Method and apparatus for the dialysis of blood

Abstract

A catheter includes: a body comprising a body side wall, a proximal end and a distal end; a septum extending from the proximal end to the distal end; a first lumen and a second lumen separated by the septum, each lumen forming a mouth at the distal end; first and second slots formed in a portion of the body side wall at the distal end and in fluid communication with the first and second lumens respectively. The first and second slots extend linearly along a direction parallel to a longitudinal axis of the body. The distal end of the body and the septum terminate in a plane perpendicular to the longitudinal axis. The distal end of the body has a substantially round cross section, while the first and second lumens each have a substantially D-shaped cross-section at the distal end. The two slots each have a width that is between 30% and 60% of a longer dimension of the D-shaped cross-section of a corresponding lumen.

Claims

1. A catheter, comprising: a body comprising a body side wall, a proximal end and a distal end; a septum extending from the proximal end to the distal end, wherein the body and the septum terminating in a substantially flat distal end surface substantially perpendicular to a longitudinal axis of the body wherein; a first lumen and a second lumen separated by the septum, the first lumen forming a first mouth at the distal end, and the second lumen forming a second mouth at the distal end; a first slot formed in a portion of the body side wall at the distal end and in fluid communication with the first lumen; and a second-slot formed in a portion of the body side wall at the distal end and in fluid communication with the second lumen; wherein each of the first and second slots has a substantially constant width that extends linearly along a direction parallel to the longitudinal axis of the body; the first and second slots are centered on a plane substantially perpendicular to the septum, the distal end of the body has a substantially round cross section, and each of the first and second lumens has a substantially D-shaped cross-section at the distal end; and each of the first and second slots has a width that is between 30% and 60% of a longer dimension of the D-shaped cross-section of a corresponding one of the first and second lumen.

2. The catheter recited in claim 1, wherein the first slot comprises a first slot proximal end and a first slot distal end, the first slot distal end extending to the first mouth; and the second slot comprises a second slot proximal end and a second slot distal end, the second slot distal end extending to the second mouth.

3. The catheter recited in claim 2, wherein each of the first slot proximal end and the second slot proximal end is rounded.

4. The catheter recited in claim 1, wherein each of the first and second slots has a length in a direction parallel to the longitudinal axis of the body between 8 mm and 30 mm.

5. The catheter recited in claim 1, wherein dimensions of the first lumen are identical to dimensions of the second lumen.

6. The catheter recited in claim 1, further comprising: a third lumen extending from the proximal end to the distal end, the third lumen forming a third mouth at the distal end; and a third slot formed in a portion of the body at the distal end and in fluid communication with the third lumen; wherein the first, second, and third lumens are separated from each other by the septum.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein:

(2) FIGS. 1 and 2 are schematic views showing one prior art hemodialysis catheter disposed in the body of a patient;

(3) FIG. 3 is a schematic view showing another prior art hemodialysis catheter disposed in the body of a patient;

(4) FIG. 4 is a schematic view showing the prior art hemodialysis catheter of FIG. 3 adhering to vascular tissue;

(5) FIGS. 5 and 6 are schematic views showing a novel hemodialysis catheter formed in accordance with the present invention;

(6) FIGS. 7 and 8 are schematic views (not necessarily to scale) showing the distal end of the novel hemodialysis catheter of FIGS. 5 and 6, with the views of FIGS. 7 and 8 being taken orthogonal to one another, and with FIG. 8 being a cross-sectional view taken along line 8-8 of FIG. 6;

(7) FIG. 9 is a schematic view (not necessarily to scale) showing the mode of operation of the novel hemodialysis catheter of FIGS. 5-8;

(8) FIGS. 10-16 are schematic views showing how blood flow into, and out of, the novel hemodialysis catheter of FIGS. 5 and 6 minimizes recirculation;

(9) FIGS. 17-25 are schematic views showing how an open/close valve may be incorporated into one or both of the blood lines of the novel hemodialysis catheter of FIGS. 5 and 6 in order to facilitate flow control;

(10) FIGS. 26-35 are schematic views showing a novel tunneling tool which may be used in connection with the novel hemodialysis catheter of FIGS. 5 and 6;

(11) FIGS. 35A and 35B are schematic views showing another form of tunneling tool which may be used in connection with the novel hemodialysis catheter of FIGS. 5 and 6;

(12) FIG. 36 is a schematic view showing two single-lumen hemodialysis catheters also formed in accordance with the present invention;

