The ASIST study is a medical device study testing the safety and efficacy of a new hemodialysis machine software in chronic haemodialysis patients. The software's intention is to reduce hemodialysis related symptoms such as unwell being, blood pressure changes by adapting the dialysis fluid ion concentration to the patients plasma ion concentration by conductivity measurement.

Inclusion Criteria:

• Subject must be in clinically stable condition as judged by the treating physician, and demonstrated by stable medical history, physical examination, and laboratory testing for 30 days prior to enrollment.
• Subject must be receiving HD or hemodiafiltration (HDF) for at least 30 days prior to study enrollment, be dialyzing a minimum of 3 times per week in an in-center setting and each treatment session must be between 3.5 and 5 hours in duration.
• Subject has a stable functioning vascular access (arteriovenous [AV] fistula, graft, or dual-lumen tunneled catheter) based on the judgment of the treating physician and is performing dual-needle therapy with an actual blood flow rate of 250 - 400 mL/min.
• Subject has a pre-dialysis plasma sodium of ≥132 mmol/L for at least 60 days prior to study enrollment.
• Subject has achieved a dialysis dose of stdKt/Vurea ≥ 2.1 within 60 days prior to enrollment.
• Subject has a pre-dialysis hemoglobin ≥ 90 g/L measured at Screening.

Exclusion Criteria:

• Female subjects who are pregnant, lactating, or planning to become pregnant during the study period.
• Subjects who have a significant psychiatric disorder or mental disability that could interfere with the subject's ability to provide Informed Consent and/or comply with protocol procedures.
• Subjects with a medical condition that the investigator thinks may interfere with the study objectives.
• Subjects with significant signs of access recirculation as judged by the treating physician.