High flow rate dialysis catheters and related methods

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

(Cross-reference of related applications) The present invention is incorporated with reference to US Provisional Patent Application No. 60 / 075,724 filed on February 24, 1998, to which priority and this benefit are claimed. [0002]

(Technical field) The present invention relates to catheter design and methods of arranging and making catheter designs. More specifically, the present invention relates to catheter designs that increase flow through catheters, methods for arranging catheters of these designs, and methods of making catheters of these designs. [0003]

(Background of invention) The dialysis procedure often uses a double luminal catheter, for example, to transport blood from the patient to the dialyzer and then to return the processed blood to the patient. See, for example, McIntosh et al., JAMA169 (8): 137-38 (1959). Functionality, comfort, ease of manufacture, and ease of use are all important considerations for catheter design. Specifically, a high flow rate through the catheter is needed to maximize the efficiency of the dialysis procedure. Both blood physiology and conventional catheter design limit flow rates. Blood cells do not survive high pressure differences or excessive mechanical shear. [0004]

Conventional catheters are useful, but have a design that does not maximize flow velocity within the constraints of these physiological constraints. In addition, conventional catheter designs have some other disadvantages. First, the uptake lumen located in the vessel reduces the flow through the catheter, which is often aspirated against the vessel wall. Second, conventional catheter shafts tend to twist, again reducing flow. Third, the internal septum that divides into multiple lumens within the catheter tends to warp due to pump pressure. [0005]

(Gist of the invention) It is known that the flow rate through the catheter can be maximized despite the design constraints of the maximum catheter outer diameter (french size) and the limited permissible pressure drop. In the catheter design of the present invention, the internal structure of the catheter, the thickness of the catheter wall, when exposed to a pressure gradient to reduce resistance to flow, to reduce the tendency of the catheter to twist, and to maximize flow velocity. The ability of the internal divider and / or catheter to resist curvature can be adjusted. These design concepts can be applied equally to single luminal catheters, double luminal catheters, or multiple luminal catheters. Also, the presence of a particular tip structure at the entrance to at least one lumen minimizes the tendency of the catheter to be aspirated against the vessel wall and ensures high flow rates. [0006]

In one aspect, the invention relates to a catheter comprising a hub and a substantially elongated duct with a substantially continuous and smooth wall. This duct defines at least one duct and has a length that extends from the proximal end to the distal end of the duct. The proximal end is attached to the hub and the distal end has an opening that communicates with the lumen. The conduit is conical and tapers along the length from the hub to the opening. A substantially continuous and smooth conduit has no opening, aperture, hole, roughness, or depression over virtually all of its length. [0007]

Embodiments of this aspect of the invention may include the following features: For example, the wall can have a notch distal to the distal end, and this notch can communicate with at least one lumen. This notch may have a longitudinal notch in the conduit. This notch may include a distal appendage. This notch may comprise an opening having an area larger than the cross-sectional area of the conduit immediately proximal to the opening. In an embodiment of a double lumen, the first lumen can extend from the proximal end to the distal end opening, and the second lumen can have a proximal end to the second opening. It can extend beyond the opening distally. Also, the conduit can be conical and can taper from the proximal end to a point distally beyond the opening. [0008]

The duct can have a greater thickness at the proximal end compared to the distal end, and the wall thickness can vary between the proximal and distal ends. At least one lumen can increase the cross-sectional area from the distal end to the proximal end or its proximal portion. The surface of the conduit can be treated with, for example, heparin, to prevent the association of the material containing the biological material with the conduit (eg, to prevent the deposition of material on the surface, and / or to remove the material from around the conduit. Deter). This conduit can be substantially conical and can be in the shape of a truncated cone. [0009]

The cross section of the conduit can be, for example, circular or oval. The cross section of at least one lumen can be, for example, circular or partially circular. At least part of the conduit can be curved. At least a portion of the conduit can be reinforced, for example, with fibers, wires, a material that is harder than the conduit, and / or a material that can be softer than the conduit. The conduit further comprises at least one cuff. The conduit also further comprises at least one internal divider that defines at least two lumens. [0010]

The catheter further comprises at least one connecting tube connected to the hub. At least one connecting tube may communicate with at least one lumen. At least one connecting tube can be curved and oriented parallel to the distal portion of the conduit, or can be straight and oriented approximately 180 ° from the distal portion of the conduit, or these two positions. Can be oriented somewhere in between. One or more connecting tubes may be selectively removable (eg, so that they can be replaced in case of damage). [0011]

At least one internal divider can have a large thickness at the proximal end compared to the distal end, and this thickness can vary between the proximal and distal ends. At least part of one internal divider can be reinforced with a harder material than the conduit. One or more internal dividers may be connected to the wall of the conduit distal to the notch. [0012]

In another aspect, the catheter according to the invention comprises a hub, as well as a flexible, substantially elongated duct having an outer wall and defining at least one lumen. The conduit comprises a proximal portion (connected to a hub) that extends from the proximal end to the first point. The proximal portion has a first cross-sectional area along its length. The central part extends from the first point to the second point. The first cross-sectional area at the first point is larger than the second cross-sectional area at the second point. The distal part extends from the second point to the distal end. The distal portion has a second cross-sectional area along its length. Wall thickness increases distally to proximally over at least part of the conduit. At least one lumen has a cross-sectional area that increases distally to proximally over at least part of the conduit. In some embodiments, the wall thickness increases from a second point to a first point, and the cross-sectional area of at least one lumen increases from a second point to a first point. [0013]

