Abstract:
A catheter apparatus is provided for reducing blood clotting in connection with hemodialysis treatment. The catheter apparatus can comprise a first conduit defining an arterial lumen and a second conduit defining a venous lumen. Large staggered apertures can be provided in side walls of the conduits with at least one of the apertures having a cross-sectional area equal or greater than a cross-sectional area of one of the lumens. The catheter apparatus can further include first and second removable obturators adapted for axial insertion into the conduits and for occluding the apertures while so inserted. Advantageously, the obturators can wipe the apertures during removal, causing blood clots incident on the apertures to be dislodged from the apertures. Related methods for using the catheter apparatus in performing hemodialysis treatment are also provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the benefit of U.S. Provisional Application Ser. No. 60/693,299 entitled “HEMODIALYSIS CATHETER APPARATUS” filed Jun. 23, 2005, the entirety of the disclosure of which is expressly incorporated herein by reference. 
     
    
     STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT  
       [0002]     Not Applicable  
       BACKGROUND  
       [0003]     The present disclosure relates generally to catheters, and more particularly to catheters for use in hemodialysis treatment.  
         [0004]     In the area of health care, it is often necessary to perform hemodialysis treatment on patients that have malfunctioning or failed kidneys. Such procedures are typically performed on a periodic basis and can require up to several treatments per week.  
         [0005]     Hemodialysis treatments can sometimes require the insertion of a catheter into a patient in order to perform the treatment. However, because of the frequency of such treatments, it can become inconvenient to remove the catheter after treatment and re-insert the catheter for the next treatment. This is especially true for procedures which require insertion of the catheter into the patient&#39;s groin area which can cause substantial patient discomfort. As a result, it is often preferable to leave the catheter in place between treatments.  
         [0006]     One primary problem associated with leaving the catheter in place is the tendency for blood to clot at openings of the catheter, thereby obstructing blood flow through the catheter during subsequent uses. When blood flow is obstructed, the time required to perform hemodialysis can substantially increase due to the greater length of time required to process a given volume of the patient&#39;s blood. This can result in further inconvenience to the patient and increased health care expenses related to the operation of hemodialysis equipment for longer periods of time.  
         [0007]     One approach to removing such blood clotting involves the introduction of Heparin into the catheter after each use. Unfortunately, the use of Heparin in conjunction with every successive dialysis treatment can complicate the administration of such treatments while simultaneously increasing costs.  
         [0008]     To reduce the possibility of clotting, prior art catheters are often additionally limited in the number and size of apertures provided for receiving the patient&#39;s blood and returning processed blood back to the patient. Unfortunately, these limits on the apertures can also lead to prolonged dialysis time due to reduced blood flow rates.  
         [0009]     Accordingly, there exists a need for an improved catheter apparatus and associated methods that reduce blood clotting and promote high blood flow rates in connection with hemodialysis treatment.  
       BRIEF SUMMARY  
       [0010]     The present disclosure, roughly described, provides an improved catheter apparatus and methods associated therewith for reducing blood clotting and improving blood flow in connection with hemodialysis treatment. The catheter apparatus can comprise a first conduit defining an arterial lumen, the first conduit having proximal and distal ends, and a second conduit defining a venous lumen, the second conduit having proximal and distal ends. The second conduit and venous lumen can be shaped to be longer than the first conduit and arterial lumen.  
         [0011]     A plurality of staggered first apertures can be provided in a side wall of the first conduit for receiving blood therethrough into the arterial lumen during hemodialysis treatment, with at least one of the first apertures having a cross-sectional area equal or greater than a cross-sectional area of the arterial lumen. The first apertures may decrease in size upon approaching the distal end of the first conduit. A plurality of staggered second apertures can also be provided in a side wall of the second conduit for expelling blood therethrough from the venous lumen during hemodialysis treatment, with at least one of the second apertures having a cross-sectional area equal or greater than a cross-sectional area of the venous lumen. The second apertures may increase in size upon approaching the distal end of the second conduit. Furthermore, the first apertures may include at least two apertures of different sizes, and the second apertures may include at least two apertures of different sizes. Finally, it is also contemplated that the size of each of the first apertures may successively decrease upon approaching the distal end of the first conduit, and that the size of each of the second apertures may successively increase upon approaching the distal end of the second conduit.  
