title: Determination of fluid status in haemodialysis patients with whole body and calf bioimpedance techniques.
abstract: OBJECTIVE
  The aim of this study was to demonstrate the ability of widely used bioimpedance techniques to assess dry weight (DW) and to predict a state of normal hydration in haemodialysis patients whose post-dialysis weight had been gradually reduced from baseline in successive treatments over time.
  
  
  METHODS
  Calf bioimpedance spectroscopy (cBIS) was employed to determine DW (DW(cBIS) ) as defined by flattening of an intradialytic continuously measured resistance curve and by normalized resistivity (nRho) being in the gender-specific normal range. The wECV/TBW ratio was determined by 'classical' wrist-to-ankle whole body bioimpedance spectroscopy (wBIS); in addition, a novel whole body model (WBM) based on wBIS was used to predict normal hydration weight (NHW(WBM) ).
  
  
  RESULTS
  Twenty-one haemodialysis patients were studied; 11 ± 6 measurements were performed per patient. Nine patients reached DW(cBIS) (DW(cBIS) group), while 12 patients remained fluid-overloaded (non-DW(cBIS) group). Change in wECV as measured by wBIS accounted for 46 ± 23% in DW(cBIS) group, which was higher than in non-DW(cBIS) group (33 ± 48%, P < 0.05) of actual weight loss at the end of study. In both groups the wECV/TBW ratio did not change significantly between baseline and study end. Mean predicted NHW(WBM) at baseline was 3.55 ± 1.6 kg higher than DW(cBIS) . The difference in DW(cBIS) and NHW(WBM) was 1.97 ± 1.0 kg at study end.
  
  
  CONCLUSIONS
  WBM could be useful to predict a target range of normal hydration weight particularly for patients with substantial fluid overload. The cBIS provides an accurate reference for the estimation of DW so that combined use of cBIS and WBM is promising and warrants further studies.
authors.affiliation: Renal Research Institute, Beth Israel Medical Center, New York, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Liu
authors.forename: Fansan
authors.initials: F
authors.lastname: Zhu
authors.forename: Jochen
authors.initials: J
authors.lastname: G Raimann
authors.forename: Stephan
authors.initials: S
authors.lastname: Thijssen
authors.forename: Murat H
authors.initials: MH
authors.lastname: Sipahioglu
authors.forename: Gregory
authors.initials: G
authors.lastname: Wystrychowski
authors.forename: Thomas
authors.initials: T
authors.lastname: Kitzler
authors.forename: Ciro
authors.initials: C
authors.lastname: Tetta
authors.forename: Peter
authors.initials: P
authors.lastname: Wabel
authors.forename: Peter
authors.initials: P
authors.lastname: Kotanko
authors.forename: Nathan W
authors.initials: NW
authors.lastname: Levin
mesh_terms: D000368:Aged; D001794:Blood Pressure; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D058266:Dielectric Spectroscopy; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009519:New York City; D006435:Renal Dialysis; D013997:Time Factors; D014882:Water-Electrolyte Balance