In certain embodiments, the surface of the conduit can be treated with, for example, heparin, to prevent association of the conduit with a material containing biological material (eg, to prevent the deposition of material on the surface, and / or the conduit. Deter material from around). This conduit may further comprise at least one cuff. The conduit may also further comprise at least one internal divider that defines at least two lumens. At least one internal divider can have a large thickness at the proximal end compared to the distal end, and this thickness can vary between the proximal and distal ends. The first lumen can extend from the proximal end to the opening at the distal end, and the second lumen can extend distally from the proximal end to the opening that may have a second opening. Can extend to. At least a portion of the conduit can be reinforced, for example, with fibers, wires, a material that is harder than the conduit, and / or a material that is softer than the conduit. The catheter may further comprise at least one connecting tube connected to the hub. At least one connecting tube can be communicated with at least one lumen. [0014]

According to the present invention, a method of positioning or arranging the catheter, and a method of producing the catheter by extrusion are described, which constitutes an aspect of the present invention. One method involves placing a catheter of the type described above by inserting the catheter into a blood vessel with a breach and then positioning the catheter within the blood vessel. Another method involves making a desired shape, such as a cone, by extruding a catheter of the type described above. [0015]

The above and other aspects, features, and advantages of the present invention will become apparent from the following description and claims. [0016]

(Details) In drawings, the same reference numerals generally refer to the same parts throughout different drawings. Also, the drawings are not necessarily on scale and focus on exemplifying the principles of the invention. [0017]

I. Introduction The present invention relates to catheters designed for high flow rates and methods for arranging and manufacturing such catheters. The present invention minimizes the pressure drop over the length of the catheter and minimizes the shear applied to blood cells moving through it. Therefore, the flow velocity through the catheter is maximized. The designs and methods of the present invention apply equally to embodiments of single, double, and multiple cavities. Moreover, the designs and methods of the present invention apply equally to all situations (or any other similar measurement) where the flow velocity needs to be increased and / or maximized through the conduit. [0018]

In addition, during use, the entrance to the suction lumen of a conventional catheter can be aspirated against the vessel wall, reducing the amount and flow of blood that can enter the catheter. The present invention provides a design for advanced structures that minimizes the occurrence of this problem. [0019]

Moreover, if any part of the conventional catheter is twisted, the effective cross-sectional area of at least one lumen is reduced, and a decrease in flow velocity through the catheter occurs. Twisting usually occurs within the tunneled section of a conventional catheter that follows a curved path between the venous cut and the percutaneous exit site of the catheter. Twisting of conventional catheters is a problem. Because many of these catheters maximize luminal size (eg, suitable) while maintaining the French size of the catheter being accepted (eg, so that the catheter can be comfortably placed in the patient). This is to minimize the wall thickness (to obtain the flow velocity). The present invention provides designs for the internal structure of the catheter and the wall thickness of the catheter to achieve high flow rates without compromising effective clinical French size and to reduce the tendency of the catheter to twist. .. [0020]

Also, in conventional catheters, if the septum or divider (separating the lumen) is very flexible, the flow velocity is reduced. This partition is a flow pressure formed by a relatively high positive pressure in the release (venous) leg / lumen and a relatively low negative pressure formed in the uptake (arterial) leg / lumen. Warps at the proximal part of the catheter. This warp limits the flow. Maximize the cross-sectional area of the lumen (ie, maximize the cross-sectional area of the lumen) by both minimizing the warpage and minimizing the thickness of the bulkhead while maintaining the accepted French size. The need to constrain the thickness of the bulkhead in the current design. The present invention provides optimization of the thickness of the internal divider to minimize septal flexibility under pressure differences without compromising the cross-sectional area of the lumen within effective clinical French size constraints. .. [0021] [0021]

Therefore, the present invention provides a novel catheter design that maximizes the flow velocity through the catheter according to the following three principles. (1) Maximize the ratio of internal volume to surface area of the catheter, (2) Minimize the potential for suction lumen inlet so that it is aspirated against the vessel wall, (3) Wire reinforcement Minimize potential for torsion of catheter shaft without addition. [0022]

(II. Cavity cross-sectional area) Ohm's law shows the relationship between flow velocity (Q), pressure drop (ΔP), and resistance (R) in the catheter as follows: Q = ΔP / R or ΔP = Q × R One option for increasing the flow velocity is to increase the pump pressure in combination with an existing catheter (ie, increase ΔP). This option is not feasible. Because the increased pressure destroys blood cells. Physiological restrictions on blood cells to resist changes in pressure constrain ΔP across devices. Therefore, in order to increase Q, R must be decreased. [0023]

Increasing luminal size is one way to reduce R and is generally considered. Catheter currently in use increases the size of the lumen, but this increase is only within the accepted French size constraints. The present invention simply travels across large lumens and further reduces resistance to flow throughout the catheter. Friction is the cause of R. The two main causes of friction are the viscosity of the blood (ie, the friction that occurs when cells and molecules move in relation to each other), and the friction that is applied to the bloodstream by the walls of the catheter that define the lumen. Although varying the blood viscosity is generally not an option, the catheters of the present invention are designed so that the frictional effect on the blood flow of the catheter wall is minimized or at least reduced compared to known designs. Will be done. [0024]

In a two-dimensional flow model, friction, or R, decreases as the ratio of the lumen cross-sectional area to the perimeter increases. The circular structure allows for maximum ratios because the circular lumen has a higher flow velocity than a semi-circular or non-circular lumen of the same area. In a three-dimensional model, friction, or R, decreases as the ratio of luminal volume to luminal surface area increases. In the case of any given ΔP, maximizing this ratio of the present invention minimizes R and maximizes Q. [0025]

