title: High Dialysate Calcium Concentration May Cause More Sympathetic Stimulus During Hemodialysis.
abstract: OBJECTIVE
  Acute activation of sympathetic activation during hemodialysis is essential to maintain blood pressure (BP), albeit long-term overactivity contributes to higher mortality. Low heart rate variability (HRV), a measure of autonomic nervous system activity, and abnormal ankle-brachial index (ABI) are associated with higher mortality in patients on hemodialysis. In this study, we assessed HRV and ABI pre and post dialysis in incident patients on hemodialysis using high (1.75mmol/l) and low (1.25mmol/l) dialysate calcium concentration (DCa).
  
  
  METHODS
  HRV was measured as the ratio between low frequency and high frequency power (LF/HF). Thirty patients (age 47±16 years, 67% men) were studied in two consecutive mid-week hemodialysis sessions.
  
  
  RESULTS
  Mean BP variation was positive with DCa 1.75 and negative with DCa 1.25 [4.0 (-6.0, 12.2 mmHg) vs. -3.2 (-9.8, 1.3 mmHg); p=0.050]. Reduction of ABI from pre to post HD was related to higher sympathetic activity (p=0.031). The increase in LF/HF ratio was higher with DCa 1.75 (58.3% vs. 41.7% in DCa 1.75 and 1.25, respectively, RR 2.8; p=0.026).
  
  
  CONCLUSIONS
  Although higher DCa is associated with better hemodynamic tolerability during hemodialysis, this occurs at the expense of increased sympathetic activity. Higher sympathetic activity was associated with a decrease of ABI during hemodialysis.
authors.affiliation: Nephrology Division, Universidade São Paulo São Paulo, Brazil.
authors.forename: Zaida N C
authors.initials: ZN
authors.lastname: Jimenez
authors.forename: Bruno C
authors.initials: BC
authors.lastname: Silva
authors.forename: Luciene Dos
authors.initials: LD
authors.lastname: Reis
authors.forename: Manuel C M
authors.initials: MC
authors.lastname: Castro
authors.forename: Camila D
authors.initials: CD
authors.lastname: Ramos
authors.forename: Valeria
authors.initials: V
authors.lastname: Costa-Hong
authors.forename: Luiz A
authors.initials: LA
authors.lastname: Bortolotto
authors.forename: Fernanda
authors.initials: F
authors.lastname: Consolim-Colombo
authors.forename: Wagner V
authors.initials: WV
authors.lastname: Dominguez
authors.forename: Ivone B
authors.initials: IB
authors.lastname: Oliveira
authors.forename: Rosa M A
authors.initials: RM
authors.lastname: Moysés
authors.forename: Rosilene M
authors.initials: RM
authors.lastname: Elias
mesh_terms: D000328:Adult; D002118:Calcium / Q000494:pharmacology*; D015314:Dialysis Solutions / Q000737:chemistry*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D006435:Renal Dialysis; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000378:metabolism
chemical_list: D015314:Dialysis Solutions; D002118:Calcium