embodiments of the presently disclosed catheters are discussed in terms of medical catheters for the administration of fluids and , more particularly , in terms of hemodialysis catheters . 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 presently disclosed catheters include , for example , hemodialysis , cardiac , abdominal , urinary , intestinal , in chronic and / or acute applications . in the discussion that follows , the term “ proximal ” will refer to the portion of a structure closer to an operator , while the term “ distal ” or will refer to the portion further from the operator . as used herein , the term “ subject ” refers to a human patient or other animal . the term “ operator ” refers to a doctor , nurse or other care provider and may include support personnel . referring now to fig1 - 2 , a catheter 10 includes a catheter body 20 and a catheter tip 40 . the catheter body 20 defines a longitudinal axis “ a ” and may have a substantially circular cross - section . the catheter body 20 defines a pair of lumens 22 , 23 extending the length of catheter 10 . alternately , the catheter 20 may define a third lumen for receiving a guidewire or the like . the lumens 22 , 23 may include oblong , kidney - shaped , and / or d - shaped cross - sectional configurations . a septum 24 defined by the catheter body 20 is disposed between the adjacent lumens 22 , 23 and can define at least a portion of each lumen 22 , 23 . in some embodiments , the catheter tip 40 has a substantially frusto - conical profile . the frusto - conical shape may aid in the insertion of the catheter 10 , for example , in time - sensitive circumstances in which acute catheters are utilized . the components of the catheter 10 may be fabricated from materials suitable for medical applications , such as , for example , polymers , silicone and / or polyurethane . the catheter body 20 is flexible and may be formed by injection molding or extrusion . the catheter body 20 may have a preformed bend in its normal condition to facilitate conforming to an internal body cavity or vessel in which the catheter body 20 is to be positioned . alternatively , catheter body 20 may be substantially straight . the catheter tip 40 may be fabricated from material suitable for medical application , including , for example , polymers , silicone , and / or polyurethane . in addition , the catheter tip 40 fabricated from the same material or a different material than catheter body 20 . in some embodiments , catheter tip 40 is formed separately from catheter body 20 and is secured to a distal end portion of the catheter body 20 . in certain embodiments , the catheter tip 40 is integrally or monolithically formed with the catheter body 20 . the catheter tip 40 includes a partition 44 . the catheter tip 40 and the partition 44 define the lumens 42 . an outer surface 47 of catheter tip 40 is tapered distally and approaches a closed , distal end 46 to aid insertion of the catheter 10 . while the distal end 46 is shown as having a rounded , blunt profile , other shapes and profiles of the distal end 46 are possible . when the catheter body 20 and the catheter tip 40 are assembled , the lumens 42 of tip 40 are in fluid communication with and are aligned with the lumens 22 , 23 of the catheter body 20 . similarly , the septum 24 and the partition 44 are aligned such that lumens 22 , 23 and the respective lumens 42 define substantially parallel and separate pathways parallel to the longitudinal axis a along the catheter body 20 . at least a distal portion of the septum 24 and a proximal portion of the partition 44 have substantially similar dimensions to provide a smooth transition between the catheter body 20 and the catheter tip 40 . the catheter tip 40 may include a pair of proximally extending connecting members 48 that are insertable into lumens 22 , 23 . the connecting members 48 are spaced to receive septum 24 and define channels 50 . the channels 50 are in fluid communication with the lumens 22 , 23 of the catheter body 20 when the catheter body 20 and the catheter tip 40 are assembled . the connecting members 48 may engage the lumens 22 , 23 with an interference or frictional fit , forming a substantially fluid tight seal with lumens 22 , 23 . alternatively or additionally , the connecting members 48 may be secured within with lumens 22 , 23 using chemical adhesives or mechanical coupling , such as by welding . referring now to fig3 a - 3c , a pair of side openings 52 is defined in the outer surface 47 of the catheter tip 40 . the side openings 52 are substantially elongated , oval shaped slots that extend along