Patent Application
20050004504
1. Technical Field
The present application relates generally to a multi-lumen catheter for use in the extracorporeal treatment of bodily fluids, and more particularly, to a dual lumen catheter for use in a hemodialysis procedure.
2. Background Information
Catheters used in extracorporeal treatments of bodily fluids generally are provided with separate ingress and egress lines for transport of the bodily fluid to and from the patient. A bodily fluid, such as blood, is withdrawn from the body through one of the lines, generally referred to as the withdrawal line. The fluid is subjected to a treatment process and thereafter returned to the body through the other line, generally referred to as the infusion line.
With specific reference to the use of such catheters in a hemodialysis procedure, blood is withdrawn from the body through the withdrawal line of the catheter, passed through a dialyzer for treatment, and returned to the body through the infusion line. When such catheters are used in a hemodialysis procedure, they are generally inserted into the body through a major vein, such as the jugular vein, subclavian vein or the femoral vein. In addition to hemodialysis, extracorporeal catheters are also used for other medical procedures wherein a body fluid is removed from the body and thereafter returned following certain prescribed activity, such as pheresis and hemofiltration.
One problem with existing extracorporeal catheters is that such catheters can experience decreased flow rates over time. Decreased flow rates may be caused by, among other things, blockage of the withdrawal and/or infusion ports in the catheter. Various factors can cause a port to become blocked. Probably the most common causes of port blockage are the inadvertent positioning of one or more ports of the catheter against the vessel wall, thereby preventing or at least hindering free flow of fluid through the obstructed port, and the formation of fibrin sheaths that may occur along the ports in response to the vessel wall washing effect or clotting.
Several attempts have been made in the past to reduce port blockage. One method has been to provide multiple side ports that are spaced at various locations along the length of the catheter. The presence of multiple side ports, rather than a single port, reduces the effect of blockage of a single port. However, when multiple side ports are present, even these ports are still subject to blockage when placed against the vessel wall, or as a result of fibrin formation on the port. Other attempts have been made to reduce port blockage by providing a side-by-side dual lumen design having a stepped feature, wherein the respective withdrawal and infusion tubes are of different lengths. With this configuration, the ports withdraw and infuse the bodily fluid at different axial locations of the catheter. This arrangement may avoid some problems involved in maintaining adequate flow through the lumens, however such ports can still become blocked and be subject to suboptimal flow issues.
It is desired to provide a multi-lumen catheter for extracorporeal treatment of bodily fluids that minimizes port blockage, and that optimizes the flow of fluids through the lumens of the catheter.
The present invention addresses the problems of the prior art by providing a multi-lumen catheter for extracorporeal treatment of bodily fluids, such as blood.
In one embodiment, the invention comprises a catheter assembly for use in extracorporeal treatment of a bodily fluid. The catheter assembly comprises a catheter body comprising outer and inner tubular members, each having a lumen extending therethrough. The inner tubular member is substantially positioned within the lumen of the outer tubular member. One of the tubular members, such as the outer tubular member, comprises a withdrawal tube for withdrawing bodily fluid from a body vessel for extracorporeal treatment, and the other tubular member, such as the inner tubular member, comprises an infusion tube for infusing the bodily fluid back into the body vessel following extracorporeal treatment of the fluid. At least one of the tubular members includes an expansion member, such as a malecot, for substantially centering the apparatus in a body vessel.
In another embodiment thereof, the invention comprises an assembly for use in treating a bodily fluid. The assembly comprises an outer tubular member having a lumen extending therethrough. The distal end of the outer tubular member has an exit opening, and an expansion member is positioned at said distal end. A dilator having a tapered distal end is selectively receivable in the outer tubular member lumen and removable therefrom. The tapered distal end is sized relative to the outer tubular body exit opening such that a portion of the tapered dilator distal end that has a diameter smaller than the diameter of the exit opening extends distally through the exit opening when the dilator is positioned in the lumen, and a portion of the tapered dilator distal end that has a diameter larger than the diameter of the exit opening abuts but does not pass through the exit opening. The outer tubular member and the dilator are lockingly engageable to maintain the dilator and the outer tubular member in a substantially fixed relative position when the dilator is received in the lumen of the outer tubular member. The expansion member is selectively movable between an expanded condition and a collapsed condition. When the dilator is positioned in the lumen, the expansion member is in a collapsed condition, and when the dilator is removed from the lumen, the expansion member is in an expanded condition.
