title: Negative dialysate to sodium gradient does not lead to intracellular volume expansion post hemodialysis.
abstract: BACKGROUND
  Intradialytic hypotension remains the most common complication of routine outpatient hemodialysis treatments. There is debate as to the optimum dialysate sodium concentration, with hypotonic dialysates potentially causing intracellular swelling and hypertonic ones intracellular dehydration.
  
  
  METHODS
  Multi-frequency bioimpedance was used to assess extracellular and intracellular fluid volumes in 53 adult hemodialysis patients. Dialysate sodium was checked by ion electrophoresis.
  
  
  RESULTS
  The mean decrease in extracellular volume and intracellular volumes were 1.01 ±0.09 and 0.88 ±0.18 kg, respectively. The median dialysate to sodium gradient was -3 mmol/L (-1 to -6), with a median dialysate sodium of 136 mmol/L (136-138). There was no association between changes in body fluid composition and sodium concentrations, or gradients. The mean difference between dialysate sodium prescribed and delivered was 2.4 ±0.8 mmol/L.
  
  
  CONCLUSIONS
  In this study we were unable to demonstrate a relationship between predialysis serum sodium and the dialysate sodium prescribed and changes in extracellular or intracellular fluid volumes. However this study showed that using a negative sodium gradient, patients can be successfully ultrafiltrated without setting up intracompartmental fluid gradients. The caveat is that the prescribed dialysate to serum sodium gradient may differ from the actual gradient.
authors.affiliation: Center for Nephrology, University College London Medical School, Royal Free Campus, Rowland Hill Street, London, United Kingdom. andrew.davenport@royalfree.nhs.uk
authors.forename: Andrew
authors.initials: A
authors.lastname: Davenport
mesh_terms: D001794:Blood Pressure; D001835:Body Weight; D017097:Electric Impedance; D004586:Electrophoresis; D005260:Female; D015312:Hemodialysis Solutions / Q000009:adverse effects / Q000378:metabolism / Q000627:therapeutic use*; D006801:Humans; D007022:Hypotension / Q000097:blood / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D007424:Intracellular Fluid / Q000378:metabolism*; D008131:London; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis / Q000009:adverse effects; D012964:Sodium / Q000097:blood*
chemical_list: D015312:Hemodialysis Solutions; D012964:Sodium