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

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

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.

Study Overview

• Status: Not yet recruiting
• Conditions: Kidney Disease, Chronic
• Intervention / Treatment: Other: Dialysate flow at 400mL/min; Other: Dialysate flow at 500mL/min

• Study Type: Interventional
• Enrollment (Estimated): 250
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Romain Vial, Dr; Phone Number: + 33 0491383569; Email: Romain.vial@ap-hm.fr

Study Locations

• France
  • Marseille, France
    • Assistance Publique - Hôpitaux de Marseille
    • Contact: Romain Vial, Dr; Phone Number: +33 04913883569; Email: romain.vial@ap-hm.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Dialysate flow at 400mL/min	Other: Dialysate flow at 400mL/min; Dialysate flow fixed at 400mL/min for one month.
Active Comparator: Dialysate flow at 500mL/min	Other: Dialysate flow at 500mL/min; Dialysate flow fixed at 500mL/min for one month.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mesure of Urea Kt/V	Mesure of Urea clearance by two blood samples, after dialysis minus before dialyse (of urea blood sample), at Day 0 and Month 1	Day 0, Month 1

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Mesure of Beta2-microglobulin clearance	Mesure of Beta2-microglobulin clearance by two blood samples, after dialysis minus before dialyse (of urea blood sample), at Day 0 and Month 1	Day 0, Month 1
Potassium rate before dialysis	Mesure of Potassium rate before dialysis (Blood sample), at Day 0 and Month 1	Day 0, Month 1
Phosphorus rate before dialysis	Mesure of Phosphorus rate before dialysis (Blood sample), at Day 0 and Month 1	Day 0, Month 1
Bicarbonate rate before dialysis	Mesure of bicarbonate rate before dialysis (Blood sample), at Day 0 and Month 1	Day 0, Month 1
Acid indol acetic dosage rate	Blood sample before dialysis at Day 0 and Month 1	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)	Questionnaries Quality of life EQ-5D-5L for patients, at Day 0 and Month 1. Scale ranging from 0 to 100, higher scores mean a better outcome.	Day 0, Month 1
Questionnaire The Kidney Disease Quality of Life 36-item short form survey (KDQoL)	Questionnaries Quality of life for patients KDQoL, at Day 0 and Month 1. Scale ranging from 0 to 100, higher scores mean a better outcome.	Day 0, Month 1
Indoxyl sulfate dosing rate	Blood sample before dialysis at Day 0 and Month 1	Day 0, Month 1 - Only for patient in dialysis in Assistance Publique Hopitaux de Marseille
Para cresyl sulfate dosage rate	Blood sample before dialysis at Day 0 and Month 1	Day 0, Month 1 - Only for patient in dialysis in Assistance Publique Hopitaux de Marseille

Collaborators and Investigators

• Sponsor: Assistance Publique Hopitaux De Marseille
• Collaborators: Aix Marseille Université

Study record dates

Study Major Dates

• Study Start (Estimated): January 1, 2027
• Primary Completion (Estimated): April 1, 2029
• Study Completion (Estimated): October 1, 2029

Study Registration Dates

• First Submitted: July 7, 2026
• First Submitted That Met QC Criteria: July 17, 2026
• First Posted (Actual): July 22, 2026

Study Record Updates

• Last Update Posted (Actual): July 22, 2026
• Last Update Submitted That Met QC Criteria: July 17, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: Efficicency or Quality of Hemodialysis; Green Dialysis
• Additional Relevant MeSH Terms: Urogenital Diseases; Pathologic Processes; Male Urogenital Diseases; Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Chronic Disease; Disease Attributes; Renal Insufficiency; Pathological Conditions, Signs and Symptoms; Renal Insufficiency, Chronic
• Other Study ID Numbers: RCAPHM25_0445; 2025-A02924-45 (Other Identifier: ANSM)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No