Blood treatment catheter and method

Abstract

A blood infusion and aspiration catheter has an annular lumen surrounding a central lumen. The annular lumen, whether used for infusion or aspiration, has a set of ports which are aligned along a circular circumference so that they intersect a common plane. That common plane is substantially perpendicular to the axis of the annular lumen. This structural arrangement avoids the compromise of heparin lock that occurs when the exit or entrance ports at the distal end of the annular lumen are circumferentially staggered. These ports in the annular lumen face radially outward to assure that port edges do not snag on tissue when the catheter is inserted.

Description

REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of pending application Ser. No. 10/116,299 filed Apr. 4, 2002 entitled: Blood Treatment Catheter And Method, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates in general to blood treatment catheters and more particularly to a design for use in hemo-dialysis in which blood clot build-up within the catheter between uses of the catheter is minimized.

The hemo-dialysis catheter is maintained in the patient between dialysis sessions. In order to avoid blood clot within the catheter, a charge of heparinized saline is placed in the catheter to displace the blood and prevent blood clot. This state is called heparin lock.

In a typical catheter having a central aspirating lumen and an annular infusion lumen, the openings near the distal end of the infusion lumen are staggered axially. Accordingly, when the heparinized saline is charged into the annular infusion lumen, one of two things occur that negates the function of the heparinized saline and tends to allow a blood clot to form.

In one situation, the heparinized saline exits from the proximal most port thereby failing to displace the blood distal of that exit port.

In another situation, the heparinized saline may be inserted with sufficient flow speed to displace all of the blood in the annular catheter. However, the patient's blood gradually circulates through the openings in the annular lumen, displacing the heparinized saline allowing a blood clot to develop over the zone between proximal and distal openings.

The heparinized saline is locked into the lumens and this state is often referred to as heparin lock. The blood clot at the distal zone prevents the heparin lock from performing its anti-clotting function at that zone.

Accordingly, it is an object of this invention to provide a catheter design that maximizes the effect of the heparin lock.

Accordingly, it is a further purpose of this invention to provide the above purpose in a design which provides a relatively smooth surface to facilitate ease of insertion of the catheter into the patient.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a schematic illustration of the positioning of the hemo-dialysis catheter 10 of this invention through the jugular vein. In FIG. 1, the catheter is inserted into the patient at point A and into the vein at point B.

FIG. 2 is an elevation view of an embodiment of the catheter of this invention in which an annular lumen provides infusion and a central lumen provides aspiration. Infusion ports 22 are at the distal end of the infusion lumen. An aspiration port 36 is at the distal end of the aspiration lumen.

FIG. 3 is an elevation view of the zone around the distal infusion port of a first embodiment of the FIG. 2 catheter showing a plurality of arcuate circumferential ports 22a; all of which intersect a single radial plane.

FIG. 4 is a partial longitudinal sectional view along the FIG. 3 catheter portion.

FIG. 5 is a cross-sectional view along the plane 5-5 of FIG. 3.

FIG. 6 is a longitudinal sectional view of a second embodiment of the FIG. 2 catheter in which the infusion port arrangement 22 is a circumferential port 22b interrupted by four radial ribs 34 (see FIG. 8) that support the distal end of the annular infusion tube.

FIG. 7 is a longitudinal sectional view through the ribs 34 of the FIG. 6 catheter.

FIG. 8 is a cross-sectional view along the plane 8-8 of FIG. 7 showing the four chamber section of the circumferential infusion lumen immediately adjacent to the infusion port 22b.

FIG. 9 is an elevational view of a third embodiment showing a set of triangular infusion ports.

FIG. 10 is a cross-sectional view along the plane 10-10 of the FIG. 9 catheter.

DEFINITIONS

Infusion and Aspirating Port and Ports

The embodiments shown in FIGS. 3, 6, and 9 contain a plurality of infusion exit ports. A design can be provided in which there is a single circumferential exit port with upstream supports for the annular lumen. The essential feature is that the port or ports all lie along one plane that is substantially perpendicular to the axis of the catheter.

Accordingly, it should be understood that, as applied to either infusion or aspiration lumens, the terms “port” or “ports” or “port arrangement” in the specification and claims are used to include a single port and/or a set of ports.

BRIEF DESCRIPTION

In brief, the catheter disclosed has both aspiration and infusion lumens. In the embodiments shown, at a distal zone, the tube carrying the aspiration lumen extends distally of the end of the tube defining the infusion lumen. At its distal end, the infusion lumen is substantially annular, extending around the aspiration tube and has one or more infusion ports that provide emission of fluid all within a single plane.

All of the infusion ports are deployed along a single plane that is substantially perpendicular to the axis of the catheter. This infusion exit port arrangement serves to avoid blood clot during heparin lock in the annular infusion tube.

All of the infusion ports face radially outward to minimize having the port wall edges snag tissue and impede insertion into the catheter.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 illustrate the overall design of the catheter 10 embodying the invention.

In particular, a standard infusion tube 12 and aspiration tube 14 are combined at a juncture 16 to provide a single tube 18 distal of the juncture 16. The tube 18 contains infusion and aspiration lumens. The tube 18 is inserted into a patient at point A and passed into the jugular vein 20 at point B to be positioned at a desired location; often in the right atrium.

As can be seen in the embodiments shown in FIG. 3 through 10, the infusion lumen 24 is a circumferential lumen around the aspiration lumen 26 in the zone that is immediately proximal of the infusion exit port arrangement 22. A tubular wall 28 defines the aspiration lumen 26. The infusion lumen 24 is defined by tubular wall 28 as an inner wall and an outer wall 30. The port 22 arrangement is in the outer wall 30. The outer wall 30 terminates or merges into the wall 28 at the built-up zone 32.

