Dual lumen cannula

Claim 2

A dual lumen cannula comprising a flexible elongate tubular portion extending about a longitudinal axis and consisting of an outer wall and an integral septum dividing the tubular portion into extraction and return lumens, the extraction and return lumens being adapted to be connected at the proximal end of the tubular portion to respective extraction and return tubes, the cannula having a conical leading end for insertion, the outer wall of the leading end being integral with the outer wall of the tubular portion and converging towards a return aperture at the end of the cannula and centred on the axis of the cannula, the return aperture communicating with the return lumen, the septum and the outer wall of the conical leading end converging at a location just short of the return aperture to blank off the extraction lumen, and an insert filling the extraction lumen between the converging location and an extraction aperture in the outer wall of the tubular portion to avoid blood stagnation adjacent the extraction aperture.

Claim 3

A dual lumen cannula as claimed in claim 1 in which the tubular portion terminates at its proximal end in a generally Y-shaped portion, the ends of the return and extraction lumens being flared outwardly in a conical form.

Claim 4

A dual lumen cannula as claimed in claims 1 or 2 in which the ends of the return and extraction lumens are coupled to respective blood extraction and return tubes, the walls adjacent the ends of the respective tubes inserted into respective lumens being tapered to provide minimal wall thickness at the ends of the tubes so that the interior of the tubes and the lumens form a substantially smooth surface to minimise damage to blood flowing through the lumens.

Claim 5

A dual lumen cannula as claimed in claims 1 or 2 in which the tubular portion is cylindrical.

Claim 6

A dual lumen cannula as claimed in claims 1 or 2 in which the septum blends with the walls of the tubular portion by integral curved portions.

Claim 7

A dual lumen cannula for insertion into a vein of a patient comprises: a flexible elongate cylindrical portion disposed about a longitudinal axis and consisting of a cylindrical wall combining with an integral septum to form extraction and return lumens, the cannula having at its distal end a generally conical leading portion with its wider end integral with the cylindrical portion, the leading portion tapering symmetrically about said axis and terminating at a blood return aperture communicating with the return lumen, the septum and the wall of the leading portion converging to meet at a location in the leading portion to blank off the extraction lumen, and the extraction lumen having a flexible insert filling the space in the extraction lumen between said location and a blood extraction aperture in the extracation lumen, the cannula having at its proximal end a generally Y-shaped portion, with the extraction and return lumens being flared outwardly from the cannula axis; and flexible extraction and return tubes with ends having walls tapering to terminate in minimal wall thicknesses the tubes being inserted within respective extraction and return lumens at said Y-shaped portion, such that the interior of the tapering walls of the tubes and the interior of the lumens form a substantially smooth surface to minimise blood damage as the blood flows through said extraction and return lumens.

Claim 8

A dual lumen cannula for insertion into a vein of a patient comprises: a flexible elongate cylindrical portion disposed about a longitudinal axis and consisting of a cylindrical wall combining with an integral septum to form extraction and return lumens, the cannula having at its distal end a generally conical leading portion with its wider end integral with the cylindrical portion, the leading portion tapering symmetrically about said axis and terminating at a blood return aperture communicating with the return lumen, the septum and the wall of the leading portion converging to meet at a location in the leading portion to blank off the extraction lumen, and the extraction lumen having a flexible insert filling the space in the extraction lumen between said location and a blood extraction aperture in the extracation lumen, the cannula having at its proximal end a generally Y-shaped portion, with the extraction and return lumens being flared outwardly from the cannula axis; and flexible extraction and return tubes with ends having walls tapering to terminate in minimal wall thicknesses the tubes being inserted within respective extraction and return lumens at said Y-shaped portion, such that the interior of the tapering walls of the tubes and the interior of the lumens form a substantially smooth surface to minimise blood damage as the blood flows through said extraction and return lumens.

Claim 13

A method of manufacturing a dual lumen cannula as claimed in claim 7 and further comprising the steps of: providing a hollow cylindrical collar and heat-shrinking the collar onto the other end of the outer wall so that an end of the collar and the other end of the tubular portion are substantially flush; providing two mandrels having conical ends adapted to fit into the respective lumens of the cannula; heating the mandrels to a predetermined temperature, inserting the mandrels into the lumens for a period sufficient to deform the ends of the lumens together with the collar into conical portions so that this end of the cannula becomes substantially Y-shaped; and removing the mandrels after a predetermined cooling period so that the Y-shape is permanent.