         [0012]     The catheter apparatus can further include first and second removable obturators adapted for axial insertion into the proximal ends of the respective ones of the first and second conduits. In addition, the obturators can be fashioned to occlude the apertures while inserted into the conduits. Advantageously, the obturators can be adapted for wiping the apertures during removal of the obturators from the conduits. As a result of the wiping of the apertures by the obturators, blood clots incident on the apertures can be dislodged from the apertures.  
         [0013]     The first obturator can comprise a first elongate sheath approximately equal in length to the first conduit and having a diameter approximately equal to a diameter of the arterial lumen. Similarly, the second obturator can comprise a second elongate sheath approximately equal in length to the second conduit and having a diameter approximately equal to a diameter of the venous lumen. The first obturator may lockably engage the proximal end of the first conduit while the first obturator is inserted into the first conduit, and the second obturator may lockably engage the proximal end of the second conduit while the second obturator is inserted into the second conduit.  
         [0014]     At least a portion of the first and second conduits can be implemented to share a common wall and comprise a substantially cylindrical elongate body. In addition, each of the first and second conduits may define a substantially semi-circular cross-section.  
         [0015]     In another embodiment, a method for performing hemodialysis treatment using a catheter apparatus is provided. A distal end of the catheter apparatus can be inserted into a patient, preferably into a vascular structure of the patient. First and second removable obturators can be axially inserted into proximal ends of the respective ones of first and second conduits, of the catheter apparatus. While inserted into the conduits, the first and second obturators occlude apertures in side walls of the catheter apparatus. The obturators can be removed from the conduits, resulting in the obturators wiping the apertures and causing blood clots incident on the apertures to be dislodged from the apertures.  
         [0016]     Conduits of the catheter device can be connected to hemodialysis equipment. Thereafter, blood from the patient can be allowed to flow through an arterial lumen of the catheter apparatus to the hemodialysis equipment for treatment, and blood treated by the hemodialysis equipment can be allowed to flow through a venous lumen of the catheter apparatus to the vascular structure of the patient. Following hemodialysis treatment, third and fourth removable obturators can be axially inserted into the proximal ends of the respective ones of the first and second conduits, with the third and fourth obturators occluding the apertures while inserted into the conduits.  
         [0017]     These as well as other embodiments contemplated by the present disclosure will be more fully set forth in the detailed description below and the figures submitted herewith. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIG. 1  is a top view of a catheter apparatus for use in hemodialysis treatment in accordance with an embodiment of the present disclosure;  
         [0019]      FIG. 2  is a top view of distal ends of arterial and venous conduits of a catheter apparatus in accordance with an embodiment of the present disclosure;  
         [0020]      FIG. 3  is a cross-sectional view of arterial and venous conduits of a catheter apparatus in accordance with an embodiment of the present disclosure;  
         [0021]      FIG. 4  is a side view of a distal end of a venous conduit exhibiting a plurality of staggered apertures in accordance with an embodiment of the present disclosure;  
         [0022]      FIG. 5  is a side view of a distal end of an arterial conduit exhibiting a plurality of staggered apertures in accordance with an embodiment of the present disclosure;  
         [0023]      FIG. 6  is a cross-sectional view of an obturator partially inserted into a conduit of a catheter apparatus in accordance with an embodiment of the present disclosure; and  
         [0024]      FIG. 7  is a cross-sectional view of an obturator fully inserted into a conduit of a catheter apparatus in accordance with an embodiment of the present disclosure.  
     
    
     DETAILED DESCRIPTION  
       [0025]      FIG. 1  is a top view of a catheter apparatus  100  for use in hemodialysis treatment in accordance with an embodiment of the present disclosure. As illustrated, the apparatus  100  can include a main body portion  105 , a venous obturator  130 , and an arterial obturator  170 .  
