Pill vs. machine: which fixes acid imbalance better for dialysis patients?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Age ≥ 18 years. * Chronic hemodialysis for at least 3 months. * Stable hemodialysis prescription: 3 times a week, high-flux dialyzers, no major change in dialysis prescription in the previous weeks. * Predialysis low "alkaline reserves" (serum bicarbonate concentration) according to the operational threshold used in the unit (e.g., "alkaline reserves" \< 22 mmol/L), consistent with KDIGO 2017 definition of metabolic acidosis. * Ability to give written informed consent. For the observational group: * Age ≥ 18 years. * Chronic hemodialysis for at least 3 months. * Hemodialysis 3 times a week, high-flux dialyzers. * Predialysis "alkaline reserves" considered stable and within the locally defined normal range (≥ 22mmol/L). * Ability to give written informed consent. Exclusion Criteria: * Recent hemodynamic instability (e.g., repeated intradialytic hypotension or unstable blood pressure in the previous weeks). * Recent hospitalization for an acute condition. * Acute infection or major intercurrent acute event at the time of screening. * Major change in dialysis prescription in the 2 weeks prior to inclusion (e.g., change in dialysis schedule, duration, or dialysate composition outside the study protocol). * Severe digestive disorders limiting oral intake (e.g., persistent vomiting, severe malabsorption, or any condition preventing safe oral Bicardis administration). * Known hypernatremia or high risk of uncontrolled sodium and fluid overload (as judged by the investigator). * Severe uncontrolled hypercalcemia or hypocalcemia. * Any condition that, in the investigator's judgment, would preclude safe participation or interfere with study procedures (e.g., very limited life expectancy, inability to attend scheduled visits). * Refusal to participate or inability to provide written informed consent.