Co-axial catheter

Claim 1

A co-axial dual lumen catheter of the type having a main section (34) having proximal and distal ends and including an inner tube (48) and an outer tube (46) containing the inner tube, and combining with the inner tube to define an annular intake lumen (50), the outer tube extending along a longitudinal axis and defining intake openings (40) providing access into the intake lumen, a tubulartip section (38) of smaller cross-section than the main section (34), the tip section having at least one return opening (42,44); and a transition portion (36) between the main section (34) and the tip section (38), the catheter being characterised by the transition portion (36) comprising overlapping parts (58,60,62) of the inner tube, the tip section, and the outer tube, the part (60) of the inner tube being between the parts (58,62) of the inner and outer tubes and the inner tube part (58) blending into the tip section (38) at the transition portion and the outer tube (46) blending smoothly into the tip section (38) with the intake lumen (50) ending at the transition portion, the inner tube and the tip section forming a continuous outlet lumen projecting beyond the outer tube and the outlet lumen ending at said return opening.

Claim 11

A method of making a co-axial dual lumen cath- etercharacterised by providing an outer tube (46) of a first cross-section and having a selected length; providing an inner tube (48) of a second cross-section proportioned to fit loosely within the outer tube leaving an annular passage between the tubes, the inner tube having a length comparable with said selected length; providing a short tubular tip section (38) having a third cross-section proportioned to engage between the inner and outer tubes; positioning the inner tube inside the outer tube with an end part of the tip section engaged inside the outer tube and about the inner tube at a transition portion (36); applying heat and pressure to the transition portion while supporting the outer tube internally against collapse adjacent the transition portion, and providing internal support for the inner tube on the tip section through the transition portion to maintain a return lumen and to thereby form a blended transition portion defining a smooth outer surface; and forming at least one inlet opening (40) in the outer tube adjacent the transition portion to provide for flow into an intake lumen (50) defined by the space between the inner and outer tubes.

Claim 12

A method of making a co-axial dual lumen cath- etercharacterised by providing an outer tube (46) of a first cross-section and having a selected length; providing an inner tube (48) of a second cross-section proportioned to fit loosely within the outer tube leaving an annular passage between the tubes, the inner tube having a length comparable with said selected length; providing a short tubular tip section (38) having a third cross-section proportioned to engage between the inner and outer tubes; positioning the inner tube inside the outer tube with an end part of the tip section engaged inside the outer tube and about the inner tube at a transition portion (36); applying heat and pressure to the transition portion while supporting the outer tube internally against collapse adjacent the transition portion, and providing internal support for the inner tube on the tip section through the transition portion to maintain a return lumen and to thereby form a blended transition portion defining a smooth outer surface; and forming at least one inlet opening (40) in the outer tube adjacent the transition portion to provide for flow into an intake lumen (50) defined by the space between the inner and outer tubes.