In yet another embodiment, the present invention comprises a method for treating a bodily fluid. An assembly is provided for transporting the bodily fluid to and from a treatment instrument. The assembly comprises a catheter body having an outer tubular member and an inner tubular member, each of the tubular members having a proximal end and a distal end and a lumen extending therethrough. The inner tubular member is substantially positioned within the lumen of the outer tubular member and extends distally beyond the distal end of the outer tubular member. At least one of the tubular members has an expansion member for substantially centering the assembly in a body vessel. One of the tubular members comprises a withdrawal tube for withdrawing a bodily fluid from the vessel for treatment, and the other tubular member comprises an infusion tube for infusing treated fluid back into the vessel. The distal end of this assembly is inserted into a body vessel. Bodily fluid to be treated is withdrawn from the vessel through the withdrawal tube, and transported to a treatment instrument. Following treatment in the treatment instrument, the treated fluid is transported to the infusion tube for infusion into the vessel through an aperture in the infusion tube.
In a still further embodiment, the present invention comprises a method for treating a bodily fluid. An assembly for transporting the fluid is provided, the assembly comprising an outer tubular member and a dilator. The outer tubular member has a proximal end, a distal end having a distal opening, and a lumen extending therethrough. The outer tubular member further includes an expansion member positioned at its distal end. The dilator is selectively positionable in the lumen of the outer tubular member and removable therefrom. The dilator has a tapered distal end, wherein a portion of the tapered distal end is sized to extend distally through the distal opening of the outer tubular member when the dilator is positioned in the lumen. The expansion member is in a collapsed condition when the dilator is positioned in the lumen. An opening is formed in the body vessel, and the vessel opening is dilated by inserting a distal end of the treatment assembly having the dilator positioned therein into the vessel. The dilator is removed from the dilated opening and from the assembly, thereby allowing the expansion member to attain an expanded condition. An inner member is then inserted in the lumen of the outer tubular member. The inner member has a lumen extending therethrough, and a distal end extending distally beyond the distal end of the outer tubular body. Fluid is withdrawn from the vessel through the lumen of one of the tubular members and transported to a treatment instrument. The fluid is treated in the instrument, and the treated fluid is transported to the other tubular member. The treated fluid is then infused into the vessel through a lumen in the other tubular member and an aperture in the tubular member.
For purposes of promoting an understanding of the present invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It is nevertheless to be understood that no limitation of the scope of the invention is thereby intended, the proper scope of the invention being indicated by the claims appended below and the equivalents thereof. The figures are not all drawn to the same scale to avoid obscuring the details of the finer structures. The following detailed description of the preferred embodiments will make clear the preferred arrangement, size relationships and manner of using the components shown herein.
The present invention comprises a multi-lumen catheter for use in the extracorporeal treatment of bodily fluids. In a preferred embodiment, the invention comprises a dual lumen catheter for extracorporeal use, such as for use in a hemodialysis procedure. In addition to hemodialysis, the catheter can be used for other extracorporeal fluid treatments in which a body fluid is withdrawn from the body, subjected to a treatment process, and thereafter returned to the body. Pheresis and hemofiltration are non-limiting examples of such procedures.
The dual lumen catheter of the preferred embodiment includes two elongated tubular members, each having a lumen therethrough. At least one of the tubular members includes an expansion member, such as a malecot cut in the wall of the tubular member. The expansion member expands the effective diameter of the catheter at the point of the expansion member, and thereby assists in centering the main portion of the catheter in the centermost portion of the vessel. Fluid passing through the center area of a body vessel generally flows at a higher flow rate than fluid passing near the vessel walls. Formation of fibrin and other types of blockages are less likely to occur on catheters and other medical devices when the device is positioned in a high flow area, such as in the center area of the vessel. In addition, the structure of the expansion member will generally also include open areas. These open areas also serve to further enhance the flow rate of fluids into or out of the catheter, by expanding the ingress or egress areas of the catheter through which the fluid may flow. Although the description herein specifically makes reference to a dual lumen catheter, those skilled in the art will appreciate that additional lumens can be provided on the catheter assembly for other purposes well known in the art, such as the administration of medicaments and the like.