(13) FIGS. 37-39 are schematic views showing a novel apheresis catheter also formed in accordance with the present invention; and

(14) FIG. 40 is a schematic view like that of FIG. 5, except that the two lumen hemodialysis catheter has its connector portion replaced by an implantable port.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(15) The present invention provides a novel method and apparatus for the dialysis of blood. Among other things, the present invention comprises the provision and use of a novel hemodialysis catheter which is configured to minimize the aforementioned undesirable recirculation of dialyzed blood, yet which allows its lumens to be interchangeably used for suction or return functions. The novel hemodialysis catheter of the present invention is also designed to minimize the possibility of the catheter inadvertently adhering to vascular walls, and to simplify removal of any clots which might form adjacent to the distal end of the catheter. And the novel hemodialysis catheter of the present invention is easy to manufacture and inexpensive to produce.

(16) More particularly, and looking now at FIGS. 5-8, there is shown a novel hemodialysis catheter 105 which is intended for use in the dialysis of blood. Hemodialysis catheter 105 generally comprises a catheter portion 110 comprising a dual-lumen catheter element 115, and a connector portion 120 comprising an extracorporeal connector element 125. The catheter's extracorporeal connector element 125 is disposed against the chest 130 of the patient, with the distal end 135 of catheter element 115 extending down the patient's internal jugular vein 140 and into the patient's superior vena cava 145. More particularly, the distal end 135 of dual-lumen catheter element 115 is positioned within the patient's superior vena cava 145 such that the mouth 150 of a first lumen 155, and the mouth 160 of a second lumen 165, are both located between the patient's right atrium and the patient's left subclavia vein and right subclavia vein. Alternatively, the distal end 135 of dual-lumen catheter element 115 may be positioned so that mouth 150 of first lumen 155, and mouth 160 of second lumen 165, are located within the patient's right atrium. The hemodialysis catheter 105 is then left in this position relative to the body, waiting to be used during an active dialysis session.

(17) Significantly, mouth 150 of first lumen 155 and mouth 160 of second lumen 165 are disposed in a side-by-side configuration, with the dual-lumen catheter element 115 terminating in a substantially flat distal end surface 175. Flat distal end surface 175 of dual-lumen catheter element 115 preferably extends substantially perpendicular to the longitudinal axes of first lumen 155 and second lumen 165. By disposing mouths 150 and 160 in the aforementioned side-by-side configuration, lumens 155 and 165 may be interchangeably used for suction or return applications, as will hereinafter be discussed.

(18) Also significantly, a pair of longitudinal slots 180, 185 are formed in the side walls of distal end 135 of dual-lumen catheter element 115, with longitudinal slot 180 extending along and communicating with the interior of first lumen 155, and with longitudinal slot 185 extending along and communicating with the interior of second lumen 165. Preferably longitudinal slots 180, 185 extend at a right angle to the plane of the septum 190 which separates first lumen 155 from second lumen 165. By providing first lumen 155 and second lumen 165 with the aforementioned longitudinal slots 180, 185, respectively, the aforementioned undesirable recirculation of dialyzed blood is minimized, even though the mouths 150, 160 of the lumens 155, 165, respectively, are disposed in a side-by side configuration, as will hereinafter be discussed.

(19) In one preferred form of the present invention, the distal end 135 of catheter element 115 has a substantially round outer surface (i.e., the distal end 135 of catheter element 115 has a substantially round cross-section), and first lumen 155 and second lumen 165 are each formed with a substantially D-shaped cross-section (FIG. 6), characterized by a longer dimension 195 and a shorter dimension 200.

(20) When hemodialysis is to be performed on a patient, extracorporeal connector element 125 of hemodialysis catheter 105 is appropriately connected to a dialysis machine (not shown), e.g., first line 155 is connected to the suction port of the dialysis machine, and second line 165 is connected to the return port of the dialysis machine. In this case, first line 155 serves as the suction line and second line 165 serves as the return line. Alternatively, first line 155 is connected to the return port of the dialysis machine, and second line 165 is connected to the suction port of the dialysis machine. In this case, first line 155 serves as the return line and second line 165 serves as the suction line. It is a significant aspect of the present invention that the lumens of the hemodialysis catheter 105 are not dedicated to a particular function, i.e., either lumen may be used for suction function and either lumen may be used for return function.

(21) For the purposes of the description which hereinafter follows, it will be assumed that first line 155 is connected to the suction port of the dialysis machine, and second line 165 is connected to the return port of the dialysis machine. In this case, first line 155 serves as the suction line to withdraw undialyzed blood from the patient and second line 165 serves as the return line to return dialyzed blood to the patient.

