Occlusion resistant catheter

The present invention relates to indwelling catheter devices, and more specifically, indwelling catheter devices that minimize, prevent, disrupt, and/or treat catheter occlusion.

There are a number of implantable medical devices, such as indwelling catheters, that are used for the repeated and prolonged access to a patient's vascular system, urinary system, or other bodily conduits. Such devices include peripherally-inserted central catheters (“PICC's”), central venous catheters (“CVC's”), dialysis catheters, implantable ports, midline infusion catheters, and drainage catheters. These devices are typically implanted into a patient for an extended period of time to allow for multiple treatments, such as the delivery of therapeutic agents or dialysis treatments. Use of such devices eliminates the need for multiple placements of single-use devices, thus reducing the risk of infection and placement complications, and reducing the overall cost of patient care. Examples of such implantable medical devices include Vaxcel® PICC's and ports, Xcela® PICC's and ports, Vaxcel® Plus Chronic Dialysis catheters, and the Exodus™ drainage catheter (all from Navilyst Medical, Inc., Marlborough, Mass.).

Like any implantable device placed into the bloodstream, PICC's, ports, and other similar indwelling devices are susceptible to occlusion due to factors relating to thrombosis, encrustation, and the like. Catheter occlusion remains one of the most common noninfectious complications of long-term indwelling devices. Such occlusions can result in catheter malfunction, infection, and/or major vessel thrombosis. Thrombotic causes for catheter obstruction include intraluminal thrombus, extraluminal fibrin sleeve, mural thrombus, or major vessel occlusion and present as either complete or partial occlusion. For example, venous catheters may become encased with a fibrin material shortly after placement within a patient. This fibrin sheath is believed to be comprised of fibrin, platelets, and/or a fibrous collagen substance, and can lead to subsequent catheter occlusion.

In other types of indwelling catheters, such as those that are inserted into the urinary system, catheter occlusion may result from infection of the urine by a urease producing bacteria. Such infection may lead to the formation of a thickening biofilm that results in catheter occlusion. Occlusion may also result from the crystallization of salts from bodily fluids onto the catheter. It is estimated that recurrent blockage of urinary catheters occurs in as many as 50% of long-term catheterized patients.

Current techniques used to minimize, prevent, or treat catheter occlusion include flushing the catheter with fluids, such as heparinized saline to prevent thrombus formation, or citric acid to dissolve encrustation. It would be advantageous, however, to provide catheters that include means to minimize, prevent, disrupt, and/or treat occlusion.

In one aspect, the present invention comprises embodiments of indwelling catheters for inserting into a patient. The catheters comprise a proximal section, a distal end, and a tubular sidewall extending between the proximal and distal ends and defining a lumen for the passage of fluid therethrough. The catheters include at least one cut in the sidewall that extends to the catheter distal end and separates the sidewall into sidewall portions. When the distal end is subjected to a force greater than a threshold force, the sidewall portions move relative to each other to thereby minimize, prevent, disrupt, and/or treat catheter occlusion.

In another aspect, the present invention comprises a method of treating a patient using the catheters of the present invention.

In yet another aspect, the present invention comprises a kit that includes one or more catheters of the present invention.

FIGS. 1 a and 1 b are perspective and end views, respectively, of a catheter according to an embodiment of the present invention that includes two parallel cuts.

FIGS. 2 a and 2 b are side and cross-sectional views, respectively, showing a distal section of the embodiment of FIG. 1 when fluid passes through the catheter at a pressure greater than a threshold pressure.

FIGS. 3 a and 3 b are side views, and FIG. 3 c is a cross-sectional view, showing a distal section of an embodiment of the present invention that includes a single spiral cut.

FIGS. 4 a and 4 b are side views of a distal section of a catheter according to an embodiment of the present invention that includes relief cuts.

FIG. 5 is a side view of a distal section of a catheter according to an embodiment of the present invention that includes a curved cut.

FIG. 6 is a side view of a distal section of a catheter according to an embodiment of the present invention that includes an angled cut.

FIG. 7 is an end view of a dual-lumen catheter, according to an embodiment of the present invention.

