Asahi Kasei Kuraray Medical has raised overall dialyzer performance by combining its polysulfone membrane REXBRANE with a new housing design providing optimum flow dynamics. The inner surface incorporates Asahi’s unique hydrophilic gel layer technology, which minimizes blood-membrane interaction and plays a crucial role in anticoaguration requirements. These design elements together created the REXEED Dilayzers.

Features

• Surface areas from 1.3 m² to 2.5 m², largest surface area available
• REXBRANE membrane
• New housing design for improved flow dynamics
• Exceptional urea, creatinine, and phosphate clearance rates
• High mid-sized molecule removal rate for REXEED-A/AX and REXEED-UX
• Low albumin loss
• Proprietary fiber inner gel layer minimizes platelet activation
• ETO Free and gamma (-A/GL/L), electron beam (-AX/UX/LX) sterilized
• Color-coded headers

Improved anticoagulation

The membrane inner surface plays a crucial role in patient anticoagulation requirements during treatment because it comes into direct contact with the blood. Asahi Kasei Kuraray Medical improved the membrane by creating a hydrophilic gel layer on the membrane surface, which provides optimum conditions of hydrophilic agents including their concentration.

Preserving the natural flow of blood components

In the images below, the hydrophilic gel layer on the REXBRANE membrane inner surface when wet is shown on the left. It appears softer than the other wet polysulfone inner surface shown on the right because the hydrophilic gel layer retains water molecules, a major characteristic of the REXBRANE membrane. REXBRANE is designed to cushion platelets and other blood components from activation caused by the blood-membrane interaction.

Softness of the hydrophilic layer on the surface of internal membrane

On exposure to water, the hydrophilic gel layer formed on the inner surface of REXEED membrane is softer than that formed in the case of other membranes, as shown in the graph below. This is also one of the major salient features of REXEED. A softer inner surface helps to alleviate the blood-membrane interaction.

Each membrane was in the distilled water for 30 min, and then, force-distance curve measurements using Atomic Force Microscopy (AFM) were performed to ensure softness of the inner surface of the membrane.
Each parameter was measured 100 times at different points, and then, the average and standard deviation was calculated. The major axis of each ellipse shows the standard deviation and center shows the average value.

(In-house data)

The above diagrams are schematic representations of the platelet-membrane interaction. If platelets come in direct contact with the membrane surface, the platelets may be activated, leading to adhesion of platelets to the membrane surface. The coagulation system is also highly susceptible to such activation. The hydrophilic gel layer on REXEED membrane inner surface is designed to cushion the platelets and other blood components from activation caused by blood-membrane interaction.

(Reference)
Matsuda M, et al., Jpn. J. High Performance Membrane ‘08 Kidney and Dialysis, Suppl., 65:56-59, 2008

Advanced engineering

 

Our conventional dialyzers
Straight fibers, a non-tapered housing and a partial baffle in the header can cause dialysate to enter the fiber bundle with asymmetric flow patterns.

 

REXEED dialyzers
Careful design of the fiber shape and fiber bundle, combined with improved geometry of the housing (a short tapered housing and an extended baffle) enable rapid and uniform penetration of dialysate throughout the entire fiber bundle, improving the diffusive clearances of REXEED dialyzers.

Flow distribution of dialysate

Dye was injected into the dialysate inlet port, with dialysate flow at 500 mL/min, then fractions were collected at the outlet port and measured for dye concentration by absorbance.

A sharp, symmetrical peak indicates rapid and complete penetration of dye into the center of the fiber bundle to give uniform flow distribution, proving the benefits of fiber bundle and housing design optimization.

REXEED dialyzer shows a homogeneous dialysate distribution figure (right), while the other dialyzer exhibits an uneven distribution of the dialysate flow (left).

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