5,374,245
`[11] Patent Number:
`[19]
`United States Patent
`*
`
`Mahurkar [45] Date of Patent:~Dec. 20, 1994
`
`
`US005374245A
`
`[76]
`
`[54] REINFORCED MULTIPLE-LUMEN
`CATHETER AND APPARATUS AND
`METHOD FOR MAKING THE SAME
`Inventor:
`Sakharam D. Mahurkar, 6171 N.
`Sheridan Rd., #1112, Chicago, Il.
`60660
`The portion of the term of this patent
`esguer to Jun. 22, 2010has been
`[21] Appl. No.: 55,830
`[22] Filed:
`Apr. 28, 1993
`
`[*] Notice:
`
`.
`
`19 Claims, 17 Drawing Sheets
`
`_
`
`Dow Corning, Fabricating With Silastic Silicone Rubber,
`
`FOREIGN PATENT DOCUMENTS
`834211
`2/1976 Belgium .
`1092927
`1/1981 Canada .
`: eons wri083 Canada
`1193508 of 1984 Canada.
`1167727 5/1984 Canada «
`(List continued on next page.)
`OTHER PUBLICATIONS
`&
`8
`©1990.
`McIntoshet al., “Double Lumen Catheter,” J.A.M.A.,
`Feb. 21, 1959 pp. 137/835-138/836.
`Dorland’s Ilustrated Medical Dictionary, 25th Ed., W.
`List
`i
`t
`.
`(List continued on next page.)
`Primary Examiner—Ralph A. Lewis
`Attorney, Agent, or Firm—Arnold, White & Durkee
`[57]
`ABSTRACT
`A method of making amultiple-lumen catheter using a
` 00-extrusion die comprises the step of forming an elon-
`gated cylindrical tube madeofsilicone and having an
`internal septum extending along the length thereof to
`form at least a pair of longitudinal Jumens. While the
`elongated cylindrical tube is being formed, a nylon
`reinforcing strip is arranged inside the tube such that the
`‘strip extends along the length of the tube. The tube is
`solidified and cut into individual multiple-lumen cathe-
`ters. The nylonstrip includes a pair of orthogonal side
`plates which aid in anchoring the nylon strip within the
`solidified tube.
`
`An apparatus for making the multiple-lumen catheter
`comprises a co-extrusion die, a silicon extruder for in-
`jecting silicone into the die, and a pair of rollers for
`feeding a nylon strip into the die. The co-extrusion die
`has a circular opening containing a
`pair of mandrels
`:
`wa:
`P :
`extending within the die for a predetermined length, the
`mandrels being arranged substantially parallel to each
`other with a gap therebetween. The rollers feed the
`nylon strip into the gap between the mandrels while the
`extruder is injecting the silicone into the die.
`8
`
`Nevro Corp.
`Ex. 1013
`U.S. Patent No. 7,891,085
`
`Related U.S. Application Data
` Continuation-in-part ofSer. No. 776,873, Oct. 16, 1991,
`Pat. No. 5,221,244, which is a continuation of Ser. No.
`463,285, Jan. 10, 1990, abandoned, and a continuation-
`in-part of Ser. No. 903,896, Jun. 25, 1992, abandoned.
`
` ;
`
`[63]
`
`[56]
`
`Cy me Ch. secreOdOB
`[58] Field of Search o....cccccssssssscssessssseeesee 604/43-45,
`604/264, 280, 281, 282
`.
`References Cited
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`
`Nevro Corp.
`Ex. 1013
`U.S. Patent No. 7,891,085
`
`

