Comparison of Cardiac Index and Cardiac Output Effect During Maintenance Hemodialysis Between Acetate-Free and Acetate-Based Online Hemodiafiltration

Inclusion Criteria: * End-stage renal disease patients with age over 20 years and stable clinical status * Dialytic age \> 6 months * Maintenance hemodialysis with online-hemodiafiltration mode at King Chulalongkorn Memorial Hospital * Use arteriovenous fistula or arteriovenous graft as vascular access for hemodialysis * No vascular access recirculation * No liver impairment * No severe, intractable metabolic acidosis or alkalosis (HCO3 \<15, \>30) * No pre-existing severe, intractable hypocalcemia (Ca \< 7.5) or clinical of hypocalcemia Exclusion Criteria: * On hemodialysis via tunnel catheter * Vascular access recirculation * Liver dysfunction * Severe, intractable metabolic acidosis or alkalosis (HCO3 \<15, \>30) * Pre-existing severe, intractable hypocalcemia (Ca \< 7.5) or clinical of hypocalcemia * Acute or recent myocardial ischemia or congestive heart failure (within 1 months) * Threatening arrhythmia (VT, VF, sustained SVT, AF with rapid ventricular response) * Patients affected by acute or chronic infections, malignant tumor