With reference to FIG. 11, the graph shows Q as a function of ΔP for two existing dialysis catheters (Medcomp's "Hemocath" and Quinton's "Perm Cath". The slope of this curve indicates the R of the individual device. (The gentler the slope, the smaller the resistance). These catheters have substantially the same luminal cross-sectional area. Both are silicone catheters. The main difference between the two is Perm Cath 2 It has one circular lumen, and Hemocath has one crescent-shaped intake lumen and one circular lumen. The area of the Hemocath intake lumen is 35% of the area of the Perm Cath. Large. The cross-sectional area and volume of the lumen in these two catheter shafts are equal. The cross-sectional area of the lumen is constant along the length of both catheters. Therefore, Perm Cath is compared to Hemocath. Large luminal volume relative to luminal surface area. Resistance to flow R is about 20% smaller for Perm Cath, as indicated by the slope of the curve. These data maximize the ratio of luminal volume to surface area. Illustrate the advantages of flow velocity. [0026]

Embodiments of the catheter of the present invention have a lumen that increases in cross-sectional area along the length of the catheter conduit and through the hub and inflatable tube assembly. Therefore, an embodiment of the catheter of the present invention maximizes the ratio of luminal volume to luminal surface area. As a result, R decreases and the flow velocity Q increases. In addition, increasing cross-sectional area maximizes the ratio of luminal volume to luminal surface area, whether the cavities are circular, semi-circular, or non-circular. [0027]

In one embodiment of the invention, the substantially conical catheter conduit 100 is tapered along the overall length from the proximal end 11 to the distal end 15 (FIG. 1A). In an alternative embodiment, the catheter conduit 102 is not a simple columnar, but instead consists of a pedestal-conical central portion 20, which is the proximal end. A relatively large diameter columnar proximal portion 22 with 21 connects proximally at the first point 26, and a relatively small diameter columnar distal portion 24 with a distal end 25 second Connects distally at point 28 (Fig. 2A). In both of these embodiments, the cross-sectional area of cavities 500, 502 obtained along line 1-1'or 2-2'is line 1''-1''' or 2''-2''. It is larger than the cross-sectional areas of the cavities 500 and 502 obtained along'(Fig. 1B, 1C and Fig. 2B, 2C, respectively). Of course, catheter conduits with arbitrary cross-sectional lumens that increase or maximize the ratio of lumen volume to lumen surface area are useful catheter designs of the present invention. [0028]

With reference to FIG. 3A, in another embodiment, the conduit 104 is substantially conical and substantially tapered. The conduit 104 is substantially smooth and continuous over its substantially overall length and has no holes, openings, apertures, roughness, or depressions. The total length of the conduit 104 is 28 cm. The proximal end 31 connects to the hub 900, and the distal end 35 is immediately proximal to the notch 200. The conduit 104 has an outer diameter of 16F at the proximal end 31 and a width of 13F at the distal end 35. The conduit 104 has a constant taper along the length from the proximal end 31 to the distal end 35. The conduit 104 extends beyond the distal end 35 to the notch 200, the distal appendage 202, and then the physical end 37 of the conduit. In an alternative embodiment, the constant taper can extend distally beyond the distal end, eg, to the physical end of the conduit. [0029]

FIG. 4A shows a stylized side view of an embodiment of the conduit 104, excluding a portion of the conduit 104 distal to the distal end 35. The cross-sectional area of the proximal end 31 obtained along line 4-4'has a larger outer diameter than the cross-sectional area of the distal end 35 obtained along line 4''-4''' (Fig. 4C). Has a French size of (Fig. 4B). In addition, the wall 400 at the proximal end 31 is thicker than the wall 402 at the distal end 35. This embodiment is shown with internal dividers 300, 302 that divide the interior space of the conduit 104 into two cavities 504, 506. Each of these two cavities 504, 506 passes through the hub 900 and connects to the corresponding connecting tubes 600, 602. Typically, the hub comprises a gap connecting the cavities 504, 506 with one of the connecting tubes 600, 602, respectively. [0030]

Of course, the catheter ducts of the present invention need not have these accurate measurements. One of ordinary skill in the art can make a catheter designed according to the present invention in any form suitable for a particular use. One of ordinary skill in the art will only need to apply the general principles of the invention to a particular situation. [0031]

In some other embodiments of the catheter design of the present invention, the actual luminal structure for achieving high velocity dialysis is calculated using it based on the magnitude of the numbers provided in Table 1 below. Can be done. In Table 1, "outer diameter" represents the diameter of the conduit as measured from the outermost point of the outer wall to the outermost point of the outer wall; "width" is from the innermost point of the outer wall to the innermost point of the outer wall. Represents the diameter of the conduit as measured; "height" represents the radius of the conduit as measured perpendicular to the internal divider from the internal divider to the innermost point of the outer wall; "internal divider" Represents the thickness of the internal divider; "outer wall" represents the thickness of the outer wall; the distal part represents the part of the conduit that is approximately towards the tip of the conduit; and the proximal part is approximately the hub. Represents the part of the conduit on the side. For example, Table 1 is useful for calculating luminal volume, luminal surface area, and other physical properties of the drawn conical conduit design. [0032]

[table 1]

<img file="JP2002503528A_D0001.tif" /> 【0033】

In another embodiment, with reference to FIGS. 5A and 6, the conduit 106 extends from a first point 36 to a proximal end 41 connected to a hub 904, a columnar proximal portion 32, a truncated cone central portion 30, It has a columnar distal portion 34 extending from a second point 38 to the distal end 45, a notch 210, a distal appendage 212, and finally a physical end 47 of the conduit. The total length of the conduit 106 is 28 cm, with an outer diameter width of 15F at the proximal end 41 and a width of 13F outer diameter at the distal end 45. The portion of the conduit 106 obtained along lines 5-5'and 5''-5'''is more proximally located (5-5', Figure 5B) than having a wall 412 and an internal divider 312. It is shown to have a thicker wall 410 and a thicker internal divider 310 compared to the distal position (5''-5''', Figure 5C). The internal dividers 310 and 312 divide the interior space of the conduit 106 into two cavities 508 and 510. Each of these two cavities 508, 510 connects to the corresponding connecting tubes 610, 612 through the hub 904. Typically, the hub contains a hole that connects the cavities 508, 510 to one of the connecting tubes 600, 602, respectively. [0034]

