Double-lumen catheter

Details Double-lumen catheter Double-lumen catheter

2001-06-08

2002-11-19

Walberg, Teresa (Department: 3742)

Surgery

Blood drawn and replaced or treated and returned to body

Body inserted tubular conduit structure

C607S105000

Reexamination Certificate

active

06482169

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to catheters and, in particular, though not exclusively, to double-lumen catheters used for hemodialysis.
BACKGROUND OF THE INVENTION
Hemodialysis catheters are conventionally large double-lumen catheters. Generally, the lumens must be large enough to support flow rates greater than 250 c c/min through each lumen. A hemodialysis catheter resides within a large vein within the body or within the right atrium of the heart. The end of the catheter placed into a patient's body is referred to as the distal end of the catheter, while the end connected to a dialysis machine is called the proximal end. Blood is withdrawn out of a vein via an uptake lumen of the catheter and into the dialysis machine. The uptake lumen is also referred to herein as the withdrawal lumen. The dialyzed blood is returned to the body via the return lumen. The uptake lumen has an uptake lumen hole (also referred to as an uptake lumen opening) for withdrawal of blood from the body. The uptake lumen hole is typically disposed at the distal end of the uptake lumen. Similarly, the return lumen has a return lumen hole for return of blood to the body. The return lumen hole is typically disposed at the distal end of the return lumen. The uptake and return lumen holes are generally spatially separated from each other, typically with the uptake lumen hole located proximal to the return lumen. This is usually accomplished by making the uptake lumen shorter than the return lumen. The above configuration of the uptake and return lumen holes minimizes the immediate redialysis of blood just returned to the body.
FIG. 1
is a side view of a first embodiment of double lumen catheters in the prior art. In
FIG. 1
, catheter
100
includes a proximal end
110
, a distal end
120
, and a central axis
130
. The central axis may also herein be referred to as the longitudinal axis. Catheter
100
also includes an uptake lumen end hole
141
and a return lumen end hole
142
. As can be seen in
FIG. 1
, uptake lumen end hole
141
is located proximally with respect to return lumen end hole
142
.
On occasion, prior art catheters, such as that shown in
FIG. 1
, fail to perform their intended function. The failure modes of these catheters are numerous. One common type of failure is occlusion of the uptake lumen end hole by the adjacent wall of the vein or by the wall of the right atrium. That is, when blood is withdrawn at a rapid rate from the vein via the uptake lumen, the uptake lumen end hole has a propensity to aspirate (or “suck up”) against any adjacent structure. This adverse action of the uptake lumen end hole either limits the flow rate of the catheter or occludes blood flow entirely through the catheter.
Some of the available hemodialysis catheters address this problem by designing the uptake lumen to have several side holes.
FIG. 2
is a side view of a prior art catheter having such side holes. Catheter
200
, in
FIG. 2
, has a proximal end
210
, a distal end
220
, and a central axis
230
. Catheter
200
also includes uptake lumen side holes
241
in the uptake lumen and return lumen side holes
242
in the return lumen. With this configuration, even if one side hole of the uptake lumen is sucked or aspirated against an adjacent wall, the catheter functions because the other side holes of the uptake lumen are not aspirated against the wall.
However, this design, in which multiple side holes are present to prevent occlusion by adjacent walls, presents a drawback of its own. When any hemodialysis catheter is not in use, both lumens are filled (or “locked”) with an anticoagulant solution, typically concentrated heparin sulfate. This solution is intended to prevent blood clots from forming on or within the catheter's lumens. Such blood clots would occlude the lumens, leading to catheter failure. If the uptake lumen has multiple side holes, the anticoagulant solution leaks away at the catheter tip through these multiple side holes, causing an increased risk of blood clot formation on the catheter's tip, thus causing subsequent catheter failure.
A hemodialysis catheter whose uptake lumen consists of a single end hole will retain the anticoagulant solution. However, as detailed above, such a prior-art hemodialysis catheter retains a tendency to have its uptake lumen end hole aspirate against an adjacent wall and occlude the uptake lumen.
The intravenous portion of conventional hemodialysis catheters are linear in configuration. The lumens of such catheters run parallel to each other within a single, flexible silicone housing, with the lumens separated by a silicone septum.
FIGS. 3
a
,
3
b
, and
3
c
are a first, second, and third embodiments, respectively, of the cross sectional view along each of lines
3
—
3
in
FIGS. 1 and 2
. The views in
FIGS. 3
a
,
3
b
, and
3
c
represent different embodiments for partitioning the uptake and return lumens. In
FIGS. 3
a
,
3
b
, and
3
c
, cross sections
301
and
302
represent cross sections of the uptake lumen and return lumen, respectively, in the three different embodiments of the cross sections of the catheter.
FIGS. 3
a
,
3
b
, and
3
c
also represent three different embodiments of the view along the central axis from the distal end to the proximal end (as well as the view along the central axis from the proximal end to the distal end) in the catheters of
FIGS. 1 and 2
.
Discussion of prior art catheters, such as those described above, can be found in U.S. Pat. No. 5,209,723, U.S. Pat. No. 5,947,953, and U.S. Pat. No. 6,001,079, which are incorporated by reference herein.
Accordingly, there is a need for a catheter that addresses the above disadvantages of prior art catheters.
SUMMARY OF THE INVENTION
The present invention encompasses a catheter. In one embodiment, the catheter includes: a shaft segment, the shaft segment including a proximal end of the catheter and a shaft segment central axis, the shaft segment further including a shaft S segment uptake lumen and a shaft segment return lumen; a distal end segment coupled to the shaft segment, the distal end segment including a distal end of the catheter and a distal end segment central axis, the distal end segment further including a distal end segment uptake lumen and a distal end segment return lumen, where the distal end segment uptake and return lumens are coupled to the shaft segment uptake and return lumens, respectively; where the distal end segment central axis forms a non-zero angle with the shaft segment central axis when the catheter is in its unstressed configuration.
In a second embodiment, the catheter includes: a shaft segment, the shaft segment including a proximal end of the catheter and a shaft segment central axis; a distal end segment coupled to the shaft segment, the distal end segment including a distal end of the catheter and a distal end segment central axis; where the distal end segment central axis is parallel to the shaft segment central axis when the catheter is in its unstressed configuration, further where the distal end segment includes a return lumen and an uptake lumen having a return lumen distal end and an uptake lumen distal end, respectively, further where the uptake lumen distal end is terminated by a closed surface, further where the uptake lumen distal segment includes only one side hole.
In a third embodiment, the catheter includes: an uptake lumen including an uptake lumen shaft segment and an uptake lumen distal segment with an uptake lumen distal end; a return lumen including a return lumen shaft segment and a return lumen distal segment with a return lumen distal end; where the uptake lumen shaft segment is substantially parallel to the return lumen shaft segment, further where at least a portion of the return lumen distal segment is helically coiled around the uptake lumen distal end.


REFERENCES:
patent: 4770652 (1988-09-01), Mahurkar
patent: 5163928 (1992-11-01), Hobbs et al.
patent: 5171216 (1992-12-01), Dasse et al.
patent: 5209723 (1993-05-01), Twardowski et al.
patent: 5222949 (199

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