`

`Page 2—_——
`
`5,374,245
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`.
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`.
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`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`
`.
`.
`.
`
`4,016,879
`4,027,668
`4,037,599
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`4,096,860
`4,098,275
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`4,217,895
`4,245,383
`4,257,416
`4,270,535
`
`4/1977
`Mellor .
`Dunn .
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`Raulerson .
`Thow .
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`7/1978
`Sorensonet al.
`Frisch .
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`Megahed .
`1/1979
`Mahurkar .
`2/1979
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`.
`9/1979
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`Jacobsen et al.
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`.
`Youval et al.
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`.
`Bogue et al.
`(List continued on next page.)
`
`.
`
`.
`
`.
`
`.
`
`FOREIGN PATENT DOCUMENTS
`36642
`9/1981
`European Pat. Off.
`.
`0079719
`11/1982
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`.
`79719
`3/1983
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`.
`333308
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`.
`322225
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`.
`592193
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`2297640
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`821344
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`2530958
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`France .
`935625
`11/1955
`Germany .
`(List continued on next page.)
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`B. Saunders Co., Philadelphia, 1974, p. 274.
`Tsuchida et al., “Single Two-Lumen Cannula Dialy-
`sis”, Toboku Journal Exp. Med., 1974, pp. 114, 159-101.
`Tsuchida et al., “Design of a Two-Lumen-Piercing
`Needle That is Capable of Carrying Out Dialysis By
`Single Puncture”, Journal of The Urological Society of
`Japan, vol. 65 (12), 1974, pp. 805-807.
`Brenner & Rector, The Kidney, vol. I, W. B. Saun-
`ders Co., Philadelphia, 1976, p. 164.
`(List continued on next page.)
`
`

`

`Page 3
`
`
`5,374,245
`
`.
`
`U.S. PATENT DOCUMENTS
`;
`tages S198 Seae .
`4,403,983
`3/1983 Edelman etal
`-
`4403°985
`9/1983 Boretos
`4406656 9/1983 Hattler cal. .
`4,419,095 12/1983 Nerbergall et al.
`4,443,333
`4/1984 Mahburkar .
`4451252 571984 Marth
`4452473 6/1984. Ruschke .
`4,462,778
`7/1984 Calcagni ....scccsssssseeeeeen 264/173
`4,473,369
`9/1984 Lueders et al.
`.
`4,484,585 11/1984 Baier .
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`4,543,087 9/1985 Sommercorn etal. .......... 604/43
`4,547,193 10/1985 Rydell .
`4568329 2/1986 Mahurkar .
`4,583,968
`4/1986 Mahurkar
`4,592,749
`6/1986 Ebling etal. .
`.
`4,617,433 10/1986 Hoshikawaet al.
`4,619,643 10/1986 Bai sessccsrsrsennerectetenense 604/43
`4,623,327 11/1986 Mahurkar .
`4,626,240 12/1986 Edelman etal. .
`4,643,711
`2/1987 Bates .
`.
`4,661,110 4/1987 Fortier et al.
`4,682,978
`7/1987 Martin ....cs.cccssccsssssssssessscesesess 604/43
`4,684,363
`8/1987 Arietal. .
`4,692,141
`9/1987 Mahurkar ooecsccssssssssssssseenee 604/43
`toyoan ions oe ctal .
`4753640 6/1988 Nichols etal. .
`4,762,128
`8/1988 Rosenbluth .
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`9/1988 Bates .
`4,790,813 12/1988 Kensey .
`4,795,439
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`
`4,878,492 11/1989 Sinofsky .
`4,894,057
`1/1990 HHOWES veveccsccsssssecesceesecesssseses 604/280
`4,904,431
`2/1990 O’Maleki .....
`». 264/103
`
`4,995,865 2/1980 Gaharaet al.
`-
`5,006,291
`4/1991 Fish ..sssseseueuniesnstennee 264/103
`5,063,018 11/1991 Fontirrocheetal. .
`ote00 e099 Rarpiel
`
`r+ 604/43
`in et al. .....
`oe
`
`w. 604/43
`5,221,255
`6/1993 Mahurkar et al.
`.
`6/1993 Maburkar et al. svssssssssssssse 604/43
`5,221,256
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`2259865
`6/1974 Germany.
`3010841 of 1980 Germany .
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`°
`apan .
`3427346
`1/1986 Netherlands .
`688450 3/1952 United Kingdom .
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`1503469 10/1976 United Kingdom .
`onesie 3/ons uated Kingdom .
`3404043 lovieke Wieo
`wost/oaés 1/1984 WIPO.
`’
`
`OTHER PUBLICATIONS
`ASAIO Abstracts, vol. 5, 22nd Annual Meeting, San
`Francisco, Calif., Apr., 1-3, 1976, p. 164.
`Kaplan et al., “A Co-Axial Dual Flow Catheter/Can-
`nula For Single Puncture Dialysis”, Dialysis & Trans-
`plantation, Dec./Jan. 1977, pp. 38-40, 42,84.
`“Terumo Cozxial Dual Flow Catheter’, Terumo
`America, Inc. Apr., 1979 (two pages).
`Reus et al. “Double~Lume Catheter in Extracorporeal
`Hemodialysis” Archives of Internal Medicine, vol. 113,
`Apr. 1964.
`
`

