Determination of in Vivo Ultrafiltration Coefficient (KUF) in Patients With Chronic Kidney Disease (CKD)

Inclusion Criteria: * Written informed consent obtained from patient or parents/ guardian. * Subject age \>= 18 * Effective blood flow 350 ml/min and dialysate flow of 500 ml/min * On hemodialysis for a minimum of 3 months * Use of Cimino- or Gore-tex shunts * Routine dialysis-treatment for 240 min * Documented dialysis adequacy parameter that has been stable for past 3 months * Plan to dialyze at participating hemodialysis centre for at least 3-months duration. * Free from any currently known unusual clotting or access problems * Hepatitis B surface antigen (HbsAg) negative, documented within the past 90 days or Hepatitis B surface antibody (anti-HBs) positive. * Anti Hepatitis C Virus (Anti-HCV) negative, documented within the past 90 days * Anti Human Immunodeficiency Virus (Anti HIV) negative, documented within the past 90 days * Hematocrit (HCT) between 25 and 40% or haemoglobin (Hb) not less than 8 g/dL, as documented 14 days prior to the first treatment Exclusion Criteria: * Patients who are unable to tolerate an effective blood flow of 350 ml/min * Patients using catheter for dialysis * Pregnant or nursing woman. Women of childbearing potential must agree to avoid pregnancy during the study period by use of hormonal contraception (implantable; patch; oral) and/ or double-barrier methods (any double combination of: IUD; condom with spermicidal gel; diaphragm; sponge; cervical cap) * Previous plan for extended absences from the participating hemodialysis centre * Expected to be transplanted (living related donor) within the maximum of 3 months for the study period * Any serious medical conditions or disability, which in the opinion of the investigator, would interfere with treatment or assessment or preclude completion of the study