Not surprisingly, the catheter ducts of the present invention do not require these accurate measurements. One of ordinary skill in the art can make a catheter design according to the present invention in any form suitable for a particular use. One of ordinary skill in the art will only need to apply the general principles of the invention to a particular situation. [0035]

In some other embodiments of the catheter design of the present invention, the actual luminal structure for achieving high velocity dialysis is based on the numerical magnitudes provided in Tables 2 and 3 below. Can be calculated. In Table 2, "outer diameter" represents the diameter of the conduit as measured from the outermost point of the outer wall to the outermost point of the outer wall; "width" is from the innermost point of the outer wall to the innermost point of the outer wall. Represents the diameter of the conduit as measured; "height" represents the radius of the conduit as measured perpendicular to the internal divider from the internal divider to the innermost point of the outer wall; "internal divider" Represents the thickness of the internal divider; "outer wall" represents the thickness of the outer wall; in Table 3, "proximal length" is the proximal portion measured from the proximal end to the first point. The "central part length" represents the length of the central part when measured from the first point to the second point; and the "distal part length" represents the length from the second point. Represents the length of the distal part when measured to the distal end. For example, Tables 2 and 3 are useful for calculating luminal volume, luminal surface area, and other physical properties of the drawn columnar / truncated cone-conical / columnar conduit design. [0036]

[Table 2]

<img file="JP2002503528A_D0002.tif" /> 【0037】

[Table 3]

<img file="JP2002503528A_D0003.tif" /> 【0038】

(III. Advanced design) The catheter design of the present invention provides a catheter tip design that minimizes the possibility of restricted flow into the catheter due to contact between the catheter and the blood vessel. References to FIGS. 3A and 3B show embodiments of the invention for advanced structures. This structure includes a "fin-shaped" distal appendage 202 between the notch 200 and the physical end 37 of the conduit. Referring to FIGS. 5A and 5D, another embodiment of the invention for another tip structure is shown. This embodiment also includes a "trapezoidal" distal appendage 212 between the notch 210 and the physical end 47 of the conduit. [0039]

FIG. 9 shows another embodiment of the invention of a tip structure comprising a distal appendage 222 between the notch 220 and the physical end 57 of the conduit placed relative to the vessel wall. Note that the distal appendage 222 of the present invention prevents the catheter inlet from making direct contact with the blood vessel, reducing the possibility of the blood vessel obstructing flow into the catheter. [0040]

In embodiments of the present invention, the tip structure comprises an internal divider that is attached to the inner surface of the lumen wall (eg, the intake lumen) distal to the notch. This arrangement achieves two points: (1) This arrangement closes the empty (dead) lumen space distal to the notch, and (2) This arrangement is the first distal to the notch. Extend the cross-sectional area of the two lumens (eg, the release lumen). [0041]

With reference to FIGS. 14A and 14B, another embodiment of the tip structure has no notch or distal appendage. The tip is defined by an internal divider 322 and surrounds an opening at the distal end 65 and two cavities 522, 524 that terminate at the physical end 67 of the conduit, respectively. Holes 69, 69'in the conduit wall immediately proximal to the distal end 65 communicate with lumen 522. Holes 69, 69'are useful, for example, as an alternative fluid uptake position when the distal end 65 is aspirated against the vessel wall. An alternative embodiment may have multiple holes located just proximal to the distal end of the conduit. [0042]

(IV. Resistance to twist) The present invention provides catheter designs that reduce the potential for conduit twisting and thus reduce the potential for reduced flow velocity through the catheter. Figures 5B and 5C show the conduit 106 at points 5-5'(towards the proximal end 41 of the conduit 106) and 5''-5''' (towards the distal end 45 of the conduit 106), respectively. The cross-sectional area of one embodiment is shown. Vessel 106 wall 410 (Fig. 5B) at point 5-5'is thicker than wall 412 (Fig. 5C) located more distally to Vessel 106 at point 5''-5'''. Therefore, the wall of the conduit 106 becomes thinner distally along its length. This change in wall thickness has two advantages. First, a significant increase in wall thickness in the proximal region reduces the tendency of the duct to twist when it is curved. Second, a decrease in the thickness of the distal portion can increase the cross-sectional area of the lumen. Not surprisingly, other embodiments of the invention (eg, catheters with a conical conduit along the length from the hub to the opening or to the end of the conduit) are also proximal to distal. Can have this variation in wall thickness up to. [0043]

With reference to FIG. 9 again, in this embodiment of the invention, a portion of the conduit 112 distal to the vein 150 is suspended inside the vessel in a relatively linear fashion with respect to the vein 150 (in the tunnel). Note that the proximal conduit 112 is sharply curved. A tunnel is an intrabody route that a catheter follows from the point of entry into the body, through the area between the skin and the underlying fascia, to the point of entry into the blood vessels. Cufflinks 910, 912 assist in proper placement and retention of the catheter. [0044]

A doctor or other device operator inserts a catheter into the body at the entrance point, digs a tunnel through the body tissue to a hole in the vessel wall, and advances the catheter through the hole, resulting in the catheter. At least part of it is placed in the blood vessel. Generally, the catheter is inserted into and through a portion of the internal jugular vein. Often, the catheter tip is located at the superior vena cava and / or right atrial junction. However, the catheters of the present invention are useful in any vessel that adapts to the dimensions of the catheter (eg, inserting the catheter into and through a portion of the femoral vein, and placing the tip of the catheter in the aorta. thing). The thicker the wall of this embodiment of the present invention, the sharper the curvature of the conduit 112, without twisting, as compared to conventional catheters. Therefore, a physician or other device operator has more options in choosing a tunnel route than using a conventional catheter. This is because the catheter of this embodiment of the present invention can move in a larger range than the conventional catheter. In addition, the physician or other device operator may consider other considerations such as patient comfort, appearance, and presence of other devices when arranging the device. [0045]

