title: Changes in upper limb extracellular water content  during hemodialysis measured by multi-frequency bioimpedance.
abstract: BACKGROUND
  Hemodialysis patients are at risk of chronic volume overload, with consequent increased cardiovascular morbidity and mortality. Multifrequency bioimpedance allows assessment of body fluid volumes. Devices vary from two paired electrodes which measure bioimpedance down one side of the body to four paired electrodes which measure both sides of the body. As arteriovenous fistulae may cause arm swelling, we investigated whether the presence of a fistula affected bioimpedance limb measurements.
  
  
  METHODS
  We audited the change in extracellular water (ECW) and total body water (TBW) in the arms following hemodialysis in 414 adult patients attending for routine mid-week hemodialysis session  by multifrequency bioimpedance using a four-paired electrode bioimpedance device (InBody 720; Biospace, Seoul, South Korea).
  
  
  RESULTS
  Patients with right-sided brachial fistulae had a greater percentage ECW/TBW in the fistula arm both prior to and post dialysis compared to those dialyzing with catheters (pre 39.6 ± 3.5 vs. 38.4.3 ± 1.6 and post 38.5 ± 1.3 vs. 37.8 ± 1.1, p<0.01), but there was no difference in the ECW/TBW in the non-fistula arm, pre dialysis between those dialyzing with fistulae compared to catheters, but the ECW/TBW was greater post dialysis with both brachial (38.4 ± 1.1) and radial fistulae (38.1 ± 1.3) compared to those with catheters (37.7 ± 0.9, p<0.05 respectively).
  
  
  CONCLUSIONS
  Although absolute and also relative extracellular fluid volumes are increased in the fistula arm of hemodialysis patients, particularly right-sided and with brachial fistulae, the amount of fluid is unlikely to be of clinical significance when making bioimpedance measurements in the non-fistula side of the body to determine volume status.
authors: UCL Center for Nephrology, Royal Free Hospital, University College London Medical School, London NW3 2PF, United Kingdom.
authors: Sanjeev
authors: S
authors: Kumar
authors: Maryam
authors: M
authors: Khosravi
authors: Annick
authors: A
authors: Massart
authors: Madhu
authors: M
authors: Potluri
authors: Andrew
authors: A
authors: Davenport
mesh_terms: D000368:Aged; D001823:Body Composition / Q000502:physiology*; D001834:Body Water; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D034941:Upper Extremity / Q000503:physiopathology*; D014883:Water-Electrolyte Imbalance / Q000503:physiopathology*