`

`5,374,245
`
`WALSAS
`
`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 1 of 17
`
`SISATVIG
`
`
`

`

`Dec. 20, 1994
`
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`Sheet 2 of 17
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`5,374,245
`
`U.S. Patent
`
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`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 3 of 17
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`5,374,245
`
`
`
`

`

`U.S. Patent
`
`Dec.
`
`20, 1994
`
`Sheet 4 of 17
`
`5,374,245
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`Dec. 20, 1994
`
`Sheet 5 of 17
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`U.S. Patent
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`Dec. 20, 1994
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`Sheet 6 of 17
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`5,374,245
`
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`

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`U.S. Patent
`
`Dec. 20, 1994
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`U.S. Patent
`
`Dec. 20, 1994
`
`Sheet 8 of 17
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`5,374,245
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`

`Sheet 9 of 17
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`5,374,245
`
`US. Patent
`
`Dec. 20, 1994
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`FIG.25
`FIG.26FIG.27FIG.28
`
`

`

`U.S. Patent
`
`Dec. 20, 1994
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`Sheet 12 of 17
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`U.S. Patent
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`

`1
`
`5,374,245
`
`REINFORCED MULTIPLE-LUMEN CATHETER
`AND APPARATUS AND METHOD FOR MAKING
`THE SAME
`
`REFERENCE TO RELATED APPLICATION
`
`The present application is a continuation-in-part of
`U.S. application Ser. No. 07/903,896 filed Jun. 25, 1992
`(now abandoned), and U.S. application Ser. No.
`07/776,873 filed Oct. 16, 1991 (now issued as U.S. Pat.
`No. 5,221,244), which is a continuation of U.S. applica-
`tion Ser. No. 07/463,285 filed Jan. 10, 1990 (now aban-
`doned).
`
`FIELD OF THE INVENTION
`
`The present invention relates generally to multiple-
`lumen catheters for use in medical applications such as
`hemodialysis where fluids must flow simultaneously to
`and from a patient. In particular, the present invention
`relates to multiple-lumen catheters which are con-
`structed to avoid deformation or collapse of one or
`more of the lumens.In addition, the invention relates to
`an apparatus and method for making multiple-lumen
`catheters using a co-extrusion die. The invention is also
`particularly concerned with a multiple-lumen catheter
`which permits the catheter to be positioned in conve-
`nient anatomical sites during the periods between suc-
`cessive extracorporeal blood treatments to avoid patient
`discomfort and accidental displacement of the catheter,
`and to facilitate sterile attachment of the catheter to the
`patient during such periods.
`BACKGROUND OF THE INVENTION
`
`Dual-lumen catheters have come into widespread use
`for extracorporeal blood purification procedures such
`as hemodialysis. Blood is withdrawn from the patient
`through one of the lumensof the catheter and supplied
`to a hemodialysis unit where the blood is purified, and
`the resulting purified blood is then returned to the pa-
`tient through the other lumen of the catheter. Examples
`of such catheters are shown in U.S.Pat. Nos. 4,134,402;
`4,583,968; 4,568,329 and 4,692,141.
`At the present time most dual-lumen catheters used
`for hemodialysis are made of either polyurethane or
`silicone rubber. The polyurethane catheters are suffi-
`ciently rigid that they can be introducedinto a patient’s
`vein percutaneously, without surgery, but such cathe-
`ters tend to be incompatible with by the human body
`whenleft in place for long periods oftime (e.g., a month
`or more). The silicone catheters can be left in place
`indefinitely without allergic reactions or traumatic
`problems in most patients, but the initial insertion of
`such catheters usually requires surgical intervention;
`the soft, pliable, elastic properties of the silicone which
`contribute to its compatibility with the human bodyare