Claim 14

A double lumen catheter having an elongated cylindrical tube enclosing first and second lumens, the proximal end of said cylindrical tube connection to two separate tubes communicating with the respective first and second lumens for the injection and removal of fluid, the first lumen extending from the proximal end of said cylindrical tube to an opening at the distal end of said cylindrical tube, and the second lumen extending from the proximal end of said cylindrical tube to at least one opening in the side of the cylindrical surface of said cylindrical tube, wherein the improvement comprises; said cylindrical tube having at its distal end a smooth conical tapered tip that smoothly merges with the cylindrical surface of said cylindrical tube, and having a uniform diameter along its entire length from its proximal end to said conical tapered tip.

Claim 15

A double lumen catheter having an elongated cylindrical tube enclosing first and second lumens, the proximal end of said cylindrical tube connection to two separate tubes communicating with the respective first and second lumens for the injection and removal of fluid, the first lumen extending from the proximal end of said cylindrical tube to an opening at the distal end of said cylindrical tube, and the second lumen extending from the proximal end of said cylindrical tube to at least one opening in the side of the cylindrical surface of said cylindrical tube, wherein the improvement comprises; said cylindrical tube having at its distal end a smooth conical tapered tip that smoothly merges with the cylindrical surface of said cylindrical tube, and having a uniform diameter along its entire length from its proximal end to said conical tapered tip.

Claim 16

The double lumen catheter as claimed in claim 10, wherein the cylindrical surface of said cylindrical tube includes at least one opening to said first lumen axially spaced between the opening to said second lumen and said conical tapered tip, and circumferentially disposed on the side of said cylindrical tube opposite said opening to said second lumen.

Claim 17

The double lumen catheter as claimed in claim 10, wherein the cylindrical surface of said cylindrical tube includes a plurality of holes exposing said first lumen that are axially spaced between the opening to said second lumen and said conical tapered tip, and circumferentially disposed on the side of said cylindrical tube opposite said opening to said second lumen.

Claim 18

The double lumen catheter as claimed in claim 10, wherein an internal planar divider in said cylindrical tube separates said first and second lumens, and the cylindrical surface of said cylindrical tube includes at least one side hole exposing said second lumen that is axially spaced between the opening to said second lumen and the proximal end of said cylindrical tube and is circumferentially disposed on the same side of the cylindrical tube as the opening to said second lumen, and the cylindrical surface of said cylindrical tube includes at least one side hole exposing said first lumen axially spaced between said opening to said second lumen and said conical tapered tip, and circumferentially disposed on the opposite side of said cylindrical tube as said opening to said second lumen.

Claim 19

The double lumen catheter as claimed in claim 10, wherein said conical tapered tip comprises a concentration of material substantially exceeding the concentration of material in the cylindrical body of said cylindrical tube.

Claim 20

The double lumen catheter as claimed in claim 10, wherein said cylindrical tube comprises a relative concentration of material extending axially from said opening in the side of said cylindrical surface of said cylindrical tube to the distal end of said cylindrical tube.

Claim 21

The double lumen catheter as claimed in claim 10, wherein said cylindrical tube has an internal planar divider bisecting said cylindrical tube into said first and second lumens, said second lumen terminates at said opening in the side of said cylindrical surface of said cylindrical tube, and a relative concentration of material extends axially from said opening in the side of said cylindrical surface of said cylindrical tube to the distal end of said cylindrical tube.

Claim 22

The double lumen catheter as claimed in claim 10, wherein the apex of said conical tip is substantially aligned with the axis of said cylindrical tube.

Claim 23

The double lumen catheter as claimed in claim 10, wherein the length of said conical tip is at least approximately two diameters of said cylindrical tube.

Claim 24

The double lumen catheter as claimed in claim 10, wherein the first and second lumens are semicircular.

Claim 25

The double lumen catheter as claimed in claim 10, wherein the proximal end of said cylindrical tube is connected to said separate tubes by a connector including a sleeve coaxial with said cylindrical tube at the junction of the coaxial tube and the connector.

Claim 26

A double lumen catheter as claimed in claim 10, wherein the opening at the distal end of the said cylindrical tube is eccentric with respect to the axis of the conical tapered tip.

Claim 27

The double lumen catheter as claimed in claim 10, wherein the wall thickness of the conical tapered tip is eccentric with respect to the axis of the conical tapered tip.

