関: BIA

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an investigation of the component parts of a whole and their relations in making up the whole
the abstract separation of a whole into its constituent parts in order to study the parts and their relations (同)analytic thinking
a branch of mathematics involving calculus and the theory of limits; sequences and series and integration and differentiation
a form of literary criticism in which the structure of a piece of writing is analyzed
the use of closed-class words instead of inflections: e.g., `the father of the bride instead of `the brides father

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(内容・状況などの)『分析』,分解;(詳細な)検討 / (化学・物理で)分析;《米》(心理学で)[精神]分析;(数学で)解析
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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2016/04/10 19:59:53」(JST)

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Bioelectrical impedance analysis (BIA) is a commonly used method for estimating body composition, and in particular body fat. Since the advent of the first commercially available devices in the mid-1980s the method has become popular owing to its ease of use, portability of the equipment and its relatively low cost compared to some of the other methods of body composition analysis. It is familiar in the consumer market as a simple instrument for estimating body fat. BIA^[1] actually determines the electrical impedance, or opposition to the flow of an electric current through body tissues which can then be used to calculate an estimate of total body water (TBW). TBW can be used to estimate fat-free body mass and, by difference with body weight, body fat.

Accuracy

Many of the early research studies showed that BIA was quite variable and it was not regarded by many as providing an accurate measure of body composition. In recent years technological improvements have made BIA a more reliable and therefore more acceptable way of measuring body composition. Nevertheless it is not a "gold standard" or reference method.

Although the instruments are straightforward to use, careful attention to the method of use (as described by the manufacturer) should be given.

Simple devices to estimate body fat, often using BIA, are available to consumers as body fat meters. These instruments are generally regarded as being less accurate than those used clinically or in nutritional and medical practice. They tend to under-read body fat percentage.^[2]

Dehydration is a recognized factor affecting BIA measurements as it causes an increase in the body's electrical resistance, so has been measured to cause a 5 kg underestimation of fat-free mass i.e. an overestimation of body fat.^[3]

Body fat measurements are lower when measurements are taken shortly after consumption of a meal, causing a variation between highest and lowest readings of body fat percentage taken throughout the day of up to 4.2% of body fat.^[4]

Moderate exercise before BIA measurements lead to an overestimation of fat-free mass and an underestimation of body fat percentage due to reduced impedance.^[5] For example moderate intensity exercise for 90–120 minutes before BIA measurements causes nearly a 12 kg overestimation of fat-free mass, i.e. body fat is significantly underestimated.^[6] Therefore it's recommended not to perform BIA for several hours after moderate or high intensity exercise.^[7]

BIA is considered reasonably accurate for measuring groups, or for tracking body composition in an individual over a period of time, but is not considered sufficiently accurate for recording of single measurements of individuals.^[8]

Consumer grade devices for measuring BIA have not been found to be sufficiently accurate for single measurement use, and are better suited for use to measure changes in body composition over time for individuals.^[9] Two-electrode foot-to-foot measurement is less accurate than 4-electrode (feet, hands) and eight-electrode measurement. Results for some four- and eight-electrode instruments tested found poor limits of agreement and in some cases systematic bias in estimation of visceral fat percentage, but good accuracy in the prediction of resting energy expenditure (REE) when compared with more accurate whole-body magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA).^[10]

Historical background

Electrical properties of tissues have been described since 1872. These properties were further described for a wider range of frequencies on larger range of tissues, including those that were damaged or undergoing change after death. Thomasset conducted the original studies using electrical impedance measurements as an index of total body water (TBW), using two subcutaneously inserted needles. Hoffer et al. and Nyboer first introduced the four-surface electrode BIA technique. A disadvantage of surface electrodes is that a high current (800 μA) and high voltage must be utilized to decrease the instability of injected current related to cutaneous impedance (10 000 Ω/cm²). By the 1970s the foundations of BIA were established, including those that underpinned the relationships between the impedance and the body water content of the body. A variety of single frequency BIA analyzers then became commercially available, and by the 1990s, the market included several multi-frequency analyzers. The use of BIA as a bedside method has increased because the equipment is portable and safe, the procedure is simple and noninvasive, and the results are reproducible and rapidly obtained. More recently, segmental BIA has been developed to overcome inconsistencies between resistance (R) and body mass of the trunk.