`the same properties that makeit difficult or impossible
`to insert such catheters percutaneously into a patient’s
`vein.
`
`SUMMARY OF THE INVENTION
`
`It is a primary object of this invention to provide an
`improved multiple-lumen catheter which can be made
`of silicone or other relatively soft, elastic materials
`whichare unlikely to be rejected by the body, and thus
`can be used for long-term applications, and yet can be
`inserted into a patient without surgery.
`It is another important object of this invention to
`provide an improved multiple-lumen catheter which
`
`15
`
`20
`
`25
`
`35
`
`45
`
`30
`
`35
`
`65
`
`2
`can be madeofsilicone, and yet can be inserted with the
`use of a needle, guide wire and peel-apart sheath,i-e.,
`without surgical intervention.
`A further object of this invention is to provide an
`improved multiple-lumen catheter which can be
`adapted for long-term use in femoral veins with little or
`no danger of infection. In this connection, a related
`object of the invention is to provide such an improved
`catheter which permits the accesssite for the catheter to
`be located above the thighs of the patient.
`A still further object of this invention is to provide an
`improved apparatus and method for making a multiple-
`lumen catheter.
`Another object of this invention is to provide an
`improved multiple-lumen catheter-connecting system
`which permits the catheter to remain relatively stable
`during the entire time the catheter remains inserted in
`the patient, even during long-term use of the catheter
`extending over numerous extracorporeal blood treat-
`ments. In this connection, related objects of the inven-
`tion are to provide such a catheter-connecting system
`which significantly improves the comfort level of the
`patient in whom the catheter is inserted, and which
`greatly reduces the risk of venous damage.
`In accordance with the present invention, the forego-
`ing objectives are realized by providing a multiple-
`lumen catheter, comprising an elongated cylindrical
`tube madeofa soft elastic material and having an inter-
`nal septum extending along the length thereof to form a
`pair of longitudinal lumens; and a reinforcing member
`extending along the full length of at least one of the
`lumens for transmitting forces applied to the proximal
`end of the tube to the distal end of the tube. In a pre-
`ferred embodiment, the reinforcing memberis I-shaped,
`is embedded in the septum, and is made of a material
`which is substantially stiffer than the material of the
`tube so that the catheter can be advanced against a
`resistance by the application of force to the proximal
`end of the catheter. The reinforcing memberalso avoids
`deformation and/or collapse of one or more of the lu-
`mens when a pressure gradient exists across the septum.
`This invention also provides an apparatus for making
`a multiple-lumen catheter, comprising a co-extrusion
`die having a pair of mandrels extending along a portion
`of the length of the die, and an extruder androllers for
`simultaneously feeding different resins through the co-
`extrusion die. In a preferred embodiment, each of the
`mandrels has a D-shaped transverse cross-section such
`that each of the mandrels has a flat side extending along
`the length thereof. The flat side of one of the mandrels
`is positioned opposite to the flat side of the other of the
`mandrels, the flat faces being separated to form a gap
`between them. The extruder feeds a soft, elastic first
`resin into the co-extrusion die, and the rollers simulta-
`neously feed a substantially stiffer second resin into the
`gap between the mandrels.
`In addition,
`this invention provides a method for
`making a multiple-lumen catheter, the method compris-
`ing the steps of: (1) forming an elongated cylindrical
`tube with an internal septum extending along the length
`thereof to form a pair of longitudinal lumens; (2) while
`the elongated cylindrical tube is being formed, a rein-
`forcing memberis arranged within the septum; and (3)
`solidifying the elongated cylindrical tube.
`Furthermore,
`this invention provides a multiple-
`lumen catheter assembly, comprising a multiple-lumen
`catheter having a distal end and a proximal end; a hub
`
`

