Patent Publication Number: US-2019167946-A1

Title: Catheter having an expandable lumen and method of manufacture

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/748,392 filed Jun. 24, 2015, which is a divisional of U.S. application Ser. No. 12/826,795, filed Jun. 30, 2010, now abandoned, which claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 61/222,561, filed Jul. 2, 2009, the entire contents of each of which are incorporated by reference herein. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a medical catheter and, more particularly, to a medical catheter including an expandable lumen. 
     2. Background of Related Art 
     Catheters for supplying and/or withdrawing fluids into and/or from the body are well known in the art. Such catheters may be employed for medication delivery, urine removal, blood treatment, e.g., dialysis, etc. In the area of dialysis, single, double and triple lumen catheters are well known. Typically, double or dual lumen dialysis catheters define an arterial lumen and a venous lumen for simultaneously withdrawing and returning blood from and to the body. A pair of single lumen catheters can be used to achieve the same function. Triple lumen catheters generally include arterial and venous lumens and a guidewire lumen. The guidewire lumen is provided to accommodate a guidewire to facilitate catheter placement within the body and/or facilitate delivery of a medical fluid into the body. 
     One drawback associated with providing a guidewire lumen within a catheter is that the inclusion of a guidewire lumen effectively reduces the cross-sectional area available to accommodate the remaining lumen or lumens. Thus, the maximum fluid flow rate in the remaining lumen or lumens of the catheter as compared to a catheter not having a guidewire lumen is reduced. 
     Accordingly, a continuing need exists in the medical arts for a catheter including a guidewire lumen with improved flow rates through the existing lumen or lumens. 
     SUMMARY 
     The present disclosure relates to a catheter comprising an elongated body having a proximal end and a distal end and defining at least one lumen. The body includes a longitudinal slit which is expandable from a substantially sealed configuration to an expanded configuration to define an expandable lumen positioned adjacent the at least one lumen. The expandable lumen is dimensioned to receive a guidewire and/or a stylet in the expanded configuration. In one embodiment, the catheter includes a single lumen and the expandable lumen extends longitudinally along an inner wall of the elongated body defining the single lumen. 
     In one embodiment, the expandable lumen is defined between the inner wall of the elongated body and a resilient membrane. The resilient membrane may be formed integrally with the elongated body. Alternatively, the resilient membrane may be secured to the inner wall of the elongated body using for example, adhesives or welding. 
     In an alternative embodiment, the at least one lumen includes a first lumen and a second lumen and a longitudinal septum positioned between the first lumen and the second lumen. In this embodiment, the longitudinal slit extends through the septum such that when the longitudinal slit is in the expanded configuration, the expandable lumen extends through the septum. The septum can be positioned substantially along the diameter of the elongated body such that the first lumen and the second lumen are substantially D-shaped. Alternatively, the septum may be positioned to define first and second lumens which have different cross-sectional areas. 
     The catheter may be formed of a first material having a first coefficient of friction and a second material having a second coefficient of friction which is less than the first coefficient of friction, wherein at least a portion of the elongated body defining the slit is formed of the second material. 
     The present disclosure also relates to a method of manufacturing a multi-lumen catheter, comprising the following steps: 
     i) extruding a catheter body having a first lumen and a second lumen and a septum separating the first lumen from the second lumen, the septum including a removable material positioned within and extending along the length of the septum, wherein the septum is extruded from an elastomeric material; and 
     ii) removing the removable material from the septum to define a slit which extends through the septum along the length of the septum, the slit being expandable to define a third lumen. 
     In one embodiment, the step of removing the removable material from the septum includes pulling the removable material from the septum. In another embodiment, the removable material is a dissolvable or degradable material and the step of removing the removable material from the septum includes exposing the catheter to a solvent to dissolve or degrade the removable material within the septum. This method may also include the step of flushing the third lumen to remove the dissolved/degraded material from the third lumen. 