FIG. 9 also shows this embodiment of a catheter having two connecting tubes 620, 622. Each connecting tube 620, 622 has clamps 720, 722 and luer fittings 820, 822, which allow the dialysis procedure to be performed efficiently. At least one of these connecting tubes 620, 622 is connected to a dialysis pump that assists in moving blood through the dialysis machine. Connection tubes 620, 622 also connect to the corresponding lumen through hub 908. As the conduit wall of this embodiment becomes thicker, the resistance to pressure immersion by suction of the dialysis pump increases. [0046]

(V. Internal divider thickness) With reference to the embodiments of the present invention shown in FIGS. 5B and 5C again, the internal divider 310 of the conduit 106 at one position (FIG. 5B) is an internal divider located more distal to the conduit 106 at the second position. It is thicker than 312 (Fig. 5C). Therefore, the internal divider within the conduit 106 becomes thinner distally along its length. The thickness of the internal divider is tapered and thicker within the portion of the conduit that is closer to the proximal end 41 than within the portion of the conduit that is closer to the distal end 45. This change in thickness can be achieved without reducing the cross section of the lumen, i.e. limiting the flow. The additional thickness keeps the internal divider in the proximal portion fixed in place when exposed to high differential pressures exerted within this region during dialysis or other procedures. Can be done. Not surprisingly, other embodiments of the invention, such as a catheter having a conical conduit along the length from the hub to the opening or end of the conduit, are also internal from the proximal end to the distal end. It has such a change in the thickness of the divider. [0047]

(VI. Cylindrical design vs. conical design) Achieving high flow rates is an important performance characteristic of dialysis catheters. Blood viscosity and the ability of cells to withstand large pressure drops are uncontrollable factors in the dialysis flow equation. These controllable factors that are most relevant to maximizing the flow velocity through the catheter are French-sized catheters (indicating effective lumen dimensions) and catheter lengths (shorter lumens have smaller surface areas and cause friction. Includes resistance to twisting of the catheter (twisting limits flow). A small, circular catheter conduit is desirable in order to minimize the size of the veins and maximize patient comfort / acceptance of the device for the catheter user to place the device percutaneously. Conventional catheters meet these needs through a fully cylindrical shaft. One embodiment of the present invention provides a catheter design with conical or substantially conical conduits having the same desired properties as a columnar shaft. For example, often the catheter twists during placement. A duct with a circular cross section can twist within a hole in a blood vessel without enlarging the hole. In contrast, non-circular cross-section ducts enlarge the holes as they are tampered with, thereby preventing the holes from properly closing around the conduit. [0048]

In addition, the catheters of the present invention with conical or substantially conical conduits have other advantages that a fully cylindrical shaft cannot be achieved. Higher flow rates can be achieved, for example, because a larger luminal volume can be designed within the proximal portion of the conduit (ie, part of the conduit adjacent to the hub). Also, a thicker wall can be designed within the proximal portion of the conduit, which reduces the tendency of the conduit to twist. In addition, the final size of the hole in the blood vessel is determined by the removable sheath. The sheath is inserted into the hole as usual, and then the catheter is inserted through the sheath. Once the catheter is inserted, the sheath is stripped. Smaller sheaths are used because the distal portion of the conduit of the invention (ie, the portion of the conduit towards the end and / or tip of the catheter) can be smaller than conventional catheters with lower flow rates. Get (as a result, smaller holes are needed). A smaller area is required to insert a smaller distal portion through the hole to facilitate catheter placement. Moreover, conical or substantially conical designs are safer than fully conical designs. This is because the increase in cross-sectional area of the conduit closes the hole as the catheter is advanced through the hole. In current catheter designs, the area of the hole around the catheter must be manually compressed until condensation occurs. Therefore, the conical catheter can be advanced immediately after placement to fill the annular space in the vein. [0049]

In addition, the conical duct is a more efficient structure for maximizing flow within the dialysis catheter compared to a fully columnar catheter. FIG. 7 shows a conical vessel 108 according to one embodiment of the present invention. FIG. 8 shows a columnar conduit 110 of equal length to the vessel 108 of FIG. Each conduit 108, 110 has cavities 516, 518 (FIGS. 7 and 8, respectively). The wall thicknesses 432 and 430 increase from the distal end to the proximal end of the conduit 108 of the embodiment shown in FIG. 7, respectively, while the wall thicknesses 442 and 440 are the lengths of the conduit 110 shown in FIG. It is constant along. The smaller end of the conical conduit 108 has an inner diameter equal to the inner diameter of the columnar conduit 110 (ie, measured from inner wall to inner wall). For example, in a hypothetical setting, the inner diameter of the smaller end of the conical vessel 108 is equal to the diameter of the cylindrical vessel 110 (2 units in this case). The inner diameter of the larger end of the conical conduit 108 is 3 units. The length of both conduits 108 and 110 is 10 units. Cavity volume (V), surface area (SA) and volume to surface area ratio (V / SA) are calculated according to standard structural principles based on a given size. Therefore, for the conical conduit 108, the cavity volume, surface area, and volume to surface area ratio are 49.74 units, respectively.³, 78.64 units², And 0.63 units. The vessel volume, surface area, and volume-to-surface area ratio for columnar conduit 110 are 31.42 units, respectively.³, 62.83 units², And 0.50 units. The V / SA for conical conduits is larger than that for columnar conduits. This result is always true if the smaller ends of the conical ducts are equal to or greater than the inner diameter of the columnar ducts, and if those ducts are of equal length. [0050]