`

`3
`having one end fastened to the proximal end of the
`catheter; and extension tubes each having one end fas-
`tened to the opposite end of the hub from the catheter.
`The distal end of the catheter is bent back toward the
`extension tubes to form a bend having a predetermined
`shape. The bend is adapted to flex and deform from the
`predetermined shape in response to an external force
`and is adapted to return to the predetermined shape in
`response to removal of the external force.
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Other objects and advantages of the invention will
`become apparent upon reading the following detailed
`description and upon reference to the accompanying
`drawings, in which:
`FIG.1 is a perspective view of a dual-lumen hemodi-
`alysis catheter assembly embodying the present inven-
`tion;
`FIG.2 is an enlarged longitudinal section taken along
`a diameter of the distal portion of the catheter of FIG.
`1, perpendicular to the septum inside the catheter, as
`generally illustrated by line 2—2 in FIG.1;
`FIG. 3 is an end elevation taken at the distal end of
`the catheter portion shownin FIG.2, as illustrated by
`line 3—3 in FIG.2;
`FIG.4 is a section taken generally along line 4—4 in
`FIG.2;
`FIG.5 is a section taken generally along line 5—5 in
`FIG.2;
`FIG.6 is a section taken generally along line 6—6 in
`FIG.2;
`FIG. 7 is an enlarged horizontal section taken
`through the center of the y-shaped hub of the catheter
`of FIG.1;
`FIG.8 is a section taken generally along line 8—8 in
`FIG.7;
`FIG.9 is a section taken generally along line 9—9 in
`FIG.7;
`FIG.10 is a section taken generally along line 10—10
`in FIG.7;
`FIG.11 is a fragmentary longitudinal section through
`the main bodyportion of a dual lumen catheter, normal
`to the septum, containing a modified reinforcing mem-
`ber;
`FIG.12 is a section taken generally along line 12—12
`in FIG. 11;
`FIG. 13 is a perspective view of a modified dual-
`lumen hemodialysis catheter assembly embodying the
`invention;
`FIG. 14 is an enlarged longitudinal section taken
`generally along line 14—14 in FIG.13;
`FIG. 15 is an end elevation taken at the distal end of
`the catheter portion shown in FIG.14, as illustrated by
`line 15—15 in FIG. 14;
`FIG.16 is a section taken generally along line 16—16
`in FIG. 14;
`FIG.17 is a section taken generally along line 17—17
`in FIG. 14;
`FIG.18is a section taken generally along line 18—18
`in FIG.14;
`FIG.19 is a longitudinal section similar to FIG. 2 but
`showing a modified embodimentof the invention;
`FIG. 20 is an end elevation taken at the distal end of
`the catheter portion shown in FIG.19, as illustrated by
`line 20—20 in FIG. 19;
`FIG.21is a section taken generally along line 2i—21
`in FIG. 19;
`
`30
`
`4
`FIG.22 is a section taken generally along line 22—22
`in FIG.19;
`FIG.23 is a section taken generally along line 2323
`in FIG.19;
`FIG.24 is a longitudinal section similar to FIG. 2 but
`showing another modified embodiment of the inven-
`tion;
`FIG.25 is an end elevation taken at the distal end of
`the catheter portion shown in FIG. 24,as illustrated by
`line 25—25 in FIG.24;
`FIG.26 is a section taken generally along line 26—26
`in FIG.24;
`FIG.27 is a section taken generally along line 27—27
`in FIG.24;
`FIG.28 is a section taken generally along line 28—28
`in FIG. 24,
`FIG.29 is a longitudinal section similar to FIG. 2 but
`showing a further modified embodiment of the inven-
`tion;
`20.
`FIG.30 is an end elevation taken at the distal end of
`the catheter portion shownin FIG.29,as illustrated by
`line 30—30 in FIG.29;
`FIG.31 is a section taken generally along line 31—31
`in FIG. 29;
`FIG.32 is a section taken generally along line 32—32
`in FIG. 29;
`FIG.33is a section taken generally along line 33—33
`in FIG.29:
`FIG. 34 is a perspective view of an apparatus for
`making a multiple-lumen catheter, the apparatus includ-
`ing a co-extrusion die;
`FIG.35 is an enlarged section taken generally along
`line 35-35 in FIG.34;
`FIG.36 is an enlarged section taken generally along
`line 36—36 in FIG. 35:
`FIG.37 is an enlarged perspective view ofthe distal
`portion of the catheter embodying the present inven-
`tion, the catheter having a conical tip;
`FIG.38 is an enlarged section taken generally along
`line 38—38 in FIG.37;
`FIG.39 is an enlarged section taken generally along
`line 39—39 in FIG.37;
`FIG.40 is an enlarged section taken generally along
`line 40—40 in FIG. 37;
`FIG.41 is an enlarged perspective view ofthe distal
`portion of a modified catheter embodying the invention,
`the catheter having a sliced tip;
`FIG.42 is an enlarged section taken generally along
`line 42—42 in FIG.41,
`FIG.43 is an enlarged section taken generally along
`line 43—43 in FIG. 41;
`FIG.44 is an enlarged section taken generally along
`line 44—44 in FIG.41;
`FIG. 45 is an enlarged perspective view ofthe distal
`portion of a modified catheter embodying the invention,
`the catheter having a blockedtip;
`FIG.46 is an enlarged section taken generally along
`line 46—46 in FIG.45;
`FIG.47 is an enlarged section taken generally along
`line 47—47 in FIG.45;
`FIG.48 is an enlarged section taken generally along
`line 48—48 in FIG.45;
`FIG.49 is a perspective view of a dual-lumen cathe-
`ter assembly with a U-bend in the catheter, embodying
`the present invention;
`FIG.50 is a perspective view ofa triple-lumen cathe-
`ter assembly with a U-bend in the catheter, embodying
`the present invention; and
`
`5,374,245
`
`10
`
`15
`
`25
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`