(22) The dialysis machine is then activated (i.e., the dialysis machine's blood pump is turned on and the flow rate set), whereupon the dialysis machine will withdraw relatively “dirty” blood from the patient through suction line 155 and return relatively “clean” blood to the patient through return line 165.

(23) Significantly, with the novel hemodialysis catheter of the present invention, there is minimal undesirable recirculation of the undialyzed blood, even though mouth 150 of first lumen 155 (i.e., the mouth of the suction line) is disposed immediately adjacent to mouth 160 of second lumen 165 (i.e., the mouth of the return line) in a side-by-side relation. This is due to the novel provision of the aforementioned longitudinal slots 180, 185. More particularly, and looking now at FIGS. 9 and 10, longitudinal slots 180, 185 are configured such that the majority of the blood taken in by suction line 155 is admitted at the proximal end of longitudinal slot 180, where the level of suction is the greatest; and the majority of the blood discharged by return line 165 is ejected at the distal end of lumen 165, i.e., out mouth 160, since this is in direct line with the longitudinal axis of return line 165. As a result, there is minimal undesirable recirculation of the dialyzed blood, even though the mouths 150, 160 of lumens 155, 165, respectively, are disposed in side-by-side configuration. This result is ensured by forming longitudinal slots 180, 185 with the proper configuration (i.e., the proper length and width) relative to the dimensions of the hemodialysis catheter and the blood flow rates through the catheter.

(24) More particularly, it has been discovered that, by controlling certain parameters of the hemodialysis system, the recirculation rate of the dual-lumen, flat-end hemodialysis catheter 105 can be minimized. These parameters include, but are not limited to, (i) the size of lumens 155, 165; (ii) the length and width of longitudinal slots 180, 185; (iii) the thickness of the side wall of hemodialysis catheter 105 at longitudinal slots 180, 185; and (iv) the rate of flow through hemodialysis catheter 105. Another factor affecting the rate of recirculation of hemodialysis catheter 105 is the rate of flow of the ambient blood surrounding hemodialysis catheter 105.

(25) In general, it is preferred that longitudinal slots 180, 185 be sized so that greater than 85% of the flow out of the return line exits the distal mouth of that line, and so that greater than 85% of the flow into the suction line enters the proximal ⅓.sup.rd of its associated longitudinal slot, and so that the hemodialysis catheter has a recirculation rate of less than 1%.

(26) In general, it is also preferred that longitudinal slots 180, 185 have a length of between approximately 8 mm and 30 mm, since this length is long enough to adequately separate the inflow and outflow streams and thereby minimize recirculation, but short enough that the entire length of the longitudinal slots 180, 185 can fit within the right atrium of the heart. In addition, it has been found that by providing longitudinal slots 180, 185 with a length of between approximately 8 mm and 30 mm, the hemodialysis catheter will function with the desired minimal recirculation rate while minimizing loss of the catheter lock solution through longitudinal slots 180, 185.

(27) In general, it is preferred that the lumens 155, 165 have a D-shaped configuration, and that the width of the longitudinal slots 180, 185 be between approximately 30% and 60% of the longer dimension 195 of the D-shaped lumen.

(28) By way of example but not limitation, where the hemodialysis catheter 105 has a diameter of 15.5 French (i.e., 0.202 inch), where its lumens 155, 165 have a substantially D-shaped cross-section characterized by a longer dimension 195 of 3.5 mm (i.e., 0.14 inch) and a shorter dimension 200 of 1.5 mm (i.e., 0.060 inch), and where the flow rate of each lumen is to be set at 350-450 mL per minute, it is desirable that longitudinal slots 180, 185 have a length of 10 mm (i.e., 0.394 inch) and a width of 1.5 mm (i.e., 0.059 inch), whereby to produce a recirculation rate of less than 1%.

(29) Among other things, it should be appreciated that an appropriate slot width is important to allow sufficient flow rates at acceptable pressure gradients, and an appropriate slot length is important to minimize recirculation. In this respect it will be appreciated that a wider slot and lower pressure gradients help minimize hemolysis.

(30) FIGS. 11-16 illustrate experimental results confirming that, by providing lumens 155, 165 with appropriately-sized longitudinal slots 180, 185, recirculation can be effectively eliminated even where mouths 150, 160 of lumens 155, 165 are arranged in a side-by-side configuration.

