Jaffrin Michel Y, Kieffer Roland, Moreno Marie-Valérie
Biomechanics and Biomedical Engineering laboratory, UMR CNRS 6600, Technological University of Compiegne, Compiegne, France.
Nutrition. 2005 Jul-Aug;21(7-8):815-24. doi: 10.1016/j.nut.2004.11.016.
The first objective was to compare the accuracy of a foot-to-foot impedance meter with a multifrequency bioimpedance for measurements of fat-free mass (FFM) and fat mass (FM) using dual energy X-ray absorptiometry (DXA) as reference. The second objective was to validate measurements of extracellular water resistance and volume by the foot-to-foot impedance meter, using multifrequency bioimpedance as reference.
This investigation was carried out in 60 volunteers 18 to 71 y of age. Impedance meters were a Tefal Bodymaster Vision (foot-to-foot) that featured a square wave signal and a Xitron Hydra 4200 (5 to 1000 kHz) by using the bioimpedance spectroscopic method.
Bland-Altman tests showed that FFM differences between Tefal and DXA data were 1.98 +/- 3.09 kg in men and -0.08+/-2.98 kg in women. Total body water was measured by the Xitron, and FFM as measured with the Xitron was calculated as total body water divided by 0.732. Mean differences between Xitron-measured and DXA-measured FFM were 2.37+/-3.03 kg for men and 2.84+/-2.40 kg for women, indicating a systematic underestimation by the Xitron of intracellular volume. Extracellular water resistances measured by Tefal were in good agreement with those measured by Xitron with electrodes pasted under the subject's feet (mean difference 8.5+/-31 Omega). Extracellular water volumes were calculated from Tefal-measured extracellular water resistances by using a modified bioimpedance spectroscopic method and differed from those measured with Xitron by-0.03+/-0.66 L.
Limits of agreement with DXA-measured FFM produced by the foot-to-foot impedance meter tested are too large for clinical measurements in individuals, but they are sufficient to assess FFM in groups of subjects and for home use. Our prototype was also capable of estimating extracellular water volume with a similar accuracy as multifrequency bioimpedance in normal subjects.
第一个目的是将足对足阻抗仪与多频生物阻抗法测量去脂体重（FFM）和脂肪量（FM）的准确性进行比较，以双能X线吸收法（DXA）作为参照。第二个目的是用多频生物阻抗法作为参照，验证足对足阻抗仪对细胞外水电阻和体积的测量。
本研究在60名年龄在18至71岁的志愿者中进行。阻抗仪分别是采用生物电阻抗光谱法的特福身体大师视觉型（足对足），其具有方波信号，以及希特龙Hydra 4200（5至1000千赫）。
布兰德-奥特曼检验表明，特福测量数据与DXA测量数据之间的去脂体重差异在男性中为1.98±3.09千克，在女性中为-0.08±2.98千克。希特龙测量总体水，并用总体水除以0.732计算出希特龙测量的去脂体重。希特龙测量的去脂体重与DXA测量的去脂体重之间的平均差异在男性中为2.37±3.03千克，在女性中为2.84±2.40千克，表明希特龙对细胞内体积存在系统性低估。特福测量的细胞外水电阻与在受试者脚下粘贴电极的希特龙测量结果高度一致（平均差异8.5±31欧姆）。细胞外水体积通过使用改良的生物电阻抗光谱法，根据特福测量的细胞外水电阻计算得出，与希特龙测量结果相差-0.03±0.66升。
所测试的足对足阻抗仪与DXA测量的去脂体重之间的一致性界限对于个体的临床测量来说太大，但足以评估受试者群体的去脂体重并用于家庭使用。我们的原型在正常受试者中也能够以与多频生物阻抗法相似的准确性估计细胞外水体积。