Maximizing this ratio of a given minimum diameter and given length of lumen is an important factor in improving flow through the device. The higher this ratio, the lower the resistance through the conduit and the device achieves higher flow rates. When maximum pressure blood is acceptable, higher flow rates occur in conical ducts than in through columnar ducts. This is because a low percentage of blood in the conical lumen comes into contact with the surface of the lumen without delay at a given point. In addition, the increased area increases the proportion of fluid that passes through without contacting the wall, reducing resistance to flow through the device. [0051]

At any point, the wall thickness of the columnar conduit cannot increase without a decrease in the cross-sectional area of the lumen and an increase in resistance to flow. Both wall thickness and cross-sectional area can increase from the distal end (near the tip) to the proximal end (near the hub) of the conical or substantially conical conduit. The proximal portion of the catheter typically curves as it passes through a subcutaneous tunnel. The distal portion of the catheter hangs straight in the aorta. Wall thickness is minimized to maximize luminal cross-sectional area and minimize venous dimensions. The increased wall thickness increases the resistance of the catheter to twisting and reduces the tendency of the catheter to twist as it bends or bends. Twist always limits the flow. Therefore, the elimination of twist also increases the flow. [0052]

Conical or substantially conical catheters can be extruded. Generally, the material forming the conduit is placed within the device. This material is often heated and molded. As the material moves through the mold, a pressurized gas such as air is introduced to form one or more cavities. In addition, as the material passes through the mold, the extruded material is pulled from the lead end. Often, this material is cooled as it is pulled. Therefore, this extrusion system has at least three modifications that affect the extruded product: the mode in which the material is passed through the mold (ie, the applied force and / or the extrusion rate), the introduction of the gas. The mode in which the material is pulled (eg, the pressure of the gas or the length of application) and the style in which the material is pulled (eg, the rate at which the material is pulled). If these modifications remain constant over time and the extruded tube is pulled at the same rate as it is extruded, a uniform tube is produced. Nonconformities in extrusion and tensile speeds, and / or changes over time in these modifications, produce non-uniform conduits, including the designs of the present invention. [0053]

(VII. Double luminal catheter) In one embodiment of the invention, the catheter comprises a conical and tapered conduit along the length extending from the proximal end to the distal end. The conduit is substantially continuous and smooth and has no openings, holes, apertures, roughness, or depressions over its substantially overall length. This embodiment has an internal divider and conduit wall that define the two lumens. A catheter is structured so that at least one lumen tapers along its length. The tapered conduit and the tapered lumen have a substantially larger cross-sectional area at the proximal end than at the distal end. The proximal end of the conduit connects to the hub. The hub then connects to the connecting tube on the proximal side of the hub. Each of the two cavities connects to the corresponding connecting tube through a hub. Typically, this hub contains a void that connects each lumen with one of the connecting tubes. [0054]

For example, FIG. 3A shows two connecting tubes 600, 602, each of which communicates with one different lumen through the hub 900. Each connecting tube 600, 602 has clamps 700, 702, and luer fittings 800, 802, the clamps 700, 702 can be actuated to limit or suppress flow through connecting tubes 600, 602, luer fitting 800. , 802 can be used to connect other tubes (eg, to a dialysis pump). Cufflinks 902 are included for proper placement and operation of the catheter. FIG. 10A shows a side view of one embodiment of the connecting tube 630, while FIG. 10B shows a cross-sectional view of the same connecting tube 630. One of the tapered cavities terminates at the distal end 35, resulting in a notch 200 located more distally through the opening at the distal end 35 and within the wall of the extending tapered conduit 104. Through, communicate with the environment outside the catheter. The notch 200 has a larger area than the cross-sectional area of the lumen immediately proximal to the notch 200. The other tapered lumen terminates at the physical end 37 of the conduit and faces the connecting tubes 600, 602, so that this lumen communicates with the environment outside the catheter. [0055]

This double lumen, conical conduit embodiment of the catheter design of the present invention comprises the following properties alone or in combination: The notch provides a longitudinal notch in the catheter wall. The cross section of the conduit is circular or oval. The cross section of the lumen is circular or partially circular (eg, semicircular). The outer wall at the proximal end of the conduit has a maximum thickness that tapers to a smaller thickness at the distal end of the conduit. The internal divider at the proximal end of the conduit has a maximum thickness that tapers to a smaller thickness at the distal end of the conduit. The near and / or central portion of the conduit has a curved portion as it approaches the connecting tube. The connecting tube is straight or curved, and oriented so that it faces away from the distal end of the conduit, is parallel to the distal direction, or is oriented between these two positions. The periphery of the proximal, central and / or distal portion of the conduit is reinforced with a layer of material that is harder than the fiber, wire and conduit material, and / or a material layer that is softer than the conduit. Under pressure, the internal divider is generally reinforced with a harder material than the material of the conduit wall to minimize the tendency to warp. The connecting tube is selectively removed so that the connecting tube can be replaced while the catheter is placed within the patient. At least one cuff is included on the conduit for proper placement and operation of the invention. [0056]

This double luminal conical embodiment of the catheter design of the invention and other desired aspects of other possible embodiments of the invention may also include the following properties: The surface of the conduit is processed to affect the ability of the body fluid (eg, blood) to bind the material (eg, biological material) to the conduit (eg, to the ability to deposit the material on the surface of the conduit). And / or the ability of the material to surround the conduit). For example, the outer surface is coated with an anticoagulant such as heparin. The use of heparin to treat surfaces is known in the art and is described, for example, in Riesenfeld et al., MEDICAL DEVICE TECHNOLOGY (March 1995), which is incorporated herein by reference. [0057]