catheter tip 40 and are symmetrical about the longitudinal axis a . the side openings 52 allow fluid streams f , f ′ to travel between an environment , such as an internal body cavity , and the internal lumens 42 . the side openings 52 may have contoured edges formed , for example , by laser cutting , molding with catheter tip 40 , and / or otherwise smoothed to minimize flow disruption and thrombus formation . in a hemodialysis application , a proximal end portion of catheter body 20 ( fig1 ) is connected to a dialyzer ( not shown ) such that blood is withdrawn from a body vessel through one lumen 22 ( fig2 ), the arterial lumen , of the catheter body 20 via the respective side opening 52 of the catheter tip 40 and delivered to a dialyzer for purification . the purified blood is then returned to the body vessel through the second lumen 23 , the venous lumen , of the catheter body 20 via the other side opening 52 of the catheter tip 40 . because of the symmetrical configuration of the catheter body 20 , and the catheter tip 40 and the lumens 42 , either lumen 22 , 23 may serve as the arterial lumen or the venous lumen . because of the configuration of the catheter tip 40 , the blood flow stream f into the side opening 52 communicating with the arterial lumen 22 and the blood flow stream f ′ exiting the side opening 52 communicating with the venous lumen 23 are separated such that the degree of fluid recirculation is minimized . the symmetrical nature of the catheter tip 40 , the diametrically opposed positioning of side openings 52 along the tip 40 , and the elongated shape of side openings 52 enables the spacing between the fluid stream f ′ exiting venous lumen 23 and the fluid stream f entering arterial lumen 22 to be maximized , which minimizes the degree of recirculation of purified blood between the venous lumen 23 and the arterial lumen 22 of the catheter 10 ( fig1 ). specifically , blood enters proximally through the side openings 52 and exits distally through the side openings 52 . the outer surface 47 and the distal end 46 of the catheter tip 40 provide spacing that substantially minimizes the fluid stream f ′ exiting the venous lumen 23 from migrating toward the fluid stream f entering the arterial lumen 22 , which can also minimize the degree of fluid recirculation . referring now to fig4 a - 4c , a catheter tip 140 includes a proximal portion 141 and a distal portion 143 . the distal portion 143 of the catheter tip 140 gradually tapers towards a closed distal end 146 , which may have a blunt or a traumatic shape . the proximal portion 141 increases in diameter in a direction toward the distal portion 143 . the increase in diameter along proximal portion 141 provides a radially expanding surface proximal to side openings 152 . this radially expanding surface can direct fluid stream f ′ away from the side openings 152 . the side openings 152 can be similar in configuration to side openings 52 and define an elongated oval configuration formed along the sides of the outer surface 147 of catheter tip 140 . because of the configuration of the catheter tip 140 , the blood flow stream f into the side opening 152 communicating with an arterial lumen and the blood flow stream f ′ exiting the side opening 152 communicating with a venous lumen are separated such that the degree of fluid recirculation is minimized . referring now to fig5 a - 5c , a catheter tip 240 includes a proximal portion 241 and a distal portion 243 . the distal portion 243 has a substantially tapered profile that gradually tapers towards a closed distal end 246 . the catheter tip 240 defines a pair of side openings 252 disposed along opposed sides of the outer surface 247 of the catheter tip 240 . the proximal portion 241 of the catheter tip 240 is a curved spheroid region adjacent the distal portion 243 . the curved spheroid region of the proximal portion 241 provides a radially expanding surface proximal to the side openings 252 that directs fluid stream f ′ away from side openings 252 to minimize recirculation of fluid stream f ′ in the manner discussed above with respect to catheter tip 140 . referring now to fig6 a - 6c , a catheter tip 340 includes diametrically opposed planar surfaces 354 , a proximal portion 341 and a distal portion 343 . lateral surfaces 360 of proximal portion 341 diverge outwardly in a direction toward distal portion 343 . each planar surface 354 extends the length of the catheter tip 340 and converges inwardly approaching a blunt distal end 346 . side surfaces 362 of the distal portion 343 taper inwardly in a direction approaching the distal end 346 . side openings 352 