title: Effect of serum electrolyte and bicarbonate concentration changes during hemodialysis sessions on heart rate variability.
abstract: BACKGROUND
  Heart rate variability (HRV) is decreased in dialysis patients, and decreased HRV is an independent risk factor for sudden cardiac death. We aimed to determine the effect of sudden changes in serum electrolyte, bicarbonate concentration and blood pressure on HRV during hemodialysis (HD) sessions in chronic HD patients.
  
  
  METHODS
  The study population included 75 HD patients (mean age 44.5 ± 10.3 years; 53% female, 13% diabetic) and 35 healthy volunteers (mean age 42.44 ± 11.5 years, 62% female). HRV indexes were analyzed from 24-hour ECG recordings. The time-domain HRV indexes (SDNN, SDANN, RMSSD, pNN50 [%] and HRV TAI) were calculated from these recordings. Pre- and post-HD blood samples were drawn from an arterial line to calculate Na+, K+, Ca2+, iCa2+ and HCO3- concentration gradients.
  
  
  RESULTS
  All HRV indexes were significantly lower in dialysis patients than in healthy volunteers (p<0.05).The detected SDNN and HRV TAI values were lower in diabetic patients than in nondiabetics. While K+ concentration was decreased, Ca2+ and bicarbonate increased significantly during HD.
  
  
  CONCLUSIONS
  HRV decreased in chronic HD patients. The decrease in HRV in diabetic uremic patients was higher than in uremic patients without diabetes. The change of serum electrolyte and bicarbonate concentrations during HD did not affect HRV.
authors.affiliation: Department of Nephrology, Erciyes University Medical Faculty, Kayseri, Turkey.
authors.forename: Murat Hayri
authors.initials: MH
authors.lastname: Sipahioglu
authors.forename: Ismail
authors.initials: I
authors.lastname: Kocyigit
authors.forename: Aydin
authors.initials: A
authors.lastname: Unal
authors.forename: Melek
authors.initials: M
authors.lastname: Karakurt
authors.forename: Ahmet
authors.initials: A
authors.lastname: Celik
authors.forename: Bulent
authors.initials: B
authors.lastname: Tokgoz
authors.forename: Oktay
authors.initials: O
authors.lastname: Oymak
authors.forename: Cengiz
authors.initials: C
authors.lastname: Utas
mesh_terms: D000328:Adult; D001639:Bicarbonates / Q000097:blood*; D002118:Calcium / Q000097:blood; D016022:Case-Control Studies; D003928:Diabetic Nephropathies / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D015536:Down-Regulation; D015716:Electrocardiography, Ambulatory; D004573:Electrolytes / Q000097:blood*; D005260:Female; D006339:Heart Rate; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011188:Potassium / Q000097:blood; D006435:Renal Dialysis; D012964:Sodium / Q000097:blood; D013997:Time Factors; D014421:Turkey; D014511:Uremia / Q000097:blood / Q000503:physiopathology / Q000628:therapy*
chemical_list: D001639:Bicarbonates; D004573:Electrolytes; D012964:Sodium; D011188:Potassium; D002118:Calcium