(31) In addition to the foregoing, it should also be appreciated that, even though the distal end of novel hemodialysis catheter 105 terminates in a flat distal end surface 175, with mouths 150 and 160 arranged in a side-by-side configuration, the construction of hemodialysis catheter 105 minimizes the possibility of the catheter inadvertently adhering to vascular walls. This is also due to the provision of the aforementioned longitudinal slots 180, 185. More particularly, with the hemodialysis catheter of the present invention, if the flat distal end surface 175 of the dialysis catheter should encounter a vascular wall, the longitudinal slot associated with the suction line will admit blood into the suction lumen, thereby keeping the distal end of the hemodialysis catheter from significantly adhering to the vascular wall. This happens because “suction forces” to adhere the catheter to the vascular wall cannot be maintained, since there are two openings (i.e., the slot opening and the distal end opening) and these two openings are spaced from one another and located 90° apart.

(32) Also, if a blood clot should form at the distal end of hemodialysis catheter 105, e.g., during periods between dialysis sessions, the construction of the hemodialysis catheter makes it a simple matter to clear the blood clot from the distal end of the catheter. More particularly, inasmuch as the longitudinal slots 180, 185 extend all the way to the distal end of the hemodialysis catheter, any blood clots forming on the distal end of the hemodialysis catheter can be easily removed from the hemodialysis catheter by simply “blowing” the blood clots out the distal end of the hemodialysis catheter—there is no mechanical adhesion of the blood clot to the hemodialysis catheter, as there might be, for example, if the longitudinal slots 180, 185 were replaced by windows, in which case a portion of the blood clot might protrude through the window and mechanically “lock” the blood clot to the hemodialysis catheter.

(33) And the hemodialysis catheter is exceedingly simple in design, making it easy to manufacture and inexpensive to produce.

(34) Thus it will be seen that the present invention provides a novel hemodialysis catheter which is configured to minimize undesirable recirculation of dialyzed blood, yet which allows its lumens to be interchangeably used for suction or return functions. And the present invention provides a novel hemodialysis catheter that minimizes the possibility of the catheter inadvertently adhering to vascular walls, and which simplifies the removal of any clots which might form on the distal end of the catheter. And the present invention provides a novel hemodialysis catheter which is easy to manufacture and inexpensive to produce.

Blood Lines With Open/Close Valves

(35) If desired, a novel open/close valve may be incorporated into each of the blood lines of novel hemodialysis catheter 105 in order to facilitate flow control through the blood line.

(36) More particularly, in prior art hemodialysis catheters, clamps are applied to the suction and return lines at the proximal end of the hemodialysis catheter in order to close off flow when desired, e.g., when the hemodialysis catheter is not connected to a dialysis machine, etc. However, these clamps are essentially hose clamps which compress the suction and return lines of the hemodialysis catheter. This can cause damage to the suction and return lines, particularly over time. Furthermore, these clamps are bulky and present edges, which makes them uncomfortable for the patient. To this end, the present invention provides a novel open/closed valve which may be incorporated into each of the blood lines of the novel hemodialysis catheter in order to facilitate flow control through the blood line.

(37) In one preferred form of the invention, and looking now at FIGS. 17-25, a valve 205 may be provided for each blood line 155, 165, where valve 205 comprises a cylinder 210 which extends across the lumen of the blood line. Cylinder 210 comprises a diametrically-extending through-hole 215 which may be aligned with, or set transverse to, the longitudinal axis of the flow path, so as to open up flow, or close off flow, respectively, through the flow path of the blood line. A handle 220 is attached to cylinder 210 so as to permit the user to adjust the rotational position of cylinder 210, and hence control flow through the blood line (preferably in either the “on” or “off” position).

Tunneling Tool

(38) In practice, it is generally desirable to deploy a hemodialysis catheter so that the hemodialysis catheter enters a jugular vein of the patient and, furthermore, so that the hemodialysis catheter extends a distance under the skin before entering the jugular vein of the patient. This approach allows the access end of the hemodialysis catheter to exit the skin of the patient at the chest of the patient even as the working end of the hemodialysis catheter enters a jugular vein for direct passage down to the superior vena cava or the right atrium of the heart.