`5
`FIG.51 is a side elevation of the catheter assembly in
`FIG.49, illustrating the extensions tubes, the hub, and a
`proximal portion of the catheter in three different posi-
`tions.
`
`While the invention is susceptible to various modifi-
`cations and alternative forms, specific embodiments
`thereof have been shown by way of example in the
`drawings and will herein be described in detail. It
`should be understood, however, that it is not intended
`to limit the invention to the particular forms disclosed,
`but on the contrary, the intention is to coverall modifi-
`cations, equivalents, and alternatives falling within the
`spirit and scope of the invention as defined by the ap-
`pendedclaims.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`Turning now to the drawings and referring first to
`FIGS. 1-6, there is shown a dual-lumen hemodialysis
`catheter 10 of the general type described in Mahurkar
`US. Pat. No. 4,583,968,
`issued Apr. 22, 1986, for
`“Smooth Bore Double Lumen Catheter’. This catheter
`10 has a cylindrical body portion 11 made ofsilicone.
`The body portion 11 is hollow exceptfor a flat, longitu-
`dinal, diametral septum 12 which divides the interior of
`the hollow cylinder into two parallel lumens 13 and 14,
`each having a D-shaped cross section (FIGS. 2 and 6).
`Asillustrated by the arrows in FIG. 2, the lumen 13 is
`the blood-intake lumen, and the lumen 14 is the blood-
`return lumen.
`At the distal end of the catheter, the exterior surface
`of the cylinder 11 merges into a smoothly tapered coni-
`cal tip 15. On the inside, the blood return lumen 14
`extends longitudinally all the way through the tip 15,
`bending slightly as it passes through the tip so that it
`opensat 16 near the center of the distal end of the coni-
`cal tip, as can be seen in FIGS. 2 and 3. Within the tip
`15, the cross-sectional shape of the lumen 14 gradually
`changes from D-shaped at the proximal endofthe tip 15
`(see FIG. 4) to circular at the distal end of the tip (see
`FIG.3). The transition from D to circular is illustrated
`by the brokenlines in FIG.3.
`In addition to the opening 16 at the distal end of the
`blood-return lumen 14, a pair of apertures 17 and 18 are
`formedin the side wall of the return lumen. These aper-
`tures 17 and 18, which are spaced longitudinally away
`from the distal opening 16 toward the proximal end of
`the catheter, ensure the flow of blood through the re-
`turn lumen 14 even in situations where the distal open-
`ing 16 might become wholly or partially blocked. The
`area of the apertures 16, 17 and 18 is preferably at least
`equal to the transverse cross-sectional area of the return
`lumen 14.
`In order to provide a longitudinal spacing between
`the distal openings of the two lumens 13 and 14, the
`blood-intake lumen 13 is terminated at an opening 21 in
`the side wall of the catheter. Additional openings 22-24
`spaced longitudinally from the opening 21 permit blood
`to enter the lumen 13 freely without excessive vacuum
`in the event of a blockage of the opening 21 against the
`wall of the vein into which the catheter 10is inserted.
`At the proximal end of the catheter 10, the two D-
`shaped lumens 13 and 14 open into a Y-shaped connec-
`tor or hub 30 which forms two internal passageways 31
`and 32 (see FIGS. 7-10) communicating with the proxi-
`mal ends of the catheter lumens. As can be seen in
`FIGS.7 and 9, the distal ends of the hub passageways
`31 and 32 are D-shaped so that they form extensions of
`
`15
`
`20
`
`25
`
`30
`
`40
`
`45
`
`60
`
`65
`
`3,374,245
`
`6
`the catheter lumens 13 and 14, respectively. The pas-
