Dual-lumen fistula needle

A dual-lumen fistula needle made by the process conprising the following steps:

• symmetrically tapering a portion of a longitudinally extending cylindrical shaft having a base, a distal end and an inner surface defining a fluid conduit about the longitudinal axis of the shaft to form a neck having a gradually decreasing diameter;
• forming a blood inlet in the neck;
• forming a penetrating tip at the distal end to define a blood outlet;
• applying a compressive force to the shaft along a first diameter sufficient to resiliently expand the shaft along a second diameter perpendicular to the first diameter;
• inserting a center septum into the shaft, said septum having a first rectangular portion and a second, tapered portion bent out of the plane of the first portion, said septum being inserted into the shaft through the base so that the first rectangular portion is aligned with the expanded second diameter until the second tapered portion is seated against the tapered inner surface of the neck;
• and
• releasing the compressive force so that the shaft returns to its original shape.

a dual-lumen fistula needle, comprising:

• a longitudinally extending cylindrical shaft having a smooth outer surface, a base, a distal end, and an inner surface defining a fluid conduit, a portion of the shaft being symmetrically tapered about the longitudinal axis of the shaft to form a neck having a gradually decreasing diameter, the shaft also having a substantially constant wall thickness defined by the distance between the inner and outer surfaces;
• a penetrating tip at the distal end defining a blood outlet to communicate with the fluid conduit so that blood can exit the fluid conduit longitudinally;
• a blood inlet formed in the neck such that blood can enter the fluid conduit in a direction which is transverse to the longitudinal axis of the shaft;
• and
• a center septum extending within the shaft from its base to the beginning of its neck, said septum having a first rectangular portion defining a plane containing the longitudinal axis, and a second tapered portion bent out of the plane and extending into the neck, the taper on the second portion corresponding to the taper of the neck so that the width of the septum corresponds to the transverse dimension of the inner surface, said septum dividing the fluid conduit into a blood intake lumen communicating with the blood inlet and a blood return lumen communicating with the blood outlet wherein the cross-sectional area of the blood intake lumen is substantially equal to the cross-sectional area of the blood return lumen.