are similar to openings 52 , 152 and 252 discussed above . each side opening 352 is positioned along a respective side surface 362 . the planar surfaces 354 direct fluid stream f ′ away from side openings 352 by providing a path of least resistance for fluid stream f ′ to flow toward distal end 346 . the lateral surfaces 360 of the proximal portion 341 also direct fluid outwardly of side openings 352 . referring now to fig7 a - 7c , a catheter tip 440 defines a pair of distally positioned , diametrically opposed side openings 452 along the outer surface of a catheter tip 440 . the side openings 452 extend through a portion of a distal end 446 of the catheter tip 440 . the side openings 452 are in fluid communication with internal lumens 442 of catheter tip 440 . the catheter tip 440 functions in a manner similar to that described above with respect to catheter tip 340 ( fig6 a - 6c ). referring now to fig8 a - 8c , a catheter 510 includes an elongated body 520 and a catheter tip 540 supported at the distal end of the elongated body 520 . the elongated body 520 defines first and second lumens ( not shown ) which extend from a proximal end of the catheter 510 toward the distal end of the catheter 510 . in some embodiments , the catheter tip 540 is substantially conical and tapers inwardly in the distal direction to define a blunt or a traumatic end . the catheter body 520 defines first and second side openings 526 diametrically opposed to one another along the length of body 520 . each side opening 526 is in fluid communication with a respective one of the first and second lumens . each side opening 526 has an elongated z - shaped configuration including a rectangular or rhombus - shaped central portion 527 a and triangular proximal and distal portions 527 b and 527 c . the apex of the triangular portion 527 b is at the proximal end of the triangular portion 527 b and the apex of the triangular portion 527 c is at the distal end of the triangular portion 527 c . in some embodiments , the rectangular portion 527 a defines a transverse axis t ( fig8 b ) which defines an acute angle θ with a longitudinal axis b defined by the catheter body 520 . for example , the angle θ can be between about fifteen degrees and about seventy - five degrees . in certain embodiments , sidewalls 529 defining a portion of rectangular portion 527 a and triangular portions 527 b and 527 c are substantially parallel to a longitudinal axis b defined by catheter body 520 . as discussed above , the side openings 526 are symmetrically positioned on opposite sides of the catheter body 520 and each of the side openings 526 communicates with a respective lumen of the catheter 510 . the side openings 526 facilitate separation of the fluid flow stream f into the arterial lumen of the catheter 510 and the fluid flow stream f ′ exiting the venous lumen of the catheter 510 . more specifically , because of the configuration of the side openings 526 , blood flow has a tendency to flow into a proximal end of the side opening communicating with the arterial lumen of the catheter body 520 and exit the distal end of the side opening 526 communicating with the venous lumen of the catheter body 520 . because of this , the fluid streams f and f ′ to and from the catheter 510 are spaced to minimize the degree of recirculation within the catheter body 520 . referring to fig9 a - 9c , a catheter 610 includes a body 620 defining side openings 626 that have rounded proximal and distal ends 627 . the ingress and egress points for fluid flow streams f , f ′ through arterial and venous lumens ( not shown ), respectively , are axially spaced apart as described above . thus , fluid stream f entering the arterial lumen and fluid stream f ′ exiting the venous lumen are circumferentially and axially spaced apart , to minimize the degree of recirculation . as compared to sharp edges , the rounded edges 627 of side openings 626 reduce shear stresses on the blood flow to reduce the likelihood of thrombus formation . referring to fig1 a - 10c , a catheter 710 defines a pair of diametrically opposed side openings 726 , each side opening having a proximal end 727 and a distal end 728 . the side openings 726 have a substantially teardrop - shaped profile with rounded ends . the taper of the teardrop shape of each side opening 726 tapers proximally from the proximal end 727 to the distal end 728 , with the proximal end 727 having a smaller radius of curvature than the distal end 728 . fluid stream f enters an arterial lumen at the proximal end 727 . fluid stream of f ′ exits a venous lumen at the distal end 728 . accordingly , proximal