         [0026]     Turning first to the main body portion  105 , an arterial conduit  150  is provided for receiving blood from a patient through one or more apertures at an open distal end  154  of the conduit  150 , and passing the blood to dialysis equipment (not shown) through a proximal end  152  of the conduit  150 . A venous conduit  110  is provided for receiving blood from the dialysis equipment through proximal end  112  of the conduit  110  and passing the blood back to the patient through one or more apertures at an open distal end  114  of the conduit  110 . In one embodiment, conduits  110  and  150  can be implemented using transparent PVC material.  
         [0027]     The proximal end  112  of venous conduit  110  can be provided with a venous connector  145  for connecting the conduit  110  to dialysis equipment and for receiving a venous obturator  130 , as further described herein. Similarly, the proximal end  152  of arterial conduit  150  can be provided with an arterial connector  185  for connecting the conduit  150  to dialysis equipment and for receiving an arterial obturator  170 , as further described herein. In one embodiment, venous connector  145  can be blue in color and arterial connector  185  can be red in color. As illustrated, the distal end  114  of conduit  110  extends beyond the distal end  154  of conduit  150  in order to reduce recirculation of blood processed by the dialysis equipment from the venous conduit  110  back into the arterial conduit  150 .  
         [0028]     Conduits  110  and  150  are physically separated into separate shafts at distal ends  112  and  152 . As the conduits  110  and  150  pass through anchor  190 , they are joined by a shared common wall and comprise a substantially cylindrical elongate body extending from anchor  190  to distal end  154 . Anchor  192  also comprises a plurality of suturing tabs  192  useful for securing the main body portion  105  when in use. Main body portion  105  further comprises a cuff  195  encircling the body  105  for providing frictional resistance to prevent inadvertent removal of the body  105  from a patient.  
         [0029]      FIG. 2  is a top view of distal ends  114  and  154  of venous and arterial conduits  110  and  150 , respectively, of a catheter apparatus  100  taken at line  2 - 2  of  FIG. 1 . Venous conduit  110  and arterial conduit  150  include side walls  115  and  155 , respectively, as well as shared wall  197 . Side wall  115  and shared wall  197  of the venous conduit  110  define a venous lumen  120  for passing blood through the conduit  110 . Similarly, side wall  155  and shared wall  197  of the arterial conduit  150  define an arterial lumen  160  for passing blood through the conduit  150 . Apertures in side walls  115  and  155  of the conduits are also provided, as further described herein.  
         [0030]      FIG. 3  is a cross-sectional view of catheter apparatus  100  taken at line  3 - 3  of  FIG. 1 . As illustrated, each of the conduits  110  and  150  and lumens  120  and  160  exhibit substantially semi-circular cross-sections. In one embodiment, the dimensions d 0  (outside diameter of body  105 ), d 1  (thickness of shared wall  197 ), d 2  (first lumen dimension), d 3  (second lumen dimension), R 1  (first radius), and R 2  (second radius) can be implemented as 4.83 mm, 0.64 mm, 1.46 mm, 3.18 mm, 0.38 mm, and 1.78 mm, respectively. In addition, each of lumens  120  and  160  can be implemented having a cross-sectional area of 3.69 mm 2 . However, it will be appreciated that such dimensions can vary in other embodiments.  
         [0031]      FIG. 4  is a side view of a distal end of a venous conduit  110  taken at line  4 - 4  of  FIG. 2 . A plurality of apertures  125  (i.e. fenestrations) are provided in side wall  115  of conduit  110 . The apertures  125  serve to expel blood from the venous lumen  120  back to the patient during hemodialysis treatment.  
         [0032]     As illustrated, the apertures  125  can be offset from each other in a staggered orientation in order to reduce the likelihood of blockage of the apertures  125  during hemodialysis treatment. For example, if the side wall  115  of the catheter apparatus  100  is positioned against an internal wall of a patient&#39;s vascular structure, such as an artery or vein, the staggered orientation can prevent at least some of the apertures  125  from being blocked by the internal wall. Although the apertures  125  are illustrated as being elliptical, it will be appreciated that alternative shapes can be used for the apertures  125  including but not limited to non-elliptical or circular shapes. In addition, although three apertures  125  are illustrated in  FIG. 4 , it will be appreciated that catheter apparatus  100  can be implemented with any number of apertures  125 .  
