mellitus, extracellular water, intracellular water.

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Muramatsu, Dairoku, und Ken Sasaki. „Input Impedance Analysis of Wearable Antenna and Experimental Study with Real Human Subjects: Differences between Individual Users“. Electronics 10, Nr. 10 (12.05.2021): 1152. http://dx.doi.org/10.3390/electronics10101152.

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In human body communication (HBC) systems, radio-frequency signals are excited in the human body through a wearable antenna comprised of electrodes that are in contact with the surface of the body. The input impedance characteristics of these antennas are important design parameters for increasing transmission efficiency and reducing signal reflection, similar to other wireless circuits. In this study, we discuss variations of input impedance characteristics of a wearable antenna prototype caused by differences among real human subjects. A realistic human arm model is used for simulations, and the analytical results obtained are compared to measured data obtained from real human subjects, in a range from 1 to 100 MHz. The simulations of input impedance characteristics from antennas worn on the wrists of male and female models with dry and wet skin conditions show that the impedance variation between genders is small. The moisture condition of the skin has little influence on frequencies exceeding several MHz. Measurements with a proto-type wearable antenna and 22 real human subjects reveal that HBC is robust against the variations of individual users from the viewpoint of the voltage standing wave ratio. Moreover, a simplified rectangular prism model is proposed to analyze the thickness of body tissues. Comparisons of measured input impedances indicate that individual differences in impedance are mainly due to differences in the thickness of skin and fat layers. The model also enables us to design the antenna prototype without multiple subject experiments.

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CATON, JOHN R., PAUL A. MOL??, WILLIAM C. ADAMS und DOUGLAS S. HEUSTIS. „Body composition analysis by bioelectrical impedance“. Medicine & Science in Sports & Exercise 20, Nr. 5 (Oktober 1988): 489???491. http://dx.doi.org/10.1249/00005768-198810000-00010.

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16

Boulier, A., A. L. Thomasset und M. Apfelbaum. „Bioelectrical-impedance measurement of body water“. American Journal of Clinical Nutrition 55, Nr. 3 (01.03.1992): 761–62. http://dx.doi.org/10.1093/ajcn/55.3.761.

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17

CHUMLEA, WM CAMERON, R. M. SIERVOGEL, YIXUN WU, GWENDOLYN HALL und SHUMEI S. GUO. „Bioelectrical Impedance Spectroscopy and Body Composition“. Annals of the New York Academy of Sciences 904, Nr. 1 (25.01.2006): 210–13. http://dx.doi.org/10.1111/j.1749-6632.2000.tb06452.x.

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18

Matthie, J. R., und P. Withers. „Impedance measurements of body-water compartments“. American Journal of Clinical Nutrition 61, Nr. 5 (01.05.1995): 1167–68. http://dx.doi.org/10.1093/ajcn/61.5.1167.

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19

Shaikh, M. G., N. J. Crabtree, N. J. Shaw und J. M. W. Kirk. „Body Fat Estimation Using Bioelectrical Impedance“. Hormone Research in Paediatrics 68, Nr. 1 (2007): 8–10. http://dx.doi.org/10.1159/000098481.

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20

Ajoudani, Arash, Nikos Tsagarakis und Antonio Bicchi. „Tele-impedance: Teleoperation with impedance regulation using a body–machine interface“. International Journal of Robotics Research 31, Nr. 13 (31.10.2012): 1642–56. http://dx.doi.org/10.1177/0278364912464668.

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21

Chartrand, D. A., J. M. Maarek, T. H. Ye und H. K. Chang. „Lung and chest wall mechanics in rabbits during high-frequency body-surface oscillation“. Journal of Applied Physiology 68, Nr. 4 (01.04.1990): 1722–26. http://dx.doi.org/10.1152/jappl.1990.68.4.1722.

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In eight anesthetized and tracheotomized rabbits, we studied the transfer impedances of the respiratory system during normocapnic ventilation by high-frequency body-surface oscillation from 3 to 15 Hz. The total respiratory impedance was partitioned into pulmonary and chest wall impedances to characterize the oscillatory mechanical properties of each component. The pulmonary and chest wall resistances were not frequency dependent in the 3- to 15-Hz range. The mean pulmonary resistance was 13.8 +/- 3.2 (SD) cmH2O.l-1.s, although the mean chest wall resistance was 8.6 +/- 2.0 cmH2O.l-1.s. The pulmonary elastance and inertance were 0.247 +/- 0.095 cmH2O/ml and 0.103 +/- 0.033 cmH2O.l-1.s2, respectively. The chest wall elastance and inertance were 0.533 +/- 0.136 cmH2O/ml and 0.041 +/- 0.063 cmH2O.l-1.s2, respectively. With a linear mechanical behavior, the transpulmonary pressure oscillations required to ventilate these tracheotomized animals were at their minimal value at 3 Hz. As the ventilatory frequency was increased beyond 6-9 Hz, both the minute ventilation necessary to maintain normocapnia and the pulmonary impedance increased. These data suggest that ventilation by body-surface oscillation is better suited for relatively moderate frequencies in rabbits with normal lungs.