Catheter assembly 10 includes a catheter body 11. Catheter body 11 comprises an outer elongated tubular member 12 having a distal end 14, a proximal end 16 and a lumen 18 extending therethrough (
In the preferred embodiment shown in
Inner tubular member 20 comprises the fluid infusion, or return, tube. Although outer tubular member 12 and inner tubular member 20 have been designated in this embodiment as the respective withdrawal and infusion tubes, this designation may be reversed, if desired. Arrows 25 are provided in
Inner tubular member 20 includes expansion member 28. Expansion member 28 is preferably provided at the distal end of inner tubular member 20, although it need not necessarily be situated at this end. In
Preferably, sufficient slits are cut into tubular member 20 to form four rib members 29, spaced 90° along the circumference of the inner tubular member. More, or fewer, ribs can be substituted without departing from scope of the invention. During formation of rib members 29, a spacer can be inserted inside the expansion member at the area of the slits 27 to stretch the expandable member such that it takes the desired configuration. This portion of tubular member 20 is then treated, such as by passing the catheter through steam. The catheter body is then cooled in the expanded configuration, and the spacer is removed. The heat treatment provides the catheter body with a memory, so that the natural “at rest” position of the expansion member 28 becomes the expanded condition shown in
In this embodiment, inner tubular member 20 is removable from lumen 18 of outer tubular member 12. When the distal portion of inner tubular member 20 (including expansion member 28) is disposed within lumen 18, such as during insertion and withdrawal of the apparatus, rib members 29 of inner tubular member 20 are in the compressed state shown in
The expanded configuration slightly shortens the axial length of inner tubular member 20. By increasing the effective diameter of inner tubular member 20 at the site of expansion member 28, tubular member 20 acts to substantially center catheter assembly 10 in the body vessel, thereby inhibiting blockage of the ports. The configuration of expansion member 28 also defines multiple infusion openings, e.g., between rib members 29, thereby enhancing the flow rate of blood back into the vessel.
Hemodialysis catheters are prone to blockage, which can render the device unusable. Utilization of a removable inner tubular member such as that described enables the physician to replace a blocked tube with a new one. As a result, the patient is benefited since the useful lifetime of a catheter can be extended.
In the preferred embodiment shown, catheter assembly 10 also includes a side-arm fitting, such as hub 30. Hub 30 branches in the proximal direction into two legs 32, 40. As shown in
Preferably, infusion, or return, hub leg 40 includes a conventional self-closing valve, such as hemostatic valve 41. In the embodiment shown in
In a preferred embodiment, catheter assembly 10 also includes at least one extension tube, such as extension tube 34, as well as connectors 36, 44. Extension tube 34 is engaged with the proximal end of leg 32. A luer lock or other suitable connector 36 is engaged with the proximal end of extension tube 34. Connector 36 engages in mating relationship with a connector associated with an ingress opening of a treatment instrument 50, such as a dialyzer, for establishing a flow path of blood to the dialyzer. Conventional clamp 38 may be provided for selectively opening and closing extension tube 34.
Proximal end 24 of inner tubular member 20 is engaged with the proximal end of hub leg 40. A luer lock or other suitable connector 44 is engaged with proximal end 24. Connector 44 engages in mating relationship with a connector associated with an egress opening of the dialyzer. Dialyzer 50 and its ingress and egress openings are shown schematically in
Extension tube 34 can be formed to have virtually any length, however it should be long enough to receive clamp 38. Preferably, extension tube 34 is relatively soft and flexible so that it can be easily manipulated and closed by the pressure exerted by the clamp. The clamps function in the nature of valves to control the flow of blood between the dialyzer and the catheter. Those skilled in the art will appreciate that the extension member shown in
Use of the catheter assembly 10 of
Once catheter assembly 10 has been inserted into a body vessel, sufficient negative pressure is created to commence withdrawal of blood from the vessel, such as by activation of dialyzer 50. Blood is withdrawn from the vessel in the direction of arrows 15 of
Providing a second expansion member 62 as shown further enhances the ability of catheter assembly 10 to remain centered in the vessel, and in addition, provides enhanced flow area for blood being withdrawn from the vessel to enter lumen 18. Providing a greater flow area in this manner further diminishes the possibility of blockage of the withdrawal port. In this embodiment, the inner tubular member is also removable, as in the previous embodiment.