         [0033]     In various embodiments, some or all of the apertures  125  can be sized to exhibit a cross-sectional area equal or greater than a cross-sectional area of the venous lumen  120 . Such sizing can significantly improve blood flow over prior catheters having smaller apertures. Moreover, blood clotting incident to the apertures  125  can be substantially eliminated through operation of obturator  130  as further described herein. In one embodiment, dimensions d 4 , d 5 , and d 6  of the apertures  125  can be implemented as 3.05 mm, 1.53 mm, and 25.4 mm, respectively, with each aperture  125  having a cross-sectional area of 3.69 mm. However, it will be appreciated that such dimensions can vary in other embodiments.  
         [0034]     Additionally, it is also contemplated that the size of apertures  125  can be implemented with the same or different sizes, such as with the size of each aperture  125  being larger in size than an aperture  125  immediately to its left, resulting in increasing sizes for apertures  125  closer to the distal end  114  of venous conduit  110 . Such a configuration, in which the size of apertures  125  decreases toward the distal end  114  of venous conduit  110 , recirculation of blood processed by the dialysis equipment from the venous conduit  110  back into the arterial conduit  150 .  
         [0035]      FIG. 5  is a side view of a distal end  154  of an arterial conduit  150  taken at line  5 - 5  of  FIG. 2 . A plurality of apertures  165  (i.e. fenestrations) are provided in side wall  155  of conduit  150 . The apertures  165  serve to receive blood into the arterial lumen  160  from the patient during hemodialysis treatment.  
         [0036]     Similar to the discussion above with respect to  FIG. 4 , the apertures  165  of  FIG. 5  can also be offset from each other in a staggered orientation in order to reduce the likelihood of blockage of the apertures  165  during hemodialysis treatment. Although the apertures  165  are illustrated as being elliptical, it will be appreciated that alternative shapes can be used for the apertures  165  including but not limited to non-elliptical or circular shapes. In addition, although four apertures  165  are illustrated in  FIG. 5 , it will be appreciated that catheter apparatus  100  can be implemented with any number of apertures  165 .  
         [0037]     In various embodiments, some or all of the apertures  165  can be sized to define a cross-sectional area equal or greater than a cross-sectional area of the arterial lumen  160 . Such sizing can significantly improve blood flow over prior catheters having smaller apertures. Moreover, blood clotting incident to the apertures  165  can be substantially eliminated through operation of obturator  170  as further described herein.  
         [0038]     As discussed above with respect to the size of apertures  125 , other embodiments may be implemented with the size of apertures  165  being of the same or different sizes, such as with the size of each aperture  165  being smaller in size than an aperture  165  immediately to its left, resulting in decreasing sizes for apertures  165  closer to the distal end  154  of conduit  150 . Alternatively, the size of apertures  165  can also be implemented with different sizes, with the size of each aperture  165  being smaller in size than an aperture  165  immediately to its right. However, it is contemplated that a configuration in which the size of apertures  165  decreases toward the distal end  154  of conduit  150  may tend to reduce recirculation of blood processed by the dialysis equipment from the venous conduit  110  back into the arterial conduit  150 .  
         [0039]     Furthermore, with respect to the apertures  125 / 165 , the apertures  125 / 165  may each include a plurality of apertures, as shown in  FIGS. 4 and 5 . For example, as shown in  FIG. 4 , apertures  125  may include at least two apertures of different sizes. Further, as shown in  FIG. 5 , the apertures  165  may also include at least two apertures of different sizes. Furthermore, the size of each of the apertures  125  may successively increase upon approaching the distal end  114  of the conduit  110 , and the size of each of the apertures  165  may successively increase upon approaching the distal end  154  of the conduit  150 . Thus, if three or more apertures  125 / 165  are used, each aperture  125 / 165  may have a different size than the other respective apertures  125 / 165 , such as to allow the apertures  125 / 165  to respectively increase and decrease in size with each successive aperture  125 / 165 . Other such configurations and modifications may be implemented using the teachings herein in order to reduce recirculation of blood processed by the dialysis equipment from the venous conduit  110  back into the arterial conduit  150 .  