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NAKADOMO, FUMIO, KIYOJI TANAKA, HITOSHI WATANABE, KANJI WATANABE und KAZUYA MAEDA. „ASSESSMENT OF BODY COMPOSITION BY BIOELECTRICAL IMPEDANCE ANALYSIS“. Japanese Journal of Physical Fitness and Sports Medicine 40, Nr. 1 (1991): 93–101. http://dx.doi.org/10.7600/jspfsm1949.40.93.

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23

Campa, Francesco, und Stefania Toselli. „Bioimpedance Vector Analysis of Elite, Subelite, and Low-Level Male Volleyball Players“. International Journal of Sports Physiology and Performance 13, Nr. 9 (01.10.2018): 1250–53. http://dx.doi.org/10.1123/ijspp.2018-0039.

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Purpose: To establish a specific player profile on body-composition parameters and to provide a data set of bioelectric impedances values for male volleyball players. Methods: The study included 201 athletes (age 26.1 [5.4] y, height 191.9 [9.7] cm, weight 86.8 [10.8] kg) registered in the Italian volleyball divisions. The athletes were divided into 3 groups: The elite group comprised 75 players participating in the 1st (Super Lega) division, the subelite group included 65 athletes performing in the 2nd (Serie A2) division, and the low-level group included 61 players participating in the 3rd (Serie B) division. Bioelectric impedance, body weight, and height of the athletes were measured in the second half of the competitive season. In addition, bioelectrical impedance vector analysis was performed. Results: The elite group showed a greater amount of fat-free mass (FFM) and total body water (TBW) and a lower fat mass (FM) than the subelite group (P < .05). In addition, the elite players were taller and heavier and had a higher FFM, FM, TBW, and body cellular mass than the low-level athletes (P < .05). Finally, the mean impedance vectors of the elite group significantly differed from those measured in the normal population and in the other 2 groups (P < .05). Conclusions: This study provides an original data set of body-composition and bioelectric impedance reference values of elite male volleyball players. The results might be useful for interpretation of individual bioimpedance vectors and for defining target regions for volleyball players.

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Deurenberg, Paul, Anna Tagliabue und Frans J. M. Schouten. „Multi-frequency impedance for the prediction of extracellular water and total body water“. British Journal of Nutrition 73, Nr. 3 (März 1995): 349–58. http://dx.doi.org/10.1079/bjn19950038.

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The relationship between total body water (TBW) and extracellular water (ECW), measured by deuterium oxide dilution and bromide dilution respectively, and impedance and impedance index (height2/impedance) at 1, 5, 50 and 100 kHz was studied. After correction for TBW, ECW was correlated only with the impedance index at 1 and 5 kHz. After correction for ECW, TBW was best correlated with the impedance index at 100 kHz. The correlation of body-water compartments with impedance values obtained with modelling programs was lower than with measured impedance values. Prediction formulas for ECW (at 1 and 5 kHz) and TBW (at 50 and 100 kHz) were developed. The prediction errors for ECW and TBW were 1·0 and 1·7 kg respectively (coefficient of variation 5%). The residuals of both ECW and TBW were related to the ECW/TBW value. Application of the prediction formulas in a population, independently measured, revealed a slight overestimation of TBW and ECW, which could be largely explained by differences in the validation group in body-water distribution and in body builds. The ratio of impedance at 1 kHz to impedance at 100 kHz was correlated with body-water distribution (ECW/TBW). The relation is however not strong enough to be useful as a predictor. It is concluded that an independent prediction of ECW and TBW, using impedance at low and high frequency respectively, is possible, but that the bias depends on the body-water distribution and body build of the measured subject.

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Baumgartner, R. N., W. C. Chumlea und A. F. Roche. „Estimation of body composition from bioelectric impedance of body segments“. American Journal of Clinical Nutrition 50, Nr. 2 (01.08.1989): 221–26. http://dx.doi.org/10.1093/ajcn/50.2.221.