FIGS. 3 through 5 illustrate a first embodiment of this invention in which the infusion port set 22 is constituted by four circumferential ports 22a separated by small outer wall sections 30a. The port arrangement 22 is at the distal end of the annular infusion lumen 24. The four ports 22a are along a single plane which is substantially perpendicular to the axis of the annular infusion lumen 24. The ports 22a face radially outward and thus the central axis of each port 22a is substantially perpendicular to the axis of the annular infusion lumen 24.

The small outer wall sections 30a merge into the wall 28 at the built-up zone 32. Thus small segments 30a of the outer wall 30 extend through the infusion port zone 22 and define the ports 22a. The approximate dimensions in one embodiment of the openings 22a are 135 mils by 20 mils (0.135 inches by 0.020 inches) and the segments 30b are 25 mils wide.

FIGS. 6 through 8 illustrate a second embodiment of this invention in which the exit port arrangement 22 are four circumferential ports 22b spaced apart by radial webs 34.

Over a portion of the exit port arrangement 22b, a web design shown in FIG. 8, is employed at the exit ports 22b. This web design assures that the ports 22b are maintained open and prevents the wall 30 from collapsing onto the wall 28. This web design involves four thin webs 34 which extend proximally from the ports 22b for about three millimeters in the embodiment shown.

The web 34 supports are not required in the design shown in FIGS. 3-5. In that design, the outer wall 30 extends past the ports 22a to merge into the wall of the aspiration lumen and thus does not require extra support.

It should be understood that the design of this invention includes an embodiment in which the webs 34 extend the length of the catheter from junction 16 to infusion exit ports 22. Such a design is not presently preferred because it provides a stiffer catheter with a lower flow rate than do the designs disclosed herein.

FIGS. 9 and 10 show a third embodiment in which the ports set 22 are a set of triangular ports 22c nested next to each other. The ten wall segment 30b provides a sturdy structural support for the distal end of the outer wall 30 while maximizing the cross-sectional area and flow rate of each port.

The design of this invention avoids blood clot development during heparin lock. When the catheter is implanted in a dialysis patient and is not in use, it becomes important to avoid blood clotting in the catheter. This is done by injecting a predetermined amount of heparinized saline into the catheter while the catheter is resident in the patient's body to essentially fill up the interior of the catheter with heparinized saline. The heparinized saline is held or locked into the lumens between dialysis treatment. This is called heparin lock.

In the prior art designs employing co-axial lumens, the outer annular lumen normally has a plurality of openings near the distal end axially displaced from one another. The heparinized saline fills up to the proximal most opening and then exits from that opening and thus fails to fill the space distal of that proximal most opening. A blood clot may form in that space, blocking the openings. Alternatively, if the heparinized saline does completely occupy the catheter lumen, the portion distal of the most proximal hole will gradually be replaced by the patient's blood and end up creating the blood clot that blocks the catheter openings. Clot formation leads to reduced flow rates and may require intervention to clear the catheter.

By having all the openings of the annular lumen aligned in a single plane perpendicular to the axis of the lumen, the blood clot problem that blocks certain of the ports is avoided. In each of the embodiments shown, the infusion port set 22 are the only infusion ports from the annular lumen 24.

Indeed, whether the annular lumen is used for infusion or for aspiration, this co-planar alignment of openings avoids this blood clot limitation on the heparin lock function. Although the embodiments disclosed show that the annular lumen is the infusion lumen, it should be understood that the invention has equal value where the annular lumen is an aspiration lumen.

It is important that these co-planar openings face radially outward rather than face partially forward. The radially outward facing opening structure serves two purposes. First it minimizes recirculation of filtered blood from the infusion opening to the aspiration opening. Second, it assures a smoother surface to facilitate insertion of the catheter.

In summary, to provide the above advantages, the geometry of the openings have two important characteristics. A first is that the surface of the openings are substantially parallel to the axis of the catheter. The second is that the openings are all on a common plane near the end of the annular lumen; which common plane is substantially perpendicular to the axis of the catheter.

While the foregoing description and drawings represent the presently preferred embodiments of the invention, it should be understood that those skilled in the art will be able to make changes and modifications to those embodiments without departing from the teachings of the invention and the scope of the claims.

Claims

1. A catheter comprising:

an aspiration lumen and an infusion lumen,

a first one of said lumens having a distal annular lumen segment circumferentially deployed around the second one of said lumens, said annular lumen segment having an axis and a sidewall,

a distal port arrangement in said side wall comprising one or more individual ports,

each port of said port arrangement intersecting a common plane, said common plane being substantially perpendicular to said axis of said annular lumen segment,

each of said ports has an axis substantially perpendicular to said axis of said annular lumen,

said port arrangement constituting the sole ports of said annular segment.

2. The catheter of claim 1 wherein: said ports are at the distal end of said annular lumen segment.

3. The catheter of claim 1 wherein: said infusion lumen is said annular lumen.

4. The catheter of claim 2 wherein: said infusion lumen is said annular lumen.

5. The catheter of claim 1 wherein: each of said lumens has an outer wall and wherein said distal port arrangement is in part defined by segments of said annular lumen outer wall segments extending between said ports and merging into said outer wall of said second one of said lumens.

6. The catheter of claim 5 wherein: said ports are at the distal end of said annular lumen segment.

7. The catheter of claim 5 wherein: said infusion lumen is said annular lumen.

8. The catheter of claim 6 wherein: said infusion lumen is said annular lumen.

9. The catheter of claim 1 wherein: wherein said distal port arrangement comprises a set of triangular ports nested against each other.