         [0040]     Therefore, the recirculation of blood processed by the dialysis equipment may tend to be further reduced when: 1) the size of each aperture  125  is larger in size than an aperture  125  immediately to its left, resulting in increasing sizes for apertures  125  closer to the distal end  114  of venous conduit  110 ; and 2) the size of each aperture  165  is smaller in size than an aperture  165  immediately to its left, resulting in decreasing sizes for apertures  165  closer to the distal end  154  of conduit  150 .  
         [0041]     As illustrated, apertures  165  can be distributed along a portion of side wall  155  denoted by dimension d 7 . In one embodiment, dimension d 7  can be implemented as 10 cm. However, it will be appreciated that such dimension can vary in other embodiments.  
         [0042]     Returning to  FIG. 1 , as discussed, catheter apparatus  100  can comprise a pair of obturators  130  and  170 . Distal ends  134  and  174  of the obturators can be axially inserted into the proximal ends  112  and  152  of respective ones of conduits  110  and  150 .  
         [0043]     Obturators  130  and  170  each comprise flexible elongate sheathes  135  and  175 , respectively, each having substantially semi-circular cross-sections. Sheathes  135  and  175  can be sized so as to completely fill lumens  120  and  160  and occlude apertures  125  and  165  while inserted into conduits  110  and  150 . Caps  140  and  180  attached to sheathes  135  and  175  can be provided at the proximal ends  132  and  172  of the obturators for securing the obturators  130  and  170  to connectors  145  and  185  of conduits  110  and  150  while the obturators  130  and  170  are inserted.  
         [0044]     The insertion of obturator  130  into conduit  110  can be further understood with reference to  FIGS. 6 and 7 .  FIGS. 6 and 7  provide cross-sectional views of an obturator  130  partially ( FIG. 6 ) and fully ( FIG. 7 ) inserted into a conduit  110  of a catheter apparatus  100  in accordance with an embodiment of the present disclosure.  
         [0045]     Referring to  FIG. 6 , obturator  130  comprises an elongate sheath  135  attached to a cap  140  at the proximal end  132  of the obturator  130 . As illustrated, cap  140  comprises a ring portion  141  having a plurality of locking members  149 . The ring portion  141  is connected to a male luer tapered portion  142 .  
         [0046]     Venous connector  145  comprises a plurality of locking members  148  and a female luer portion  146 . As illustrated, the female luer portion  146  can receive the male luer portion  141  of cap  140 . Venous connector  145  further comprises recessed lead-in portions  147  for facilitating the receiving of the proximal end  134  of obturator  130  into conduit  110 .  
         [0047]     Referring now to  FIG. 7 , obturator  130  is illustrated as being fully inserted into conduit  110 . While inserted, the male luer portion  142  of cap  140  completely fills the female luer portion  146  of venous connector  145 , with locking members  148  and  149  engaging each other.  
         [0048]     In addition, as illustrated at distal end  114 , the sheath  135  of obturator  130  occludes apertures  125  while inserted into the conduit  110 . Accordingly, it will be appreciated that obturator  130  can be inserted into conduit  110  after hemodialysis treatment has been completed and while the main body  105  of the catheter apparatus  100  remains inserted in a patient. Due to the occlusion of the apertures  125  by the obturator  130 , blood clotting at the apertures  125  can be substantially eliminated. When it is desired to perform dialysis treatment, obturator  130  can be removed from conduit  110 . Upon such removal, a wiping action between the obturator  130  and apertures  125  additionally removes any minor clotting incident at the apertures  125 . Furthermore, subsequent flow of blood through the apertures  125  may also tend to remove any minor clotting incident at apertures  125 .  
         [0049]     It will be appreciated that the insertion and removal of obturator  170  with respect to conduit  150  can be performed in substantially the same manner as described above with respect to obturator  130  and conduit  110 . As such, obturator  170  can occlude apertures  165  and also perform a wiping action therewith to remove clotting incident at the apertures  165 . Thus, the novel features discussed above with respect to obturator  130  and conduit  110  may also apply for the obturator  170  and conduit  150 .  