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Toselli, S., und E. Gualdi-Russo. „Estimation of body composition from bioelectrical impedance of body segments“. International Journal of Anthropology 14, Nr. 1 (Januar 1999): 71–82. http://dx.doi.org/10.1007/bf02447629.

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Kim, Ilkyu, Sun-Gyu Lee, Yong-Hyun Nam und Jeong-Hae Lee. „Investigation on Wireless Link for Medical Telemetry Including Impedance Matching of Implanted Antennas“. Sensors 21, Nr. 4 (18.02.2021): 1431. http://dx.doi.org/10.3390/s21041431.

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The development of biomedical devices benefits patients by offering real-time healthcare. In particular, pacemakers have gained a great deal of attention because they offer opportunities for monitoring the patient’s vitals and biological statics in real time. One of the important factors in realizing real-time body-centric sensing is to establish a robust wireless communication link among the medical devices. In this paper, radio transmission and the optimal characteristics for impedance matching the medical telemetry of an implant are investigated. For radio transmission, an integral coupling formula based on 3D vector far-field patterns was firstly applied to compute the antenna coupling between two antennas placed inside and outside of the body. The formula provides the capability for computing the antenna coupling in the near-field and far-field region. In order to include the effects of human implantation, the far-field pattern was characterized taking into account a sphere enclosing an antenna made of human tissue. Furthermore, the characteristics of impedance matching inside the human body were studied by means of inherent wave impedances of electrical and magnetic dipoles. Here, we demonstrate that the implantation of a magnetic dipole is advantageous because it provides similar impedance characteristics to those of the human body.

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Pelegrini, Andreia, André De Araújo Pinto, Hector Cris Colares De Angelo, Gaia Salvador Claumann, Diego Augusto Santos Silva und Mateus Augusto Bim. „Validation of a bioelectrical impedance scale for the estimation of body fat in adolescents“. Revista Brasileira de Fisiologia do Exercício 19, Nr. 5 (19.10.2020): 369. http://dx.doi.org/10.33233/rbfex.v19i5.4106.

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Several different instruments available on the market have been used for the estimation of body fat. However, many of these instruments have not been compared with reference criteria to verify their true accuracy. This study aimed to verify the validity of a bioelectrical impedance scale (OMRON-514C) for the estimation of body fat. Forty-four overweight adolescents (25 females) participated in this study, with an average age of 12.3 ± 1.1 years. All were submitted to body fat evaluations by air displacement plethysmography and bioelectrical impedance. Higher values of relative and absolute body fat were estimated by bioelectrical impedance compared to plethysmography (p < 0.05). There was no correlation between the relative body fat measurements between the two methods (r = 0.185; p = 0.228). The absolute measurements of body fat were correlated (r = 0.497, p = 0.001). Both in the measurements of relative (p= 0.034) and absolute body fat (p = 0.021), the bioelectrical impedance overestimated the measured values. Thus, in adolescents with characteristics similar to the present study, the estimate of body fat by the bioelectrical impedance (OMRON-514C) should be used with caution.Keywords: plethysmography, bioelectrical impedance, adolescents, overweight.

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Zarowitz, Barbara J., und Alison M. Pilla. „Bioelectrical Impedance in Clinical Practice“. DICP 23, Nr. 7-8 (Juli 1989): 548–55. http://dx.doi.org/10.1177/1060028089023007-803.

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Bioelectrical impedance (BI) relies on the conduction of a low-voltage alternating current through the body. Lean tissue and fluids containing electrolytes conduct the current and cell membranes serve as capacitors and account for capacitive resistance. Fat and bone are poor conductors. Measurement of the voltage drop of the applied current yields resistance (R) and reactance (Xc). R and Xc are used with height, weight, age, and gender in a number of multiple regression relationships to predict body composition compartments such as fat-free mass, lean body mass, extracellular mass, and body cell mass. The technique has been compared with and validated against traditional measures of body composition analysis. In clinical practice, BI has been used to monitor fluid status in burn and dialysis patients, assess changes of body cell mass with nutritional repletion, and predict pharmacokinetic parameters and dose of theophylline and aminoglycoside antibiotics. BI is a noninvasive, safe, rapid, and reproducible technique with exciting potential in clinical practice.

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Trone, D. W., J. A. Hodgdon und M. B. Beckett. „IMPEDANCE IMPROVES THE PREDICTION OF BODY FAT.“ Medicine & Science in Sports & Exercise 27, Supplement (Mai 1995): S207. http://dx.doi.org/10.1249/00005768-199505001-01158.