The present invention provides indwelling catheters that may reside in the vasculature or other bodily lumens of patients for prolonged periods of time. As used herein, the term “indwelling catheter” is intended to include any flexible tube that is placed and left in the body over an extended time period. The catheters of the present invention include a unique design that minimizes, prevents, disrupts, and/or treats occlusion due to thrombus formation, encrustation, or the like.

A catheter according to an embodiment of the present invention is shown in side and cross-sectional views in FIGS. 1 a and 1 b , respectively. Although an exemplary indwelling catheter is shown in the figures included herein, it should be appreciated that the present invention is applicable to any catheter device that resides within a patient for an extended period of time. Such catheters include PICC's, CVC's, dialysis catheters, infusion catheters, drainage catheters, and any other tubular devices that are inserted into bodily lumens or organs for the delivery and/or withdrawal of fluids.

The catheter 100 illustrated in FIG. 1 a includes a proximal section 110 , a distal end 120 , and a tubular sidewall 130 extending between the proximal section 100 and distal end 120 . The proximal section 110 is configured to remain outside of a patient's body when the catheter 100 is in use. For example, the proximal section 110 optionally includes suture wings 111 that are attachable to the skin of a patient via sutures or the like. The proximal section 110 also optionally includes a luer fitting 112 for connection to a fluid source, such as medications, saline, nutrients, and blood. The distal end 120 is configured to be inserted into a patient to reside within any suitable bodily structure, such as a bodily lumen (e.g., a blood vessel, the urethra, the ureter, the esophagus, or the colon) or an organ (e.g., the kidney, the heart, or the stomach). The tubular sidewall 130 extending between the proximal section 110 and distal end 120 defines a lumen 140 for the passage of such fluids to or from the patient.

The catheter 100 includes at least one cut 150 in the tubular sidewall 130 extending from the distal end 120 , the length of the cut(s) 150 defining a distal section 160 of the catheter 100 . As used herein, the term “cut” is not limited to a discontinuity created by a particular method of manufacture, but rather is intended to be broad enough to include any gap, break, cut, discontinuity, opening, or the like created in the sidewall 130 by any suitable technique. In an exemplary embodiment, the length of the at least one cut 150 , and therefore the length of the distal section 160 , is within the range of about 1 mm to about 20 mm, and preferably about 1 mm to about 5 mm. The embodiment shown in FIGS. 1 a and 1 b includes two cuts 150 in the sidewall 130 , the two cuts 150 being at about 180 degrees from each other and being substantially parallel to each other and to a longitudinal axis of the lumen 140 .

In all embodiments of the invention, the at least one cut 150 extends through to the distal end 120 and separates the sidewall 130 into sidewall portions that move relative to each other due to separation forces, such as internal or external forces, that are greater than a threshold force. An example of such an internal force can result from the passage of fluid through the lumen 140 ; and an example of such an external force can result from the patient's anatomy, such as a surrounding bodily lumen or tissue such as cyclic forces applied by the superior vena cava.

In the embodiment shown in FIGS. 1 a and 1 b , the passage of fluid through the lumen 140 at a pressure higher than a threshold pressure results in the application of a force upon the sidewall portions 131 and 132 within the distal section 160 such that they move away from each other, as shown in FIGS. 2 a and 2 b . Such movement of the sidewall within the distal section 160 is believed to be useful to minimize, prevent, disrupt, and/or treat catheter occlusion by preventing the accumulation of materials that contribute to thrombus or encrustation formation, and/or dislodging any such materials that have already adhered to the catheter on the exterior of the sidewall 130 or within the lumen 140 in the distal section 160 .

In another embodiment of the invention as shown in FIGS. 3 a - 3 c , a single cut 150 is made within the sidewall 130 of a catheter 200 and extends as a spiral from the distal end 120 to separate sidewall 140 into sidewall portions 231 as viewed in a single plane. Like the embodiment shown in FIGS. 1 and 2 , the passage of fluid through the lumen 140 of catheter 200 at a pressure higher than a threshold pressure causes the application of a force upon the sidewall portions 231 greater than a threshold force such that they move away from each other. In this embodiment, such fluid passage causes the distal section 160 to move by enlargement in a distal and/or radial direction by the separation of sidewall portions 231 that are defined by the spiral cut 150 .