Claim 28

A double lumen catheter comprising an elongated cylindrical tube including a planar axial divider bisecting said cylindrical tube into first and second lumens, the proximal end of said cylindrical tube connecting two separate tubes communicating with the respective first and second lumens for the injection and removal of fluid, the first lumen extending from the proximal end of said cylindrical tube to a first opening at the distal end of said cylindrical tube, the second lumen extending from the proximal end of said cylindrical tube to a second opening in the side of the cylindrical surface of said cylindrical tube, said second lumen terminating at said second opening and a relative concentration of material extending axially from the second opening to the distal end of said cylindrical tube, the distal end of said cylindrical tube having a smooth conical tapered tip that smoothly merges with the cylindrical surface of said cylindrical tube, the cylindrical surface of said cylindrical tube having at least one side hole exposing said first lumen axially spaced between said second opening and said conical tapered tip and circumferentially disposed on the opposite side of said cylindrical tube as said second opening, and the cylindrical surface of said cylindrical tube having at least one side hole exposing said second lumen axially spaced between said second opening and the proximal end of said cylindrical tube and circumferentially disposed on the same side of said cylindrical tube as said seond opening.

Claim 29

A double lumen catheter comprising an elongated cylindrical tube including a planar axial divider bisecting said cylindrical tube into first and second lumens, the proximal end of said cylindrical tube connecting two separate tubes communicating with the respective first and second lumens for the injection and removal of fluid, the first lumen extending from the proximal end of said cylindrical tube to a first opening at the distal end of said cylindrical tube, the second lumen extending from the proximal end of said cylindrical tube to a second opening in the side of the cylindrical surface of said cylindrical tube, said second lumen terminating at said second opening and a relative concentration of material extending axially from the second opening to the distal end of said cylindrical tube, the distal end of said cylindrical tube having a smooth conical tapered tip that smoothly merges with the cylindrical surface of said cylindrical tube, the cylindrical surface of said cylindrical tube having at least one side hole exposing said first lumen axially spaced between said second opening and said conical tapered tip and circumferentially disposed on the opposite side of said cylindrical tube as said second opening, and the cylindrical surface of said cylindrical tube having at least one side hole exposing said second lumen axially spaced between said second opening and the proximal end of said cylindrical tube and circumferentially disposed on the same side of said cylindrical tube as said seond opening.

Claim 30

The double lumen catheter as claimed in claim 23, wherein the apex of said conical tip is substantially aligned with the axis of said cylindrical tube.

Claim 31

The double lumen catheter as claimed in claim 23, wherein the length of said conical tip is at least approximately two diameters of said cylindrical tube.

Claim 32

The double lumen catheter as claimed in claim 23, wherein the first opening in the distal end of said cylindrical tube is eccentric with respect to the axis of the conical tapered tip.

Claim 33

The double lumen catheter as claimed in claim 23, wherein the wall thickness of the conical tapered tip is eccentric with respect to the axis of the conical tapered tip.

Claim 34

The double lumen catheter as claimed in claim 23, wherein the first and second lumens are semicircular.

Claim 35

The double lumen catheter as claimed in claim 23, wherein the proximal end of said cylindrical tube is connected to said separate tubes by a connector including a sleeve coaxial with said cylindrical tube at the junction of the connector and said cylindrical tube.

Claim 36

A double lumen catheter comprising an elongated unitary tube including an integral internal divider extending axially along the entire length of the tube and dividing said tube into a first and a second lumen, the outer circumference of said tube converging smoothly at the distal end portion of said tube defining a truncated cone, the first lumen opening at the truncated apex of said cone, and the second lumen being shorter in axial length than the first lumen and opening upon the outer circumference of said tube, said tube having a uniform diameter from its distal end portion to proximally beyond the opening of the second lumen upon the outer circumference.

Claim 37

A double lumen catheter comprising an elongated unitary tube including an integral internal divider extending axially along the entire length of the tube and dividing said tube into a first and a second lumen, the outer circumference of said tube converging smoothly at the distal end portion of said tube defining a truncated cone, the first lumen opening at the truncated apex of said cone, and the second lumen being shorter in axial length than the first lumen and opening upon the outer circumference of said tube, said tube having a uniform diameter from its distal end portion to proximally beyond the opening of the second lumen upon the outer circumference.

Claim 38

The double lumen catheter as claimed in claim 30, wherein the first lumen is eccentric to the axis of said cone.

Claim 39

The double lumen catheter as claimed in claim 30, wherein said second lumen opens upon the outer circumference of said tube at a plurality of openings having scaphoid margins.

Claim 40

The double lumen catheter as claimed in claim 30, wherein said first lumen also opens upon the outer diameter of said tube at a first plurality of holes located between the proximal end of said tube and the base of said cone, and said second lumen opens upon the outer diameter of said tube at a second plurality of holes located between said first plurality of holes and the proximal end of said tube.

Claim 41

The double lumen catheter as claimed in claim 30, wherein said first and second lumens are semicircular.

Claim 42

The double lumen catheter as claimed in claim 30, further comprising a branching connector at the proximal end of said tube including a sleeve coaxial with said tube at the junction of said tube and the branching connector.