(39) The procedure for deploying a hemodialysis catheter in this manner will now be described, with reference being made to FIG. 26 of the figures:

(40) 1. locate the jugular vein 40 which is to be accessed;

(41) 2. make a first incision 225 into the skin near the jugular vein;

(42) 3. use the Seldinger technique to access the jugular vein, i.e., place a guidewire (not shown) into the jugular vein, and then place an introducer sheath (not shown) over the guidewire and into the jugular vein;

(43) 4. make a second incision 230 into the skin on the chest;

(44) 5. advance the hemodialysis catheter, distal end first, through the second incision 230 on the chest, pass the hemodialysis catheter under the skin and then out first incision 225 below the clavicle; and

(45) 6. insert the distal end of the hemodialysis catheter into the jugular vein by means of the guidewire and the introducer sheath.

(46) As noted above, in the foregoing Step 5, when the hemodialysis catheter is advanced from the second incision 230 on the chest up to the first incision 225, the hemodialysis catheter is passed distal end first, so that the distal end of the hemodialysis catheter is ready to be passed into the jugular vein of the patient.

(47) In accordance with the present invention, and looking now at FIGS. 27-35, a novel tunneling tool 240 is provided to facilitate advancement of the novel hemodialysis catheter 105, distal end first, under the skin of the patient.

(48) More particularly, tunneling tool 240 generally comprises a shaft 245 terminating at its distal end in a blunt end 250 and terminating at its proximal end in a frustoconical section 255. Frustoconical section 235 supports a pair of substantially parallel fingers 260. Fingers 260 are relatively stiff, but are capable of flexing toward and away from one another. Fingers 260 preferably each include a plurality of projections 265, with the projections 265 of one finger 260 extending toward the opposing finger 260. Fingers 260 have a length and a width such that they can be received in the aforementioned longitudinal slots 180, 185 formed in the distal end of the hemodialysis catheter 105, when the flat distal end surface 175 of the hemodialysis catheter 105 abuts frustoconical section 255. A tapered sleeve 270 is slidably mounted on shaft 230. Sleeve 270 may be slid proximally along shaft 245 and over fingers 260 so as to bend fingers 260 inwardly, in a camming action, whereby to cause the fingers 260 to grip septum 190 of hemodialysis catheter 105, and hence grip the distal end of the hemodialysis catheter, e.g., in the manner of a collet. When the hemodialysis catheter 105 is to be released from tunneling tool 240, tapered sleeve 270 is slid distally, away from the hemodialysis catheter, whereby to allow fingers 260 to relax and thereby release the distal end of the hemodialysis catheter.

(49) FIGS. 35A and 35B show another form of tunneling tool 240 formed in accordance with the present invention. The construction of tunneling tool 240 shown in FIGS. 35A and 35B is generally similar to the construction of the tunneling tool 240 shown in FIGS. 27-35, except that in FIGS. 35A and 35B, each of the fingers 260 is provided with a single projection 265.

Single Lumen Construction

(50) If desired, and looking now at FIG. 36, two separate single-lumen hemodialysis catheters 275 can be provided in place of hemodialysis catheter 105, where each single-lumen hemodialysis catheter 275 comprises a central lumen 280 terminating in a mouth 285, and has a longitudinal slot 290 extending proximally from mouth 285 and communicating with lumen 280. In this case, single-lumen hemodialysis catheter 275 functions as one half of the complete hemodialysis catheter 105. Again, longitudinal slot 290 is formed with a size (i.e., length and width) adequate to substantially eliminate recirculation even when the mouths 285 of the two single-lumen hemodialysis catheters are disposed substantially adjacent to one another (e.g., within approximately 10 mm of one another).

Apheresis Catheter

(51) In still another form of the invention, and looking now at FIGS. 37-39, there is provided an apheresis catheter 300 formed in accordance with the present invention. Apheresis catheter 300 is characterized by three or more lumens 305, each terminating in a mouth 310, with septums 315 separating the lumens from one another. Mouths 310 are arranged in a side-by-side configuration. Each of the lumens 305 has a longitudinal slot 320 associated therewith, where each longitudinal slot has a size (i.e., length and width) such that recirculation is substantially eliminated even when one of the lumens is used as a suction line and one of the lumens is used as a return line.

Use of the Novel Catheter with an Implantable Port and/or with Other Systems that Exchange Bodily Fluids

(52) It should be appreciated that the aforementioned two lumen hemodialysis catheter 105, and/or the aforementioned several single-lumen hemodialysis catheters 275, and/or the aforementioned three or more lumen apheresis catheter 300 may be used in conjunction with an implantable port and/or other systems that exchange (remove and instill) bodily fluids. By way of example but not limitation, FIG. 40 shows one such configuration wherein the two lumen hemodialysis catheter 105 has its connector portion 120 replaced by an implantable port 400.

Modifications Of The Preferred Embodiments

(53) It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.