Although the embodiments shown in FIGS. 1-3 are shown such that sidewall portions defined by the at least one cut 150 abut each other when not subjected to a force above a threshold force, the present invention includes embodiments such as the embodiment of FIG. 4 in which sidewall portions are separated from each other in an as-manufactured condition and prior to being subjected to any force. It is thus intended that the at least one cut used in the embodiments of the present invention may optionally result in the removal of material from the catheter sidewall to create a distance between sidewall portions. Alternatively, the at least one “cut” may be made by radiofrequency welding or other suitable fabrication technique to leave an as-manufactured separation between sidewall portions, rather than by an actual physical cutting technique.

In the embodiment shown in FIGS. 4 a and 4 b , the distal section 160 of the catheter 300 includes a cut 150 that separates the sidewall 130 into sidewall portions 331 , 332 . The as-manufactured separation between the sidewall portions 331 , 332 is preferably about 0.001 inches to about 0.060 inches. In a preferred embodiment, the catheter 300 includes a relief cut 370 at the proximal end of the cut 150 . The relief cut 370 is preferably semi-circular, and helps to facilitate the movement of sidewall portions 331 , 332 when the distal section 160 is subjected to forces greater than a threshold force, as shown in FIG. 4 b . Although FIG. 4 b and the drawings for other embodiments show sidewall portions moving away from each other, it is within the scope of the present invention that the sidewall portions move towards each other due to the application of external forces to thereby minimize, prevent, disrupt, and/or treat catheter occlusion.

In other embodiments 400 and 500 , the catheters of the present invention include cuts 150 that are curved, as shown in FIG. 5 , and/or extend at an angle with respect to a longitudinal axis 550 of the catheter, as shown in FIG. 6 . Although the catheters of the present invention are illustrated as including one or two cuts, it should be appreciated that there is no limit to the number of cuts that may be included in the catheters of the present invention, other than ability to manufacture.

In one embodiment, the catheter of the present invention is a multi-lumen catheter, such as the dual-lumen catheter 600 shown in FIG. 7 . The dual-lumen catheter 400 includes a dividing wall 125 that extends along the length of the catheter and divides it into first and second lumens 141 , 142 . At least one cut 150 is provided in the sidewall 130 over either or both of the first and second lumens 141 , 142 . In the embodiment shown in FIG. 7 , two cuts 150 are provided in the catheter 400 , with a single cut made in the sidewall over each of the first and second lumens 141 , 142 . When fluid is passed through the first 141 and/or the second 142 lumens at a pressure above a threshold pressure, or alternatively when external forces from the patient's anatomy act upon the distal end of the catheter 600 , the respective sidewall portions 131 , 132 , and/or 133 , 134 move relative to each other.

The materials used to fabricate the catheters of the present invention are any suitable polymeric materials as are known in the art, such as thermoplastic polyurethanes, nylons, polyether block amides, ethylene vinyl acetate, silicones, polyolefin elastomers, styrenic elastomers, and polyester elastomers. The catheters are preferably manufactured by extrusion fabrication techniques, as are known in the art. The cuts provided in the catheters of the present invention may be made by any suitable cutting process, by removing sidewall material through micro-milling, radiofrequency welding, or other suitable machining technique, or by molding or extruding the catheters with the cuts in an as-manufactured configuration.

As described herein, the catheters of the present invention include sidewall portions defined by cuts that move relative to each other when the catheter is subjected to internal and/or external forces above a threshold force. As used herein, the term “threshold force” is intended to mean the force required to move at least part of the sidewall portions, as described herein, relative to each other. As such, the threshold force will differ for each catheter, and will depend upon factors such as the composition, thickness, and geometry of the catheter sidewall.

It will be apparent to those skilled in the art that various modifications and variations can be made in the structure and methodology of the present invention. Thus, it is intended that the present invention cover such modifications and variations provided that they come within the scope of the appended claims and their equivalents.