`sageways 31 and 32 diverge from each other and assume
`a circular cross section (see FIG. 10) as they extend
`toward the proximal end of the hub, and theyalso in-
`crease in cross-sectional area, as can be seen in FIGS. 7
`and 10. The hub 30 is preferably molded in place on the
`end of the catheter, using moid inserts to form the hub
`passageways 31 and 32. Alternatively, the walls of the
`catheter lumens may be expandedat the proximal end of
`the catheter to fit over the corresponding portions of a
`preformed hub 30 with the inside walls of the catheter
`lumens being bondedto the mating walls of the hub 30.
`To facilitate connection of the catheter hub 30 to the
`conventional tubes leading to a dialysis unit, and also to
`accommodate a pair of clamps for opening and closing
`the blood intake and return passageways, the hub 30
`forms a pair of extension tubes 40 and 41 (FIG. 1).
`These extension tubes 40 and 41 are long enough to
`receive a pair of conventional clamps 42 and 43 for
`opening andclosing the respective tubes. The extension
`tubes 40 and 41 are relatively soft and flexible, so that
`they can be easily manipulated andalso easily closed by
`the pressure of the clamps 42 and 43. The clamps 42 and
`43 serve as on-off valves for controlling the flow of
`blood between the catheter and the dialysis unit. At the
`proximal end of the hub 30, the hub passageways 31 and
`32 open onto a pair of ferrules 44 and 45 formed as
`integral parts of luer connectors 46 and 47. The luer
`connectors serve as coupling means for coupling the
`proximal ends of the extension tubes to theflexible tubes
`leading to the extracorporeal blood treatment unit.
`In accordance with one aspect of the present inven-
`tion, a reinforcing member is embedded in the septum
`12 and extends along the full length of the intake lumen
`13. The reinforcing memberis madeof a material which
`is substantially stiffer than the silicone used to form the
`main body of the catheter, so that the catheter can be
`advanced against a resistance by the application of force
`to the proximal end of the catheter. In the illustrative
`embodimentof FIGS.1-6, the reinforcing memberis in
`the form of a flat polymeric strip 50 inserted longitudi-
`nally within a hollow septum 12.
`The reinforcing strip 50 is made of a material thatis
`stiff enough to transmit longitudinally applied forces
`from the proximal end ofthe catheterto the conical tip
`at the distal end of the catheter so that the catheter can
`be readily inserted into a patient percutaneously, ie.,
`without surgical intervention. One suitable material for
`the reinforcing strip is nylon, which provides the requi-
`site degree of stiffness in a strip 0.135 inch wide and
`0.012 inch thick. A preferred type of nylon is Nylon
`1000, manufactured by Hoechst Celanese Corporation,
`Short Hills, N.J.
`With the reinforcing strip, a silicone catheter can be
`easily inserted through a peel-apart sheath. Such a
`sheath is typically used after a guide wire has been
`introduced into a patient’s vein by use of an access
`needle. The puncture formed by the needle is subse-
`quently dilated by a smooth plastic tip on the end of a
`dilator telescoped through the pull-apart sheath and
`inserted a short distance into the vein. The dilator is
`then removed,
`the catheter is inserted through the
`sheath, andfinally the sheath is removed bystrippingit
`apart along two longitudinal tear lines.
`Without the reinforcing member provided by this
`invention, attempts to insert a silicone catheter by the
`technique described above have usually resulted in ra-
`dial expansion of the catheter at the entry to the sheath,
`
`

