Clamping of the dialysate outlet line in the Genius dialysis system does not alter dialysate flow or clearances.

Background: The Genius dialysis system is advocated as a tool to perform slow extended daily dialysis (SLEDD) in patients with acute renal failure at the intensive care unit. At low blood flows however, it is sometimes problematic to maintain sufficient systemic pressure in the dialysate circuit, a problem that can be overcome by clamping the dialysate outflow line. This intervention can however decrease the flow in the dialysate circuit, and can thus potentially decrease the clearance. This article analyses the impact of this intervention on the blood and dialysate flows and on the removal of retention products.

Methods: The study was done in 20 stable chronic dialysis patients to avoid additional bias caused by changing comorbidities in ICU patients. Patients were treated by Genius, once with clamping and once without clamping, cross-over in a randomized fashion, and with 1 week interval. Flows in the dialysate and blood circuit were measured with a transsonic flow probe. Urea, creatinine, Beta 2 microglobulin and phosphate were measured in the dialysate, and in the serum before and after dialysis.

Results: There was no clinically significant difference in blood or dialysate flows, nor in clearance or removal of retention products during the sessions with or without clamping.

Conclusions: The technique of using clamping of the dialysate outflow line in the Genius system to increase systemic pressure, when the system is used in SLEDD, is a safe technique which does not alter the clearances.