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31

Bracken, T. D., G. G. Sias, C. Kim, R. S. Senior und R. M. Patterson. „Survey of Electrical Utility Worker Body Impedance“. IEEE Transactions on Power Delivery 23, Nr. 2 (April 2008): 1251–59. http://dx.doi.org/10.1109/tpwrd.2008.915838.

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Baumgartner, R. N., W. C. Chumlea und A. F. Roche. „Bioelectric impedance phase angle and body composition“. American Journal of Clinical Nutrition 48, Nr. 1 (01.07.1988): 16–23. http://dx.doi.org/10.1093/ajcn/48.1.16.

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Navajas, D., R. Farre, M. M. Rotger, J. Milic-Emili und J. Sanchis. „Effect of body posture on respiratory impedance“. Journal of Applied Physiology 64, Nr. 1 (01.01.1988): 194–99. http://dx.doi.org/10.1152/jappl.1988.64.1.194.

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The effects of posture on the mechanics of the respiratory system are not well known, particularly in terms of total respiratory resistance. We have measured respiratory impedance (Zrs) by the forced random noise excitation technique in the sitting and the supine position in 24 healthy subjects. Spirometry and lung volumes (He-dilution technique) were also measured in both postures. The equivalent resistance (Rrs), compliance (Crs), and inertance (Irs) were also calculated by fitting each measured Zrs to a linear series model. When subjects changed from sitting to the supine position, the real part of Zrs increased over the whole frequency band. The associated equivalent resistance, Rrs, increased by 28.2%. The reactance decreased for frequencies lower than 18 Hz and increased for higher frequencies. Consequently, Crs decreased by 38.7% and Irs increased by 15.6%. All of these parameter differences were significant (P less than 0.001). A covariance analysis showed that a significant amount of the postural change in Rrs and Crs can be explained by the reduction of functional residual capacity (FRC). This indicates that the observed differences on Zrs can in part be explained be a shift of the operating point of the respiratory system induced by the decrease in the FRC.

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Foster, K. R., und H. C. Lukaski. „Whole-body impedance--what does it measure?“ American Journal of Clinical Nutrition 64, Nr. 3 (01.09.1996): 388S—396S. http://dx.doi.org/10.1093/ajcn/64.3.388s.

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Patterson, R. „Body fluid determinations using multiple impedance measurements“. IEEE Engineering in Medicine and Biology Magazine 8, Nr. 1 (März 1989): 16–18. http://dx.doi.org/10.1109/51.32399.

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Irawan, Addie, Hiroshi Ohroku, Yasunaga Akutsu und Kenzo Nonami. „2B17 Adaptive Impedance Control with Compliant Body Balance for Hydraulic-actuated Hexapod Robot“. Proceedings of the Symposium on the Motion and Vibration Control 2010 (2010): _2B17–1_—_2B17–15_. http://dx.doi.org/10.1299/jsmemovic.2010._2b17-1_.

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Berjano, Enrique, und Andre d'Avila. „Lumped Element Electrical Model based on Three Resistors for Electrical Impedance in Radiofrequency Cardiac Ablation: Estimations from Analytical Calculations and Clinical Data“. Open Biomedical Engineering Journal 7, Nr. 1 (12.07.2013): 62–70. http://dx.doi.org/10.2174/1874120720130603001.

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The electrical impedance measured during radiofrequency cardiac ablation (RFCA) is widely used in clinical studies to predict the heating evolution and hence the success of the procedure. We hypothesized that a model based on three resistors in series can mimic the total electrical impedance measured during RFCA. The three resistors or impedances are given by: impedance associated with the tissue around the active electrode (myocardium and circulating blood) (Z-A), that associated with the tissue around the dispersive electrode (Z-DE) and that associated with the rest of the body (Z-B). Our objective was to quantify the values associated with these three impedance types by an analytical method, after which the values obtained would be compared to those estimated from clinical data from previous studies. The results suggest that an RFCA using a 7 Fr 4-mm electrode would give a Z-A of around 75 ohms, a Z-DE around 20 ohms, and Z-B would be 15±10 ohms (for body surface area variations between 1.5 and 2.5 m^2). Finally, adaptations of the proposed model were used to explain the results of previous clinical studies using a different electrode arrangement, such as in bipolar ablation of the ventricular septum.