Measurement configuration

The impedance of cellular tissue can be modeled as a resistor (representing the extracellular path) in parallel with a resistor and capacitor in series (representing the intracellular path). This results in a change in impedance versus the frequency used in the measurement. The impedance measurement is generally measured from the wrist to the contralateral ankle and uses either two or four electrodes. A small current on the order of 1-10 µA is passed between two electrodes, and the voltage is measured between the same (for a two electrode configuration) or between the other two electrodes.^[11]

References

^ Kyle, Ursula G.; Bosaeus, Ingvar; De Lorenzo, Antonio D.; Deurenberg, Paul; Elia, Marinos; Gómez, José Manuel; Heitmann, Berit Lilienthal; Kent-Smith, Luisa; et al. (2004). "Bioelectrical impedance analysis—part I: review of principles and methods". Clinical Nutrition 23 (5): 1226–43. doi:10.1016/j.clnu.2004.06.004. PMID 15380917. Downloadable as PDF: Part 1 Part 2
^ "Body fat scales review and compare". 10 January 2010. Retrieved 11 January 2010.
^ Lukaski HC, Bolonchuk WW, Hall CB, Siders WA (April 1986). "Validation of tetrapolar bioelectrical impedance method to assess human body composition" (PDF). J. Appl. Physiol. 60 (4): 1327–32. PMID 3700310.
^ Slinde F, Rossander-Hulthén L (October 2001). "Bioelectrical impedance: effect of 3 identical meals on diurnal impedance variation and calculation of body composition". Am. J. Clin. Nutr. 74 (4): 474–8. PMID 11566645. percentage of body fat varied by 8.8% from the highest to the lowest measurement in women and by 9.9% from the highest to the lowest measurement in men, The subject with the largest decrease in percentage of body fat had a decrease of 23%, from 17.9% body fat at baseline to 13.7% body fat at measurement no. 17.
^ Kushner RF, Gudivaka R, Schoeller DA (September 1996). "Clinical characteristics influencing bioelectrical impedance analysis measurements". Am. J. Clin. Nutr. 64 (3 Suppl): 423S–427S. PMID 8780358.
^ Abu Khaled M, McCutcheon MJ, Reddy S, Pearman PL, Hunter GR, Weinsier RL (May 1988). "Electrical impedance in assessing human body composition: the BIA method". Am. J. Clin. Nutr. 47 (5): 789–92. PMID 3364394.
^ Dehghan M, Merchant AT (2008). "Is bioelectrical impedance accurate for use in large epidemiological studies?". Nutr J 7: 26. doi:10.1186/1475-2891-7-26. PMC 2543039. PMID 18778488.
^ Buchholz AC, Bartok C, Schoeller DA (October 2004). "The validity of bioelectrical impedance models in clinical populations". Nutr Clin Pract 19 (5): 433–46. doi:10.1177/0115426504019005433. PMID 16215137. In general, bioelectrical impedance technology may be acceptable for determining body composition of groups and for monitoring changes in body composition within individuals over time. Use of the technology to make single measurements in individual patients, however, is not recommended.
^ Peterson JT, Repovich WES, Parascand CR (2011). "Accuracy of Consumer Grade Bioelectrical Impedance Analysis Devices Compared to Air Displacement Plethysmography" (PDF). Int J Exerc Sci 4 (3): 176–184.
^ Bosy-Westphal, A.; Later, W.; Hitze, B.; Sato, T.; Kossel, E.; GlÜEr, C. C.; Heller, M.; mÜLler, M. J. (2008). "Accuracy of Bioelectrical Impedance Consumer Devices for Measurement of Body Composition in Comparison to Whole Body Magnetic Resonance Imaging and Dual X-Ray Absorptiometry". Obesity Facts 1 (6): 6. doi:10.1159/000176061. One of the eight authors of this study is employed by body composition monitor manufacturer Omron, who financed the study.
^ "Whole body impedance- what does it measure?" (PDF). 1996. Retrieved 4 December 2013.

External links

The International Society for Electrical Bioimpedance
Bioimpedance Analysis Electronic Media Review

UpToDate Contents

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English Journal

Vibration amplitude and induced temperature limitation of high power air-borne ultrasonic transducers.

Saffar S, Abdullah A.Author information Mechanical Engineering Faculty, Amirkabir University of Technology, 424, Hafez Avenue, Tehran, Iran. Electronic address: saber.saffar@gmail.com.AbstractThe acoustic impedances of matching layers, their internal loss and vibration amplitude are the most important and influential parameters in the performance of high power airborne ultrasonic transducers. In this paper, the optimum acoustic impedances of the transducer matching layers were determined by using a genetic algorithm, the powerful tool for optimizating domain. The analytical results showed that the vibration amplitude increases significantly for low acoustic impedance matching layers. This enhancement is maximum and approximately 200 times higher for the last matching layer where it has the same interface with the air than the vibration amplitude of the source, lead zirconate titanate-pizo electric while transferring the 1 kW is desirable. This large amplitude increases both mechanical failure and temperature of the matching layers due to the internal loss of the matching layers. It has analytically shown that the temperature in last matching layer with having the maximum vibration amplitude is high enough to melt or burn the matching layers. To verify suggested approach, the effect of the amplitude of vibration on the induced temperature has been investigated experimentally. The experimental results displayed good agreement with the theoretical predictions.
Ultrasonics.Ultrasonics.2014 Jan;54(1):168-76. doi: 10.1016/j.ultras.2013.04.008. Epub 2013 Apr 19.
The acoustic impedances of matching layers, their internal loss and vibration amplitude are the most important and influential parameters in the performance of high power airborne ultrasonic transducers. In this paper, the optimum acoustic impedances of the transducer matching layers were determined
PMID 23664304

Effect of inflammation on handgrip strength in the non-critically ill is independent from age, gender and body composition.

