This is a single-center, prospective, proof-of-priciple, pilot study in 24 end-stage renal disease patients on chronic hemodiaysis.

This single-arm, proof-of-principle study will be conducted at the dialysis facility of the Ordensklinikum Linz Elisabethinen Hospital. The dialysate bicarbonate prescription will be decreased from standard of care (usually 35mmol/l) in a stepwise fashion (2 mmol/l per change) to 27 mmol/l and subsequentially increased in a stepwise fashion (2 mmol/l per change) to 37 mmol/l over the course of 6 weeks.

Inclusion Criteria:

• age ≥18 years
• chronic (≥3 months) treatment with hemodialysis or hemodiafiltration
• stable clinical condition

Exclusion Criteria:

• inability to provide informed consent
• dialysis treatment less than thrice weekly
• morbid obesity (body mass index >40 kg/m2)
• chronic inflammation (C reactive protein >10 mg/dL, reference: <0.5 g/dL)
• current immunosuppressive medication,
• severe chronic obstructive pulmonary disease (COPD stage III or IV)
• history of severe hypercapnia or hypoxemia
• overt congestive heart failure
• history of severe hypokalemia (<3.0 mmol/l) or hyperkalemia (>6.5 mmol/L) within 3 months prior to study inclusion.