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Stewart, S. P., P. N. Bramley, R. Heighton, J. H. Green, A. Horsman, M. S. Losowsky und M. A. Smith. „Estimation of body composition from bioelectrical impedance of body segments: Comparison with dual-energy X-ray absorptiometry“. British Journal of Nutrition 69, Nr. 3 (Mai 1993): 645–55. http://dx.doi.org/10.1079/bjn19930066.

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In twenty-eight healthy subjects, ten men and eighteen women, with a range in body mass index (BMI) of 17.9–31.6 kg/m2 and an age range 20–60 years, body composition was estimated by dual-energy X-ray absorptiometry (DEXA), skinfold anthropometry (SFA) and bioelectrical impedance analysis (BIA) of the ‘whole body’and body segments. In thirteen subjects muscle mass was also estimated by 24 h urinary creatinine excretion. The relationship between fat-free mass (FFM) determined by DEXA and the impedance index of each body segment (calculated as Iength2/impedance (Z)) was analysed. The strongest correlation was between FFM (DEXA) and height2/‘whole-body’Z (Zw) (r 0.97 for the combined sexes, standard error of estimate (SEE) 2.72 kg). Separate prediction equations were found to be necessary for males and females when estimating FFM from BIA measurement of the arm (for men, r 0.93, SEE 1.98 kg; for women, r 0.75, SEE 2.87 kg). Muscle mass derived from 24 h creatinine excretion showed weak correlation with FFM (DEXA) (r 0.57, P = 0.03) and no correlation with FFM (SFA). FFM (SFA) correlated well with both FFM (DEXA) (r 0.96, SEE = 3.12 kg) and with height2/Zw (r 0.92, SEE 4.52 kg). Measurement of the impedance of the arm offers a simple method of assessing the composition of the whole body in normal individuals, and it appears comparable with other methods of assessment.

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Jebb, Susan A., Timothy J. Cole, Deanne Doman, Peter R. Murgatroyd und Andrew M. Prentice. „Evaluation of the novel Tanita body-fat analyser to measure body composition by comparison with a four-compartment model“. British Journal of Nutrition 83, Nr. 2 (Februar 2000): 115–22. http://dx.doi.org/10.1017/s0007114500000155.

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The Tanita body-fat analyser is a novel device to estimate body fat, based on the principles of bioelectrical impedance. It differs from other impedance systems which use surface electrodes in that the subjects stand bare-footed on a metal sole-plate which incorporates the electrodes, hence impedance is measured through the legs and lower trunk. In 104 men and 101 women (16–78 years and BMI 16–41 kg/m2) the mean bias in body-fat mass measured using the Tanita body-fat analyser was 0·8 (2SD 7·9) KG RELATIVE TO A FOUR-COMPARTMENT MODEL. THIS IS COMPARABLE TO THE OTHER PREDICTION TECHNIQUES TESTED (CONVENTIONAL TETRAPOLAR IMPEDANCE -1·3 (2sd 6·9) kg, skinfold thicknesses 0·3 (2sd 7·4) kg, and BMI-based formulas -0·2 (2sd 9·0) kg and -0·6 (2sd 8·5) kg), but the agreement was poorer than for ‘reference’ methods to measure body fat (density 0·2 (2sd 3·7) kg, total body water -0·9 (2sd 3·4) kg and dual-energy X-ray absorptiometry 0·1 (2sd 5·0) kg). The present paper also describes the derivation of a new prediction equation for the calculation of body composition from the Tanita body-fat analyser. The equation incorporates sex, age, and a log-transformation of height, weight and the measured impedance to predict body fat measured by a four-compartment model. This approach is recommended in the derivation of other prediction equations in body composition analysis. Using this novel prediction equation the residual standard deviations were 4·8 % for men and 3·3 % for women. A similar analysis using data collected with a conventional tetrapolar system yielded residual standard deviations of 4·3 % for men and 3·1 % for women. This demonstrates that the practical simplicity of the novel Tanita method is not associated with a clinically significant decrement in performance relative to a traditional impedance device.

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Bellafronte, N. T., L. Vega-Piris, G. B. Cuadrado und P. G. Chiarello. „Comparison between whole-body and segmental bioelectrical impedance for body composition“. Clinical Nutrition ESPEN 46 (Dezember 2021): S603. http://dx.doi.org/10.1016/j.clnesp.2021.09.174.

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Zhang, Jun, Jie Huang, Hong Mei Tang, Xian Hua Li und Qing Yang Cai. „Human Physiological Signal Recognition Based on Piezoelectric Impedance Technique“. Applied Mechanics and Materials 687-691 (November 2014): 4089–92. http://dx.doi.org/10.4028/www.scientific.net/amm.687-691.4089.

