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

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Conditions studied: Kidney Disease, Chronic

In brief

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.

Key facts

Study ID

NCT07718568

Run by

Assistance Publique Hopitaux De Marseille

People needed

250

Starts

2027-01-01

Expected to finish

2029-10-01

Last updated by the study team

2026-07-22

Who can join

Age: 18 and older. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• 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

You may not qualify if…

• 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

Where it is running

• Assistance Publique - Hôpitaux de Marseille — Marseille, France

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