     In an alternative method of manufacturing a multi-lumen catheter, the method comprises the following steps: 
     i) extruding a catheter body having a first lumen, a second lumen, and a third lumen positioned between the first and second lumens and extending through a septum of the catheter body, the catheter body being formed of a first material having a first melting temperature; 
     ii) providing a layer of a second material on an inner surface of the septum defining the third lumen, the second material having a melting temperature greater than the first material; 
     iii) directing a fluid through the first and second lumens to move the third lumen to a collapsed configuration; 
     iv) melting the first material without melting the second material while the third lumen is in the collapsed configuration; and 
     v) cooling the first material to allow the first material to set with the central lumen in the collapsed configuration. 
     In yet another embodiment of the method of manufacturing a multi-lumen catheter, the method comprises the following steps: 
     i) extruding a catheter body having a first lumen, a second lumen, and a third lumen positioned between the first and second lumens and extending through a septum of the catheter body, the catheter body being formed of a first material having a first melting temperature; 
     ii) providing a layer of second material on an inner surface of the catheter body defining the first and second lumens, the second material having a melting temperature lower than the first material; 
     iii) directing a fluid through the first and second lumens to move the third lumen to a collapsed configuration; 
     iv) melting the second material without melting the first material while the third lumen is in the collapsed configuration; and 
     v) cooling the second material to allow the second material to set with the central lumen in the collapsed configuration. 
     In yet another embodiment of the method of manufacturing a multi-lumen catheter, the method comprises the following steps: 
     i) extruding a catheter body having a first lumen, a second lumen, a septum positioned between the first and second lumens, and a hollow tube extending longitudinally through the septum; and 
     ii) forcing a fluid through the hollow tube to expand the hollow tube. In this embodiment, the extruding step does not include melting the hollow tube. The hollow tube may be formed from a material which has enhanced lubricity as compared to a material forming the septum. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various embodiments of the presently disclosed catheter with expandable lumen and methods of manufacturing such a catheter are disclosed herein with reference to the drawings, wherein: 
         FIG. 1  is a side perspective view of one embodiment of the presently disclosed catheter with expandable lumen; 
         FIG. 1A  is a front view from the distal end of the catheter shown in  FIG. 1  with the lumen in a sealed configuration; 
         FIG. 2  is a front view from the distal end of the catheter shown in  FIG. 1  with the lumen in an expanded configuration and a guidewire extending through the lumen; 
         FIG. 3  is a side perspective view from the distal end of another embodiment of the presently disclosed catheter with expandable lumen; 
         FIG. 4  is a front view of the distal end of the catheter shown in  FIG. 3  with the expandable lumen in a sealed configuration; 
         FIG. 5  is a front view of the distal end of the catheter shown in  FIG. 4  with the expandable lumen in an expanded configuration. 
         FIG. 6  is a front view of another embodiment of the presently disclosed catheter with expandable lumen with the lumen in an expanded configuration and a guidewire positioned within the lumen; 
         FIG. 7  is a cross-sectional view of the catheter shown in  FIG. 6  with the lumen in an expanded configuration and a stylet positioned within the lumen; 
         FIG. 8  is a front view of an extruded catheter body, during a first manufacturing process, having a removable material positioned through a septum of the catheter body; 
         FIG. 9  is a front view of an extruded catheter body, during an alternative manufacturing process, with the expandable lumen extruded in an expanded configuration in the septum to define a lumen through the septum; 
         FIG. 10  is a front view of the extruded catheter body shown in  FIG. 9  after the expandable lumen has been collapsed and the catheter has been heated to retain the collapsed configuration of the expandable lumen; 
         FIG. 11  is a front view of an extruded catheter body during another alternative manufacturing process with the expandable lumen in an expanded configuration and a second material positioned on inner walls of the catheter body defining first and second lumens of the catheter body; 
         FIG. 12  is a front view of the catheter body shown in  FIG. 11  after the expandable lumen has been collapsed during the manufacturing process and the second material has been heated and cooled to retain the expandable lumen in the collapsed configuration; and 
         FIG. 13  is a front view of a catheter body having first and second lumens and an expandable central lumen which is coated with a material of enhanced lubricity. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Embodiments of the presently disclosed catheter having an expandable lumen and methods for manufacturing the catheter will now be described in detail with reference to the drawings wherein like reference numerals designate identical or corresponding elements in each of the several views. 