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In order to verify whether the piezoelectric impedance technology can be applied to detect the physiological signals of human body, the principle of piezoelectric coupling impedance theory and piezoelectric impedance technology using for human physiological signal detection was introduced in this paper. With an experiment platform set up, detection experiments based on the piezoelectric impedance technology were created. And the experimental1 was improved to avoid the influence of man-made factors on experiment result. Two methods were used to deal with the experimental data. The results show that the piezoelectric impedance technique can be applied to identify the human body physiological signal, and offers a totally new idea to detect the physiological signals of human body.

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Neto Angéloco, Larissa Rodrigues, Rafael Deminice, Izabel de Arruda Leme, Renata Cristina Lataro und Alceu Afonso Jordão. „Bioelectrical impedance analysis and anthropometry for the determination of body composition in rats: effects of high-fat and high-sucrose diets“. Revista de Nutrição 25, Nr. 3 (Juni 2012): 331–39. http://dx.doi.org/10.1590/s1415-52732012000300003.

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OBJECTIVE: The aim of the present study was to determine the impedance of Wistar rats treated with high-fat and high-sucrose diets and correlate their biochemical and anthropometric parameters with chemical analysis of the carcass. METHODS: Twenty-four male Wistar rats were fed a standard (AIN-93), high-fat (50% fat) or high-sucrose (59% of sucrose) diet for 4 weeks. Abdominal and thoracic circumference and body length were measured. Bioelectrical impedance analysis was used to determine resistance and reactance. Final body composition was determined by chemical analysis. RESULTS: Higher fat intake led to a high percentage of liver fat and cholesterol and low total body water in the High-Fat group, but these changes in the biochemical profile were not reflected by the anthropometric measurements or bioelectrical impedance analysis variables. Anthropometric and bioelectrical impedance analysis changes were not observed in the High-Sucrose group. However, a positive association was found between body fat and three anthropometric variables: body mass index, Lee index and abdominal circumference. CONCLUSION: Bioelectrical impedance analysis did not prove to be sensitive for detecting changes in body composition, but body mass index, Lee index and abdominal circumference can be used for estimating the body composition of rats.

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Scheltinga, M. R., W. S. Helton, J. Rounds, D. O. Jacobs und D. W. Wilmore. „Impedance electrodes positioned on proximal portions of limbs quantify fluid compartments in dogs“. Journal of Applied Physiology 70, Nr. 5 (01.05.1991): 2039–44. http://dx.doi.org/10.1152/jappl.1991.70.5.2039.

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Body resistance and reactance to the conduction of an alternating electrical current were measured using electrodes attached to distal and proximal portions of limbs in anesthetized dogs. Body impedance was calculated from these measurements obtained at 30-min time intervals during a control period and after intravenous administration of 0.9% saline. Extracellular (ECW) and total body water (TBW) were determined by bromide and heavy water dilution techniques, respectively. Baseline impedance obtained from proximal electrodes was related to ECW (r = 0.95, P less than 0.001) and TBW (r = 0.80, P less than 0.02). After saline infusion, proximal electrodes detected a significant fall in impedance (P less than 0.001), whereas distal electrodes did not (P = 0.06). Furthermore, ECW and TBW could be estimated from the drop of proximal impedance after this bolus infusion (r = 0.82, P less than 0.02, and r = 0.86, P less than 0.01, respectively), but not from distal impedance measurements. Proximally placed impedance electrodes are superior to traditionally used distal electrodes for assessment of body fluid changes in the dog.

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Mandolfo, S., M. Farina und E. Imbasciati. „Bioelectrical Impedance and Hemodialysis“. International Journal of Artificial Organs 18, Nr. 11 (November 1995): 700–704. http://dx.doi.org/10.1177/039139889501801103.

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Bioimpedance is a simple and non-invasive method of assessing body fluid composition. The aim of our study was to evaluate the reliability of impedance: a) to measure urea distribution volume considered to be coextensive with total body water (TBW); b) to assess the changes in body fluid compartments before and after dialysis; c) to predict hypotensive episodes. In twelve hemodialysis patients, TBW measured by bioelectrical impedance analysis (BIA) before a dialysis session was significantly correlated with the urea distribution volume estimated by dialysis direct quantification (r=0.64, p < 0.05) and with TBW calculated by the Watson equation (r=0.65, p < 0.05). Anthropometric values were, on average, 4.8% higher. TBW measured by BIA at the end of treatment overestimated fluid losses induced by ultrafiltration by 14% to 70%, while TBW 6 h after dialysis reflected the weight losses. On line BIA during hemodialysis has a very low positive predictive value (41.6%) and poor sensitivity (66%) for the prediction of hypotension. In conclusion, BIA is helpful in assessing the urea distribution volume but is not reliable for assessing acute fluid changes nor for predicting hypotensive episodes related to hemodialysis.

