Double lumen catheters

Claim 1

In a double lumen single needle intraveneous catheter device having a hub means including first and second spaced apart fluid conduit means, an inner lumen in fluid communication at its proximal end with the first conduit means, an outer lumen in fluid communication at its proximal end with the first conduit means, an outer lumen in fluid communication at its proximal end with the second conduit means the lumens being in concentric relationship to one another, at least one aperature being provided in the wall of the outer lumen at its distal end region, the improvement which comprises a substantially frustroconical tip element of plastics material having a bore defining an extension of the inner lumen and having an annular base section providing an annular seal between the outer surface of the distal end region and the inner lumen and the adjacent interior surface of the distal end region of the outer lumen, wherein the distal end of the outer lumen has an inwardly directed annular flange which mates with a corresponding recess in the base portion of the tip to secure the tip in fluid tight relationship with the inner and outer lumens, whereby an annular passage is defined between the inside surface of the outer lumen and the outside surface of the inner lumen which communications between the aperature and the second conduit means and which is sealed from the passage provided by the bore of the tip element and the inner lumen which communicates with the first conduit means, and whereby the substantially frustroconical surface of the tip element provides for ease of entry of the catheter into a blood vessel or fistula.