     The exemplary embodiments of the catheter disclosed herein are discussed in terms of medical catheters for the administration of fluids (withdrawal or introduction) relative to the body of a subject and, more particularly, in terms of a hemodialysis catheter. However, it is envisioned that the present disclosure may be employed with a range of catheter applications including surgical, diagnostic and related treatments of diseases and body ailments of a subject. It is further envisioned that the principles relating to the catheter disclosed include employment with various catheter related procedures, such as, for example, hemodialysis, cardiac, abdominal, urinary, intestinal, and in chronic and acute applications. Moreover, the catheter can be used for administration of fluids such as, for example, medication, saline, bodily fluids, blood and urine. 
     In the discussion that follows, the term “proximal” or “trailing” will refer to the portion of a structure that is closer to a clinician, while the term “distal” or “leading” will refer to the portion that is further from the clinician. As used herein, the term “subject” refers to a human patient or other animal. The term “clinician” refers to a doctor, nurse or other care provider and may include support personnel. 
       FIGS. 1-2  illustrate one embodiment of the presently disclosed catheter with expandable lumen shown generally as  10 . Catheter  10  includes an elongated body  12  having a proximal end  12   a  and a distal end  12   b.  Elongated body  12  defines a lumen  13  which extends from proximal end  12   a  of elongated body  12  to the distal end  12   b  of elongated body  12 . A longitudinal slit  16  is defined along the length of body  12  between body  12  and a resilient membrane  18 . Membrane  18  can be formed integrally with elongated body  12  or, alternatively, can be formed separately from and secured to body  12  using conventional techniques, e.g., welding, adhesives, etc. Resilient membrane  18  is positioned along body  12  to define an expandable lumen  20  ( FIG. 2 ) which is dimensioned to receive a stylet ( FIG. 7 ) or guidewire  22  ( FIG. 2 ) or facilitate introduction or removal of fluid, e.g., medication, contrasting agent, saline, etc., through the catheter  10 . As illustrated in  FIG. 1A , in its normal or collapsed configuration, membrane  18  is positioned adjacent an inner wall  24  of catheter  10 . Thus, when membrane  18  is in its collapsed configuration, substantially the full diameter of lumen  14  is available for fluid flow and the fluid flow rate at a given pressure for a catheter having a specified diameter can be maximized. 
       FIGS. 3-5  illustrate another embodiment of the presently disclosed catheter with expandable lumen shown generally as  100 . Catheter  100  includes an elongated body  112  having a proximal end  112   a  and a distal end  112   b.  A pair of lumens  114   a  and  114   b  extend from the proximal end  112   a  to the distal end  112   b  of body  112 . A septum  116  extends along the length of elongated body  112  between lumens  114   a  and  114   b.  Although septum  116  is illustrated as being positioned along the diameter of body  112  to define two lumens of substantially equal cross-sectional area, it is envisioned that the septum  116  can be positioned to define two lumens of unequal cross-sectional areas. 
     Catheter  100  may be made of any suitable material. In certain embodiments, catheter  10  is formed of polyurethane, such as an aliphatic or aromatic polyurethane. However, catheter  100  may be made of any suitable polymer such as thermoplastic, polyolefin, fluoropolymer (such as fluorinated ethylene propylene (“FEP”), polytetrafluoroethylene PEFE, perfluoroalkoxy (“PFA”) polyvinylidene fluoride (PVDF)), polyvinyl chlorideneoprene PVC, silicone elastomer of fluoroelasatomers (such as copolymers of hexafluoropropylene (HFP) and vinylidene fluoride (VDF or VF2), terpolymers of tetrafluoroethylene (TFE), vinylidene fluoride (VDF) and hexafluoropropylene (HFP), and perfluoromethylvinylether (PMVE)). 
