Impact of Reducing the Dialysate Flow Rate in Chronic Hemodialysis on Dialysis Quality and Environmental Impact on Water Consumption

Official title

Non-inferiority Study on the Efficacy of Hemodialysis With Dialysate Flow Rates of 400 mL/Min Versus 500 mL/Min in a Population of Patients Undergoing Chronic Hemodialysis. Impact of Reducing the Dialysate Flow Rate in Chronic Hemodialysis on Dialysis Quality and Environmental Impact on Water Consumption

Overview

In France, 60,000 patients are receiving renal replacement therapy via dialysis in 2022, 90% of whom are on hemodialysis. This technique is based on the principle of exchange across a membrane between the patient's blood and the dialysate. The goal is to purify the patient's blood as effectively as possible by removing all solutes that have accumulated due to kidney failure. The dialysate is produced from municipal water, which is treated through several processes (reverse osmosis, filtration) to produce ultrapure water. Water consumption at the La Conception Hospital center in Marseille, which conducts 37,000 sessions per year (64 hemodialysis stations), is estimated at 120 m³ of water per day, which is discharged into the sewer system after use. In France, this would correspond to an estimated total consumption of nearly one million m³ of drinking water per year. In the context of climate change, which will lead to a reduction in water resources, it is important to rethink all aspects of water consumption. The investigator's reflection is part of a growing awareness of the environmental impact of dialysis within a working group of the Francophone Society of Nephrology, Dialysis, and Transplantation: "Green Dialysis." The quality of clearance depends on blood flow and dialysate flow rate (Qd). The Qd was set at 500 mL/min based on earlier studies that showed this flow rate corresponded to maximum clearance of urea and the main toxic solutes. These studies were conducted at a time when dialysis membranes were less efficient. Today, the investigators use membranes with higher exchange efficiency. Despite this, the investigators have not reevaluated the appropriateness of a Qd of 500 mL/min. The quality criterion in dialysis is a balanced urea Kt/V measurement \>1.2 for a 4-hour session (target set at 1.4 with certain "single-pool" dialysis machine measurement techniques). At the ivnestigator's center, the average urea Kt/V is 1.55 in "single-pool" mode. Reducing the Qd could be done without risk to patients, even if it leads to a decrease in urea Kt/V. A Colombian study with 5 years of follow-up demonstrates patient safety with a Qd of 400 mL/min (vs. 500 mL/min), with no difference in mortality or dialysis efficacy. The study population was not representative of chronic dialysis patients; 10% regained renal function, and the final analysis included only 25 of the 71 patients enrolled.

Interventions

• Other Dialysate flow at 400mL/min
  Dialysate flow fixed at 400mL/min for one month.
• Other Dialysate flow at 500mL/min
  Dialysate flow fixed at 500mL/min for one month.

Primary outcome measures

• Mesure of Urea Kt/V [Time frame: Day 0, Month 1]

Secondary outcome measures (9)

• Mesure of Beta2-microglobulin clearance [Time frame: Day 0, Month 1]
• Potassium rate before dialysis [Time frame: Day 0, Month 1]
• Phosphorus rate before dialysis [Time frame: Day 0, Month 1]
• Bicarbonate rate before dialysis [Time frame: Day 0, Month 1]
• Acid indol acetic dosage rate [Time frame: Day 0, Month 1 - Only for patient in dialysis in Assistance Publique Hopitaux de Marseille]
• Questionnaire The 5-level EQ-5D version (EQ-5D-5L) [Time frame: Day 0, Month 1]
• Questionnaire The Kidney Disease Quality of Life 36-item short form survey (KDQoL) [Time frame: Day 0, Month 1]
• Indoxyl sulfate dosing rate [Time frame: Day 0, Month 1 - Only for patient in dialysis in Assistance Publique Hopitaux de Marseille]
• Para cresyl sulfate dosage rate [Time frame: Day 0, Month 1 - Only for patient in dialysis in Assistance Publique Hopitaux de Marseille]

Eligibility criteria

Inclusion criteria

• Age > 18 years
• No decompensated psychiatric disorder, acute or decompensated somatic condition
• Patients on hemodialysis for more than 3 months
• Dialysis schedule: 3 times per week for 4 hours each session
• Stable vascular access (arteriovenous fistula or tunneled central catheter)
• Blood flow > 300 mL/min
• Anuric (urine output < 500 mL/24 h)
• Dialysis method: hemodialysis or hemodiafiltration

Exclusion criteria

• Age < 18 years
• Patient on dialysis for < 3 months
• Unstable vascular access
• Blood flow rate < 300 mL/min
• Urine output > 500 mL/day
• Dialysis technique: hemofiltration
• Severe intercurrent condition (somatic or psychiatric)
• Pregnant or breastfeeding patients.
• Patients who are legally incapacitated, under guardianship, or under conservatorship

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Parallel assignment

Masking

Single blind

Primary purpose

Other

Study locations

France · 1 center

• Assistance Publique - Hôpitaux de Marseille — Marseille

Identifiers

NCT: NCT07718568 · RCAPHM25_0445 · 2025-A02924-45

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