Norman K, Stobäus N, Kulka K, Schulzke J.Author information 1] Department of Gastroenterology, Infectiology and Rheumatology, Charité-University Medicine Berlin, Berlin, Germany [2] Charité Research Group on Geriatrics, Charite University Medicine, Berlin, Germany.AbstractBackground/Objectives:We investigated whether C-reactive protein (CRP) as indicator of acute inflammation is associated with maximal isometric handgrip strength in non-critically ill patients.Subjects/Methods:Handgrip strength was measured with Jamar dynamometer in 620 hospitalized patients (56.4±15.9 years old, 52.3% men). CRP was measured with immunoturbidimetric assay. Fat free mass (FFM) was assessed by bioelectrical impedance analysis. A general linear model regression analysis corrected for confounding variables such as age, sex, FFM, body mass index, comorbidity count and diagnosis category (malignant/benign disease) was performed to test the association between elevated levels of CRP and handgrip strength.Results:CRP was an independent predictor of grip strength (CRP: β-coefficient: -0.169, P=0.018) even after adjustment for relevant confounders. All groups with inflammation showed significant reduction in handgrip strength, corresponding to a loss of ∼1.6 kg in mild inflammation, 3.2 kg in moderate inflammation and 2.9 kg in severe inflammation compared with patients without inflammation.Discussion:Our data demonstrate the independent association between inflammation and handgrip strength in non-critically ill patients. If not corrected, reduced strength may have implications for the patients' functional status and prognosis. Increasing physical activity and resistance training during convalescence are recommended.European Journal of Clinical Nutrition advance online publication, 11 December 2013; doi:10.1038/ejcn.2013.261.
European journal of clinical nutrition.Eur J Clin Nutr.2013 Dec 11. doi: 10.1038/ejcn.2013.261. [Epub ahead of print]
Background/Objectives:We investigated whether C-reactive protein (CRP) as indicator of acute inflammation is associated with maximal isometric handgrip strength in non-critically ill patients.Subjects/Methods:Handgrip strength was measured with Jamar dynamometer in 620 hospitalized patients (56.4±1
PMID 24327120

Body composition and arsenic metabolism: a cross-sectional analysis in the Strong Heart Study.

Gribble MO, Crainiceanu CM, Howard BV, Umans JG, Francesconi KA, Goessler W, Zhang Y, Silbergeld EK, Guallar E, Navas-Acien A.Abstract: To evaluate the association between measures of body composition and patterns of urine arsenic metabolites in the 1989-1991 baseline visit of the Strong Heart Study, a cardiovascular disease cohort of adults recruited from rural communities in Arizona, Oklahoma, North Dakota and South Dakota.
Environmental health : a global access science source.Environ Health.2013 Dec 9;12(1):107. [Epub ahead of print]
: To evaluate the association between measures of body composition and patterns of urine arsenic metabolites in the 1989-1991 baseline visit of the Strong Heart Study, a cardiovascular disease cohort of adults recruited from rural communities in Arizona, Oklahoma, North Dakota and South Dakota.METHO
PMID 24321145

Japanese Journal

<Originals> Estimation of Thigh Muscle Volume by Multi-Frequency Bioelectrical Impedance

KOMIYA Hideaki,TSUBAKIHARA Masayoshi
Advances in exercise and sports physiology 18(1), 17-25, 2012-06
… The aim of this study was to evaluate the validity of estimating thigh muscle volume using multi-frequency bioelectrical impedance analysis (BIA). … Thigh muscle volume obtained by MRI was used as a dependent variable, and multiple regression analysis was performed by using anthropometry values, age, BMI, impedance, and impedance index (IPI) as independent variables. …
NAID 110009470523

臨床経験帝王切開症例の脊髄くも膜下麻酔における体水分組成の検討

永坂由紀子,若松正樹,開田剛史 [他]
麻酔 61(4), 368-372, 2012-04
NAID 40019256166

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リンク元	「BIA」「生体インピーダンス法」
関連記事	「analysis」「impedance」「bioelectrical impedance」「bioelectric」「bioelectrical」