     Referring particularly to  FIGS. 4 and 5 , a slit  118  is defined along the length of septum  116 . Septum  116  is formed of an elastomeric material, such that the slit is expandable from a closed or substantially closed or collapsed configuration ( FIG. 4 ) to an expanded or open configuration ( FIG. 5 ). In the expanded or open configuration, the slit  118  defines a third lumen  120  which can be dimensioned to receive a guidewire  122  ( FIG. 6 ) or to facilitate introduction or removal of fluid, e.g., medication, contrasting agent, saline, etc. into a patient. 
       FIGS. 6 and 7  illustrate front and cross-sectional views of another embodiment of the presently disclosed catheter shown generally as  200 . Catheter  200  is substantially similar to catheter  100  and includes an elongated body  212  including a septum  216  defining a pair of lumens  214   a  and  214   b.  Septum  216  includes an expandable slit  218  which is expandable from a closed configuration (not shown) to an open or expanded configuration ( FIGS. 6 and 7 ) to define a third lumen  220 . Catheter  200  differs from catheter  100  in that at least a portion of septum  216  defining slit  218  of catheter  200  is formed of a second material different from the material used to form catheter  200 . More specifically, although it is desirable to form elongated body  212  from a soft elastomeric material, the coefficient of friction associated with soft elastomeric materials may render guidewire or stylet insertion through the expandable slit  218  difficult. As such, septum  216  or at least a portion of septum  216  defining the slit  218  can be formed of a second material having a lower coefficient of friction than the elongated body  212  of catheter  200 . In one embodiment, the slit  218  is defined by a layer, liner or coating  222  of the second material having a lower coefficient of friction than the body  212  of the catheter  200 . Alternatively, the entire septum  216  or portions of septum  216  can be formed of the second material. Yet further, during an extrusion process used to form the body  212 , a layer, liner or coating  222  can be employed having a higher melting temperature than the material used to form body  212 , thereby ensuring the slit  218  does not adhere to itself, such as by melting, during the manufacturing process. 
     As illustrated in  FIGS. 6 and 7 , slit  218  can be dimensioned to receive a guidewire  225  ( FIG. 6 ) and/or a stylet  226  ( FIG. 7 ) when slit  218  is in its expanded or open configuration. Stylet  226  may include a guidewire lumen  228  and may be formed of a material having a low coefficient of friction to facilitate stylet insertion through the slit  218 . 
     A catheter having a septum including an expandable slit  216 , or third lumen  120 , can be manufactured in a variety of different ways. Referring to  FIG. 8 , in one presently disclosed embodiment, catheter body  312  of catheter  300  is extruded of a first material, e.g., silicone, polyurethane, or other soft polymeric material, with a second removable material  330  positioned within the septum  316  to define the slit  318 . (Extrusion is a manufacturing process known in the art in which a material is forced through an orifice of a die to form an object having a desired cross-section). The extruded catheter body  312  defines a first lumen  314   a  and a second lumen  314   b.  For example, in one embodiment, the removable material  330  can be tailored to neck-down or shrink when a tensile force is applied, wherein a tensile force applied to the removable material  330  can be effective in removing the removable material  330  from the catheter body  312  and forming the slit  318 . In yet another embodiment, after catheter body  312  is extruded, catheter body  312  can be exposed to a solvent capable of swelling the first material in which the catheter body  312  is constructed, such as by a dipping process, to effect swelling of the catheter body  312 . Thereafter, removable material  330  is pulled from septum  316  to provide a slit through septum  316 . Most flexible polymer materials neck-down or shrink when a tensile force is applied and therefore could be used in the application described above. To be even more specific, polymers such as polyurethanes, polyethylenes, polypropylenes, polyvinylchlorides, polyacetal, and so forth, as well as combinations comprising multiple polymer systems or blends can be employed. Also, to one skilled in the art, it is to be apparent that the specific solvent, or chemical employed to induce swelling to the catheter body  312  can be numerous and should be suited to the specific polymer employed such that a majority of the physical properties are retained once the solvent has evaporated from the catheter. In one specific example, isopropyl alcohol can be employed to swell an aliphatic polyurethane sufficiently to pull out removable material  330 . 