`

`7
`due to the frictional resistance of the silicone surface
`engaging the inside wall of the sheath. Rather than
`causing the catheter to slide through the sheath, the
`applied insertion force resulted in expansion of the soft,
`elastic silicone material of the catheter body against the
`proximal end of the sheath,
`thereby preventing the
`catheter from sliding through the sheath.
`With the present invention, however, the insertion
`force applied to the proximal end of the catheter is
`transmitted by the reinforcing memberto thetip of the
`catheter, thereby “pulling” the catheter through the
`sheath. That is, the relatively stiff reinforcing member
`provides the catheter with sufficient column strength
`for easy insertion through the sheath. Although pres-
`ently available materials that have the stiffness needed
`in the reinforcing material are not suitable for long-term
`implantation in the human body because of incompati-
`bility problems such as localized allergic reactions, the
`present invention enables the reinforcing material to be
`isolated from the body. Thus, in the embodiment of
`FIG.1, for example, the nylon reinforcing material is
`surroundedbythesilicone material of the hollow sep-
`tum. Therefore,
`it is only the silicone material that
`comesinto contact with internal bodytissues or fluids.
`In addition, the reinforcing member prevents collapse
`of one of the lumensdueto the pressure differential that
`normally exists across the septum of a dual-lumen cathe-
`ter while it is being used to withdraw blood under a
`negative pressure in one lumen and to return blood
`under a positive pressure in the other lumen. With a
`silicone catheter, it is possible for the septum and the
`outside wail of the negative-pressure lumen to collapse
`together, thereby closing that lumen. The reinforcing
`strip, however, providessufficient rigidity to the sep-
`tum to prevent such collapsing of the negative-pressure
`lumen. Even when the outer wall of the lumen is not
`reinforced, the curvature of that wall normally prevents
`it from being collapsed against the septum as long as the
`septum itself cannot be distorted substantially toward
`the outer wall.
`In the particular embodiment illustrated in FIGS.
`1-6, the cathetertip 15 is molded as a unitary part of the
`catheter tube. This is accomplished by pl