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Stanton, Christine A., Dwayne W. Hamar, Donald E. Johnson und Martin J. Fettman. „Bioelectrical impedance and zoometry for body composition analysis in domestic cats“. American Journal of Veterinary Research 53, Nr. 2 (01.02.1992): 251–57. http://dx.doi.org/10.2460/ajvr.1992.53.02.251.

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Summary Zoometric measurements and bioelectrical impedance analysis were evaluated as methods of body composition determination in healthy cats. Zoometric and impedance measurements were taken on 22 anesthetized adult cats of various ages, genders, breeds, and body weights. The cats were then euthanatized. The bodies were processed through a tissue homogenizer and free-catch specimens were taken, freeze-dried, and analyzed for total body water, protein, fat, potassium, and ash content. Stepwise regression analysis was implemented to identify statistically significant relationships between the chemically determined dependent variables (total body water, protein, potassium, fat-free mass, fat mass, and percent body fat) and the zoometric measurements, with or without bioelectrical impedance analysis. Statistical analysis revealed high correlations between the dependent variables and the corresponding predicted values of those variables. Body weight alone was a poor predictor of body composition in these cats. On the basis of these findings, we suggest that zoometric and bioelectrical impedance measurements may serve as practical, noninvasive, simple, and accurate methods for estimating body composition in domestic cats.

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Freeborn, Todd J., Ahmed S. Elwakil und Brent Maundy. „Compact Wide Frequency Range Fractional-Order Models of Human Body Impedance against Contact Currents“. Mathematical Problems in Engineering 2016 (2016): 1–10. http://dx.doi.org/10.1155/2016/4967937.

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Three circuit models using constant phase elements are investigated to represent the human body impedance against contact currents from 40 Hz to 110 MHz. The parameters required to represent the impedance are determined using a nonlinear least squares fitting (NLSF) applied to the averaged human body impedance dataset. The three fractional-order models with 4, 6, and 7 parameters are compared to an already existing integer-order, 11-parameter model. Simulations of the fractional-order models impedance are presented and discussed along with their limitations.

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Shin, Seung-Chul, Jinkyu Lee, Soyeon Choe, Hyuk In Yang, Jihee Min, Ki-Yong Ahn, Justin Y. Jeon und Hong-Goo Kang. „Dry Electrode-Based Body Fat Estimation System with Anthropometric Data for Use in a Wearable Device“. Sensors 19, Nr. 9 (10.05.2019): 2177. http://dx.doi.org/10.3390/s19092177.

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The bioelectrical impedance analysis (BIA) method is widely used to predict percent body fat (PBF). However, it requires four to eight electrodes, and it takes a few minutes to accurately obtain the measurement results. In this study, we propose a faster and more accurate method that utilizes a small dry electrode-based wearable device, which predicts whole-body impedance using only upper-body impedance values. Such a small electrode-based device typically needs a long measurement time due to increased parasitic resistance, and its accuracy varies by measurement posture. To minimize these variations, we designed a sensing system that only utilizes contact with the wrist and index fingers. The measurement time was also reduced to five seconds by an effective parameter calibration network. Finally, we implemented a deep neural network-based algorithm to predict the PBF value by the measurement of the upper-body impedance and lower-body anthropometric data as auxiliary input features. The experiments were performed with 163 amateur athletes who exercised regularly. The performance of the proposed system was compared with those of two commercial systems that were designed to measure body composition using either a whole-body or upper-body impedance value. The results showed that the correlation coefficient ( r 2 ) value was improved by about 9%, and the standard error of estimate (SEE) was reduced by 28%.

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Organ, L. W., G. B. Bradham, D. T. Gore und S. L. Lozier. „Segmental bioelectrical impedance analysis: theory and application of a new technique“. Journal of Applied Physiology 77, Nr. 1 (01.07.1994): 98–112. http://dx.doi.org/10.1152/jappl.1994.77.1.98.

