US 20050143687 A1
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.
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.
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8. The catheter of
9. The catheter of
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.
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.
Infusion and Aspirating Port and Ports
The embodiments shown in
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.
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.
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
The small outer wall sections 30 a merge into the wall 28 at the built-up zone 32. Thus small segments 30 a of the outer wall 30 extend through the infusion port zone 22 and define the ports 22 a. The approximate dimensions in one embodiment of the openings 22 a are 135 mils by 20 mils (0.135 inches by 0.020 inches) and the segments 30 b are 25 mils wide.
Over a portion of the exit port arrangement 22 b, a web design shown in
The web 34 supports are not required in the design shown in
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.
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.