With this embodiment, catheter assembly 70 may be introduced over a wire guide. A separate introducer sheath is not necessary. When inserted, the expansion member 78 is in its compressed condition. To activate expansion member 78 following introduction of catheter assembly 70 into a vessel, connector portion 44 is pulled back in a proximal direction, and locked in place with a suitable locking mechanism 82, such as a friction O-ring. This action maintains the expansion member in its expanded condition as shown in the figure.
Another alternative embodiment of a catheter assembly 100 according to the present invention is shown in
When dilator 110 is fully inserted into the lumen of tubular member 102, as shown in
When assembly 100 is in the closed, or locked, configuration of
In the embodiment shown in
The withdrawn blood passes through the lumen of tubular member 102, and is transported under negative pressure to dialyzer 150 (
As with the previous embodiments, blood may flow between the apparatus 100 and the dialyzer in conventional fashion through any desired arrangement of extension tubes, connectors, luer locks etc. (not shown).
Although the embodiments in the figures show specific arrangements of expansion members on inner and outer catheter tubular members, the invention is not limited to those embodiments shown. Rather, expansion members can be placed on any combination of either, or both, expansion members. For multi-lumen catheters having more than two tubular members, expansion members can likewise be placed on any, or all, of the tubular members. Since the withdrawal of fluid is likely to occur under negative pressure, the formation of fibrin may be more problematic at the withdrawal port, thus perhaps making the withdrawal tube a more likely candidate for inclusion of an expansion member. The infusion of fluid back into the body vessel is likely to occur under positive pressure at the infusion port, so that, all other factors equal, it may not be as important to include an expansion member on the infusion tube as on the withdrawal tube. Nevertheless, in a particular case benefits may be obtained using an expansion member even in a positive pressure situation, particularly in view of the vessel centering function of the expansion member. Therefore, the present invention contemplates use of an expansion member in either a positive or negative pressure situation, or both.
To further enhance fluid flow, one or more apertures or side ports can also be placed on any of the tubular structures that make up the catheter, regardless of whether the particular tubular structure also includes an expansion member.
It should be noted that in each of the figures herein, the expansion member is positioned near the distal end of the tubular member. Although this is the preferred placement of the expansion member, the invention is not so limited. Rather, the expansion members can be placed anywhere along the longitudinal surface of the tubular member, and it is expected that some benefit may be obtained thereby.
If desired, various components of the catheters and assemblies described herein, such as the tubular members and the dilator, can be impregnated or coated with antimicrobial agents to minimize the risk of bacterial colonization of the catheter, and catheter-related bacteremia during use. An example of an antimicrobial combination that has been shown to be an effective antimicrobial composition in percutaneous devices is the combination of antimicrobials minocycline and rifampin. Alternatively, other well-known antimicrobials may be substituted for minocycline and rifampin, which antimicrobials need not necessarily be utilized in combination.
Although the embodiment described hereinabove discusses the extracorporeal treatment of blood, those skilled in the art will appreciate that the catheter will have use in the treatment of other body fluids, such as cerebrospinal fluid.
The use of catheter of the present invention is beneficial to a patient undergoing a procedure that requires extracorporeal treatment of a fluid, because it minimizes the number of times that such a catheter must be replaced. Each time that a catheter is replaced, a new site must be found for the new catheter. Eventually, a patient will run out of acceptable placement sites. Thus, the use of a catheter that centers the catheter in high flow areas of a vessel lessens the possibility of port blockage. In addition, the use of a removable inner tubular member enables the patient to extend use at a particular placement site even though an inner tube may have become blocked, and therefore unusable. As a result of these benefits, there is a lesser likelihood that a patient will use up all of the acceptable sites for insertion of the catheter.
While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form, details, and composition of the various components may be made therein without departing from the spirit and scope of the invention, and any such variations are considered to be within the scope of the invention. Those skilled in the art may recognize or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described specifically herein, which equivalents are intended to be encompassed in the scope of the invention.
The present patent document claims the benefit of the filing date under 35 U.S.C. §119(e) of Provisional U.S. patent application Ser. No. 60/482,149, filed Jun. 24, 2003, which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60482149 | Jun 2003 | US |