         [0050]     As discussed, catheter apparatus  100  is adapted for use in hemodialysis treatment. In operation, a substantial portion of the main body  105  of the apparatus can be initially inserted into a patient. In particular, the distal ends  114  and  154  of conduits  110  and  150  may be inserted into a patient&#39;s vascular structure. If it is desired that hemodialysis treatment not be performed immediately, then obturators  130  and  170  can be inserted into respective ones of conduits  110  and  150 , and secured to connectors  145  and  185  through locking members  148  and  149 . The presence of the obturators in the conduits  110 / 150  prevents the accumulation of blood clots within the lumens  120 / 150  as well as on apertures  125 / 165  and open distal ends  114 / 154  of the conduits  110 / 150 .  
         [0051]     When it is desired to perform hemodialysis treatment, then obturators  130 / 170  can be removed from conduits  110 / 150 , causing a wiping action between the obturators  130 / 170  and apertures  125 / 165  to remove clotting incident at the apertures  125 / 165 . Appropriate hemodialysis equipment can then be connected to connectors  145  and  185 , thereby providing a fluid path for the patient&#39;s blood to pass through lumens  120  and  150  of the conduits. During hemodialysis treatment, the sizing and placement of apertures  125 / 165 , as well as the removal of blood clots incident thereto, allow for a high blood flow rate through the catheter apparatus  100 .  
         [0052]     With particular regard to the wiping action between the obturators  130 / 170  and apertures  125 / 165 , the obturators may be formed to include a variable surface texture that enhances the wiping action. For example, the surface texture may be configured to include raised hair-like bristles. Thus, as the obturators  130 / 170  are removed, the bristles may contact the apertures  125 / 165  and jostle loose any clotting incident at the apertures  125 / 165 . The surface texture may be formed in a variety of manufacturing processes and is not limited to bristles, but may include other shapes and types of surface textures. In particular, the surface texture should be designed and configured to provide sufficient frictional contact with the apertures  125 / 165  in order to provide proper removal of clotting. Further, the surface texture may be formed continuously along the length of the obturators  130 / 170  or selectively along the lengths thereof, such as one or more rings, a helical pattern, etc. Thus, upon removing the obturators  130 / 170 , the surface texture of the obturators  130 / 170  may further facilitate wiping action between the obturators  130 / 170  and the apertures  125 / 165  to remove clotting incident at the apertures  125 / 165 . In addition to removing the obturators  130 / 170  with a single extraction stroke, the obturators  125 / 165  may be selectively moved axially back and forth or rotated past the apertures  125 / 165  in order to enhance the removal of clotting from the apertures  125 / 165 .  
         [0053]     After hemodialysis treatment is finished, a new set of sterile obturators  130 / 170  can be inserted into the respective ones of the conduits  110  and  150  and secured to connectors  145  and  185  through locking members  148  and  149 . In this regard, it will be appreciated that obturators  130 / 170  can be implemented as sterile, disposable items that are replaced after each hemodialysis treatment. While inserted, the presence of the obturators  130 / 170  in the conduits  110 / 150  prevents the accumulation of blood clots within the lumens  120 / 150  as well as on apertures  125 / 165  and open distal ends  114 / 154  of the conduits  110 / 150  between successive hemodialysis treatments. When it is desired to commence hemodialysis treatment again, the new obturators  130 / 170  can be removed in the manner previously discussed.  
         [0054]     It will be appreciated that various aspects of the present disclosure provide significant advantages over prior approaches to hemodialysis catheters. The use of obturators  130 / 170  to reduce blood clotting removes the need for costly repetitive applications of Heparin to the catheter apparatus  100  before or after hemodialysis treatment. In addition, the reduced blood clotting at the apertures  125 / 165  allows for the apertures to be sized with large cross-sectional areas, thereby improving blood flow rates through the apparatus  100 .  
         [0055]     The foregoing disclosure is not intended to limit the present disclosure to the precise forms or particular fields of use disclosed. It is contemplated that various alternate embodiments and/or modifications to the present disclosure, whether explicitly described or implied herein, are possible in light of the disclosure. Where applicable, the ordering of various steps described herein can be changed, combined into composite steps, and/or dissected into sub-steps to provide features described herein.