In another embodiment of the invention, the catheter comprises an internal divider that defines a conduit and two lumens. The catheter comprises three parts: the proximal part, the central part, and the distal part. The proximal portion is a columnar having a larger cross-sectional area than the cylindrical distal portion. Proximal and distal parts are adjacent to the truncated cone-central part of the cone. At least one internal divider and the walls of these three parts define the lumen. The dimensions of the lumen are roughly balanced with the dimensions of the part. The end of the proximal portion of the conduit (ie, the proximal end) joins the hub. This hub then connects to the connecting tube on the proximal side of the hub. Each of these two cavities is connected through a hub to the corresponding connecting tube. Typically, the hub contains a void that connects each of the cavities with one connecting tube. [0058] [0058]

For example, FIG. 5A shows two connecting tubes 610, 612, each of which communicates with a different one of the cavities through a hub 904. Each connecting tube 610, 612 has clamps 710, 712, and luer fittings 810, 812, the clamps 710, 712 can be actuated to limit or restrain flow through connecting tubes 610, 612, and luer. Fittings 810, 812 can be used to connect other tubes (eg, to a dialysis pump). Cufflinks 906 are included for proper placement and operation of the catheter. One of the tapered cavities terminates at the distal end 45, so that it is located more distally through the opening at the distal end 45 and within the wall of the extended tapered conduit 106. Communicate with the environment outside the catheter via 210. The notch 210 has a large area compared to the cross-sectional area of the lumen immediately proximal to the notch 210. The other tapered lumen terminates at the physical end 47 of the conduit and faces the connecting tubes 610, 612, so that this lumen communicates with the environment outside the catheter. [0059]

This double lumen, truncated / truncated cone-conical / cylindrical conduit embodiment of the catheter design of the present invention comprises the following properties alone or in combination: The notch comprises a longitudinal notch in the conduit wall. The cross section of the connecting tube is circular or oval. The cross section of the lumen is circular or partially circular (eg, semicircular). The outer wall at the proximal end of the conduit has the maximum thickness, and has a smaller thickness at the distal end of the conduit. The internal divider at the proximal end of the conduit is the maximum thickness and tapers to a smaller thickness at the distal end of the conduit. The proximal and / or central portion of the conduit comprises a curved portion as it approaches the connecting tube. The connecting tubes are straight or curved so that they face away from the distal end of the conduit, are oriented parallel to the distal portion, or are oriented between these two positions. Orientate. The periphery of the proximal, central and / or distal portion of the conduit is reinforced with a layer of material that is harder than the fiber, wire and conduit material, and / or a material layer that is softer than the conduit. Under pressure, the internal divider is generally reinforced with a harder material than the material of the conduit wall to minimize the tendency to warp. The connector tube is selectively removed so that the connector tube can be replaced while the catheter is placed within the patient. At least one cuff is included on the conduit for proper placement and operation of the invention. [0060]

This double luminal embodiment of the catheter design of the invention, and other desired aspects of other possible embodiments of the invention, may also include the following properties: The surface of the conduit is processed to affect the ability of the body fluid (eg, blood) to bind the material (eg, biological material) to the conduit (eg, to the ability to deposit the material on the surface of the conduit). And / or the ability of the material to surround the conduit). For example, the surface is coated with an anticoagulant such as heparin. The use of heparin to treat surfaces is known in the art and is described, for example, in Riesenfeld et al., MEDICAL DEVICE TECHNOLOGY (March 1995), which is incorporated herein by reference. [0061]

With reference to FIGS. 13 and 14, another embodiment of the invention has a hub 914 and a flexible, substantially elongated conduit 108 defining at least one lumen 518, 520. The conduit 108 has a proximal end 71 coupled to the hub 914. From the proximal end 71, the conduit 108 extends distally to the first point 76. The proximal end 71 and the first point 76 define the cylindrical proximal portion 72 of the conduit 108. From the first point 76, the conduit 108 extends to the second point 78. The first point 76 and the second point 78 define the central portion 70. The central portion 70 has a truncated cone-conical shape with a larger cross-sectional area at the first point 76 compared to the second point 78. From the second point 78, the conduit 108 extends to the distal end 75 with an opening. The opening communicates with at least one lumen 518, 520. The second point 78 and the distal end 75 define the columnar distal portion 74. [0062]

The proximal portion 72 has a constant cross-sectional area along its length, which is the same as the cross-sectional area of the first point 76. The distal portion 74 has the same constant cross-sectional area as the cross-sectional area of the second point 78. The conduit wall of the distal part 75 has a constant thickness T along its length₁Have. this Thickness T₁Is larger at first point 76, proximally through central portion 70 Thickness T₂Increases to. Therefore, the conduit wall T at the first point 76₂The thickness of the conduit wall T at the second point 78₁It is large compared to the thickness of. The conduit wall of the proximal part 72 follows its length The same thickness T as the first point 76₂Is a constant thickness T₂Have. [0063]

At least one lumen 518, 520 has a constant inner diameter A measured from the internal divider to the wall along the length of the distal portion 74.₁Have. This inner diameter A₁Grows proximally along the length of the central portion 70 over the first point 76, A₂Reach the inner diameter of. Cavity inner diameter A₂Is constant along the length of the proximal portion 72 and has the same inner diameter A as the first point 76.₂Is. Therefore, the inner diameter A of the first point 76₂Is the inner diameter A of the second point 78₁Larger than. Cavities 518, 52 using a simple structural principle Depending on the shape of the cross section of 0, the inner diameter can be converted to the cross-sectional area. Therefore, A₂From total The calculated cross-sectional area is A₁It is larger than the cross-sectional area calculated from. In fact, this implementation As the inner diameter increases through the central portion 70 of the embodiment, the cross-sectional areas of the cavities 518, 520 also increase correspondingly. [0064]

