Technical Evaluation of Dialysate Flow in a Newly Designed Dialyzer

Abstract

Rexeed was developed by Asahi Kasei Medical using wave-shaped hollow fibers, a full baffle, and a short taper housing to improve dialysate flow. The present study is clarifies improvement in dialysate flow with Rexeed-15 compared with that of a conventional dialyzer. Dialysate flow was evaluated by the pulse-response method. Dialysate pressure and tracer concentration were measured at a blood-side flow rate (QBeta) of 200 ml/min, a dialysate-side flow rate (QD) of 500 ml/min, and a net filtration rate (QF) of 0 ml/min using needles placed in the test dialyzer. Dialyzer performance was evaluated by measuring urea and vitamin B12 clearance at QB = 200 and 400 ml/min, QD = 300-800 ml/min, and QF = 0 ml/min. In the conventional dialyzer, dialysate channeling was observed. In contrast, Rexeed-15 had a uniform dialysate flow. Urea and vitamin B12 clearance with Rexeed-15 was slightly sensitive to QD. The overall mass transfer coefficient for urea with Rexeed-15 was more than 50% higher than that of the conventional dialyzer, indicating the possibility of reduced dialysate usage with Rexeed. Rexeed has a highly optimal dialysate flow, due to the wave-shaped hollow fibers and the new housing, and gives increased clearance for lower-molecular-weight substances.

Computational Evaluation of Dialysis Fluid Flow in Dialyzers With Variously Designed Jackets

“…Optimum design of taper structure is hence required to make dialysis fluid to flow into the center of the hollow‐fiber bundle, and optimum length and angle of the taper is 12.5–25.0 mm and 2–4°, respectively. We have reported performance improvement resulting from the equalization of dialysis fluid flow by comparing APS‐15SA (Rexeed‐15), which has a full baffle, taper structure, and wavy hollow fibers, with a conventional dialyzer (APS‐15S) with respect to dialysis fluid flow and dialyzer performance (9). The conventional dialyzer has a wider residence time distribution by the pulse‐response method and concomitantly produces faster and slower dialysis fluid flows, indicating the presence of dialysis fluid channeling.…”

Experimental evaluation of flow and dialysis performance of hollow-fiber dialyzers with different packing densities

“…Furthermore, MRI results may not represent the actual flow distribution of the dialysis fluid in the dialyzer because a test solution containing a contrast medium does not have the same viscosity and density as the dialysis fluid. The pulse-response method [1,17] is applicable to evaluation of the flow of dialysis fluid and blood. With this method, it is possible to evaluate the flow of the dialysis fluid and blood by using test solutions with viscosities and densities equal to those of dialysis fluid and blood.…”

Sensors and Hybrid Therapies: A New Approach with Automated Citrate Anticoagulation

“…1), a very high, fixed citrate infusion to QB ratio ensures 100% effective anticoagulation. After dialysis, >95% of citrate and calcium (Ca) have been removed in a single pass on a high-efficiency, high-flux dialyzer with optimized QD and internal convection [10,11]. Since Ca was also removed with the zero Ca dialysate, the low ionized Ca (iCa) level with the anticoagulant effect is maintained.…”

“…Backfiltration of endotoxin from contaminated dialysate can be prevented on modern machines capable of ultrapure dialysate generation. Hemofiltration may not be indispensable for middle molecule clearance [9], which can also be increased by the use of hemodialysis on new high-flux filters designed to maximize internal filtration-backfiltration and to optimize QD [10,11]. …”