and distal flow of fluid streams f , f ′ through respective lumens are both axially and circumferentially spaced to minimize recirculation . referring to fig1 a - 11c , a catheter 810 defines a pair of diametrically opposed side openings 826 . each side opening 826 has a proximal end 827 and a distal end 828 and an elongated , truncated oval shape . the distal end 828 of each side opening 826 has a generally flat or planar shape . each side opening 826 tapers proximally and narrows toward the respective proximal end 827 , which has a curved shape . fluid stream f enters an arterial lumen at the proximal end 827 and fluid stream f ′ exits a venous lumen at the distal end 828 . accordingly , proximal and distal flow of fluid streams f , f ′ through respective lumens are both axially and circumferentially spaced from one another to minimize recirculation . referring to fig1 a - 12c , a catheter 910 defines a pair of diametrically opposed side openings 926 . each side opening 926 has a proximal portion 927 , a distal portion 928 , and a substantially pear - shaped profile . the distal portions 928 of each side opening 926 is arcuate and has a first diameter “ a 1 ”, and the proximal portion 927 of each side opening 926 is arcuate and has a second diameter “ a 2 ” that is smaller than diameter a 1 . the respective proximal portions 927 and distal portions 928 intersect along a transverse axis t ′ of catheter 910 . fluid stream f enters an arterial lumen at the proximal portion 927 , and fluid stream f ′ exits a venous lumen at the distal portion 928 . accordingly , proximal and distal flow of fluid streams f , f ′ through respective lumens are both axially and circumferentially spaced relative to one another to minimize recirculation . referring to fig1 a - 13c , a catheter 1010 defines a pair of diametrically opposed side openings 1026 . each side opening 1026 has a proximal portion 1027 and a distal portion 1028 and has a substantially l - shaped profile . the distal portion 1028 of each side opening 1026 extends across a portion of the surface of the catheter 1010 in transverse relation to a longitudinal axis a ′ of catheter 1010 . the proximal portion 1027 of each side opening 1026 extends along a portion of the surface of the catheter 1010 parallel to the longitudinal axis a ′ and intersects a respective distal portion 1028 . fluid stream f enters an arterial lumen at the proximal portion 1027 and exits a venous lumen at the distal portion 1028 . accordingly , proximal and distal flow of fluid streams f , f ′ through respective lumens are both axially and circumferentially spaced from one another . referring to fig1 a - 14c , a catheter 1110 defines a pair of diametrically opposed side openings 1126 . each side opening 1126 has a proximal portion 1127 , a distal portion 1128 , and a substantially figure eight - shaped profile . the proximal portion 1127 and distal portion 1128 of each respective side opening 1126 each have a shape defined by an arcuate distal portion intersecting an arcuate proximal portion , and are symmetric about a transverse axis b ″ of the catheter 1110 . fluid stream f enters an arterial lumen at the proximal portion 1127 , and fluid stream f ′ exits a venous lumen at the distal portion 1128 . accordingly , proximal and distal flow of fluid streams f , f ′ through respective lumens are both axially and circumferentially spaced from one another to minimize recirculation . although the illustrative embodiments of the present disclosure have been described herein with reference to the accompanying drawings , it is to be understood that the disclosure is not limited to those precise embodiments , and that various other changes and modifications may be effected therein by one skilled in the art without departing from the scope or spirit of the disclosure .
a medical catheter assembly includes a catheter tip coupled to a distal end of an elongate catheter member and is symmetric about a plane defined by a septum of the elongate catheter member . the catheter tip defines first and second lumens , and the catheter tip defines first and second openings in the distal portion of the catheter tip . each opening of the catheter tip is defined by a respective side surface of the catheter tip . each opening is in fluid communication with a respective one of the first and second lumens of the catheter tip and with a respective one of a pair of lumens defined by the elongate catheter member . the distance between upper and lower surfaces of the catheter tip decreases from a distal end of the proximal portion toward a closed distal end of the catheter tip .