At the proximal end 71, the conduit 108 connects to the hub 914, so that at least one of the cavities 518, 520 communicates with the void in the hub 914. Preferably, each lumen 518, 520 communicates with a different void. On the side of the hub 914 opposite the conduit 108, at least one, and preferably two connecting tubes 630, 632 connect with each void in the hub 914. Thus, in this embodiment, each of the two cavities 518, 520 communicates with each of the two connecting tubes 630, 632 through a void in the hub 914. Each of the connecting tubes 630, 632 has luer fittings 830, 832 that connect to other tubes and / or devices (eg, dialysis pumps) at the ends, and restricts flow through specific connecting tubes 630, 632. Has clamps 730, 732 that can be actuated to or deter. Also, cufflinks (not shown in this embodiment, but similar to cufflinks 906 in FIG. 5A) are provided around the outside of the conduit 108. Cufflinks are porous materials that allow tissue to grow in it, thereby functioning to secure the device within the patient. Typically, the cuffs are placed within the central portion 70. Further, with reference to FIGS. 14A and 14B, in one embodiment having two lumens, one lumen 524 extends distally beyond the distal end 75 to the physical end 77 of the conduit 108. Extend. At the physical end 77, the opening communicates with the lumen 524. The two holes 69, 69'are located immediately proximal to the distal end 75, which communicates with the lumen 522. [0065]

In some embodiments, the catheter has a particular pressure (where the pressure leaks) and a particular tension along its length. Leak pressure is determined by clamping a closed conduit at a point immediately proximal to the notch, and by attaching the pressure source to one connecting tube, where each connecting tube is one tube through the hub. Contact the cavity. For each sample, pressure is applied to each connecting tube / cavity in steps of 12 psi, 25 psi, 35 psi, and 45 psi. In each pressure step, pressure is applied to one connecting tube / cavity for 30 seconds; move the pressure source and reattach it to the other connecting tube / cavity and apply pressure to the other connecting tube / cavity for 30 seconds. It is applied. Three samples were aged for two and a half years (aged samples) and three samples were not aged (non-aged samples). [0066]

Tension was determined along the length of the conduit at approximately equal positions to the proximal, central, and distal parts of the conduit. The tension of the proximal part is by clamping the conduit around the first point, which is about one-third the length of the conduit from the proximal end that joins the hub, and the proximal end (fixed there). It was determined by pulling the conduit at that point in the opposite direction from (where the clamp is attached). Tension in the central part is by clamping the conduit around the first point and around the second point (about two-thirds of the length of the conduit from the proximal end), and at those points. It was then determined by pulling and releasing the clamp in the opposite direction. Distal tension was determined in a manner similar to the central portion, except that the clamps were placed around the second point and around the physical ends of the conduit. For each moiety, tension was determined for 3 aged and 3 non-aged samples. The results are shown in Table 4 below. [0067]

[Table 4]

<img file="JP2002503528A_D0004.tif" /> 【0068】

Modifications, modifications, and other practices of the invention described herein will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims. Therefore, the present invention should not be preceded by an exemplary description, but instead should be defined by the spirit and scope of the aforementioned claims.

[Simple explanation of drawings]

[Fig. 1A]

FIG. 1A is a side view of one embodiment of a catheter conduit according to the present invention. [Fig. 1B]

FIG. 1B is a cross section of the conduit of FIG. 1A obtained along line 1-1'. [Fig. 1C]

FIG. 1C is a cross section of the conduit of FIG. 1A obtained along line 1''-1'''. [Fig. 2A]

FIG. 2A is a side view of another embodiment of the catheter conduit according to the present invention. [Fig. 2B]

FIG. 2B is a cross section of the conduit of FIG. 2A obtained along line 2-2'. [Fig. 2C]

FIG. 2C is a cross section of the conduit of FIG. 2A obtained along line 2''-2'''. [Fig. 3A]

FIG. 3A is a side view of one embodiment of a catheter having a conical duct. [Fig. 3B]

FIG. 3B is an enlarged view of the notch and distal appendages of the catheter of FIG. 3A. [Fig. 4A]

FIG. 4A is a side view of one embodiment of the conduit of FIG. 3A produced by extrusion. [Fig. 4B]

FIG. 4B is a cross section of the conduit of FIG. 4A obtained along line 4-4'. [Fig. 4C]

FIG. 4C is a cross section of the conduit of FIG. 4A obtained along line 4''-4'''. [Fig. 5A]

FIG. 5A is a side view of one embodiment of a catheter having a conduit comprising a columnar proximal portion, a truncated cone-conical central portion, and a cylindrical proximal portion. [Fig. 5B]

FIG. 5B is a cross section of the conduit of FIG. 5A obtained along line 5-5'. [Fig. 5C]

FIG. 5C is a cross section of the conduit of FIG. 5A obtained along line 5''-5'''. [Fig. 5D]

FIG. 5D is an enlarged view of the catheter notch and distal appendage of FIG. 5A. [Fig. 6]

FIG. 6 is a stylized side view of one embodiment of the conduit of FIG. 5A made by extrusion. [Fig. 7]

FIG. 7 is a cross section obtained along the length of one embodiment of the conical conduit. [Fig. 8]

FIG. 8 is a cross section obtained along the length of the columnar conduit. [Fig. 9]

FIG. 9 is a diagram of one embodiment of a catheter placed in a blood vessel. [Fig. 10A]

FIG. 10A is a diagram of one embodiment of the connecting tube. [Fig. 10B]

FIG. 10B is a cross section of the connecting tube of FIG. 10A obtained along line 10-10'. [Fig. 11]

FIG. 11 is a graph showing a comparison of flow velocity data in existing catheter designs. [Fig. 12]

FIG. 12 is a cross-sectional view along the length of one embodiment of the conduit. [Fig. 13]

FIG. 13 is a diagram of one embodiment of the hub assembly. [Fig. 14A]

FIG. 14A is a side view of one embodiment of the advanced configuration. [Fig. 14B]

FIG. 14B is a top view of the embodiment of FIG. 14A rotated 90 °.