Renal Research Institute, New York, N.Y., USA.
Blood Purif. 2014;37(1):48-56. doi: 10.1159/000356830. Epub 2014 Feb 12.
Bioimpedance (BI) is maturing as a clinical technique for assessing fluid volume status. The aim of this study was to compare the sensitivity of four BI methods to detect changes in fluid status in hemodialysis patients.
Forty-five patients were studied twice in the same week, i.e. once after the long and short interdialytic intervals, respectively. The four BI methods used were: (a) calf normalized resistivity (CNR) at a 5-kHz frequency, (b) whole-body multifrequency BI spectroscopy (MF-BIS) to estimate the normal hydration weight (NHWWBM), (c) whole-body MF-BIS to estimate the ratio of extracellular volume to total body water (wECV/wTBW), and (d) whole-body single-frequency (50 kHz) BI analysis to compute the ratio of ECV (sfECV) to TBW (sfTBW).
The relationship (slope of the regressive line) between relative changes (%) in the above mentioned four BI parameters and differences in weight (kg) was most pronounced with CNR (5.2 ± 1.6%/kg), followed by wECV/wTBW (1.7 ± 0.7%/kg) and NHWWBM (0.73 ± 0.2%/kg). Changes in sfECV/sfTBW and differences in weight were not correlated.
CNR is more sensitive than whole-body BIS for detecting differences in fluid status.
生物阻抗（BI）作为评估液体容量状态的临床技术日益成熟。本研究的目的是比较四种 BI 方法检测血液透析患者液体状态变化的敏感性。
45 名患者在同一周内进行了两次研究，即分别在长和短透析间隔后各进行一次。使用的四种 BI 方法是：（a）5 kHz 频率下的小腿归一化电阻率（CNR），（b）全身多频 BI 光谱法（MF-BIS）估计正常水合体重（NHWWBM），（c）全身多频 BI 光谱法估计细胞外体积与总体液比值（wECV/wTBW），（d）全身单频（50 kHz）BI 分析计算细胞外容积与总体液比值（sfECV/sfTBW）。
上述四种 BI 参数的相对变化（回归线斜率）与体重差异（kg）之间的关系，以 CNR（5.2 ± 1.6%/kg）最为显著，其次是 wECV/wTBW（1.7 ± 0.7%/kg）和 NHWWBM（0.73 ± 0.2%/kg）。sfECV/sfTBW 的变化与体重差异无相关性。
CNR 比全身 BIS 更能敏感地检测液体状态的差异。