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Bioelectrical impedance analysis (BIA) for body composition has been based on the volume conductor model that results in the mathematical relationship Ht2/R approximately FFM, where Ht is body height, R is whole body resistance or impedance, and FFM is fat-free mass. Although this relationship exists in the human subject, its strength and usefulness have been subject to conflicting reports. This study reassessed the theory and methodology of BIA and describes a new technique for measuring segmental impedance that may resolve some major limitations associated with the current whole body impedance methodology. By use of data from 200 adult subjects, a new theory and methodology for BIA were developed in four steps: 1) a rationale was presented for replacing the Ht2/R model by one based on electrical resistivity, 2) a practical six-electrode technique for segmental BIA that uses only peripheral electrode sites was described, 3) prediction equations for fat weight based on the new segmental BIA technique were developed, and 4) prediction equations for fat distribution, a potential new use of impedance methodology, were developed using a new measure of fat distribution, the impedance index.

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Arkouche, W., D. Fouque, C. Pachiaudi, S. Normand, M. Laville, E. Delawari, J. P. Riou, J. Traeger und M. La Ville. „Total body water and body composition in chronic peritoneal dialysis patients.“ Journal of the American Society of Nephrology 8, Nr. 12 (Dezember 1997): 1906–14. http://dx.doi.org/10.1681/asn.v8121906.

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In this investigation, total body water (TBW) in ten chronic peritoneal dialysis patients was studied by deuterium (TBW-2H), skinfold thickness (TBW-ST), Watson formula (TBW-WA), 58% of body weight (TBW-58%), and bioelectrical impedance (TBW-BIA), and these results were compared with the reference oxygen18 (TBW-18O) method. We also analyzed the fat-free mass (FFM) by skinfold thickness (FFM-ST), bioelectrical impedance (FFM-BIA), oxygen18 (FFM-18O), and creatinine kinetics method (FFM-CK). In addition, resting metabolic rate was measured by indirect calorimetry. Compared with TBW-18O, TBW-58% and TBW-BIA were significantly different (P < 0.01). TBW-2H overestimated TBW-18O by 4.3%. TBW-ST and TBW-WA gave slightly greater values than TBW-18O, although these values were nonstatistically significant. The best prediction of total body water from these methods was obtained with the Watson formula. When Kt/V was calculated from these results, the values obtained were statistically greater (BIA, P < 0.001) and smaller (58% BW, P < 0.01) than those obtained with either 18O or Watson formula. The fat-free mass estimation also led to discrepant findings. Indeed, FFM-CK was significantly lower (P < 0.05) as compared with FFM-ST, FFM-BIA, or FFM-18O. Resting metabolic rate was strongly correlated with FFM estimated by skinfold thickness (r = 0.91, P < 0.001), bioelectrical impedance (r = 0.85, P < 0.005), and 18O (r = 0.77, P < 0.01), but not when fat-free mass was estimated by the creatinine kinetic method. The water content of fat-free mass estimated by skinfold thickness was found to be 69.7 +/- 6.9% in these patients, a value lower than the standard 73.2% found in healthy adults. This study confirms that there is an abnormal water distribution in chronic peritoneal dialysis patients. However, when compared with the oxygen18 reference method, the Watson formula allows a reliable estimation of Kt/V.

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Heo, Jin-Chul, Doyoon Kim, Hyunsoo An, Chang-Sik Son, Sangwoo Cho und Jong-Ha Lee. „A Novel Biosensor and Algorithm to Predict Vitamin D Status by Measuring Skin Impedance“. Sensors 21, Nr. 23 (04.12.2021): 8118. http://dx.doi.org/10.3390/s21238118.

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The deficiency and excess of vitamin D cause various diseases, necessitating continuous management; but it is not easy to accurately measure the serum vitamin D level in the body using a non-invasive method. The aim of this study is to investigate the correlation between vitamin D levels, body information obtained by an InBody scan, and blood parameters obtained during health checkups, to determine the optimum frequency of vitamin D quantification in the skin and to propose a vitamin D measurement method based on impedance. We assessed body composition, arm impedance, and blood vitamin D concentrations to determine the correlation between each element using multiple machine learning analyses and an algorithm which predicted the concentration of vitamin D in the body using the impedance value developed. Body fat percentage obtained from the InBody device and blood parameters albumin and lactate dehydrogenase correlated with vitamin D level. An impedance measurement frequency of 21.1 Hz was reflected in the blood vitamin D concentration at optimum levels, and a confidence level of about 75% for vitamin D in the body was confirmed. These data demonstrate that the concentration of vitamin D in the body can be predicted using impedance measurement values. This method can be used for predicting and monitoring vitamin D-related diseases and may be incorporated in wearable health measurement devices.

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