     Referring again to  FIG. 8 , alternatively, the second removable material  330  may include a degradable/dissolvable material positioned within septum  316  to define slit  318 . The degradable/dissolvable material  330  can be a starch based material or other known degradable or dissolvable material. After the extrusion process, catheter  300  can be exposed to a solvent which causes the degrading or dissolving of the material  330  to define slit  318 . After exposure to the solvent, the expandable lumen defined by slit  318  can be flushed to remove the degraded or dissolved material from the expandable lumen. 
     Referring to  FIGS. 9 and 10 , in another embodiment of the presently disclosed manufacturing process, catheter body  412  of catheter  400  is extruded from a first material  430  with three district lumens  414   a,    414   b  and  414   c,  wherein central lumen  414   c  ( FIG. 9 ) is defined through septum  416  ( FIG. 9 ). A thin layer of a second material  432  having a higher melting temperature than the first material is provided within septum  416  to define central lumen  414   c . Second material  432  can be provided on the inner surface of septum  416  during the extrusion process or, alternatively, after the extrusion process. Next, catheter  400  is positioned within an outer mold and a heated fluid (air, liquid) is forced through lumens  414   a  and  414   b  at equal pressure such that the area of the central lumen  414   c  is decreased, i.e., the central lumen  414   c  collapses ( FIG. 10 ). The first material is then melted using the heated fluid or other heat source at a temperature which will not melt or render the second material tacky. Thereafter, the first material is cooled to allow the first material to set with the central lumen  414   c  having a decreased area or collapsed configuration ( FIG. 10 ). 
     In yet another embodiment of the presently disclosed manufacturing process, shown in  FIGS. 11 and 12 , catheter body  512  of catheter  500  is extruded with a first material  528  defining catheter body  512  and a second material  530  covering the inner walls of body  512  defining first and second lumens  514   a  and  514   b.  The second material  530  is selected to have a melting temperature lower than the first material  528 . A central lumen  514   c  of catheter body  512  is extruded in an expanded orientation. The extruded catheter  500  ( FIG. 11 ) is placed in an outer mold (not shown) and a heated fluid is forced through lumens  514   a  and  514   b  of body  512  to collapse central lumen  514   c  to define slit  518 . The catheter  500  is then heated above the melting temperature of the second material  530  but below the melting temperature of the first material  528 . A fluid can be used to collapse slit  518  and a second heating technique can be used to heat the second material  530  above its melting temperature. Alternatively, the fluid can be used to both collapse and heat the catheter body  512 . Thereafter, the second material  530  is cooled and allowed to set to provide a catheter body  512  having a closed or collapsed slit  518  ( FIG. 12 ). 
     Referring to  FIG. 13 , an additional step can be performed with respect to each of the above-identified processes to provide enhanced lubricity or ease of manufacture to the central lumen. More specifically, inner walls of septum  616  defining central lumen or slit  618  can be covered with a third material having a low coefficient of friction or enhanced lubricity or differing physical or thermal properties (e.g., higher melting temperature). In one embodiment, the catheter body  612  is extruded with a hollow tube  634  positioned within a die (not shown) to define slit  618  through septum  616 . Hollow tube  636  is not melted during the extrusion process such that a liquid can be forced through hollow tube  636  to open slit  618 . Ribbon  636  can be formed from polyethylene terephtalate (PET), polybutylene terephtalate (PBT), FEP, PTFE, or other polymer which will not become tacky or melt at the temperatures reached by the polymer melt employed to form the catheter body  612 . 
     Although specific features of the disclosure are shown in some drawings and not in others, this is for convenience only as each feature may be combined with any or all of the other features in accordance with the disclosure. 
     It will be understood that various modifications may be made to the embodiments disclosed herein. For example, the various manufacturing processes disclosed to manufacture dual lumen catheters with expandable lumens may also be used to form a single lumen catheter with an expandable lumen where applicable. Therefore, the above description should not be construed as limiting, but merely as exemplifications of embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto.