Diffusion device

A diffusion device comprising

• a) a cylindrical housing;
• b) a plurality of semi-permeable hollow fiber membranes disposed within a cylindrical shell inside the housing, wherein the cylindrical shell is formed by the hollow fiber membranes and contacts an inner wall of the cylindrical housing;
• c) a first end cap sealing a first mouth of the cylindrical housing and comprising an inlet for the introduction of blood into the cylindrical housing, the inlet being coaxial to the longitudinal axis of the cylindrical housing;
• and
• d) a rotationally symmetric blood duct connecting the inlet to an inner perimeter of the cylindrical shell, the blood duct being defined by a first inner surface and a second inner surface,
• the first inner surface comprising, in the direction of increasing diameter, a first section taking the form of a cylinder or a truncated cone, and a second section connecting the first section and the inner perimeter of the cylindrical shell, the second section taking the form of a torus segment, with an angle between the longitudinal axis of the cylindrical housing and a straight line (A) intersecting i) the longitudinal axis, ii) the intersection of the first section and the second section, and iii) the intersection of the second section and the inner perimeter of the cylindrical shell being in the range of from 55° to 80°, and the maximum of a perpendicular distance (a) between the straight line (A) and the surface of the second section being in the range of from 0.5 to 1 mm;
• the second inner surface spanning the inner perimeter of the cylindrical shell, with an angle b between the longitudinal axis of the cylindrical housing and a straight line (B) intersecting i) the longitudinal axis at its intersection with the second inner surface and ii) the intersection of the second inner surface and the inner perimeter of the cylindrical shell being in the range of from 55° to 80°, and the maximum of a perpendicular distance (b) between the straight line (B) and the surface of the second inner surface being in the range of from 0.5 to 1 mm;
• a distance (d) between the first inner surface and the second inner surface at the inner perimeter of the cylindrical shell being in the range of from 2 to 3 mm;
• and a minimal distance between the second section of the first inner surface and the second inner surface being not less than 1 mm.