title: Comparison of bioimpedance techniques to detect changes in fluid status in hemodialysis patients.
abstract: 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.
  
  
  METHODS
  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).
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  CNR is more sensitive than whole-body BIS for detecting differences in fluid status.
authors: Renal Research Institute, New York, N.Y., USA.
authors: Samer R
authors: SR
authors: Abbas
authors: Li
authors: L
authors: Liu
authors: Murat H
authors: MH
authors: Sipahioglu
authors: Laura
authors: L
authors: Rosales
authors: Mary
authors: M
authors: Carter
authors: Peter
authors: P
authors: Kotanko
authors: Nathan W
authors: NW
authors: Levin
authors: Fansan
authors: F
authors: Zhu
mesh_terms: D000368:Aged; D001794:Blood Pressure; D001826:Body Fluids / Q000737:chemistry*; D001827:Body Height; D001834:Body Water / Q000737:chemistry*; D001835:Body Weight; D058266:Dielectric Spectroscopy / Q000379:methods*; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007866:Leg / Q000033:anatomy & histology; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis