in the drawings , like numerals indicate like elements throughout . certain terminology is used herein for convenience only and is not to be taken as a limitation on the present invention . the terms “ distal ” and “ proximal ” refer to directions away from and closer to , respectively , the insertion tip of the catheter according to the present invention . the terminology includes the words specifically mentioned , derivatives thereof and words of similar import . the embodiments illustrated below are not intended to be exhaustive or to limit the invention to the precise form disclosed . these embodiments are chosen and described to best explain the principle of the invention and its application and practical use and to enable others skilled in the art to best utilize the invention . in fig1 , a dual lumen catheter assembly 100 is illustrated that includes a catheter 102 having a proximal end 104 , a distal end 106 , and an elongated body 108 extending therebetween . catheter 102 comprises first and second catheter lumens , one being known as a venous lumen for returning blood to the patient , and the other being known as an arterial lumen for withdrawing blood from the patient . while the catheter body 108 preferably has a generally circular cross section , the first and second lumens each may have a generally “ d - shaped ” cross section , juxtaposed from each other across a common sidewall . alternatively , the lumens of the catheter could have a round or oval cross - sectional shape , and the two lumens could be attached side - by - side or be split apart at the distal end . it is preferred that the cross section of the body 108 be a generally smooth curve to facilitate sealing of the patient &# 39 ; s skin around the body 108 at the incision site , as well as at the entrance to the vessel , to minimize bleeding . a hub 110 is affixed onto the proximal end 104 of catheter 102 , and preferably includes a suture wing that extends generally transverse of the body 108 and is shown to have two suture openings that allow an inserting physician to suture the hub 110 to the external skin of the patient into whom the physician has inserted the catheter assembly 100 to prevent the catheter assembly 100 from being dislodged from its inserted position within the patient . joined to the proximal ends of the first and second lumens of the catheter 102 are first and second extension tubes 112 that fluidly communicate respectively with the first and second lumens within conduits of hub 110 . proximal ends of the first and second extension tubes 112 preferably terminate at first and second connectors 114 , such as standard luer locks , as is well known in the art . first and second clamps 116 , such as a roberts clamps , are preferably disposed over the first and second extension tubes 112 and serve to releasably close off each of the first and second extension tubes , respectively , preventing fluid flow through each of the first and second extension tubes 112 when the respective clamps are in the closed position . preferably , a catheter tissue ingrowth cuff 118 is disposed along an exterior of the body 108 between the distal tip 106 and the hub 110 . the catheter tissue ingrowth cuff 118 is used for chronic catheter insertions , wherein the catheter assembly 100 is intended to be inserted into the patient for extended periods of time , such as for several months . the catheter tissue ingrowth cuff 118 is disposed within a subcutaneous tunnel according to methods known by those skilled in the art . with respect to fig2 and 3 , the present invention includes a distal tip protector 120 integrally defined on the distal tip 106 of catheter 102 . in these figures , the distal portion of the catheter is shown in position inserted within a venous vessel v . catheter 102 is shown to include first lumen 122 for withdrawal of fluids from venous vessel v , and second lumen 124 for returning blood that was withdrawn from the vessel to be returned to the vessel . the distal tip of second lumen 124 is located a distance distally of the distal tip of the first lumen , which minimizes any tendency of returned blood to be aspirated by the first lumen and which thus enhances the efficiency of the hemodialysis . flow of blood generally within the vessel v is shown by directional arrow a . flow of blood within first or arterial lumen 122 is shown by directional arrow b , with its intake occurring at first distal lumen opening 126 and preferably through one or more side ports 128 ; also , the distal tip of lumen 122 may be open . flow of blood within second or venous lumen 124 is shown by directional arrow c , with flow exiting from the lumen into the vessel from second distal lumen opening 130 and being parallel to vessel blood flow a . distal tip protector 120 is generally shaped like an umbrella or mushroom and extends proximally from the distal tip and radially outwardly , and has numerous pleats or folds 132 that allow the protector 120 to be compressed for insertion into the vessel . protector 120 also includes a generally rounded proximal or bottom edge 134 that allows the catheter to be eventually slid out of the vessel for removal . a plurality of through - openings 136 are defined on the protector serving as through - ways to allow blood flowing through the vessel past first distal opening 126 . pleats 132 define channels into the outer surface of protector 120 ; and , as best seen in fig4 to 6 in which an expanded protector 120 ′ of an alternate embodiment is illustrated , channels 135 define through - ways to allow blood to continue flowing through and past the protector with little impediment , when protector 120 ′ expands against the vessel wall . first distal lumen opening 126 is shown to be directed laterally , not axially , to further lessen the tendency of aspiration of returned blood exiting from second distal lumen opening 130 . however , such lateral orientation , without the protector 120 of the present invention , would make the opening susceptible to occlusion by the vessel wall . protector 120 , however , while being quite flexible to facilitate insertion and removal of the catheter into and from the patient , is sufficiently rigid for rounded bottom edge 134 to press against the vessel wall and to center the distal catheter portion within the vessel v thus preventing occlusion of first distal lumen opening 126 . preferably , the body 108 is constructed from a polymer or elastomer , such as polyurethane or silicone , with a radiopaque filler material therein to aid in locating the body 108 within the patient &# 39 ; s vessel after insertion , such as by ultrasound and fluoroscopy . however , those skilled in the art will recognize that other biocompatible materials may be used for the body 108 . preferably , the body 108 has a hardness of approximately 70 - a to 80 - a on the shore durometer scale , although those skilled in the art will recognize that the body 108 may be harder or softer . the thickness of tip protector 120 could be in the range of from about 0 . 0010 in ( 0 . 254 mm ) to about 0 . 0035 in ( 0 . 889 mm ), and more preferably , from about 0 . 0015 in ( 0 . 381 mm ) to about 0 . 0025 in ( 0 . 635 mm ). if the material used is silicone elastomer , the thickness may be slightly thicker . protector 120 could be molded integrally with catheter body 108 , but it could be solvent bonded or fused thereto . regarding holes 136 , they may each have a size of about 0 . 01 in ( 2 . 54 mm ) to about 0 . 10 in ( 25 . 4 mm ), and more preferably from about 0 . 03 in ( 7 . 62 mm ) to about 0 . 07 in ( 17 . 8 mm ). all holes 136 should be relatively spaced away a slight distance from distal tip 130 and bottom edge 134 to preserve structural integrity , and be spaced apart from each other about 0 . 02 in ( 5 . 08 mm ), for example . openings 136 could have different diameters from each other , if desired ; for example , the openings near to distal tip 130 could be smaller than those near rounded proximal or bottom edge 134 . the openings could have rounded , oblong or oval or other shapes , as desired . the holes could also be aligned in four or five columns extending longitudinally along the axis of the lumen . to insert the catheter assembly 100 into the patient , an incision is initially made near an insertion site on the patient &# 39 ; s skin , which is to be aspirated with a syringe or other introducer apparatus near or proximate the area to be catheterized . if the catheter assembly 100 is used for hemodialysis and the area to be catheterized is the internal jugular vein , the incision is made in the supra - clavicular triangle region . the exact location of the incision can be varied by the physician . initially , the proximal portion of the catheter would have been located within a subcutaneous tunnel in the subcutaneous area of the patient &# 39 ; s torso , using one of various tunneling techniques . in one preferred technique , the distal end region of the catheter would have been pulled through the tunnel from a remote end of the tunnel , with the tunnel formed using a trocar or other tunneling tool , leaving the proximal end region at least partially within the tunnel , with the proximal end extending beyond the tunnel and exterior of the patient . in accordance with the seldinger technique , a hollow needle is inserted through the incision and into the vein , and the vein is then aspirated . a guide wire is then passed through the needle and the needle is removed . next , after dilating the soft tissue track and venatory site , the catheter assembly 100 is inserted over the guide wire . this insertion technique eliminates the need for a sheath to be inserted over the guide wire , greatly reducing the risk of air embolism . in use , after the dialysis machine is connected to the catheter assembly 100 and turned on , the dialysis machine draws blood from the vessel through the first lumen 122 . in the event that the pressure drop in the vessel caused by the blood being drawn into the first lumen 122 forces the wall of the vessel toward the first distal opening 126 , the protector 120 prevents the vessel wall from totally occluding the first distal opening 126 and shutting off blood flow through the first lumen 122 . the blood drawn into the first lumen 122 flows to the hemodialysis machine where the blood is cleaned and processed . the blood is then pumped through the second lumen 124 for discharge back into the vessel through second distal opening 130 and side holes 136 . in fig4 to 6 another embodiment of the protected distal tip of the present invention is illustrated . the protector 120 ′ is shown to have a pleated design and have a plurality of through - ways or channels 135 defined into and axially along the outer surface thereof extending distally from the proximal end 134 thereof , through which blood may flow therepast when the protected distal tip is positioned within a blood vessel in a manner similar to that shown in fig2 . it will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof . it is understood , therefore , that this invention is not limited to the particular embodiments disclosed , but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims .
a multilumen catheter assembly including an elongated body defining a first lumen having a sidewall extending between its proximal end and a first lumen distal end proximate the body distal end and a first distal opening disposed proximate the first lumen distal end , and a second lumen connected to the sidewall and extending between the proximal end and a second lumen distal end proximate the body distal end , the second lumen distal end distal of the first lumen distal end . the second lumen includes a second distal opening disposed distally of the first distal opening . a self - expanding protector adjoins the elongate body distally of the first distal opening and extends from an inner edge along the elongate body outwardly and proximally to a free proximal edge that extends circumferentially about the elongate body proximate the first distal opening . the protector defins through - ways that permit blood flow past the protector .