a2) United States Patent
`US 6,173,199 B1
`(10) Patent No.:
`Gabriel
`(45) Date of Patent:
`Jan. 9, 2001
`
`
`US006173199B1
`
`(54) METHOD AND APPARATUS FOR
`INTUBATION OF A PATIENT
`
`(75)
`
`Inventor: Sabry Gabriel, Macon, GA (US)
`
`(73) Assignee: Syncro Medical Innovations, Inc.,
`Macon, GA (US)
`so
`
`(*) Notice:
`
`Under 35 U.S.C. 154(b), the term ofthis
`patent shall be extended for 0 days.
`
`(21) Appl. No.: 09/073,226
`.
`Filed:
`(22)
`May5, 1998
`
`(SL)
`Inte C17 cosunnnunmnnnnnrtnnnnn AGIB 5/05
`
`(52) US.CL 600/424: 128/899
`(58) Field of Search oo... cesses 600/424, 373;
`128/899; 604/264, 270, 280; 324/260, 207.11,
`00713
`
`
`
`
`5,271,400
`12/1993 Dumoulin ctal. .
`. 128/653.2
`5,273,025
`12/1993 Sakiyamaetal.
`w. 128/6
`
`5,316,024
`..
`5/1994 Hirsschi et al.
`128/899
`
`5,345,940 .
`9/1994 Seward etal. ..
`128/662.06
`128/772
`5,353,807 * 10/1994 DeMarco ....
`
`
`...
`» 128/653.1
`5,386,828 *
`2/1995 Owenset al.
`5/1995 Dumoulin et al...
`. 128/653.2
`5,419,325
`6/1995 Shapiro et al. we 128/653.1
`5,425,367
`5,431,640
`7/1995 Gabriel .
`
`ae rate anmoulin eb abe weer veo
`
`
`4/1996 Hernandezet al.
`604/264
`5,507,731
`8/1996 Avellanet et al.
`.
`.- 604/280
`5,542,938
`
`
`1/1997 Tanaka oe « 128/662.06
`5,596,991 *
`«. 600/114
`5,681,260 * 10/1997 Ueda et al.
`
`_ 128/899
`5,758,667 *
`6/1998 Slettenmark
`
`5/1999 Golden eta.
`5,902,238 *
`600/424
`
`5/1999 Vander Salm etal.
`5,906,579
`600/424
`(List continued on next page.)
`
`FOREIGN PATENT DOCUMENTS
`WO 96/05768
`2/1996
`(WO).
`WO 96/32060
`10/1996 oy,
`Primary Examiner—Marvin M. Tateef
`Assistant Examiner—Shawna J Shaw
`3,043,309
`7/1962, McCarthy vreeerrnnseseeeee 128/348
`(74) Attorney, Agent, or Firm—Amall Golden & Gregory,
`3,674,014
`- 128/2.05 R
`7/1972 Tillander
`
`
`
`4,004,298 V/L9F77 Freed coccessessenses rerenenes 3/1 LLP
`
`
`4,024,855 S/1977) Burcalo ooeeeeeeeseeteneetees 128/1 R
`
`
`12/1977 McKenna .
`4,063,561
`(57)
`ABSTRACT
`B/L9T8 MOOssun ..cessecccrscceseererseeeee 128/347
`4,077,412
`4,114,601 DQTB ADCIS oseeectseeeene 128/1 R A catheter having a distal end portion including a sensor
`
`
`
`1/1979 Smit...
`128/303 R
`4,134,405
`responsive to the presence of a magnetic field or flux of a
`6/1982 Eldridge, Ir.
`” 128/348
`4,336,806
`predetermined strength is provided. Also provided is a
`
`+ 128/283
`4,338,937
`7/1982 Terman .
`catheter system which further includes an external magnet.
`
`vo 128/737 ee the
`4,416,289
`11/1983. Bresler ..
`distal
`end
`portion
`te selected to
`reesond
`4,431,005
`2/1984. MeCormic
`” 198/656
`¢ sensorin the distal end portion is selected to respond
`6/1986 Grayet al.
`~ 128/200.26
`4,593,687
`when the distal end portion of the catheter is exposed to a
`
`1/1988 Inoue et al. ccccsseccssessssecsneens 604/264
`4,717,387
`magnetic field, such as provided by the external magnet,
`12/1988 KUntZ ooeeeeecccecccecseeeceeeeeeeeees 604/8
`4,790,809
`sufficient to capture and maneuver the distal end of the
`
`4,850,963
`7/1989 Sparks et al
`. 600/29
`catheter. A catheter having a distal end portion that includes
`9/1989 Hedberg ....
`vee 604/93
`4,865,586
`a stecring portion for mancuvering the distal cnd of the
`
`F990 Ballew oecseceeceeeseeces 128/200.11
`4,913,139
`catheter during intubation of a patient is also provided. A
`
`7/1990 Ashley-Rollmanct al.
`... 324/207.17
`4,943,770
`method for intubating a patient using the catheter systems
`
`042486 * S1901 eel a i Dees
`provided, including an external magnet, is also disclosed.
`5,253,647 * 10/1993 Takahashi et al... 128/653.1
`5,257,636
`11/1993 White .
`32 Claims, 7 Drawing Sheets
`
`(56)
`
`:
`References Cited
`U.S. PATENT DOCUMENTS
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`U.S. PATENT DOCUMENTS
`
`5,938,603 *
`8/1999 PONZE .oceseerecesesereeceeeeere 600/424
`
`5,997,473 * 12/1999 Taniguchi et al. wi... 600/117
`
`6,007,478 * 12/1999 Siess et al. oo. ee 600/16
`6,015,414 *
`1/2000 Werp ct al.eee 606/108
`
`* cited by examiner
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`U.S. Patent
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`Jan. 9, 2001
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`Sheet 1 of 7
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`US 6,173,199 B1
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`ESOPHAGUS
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`FUNDUS
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`LESSER
`CURVATURE
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`ANGULAR
`NOTCH
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`GREATER
`CURVATURE
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`DUODENUM
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`FIG.
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`7
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`Jan. 9, 2001
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`US 6,173,199 B1
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`U.S. Patent
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`Jan. 9, 2001
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`US 6,173,199 B1
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`1
`METHOD AND APPARATUS FOR
`INTUBATION OF A PATIENT
`BACKGROUND OF THE INVENTION
`
`The present invention is generally in the area of medical
`catheters, and specifically to catheters constructed to facili-
`tatc guidance and placementofa distal end portion thereof
`at a predetermined site within the body of a patient.
`Avariety of methods for placing catheters and tubes in a
`patient’s body are known. ‘or example, enteral nutritional
`products can be delivered to a patient’s gastrointestinal tract
`via a tube which is introduced through the naris of the
`patient’s nose. The tube is advanced through the patient’s
`esophagus and into the patient’s stomach. In the event that
`it
`is preferable to deliver the enteral nutritional product
`directly to the patient’s small bowel,
`the tube is further
`advanced beyondthe pylorusinto the patient’s duodenum or
`small bowel. However, advancement of the tube into the
`patient’s duodenum can be difficult in many patients. One
`method for advancing, a tube through the stomach and into
`the duodenum entails the use of the natural peristaltic
`movement of the gastrointestinal tract. Such advancement
`may require as long as three to five days in somepatients.
`Pharmaccutical products can be used in order to enhance the
`peristaltic action within the gastrointestinaltract and thereby ,
`decrease the time required to advance the feeding tube into
`the small bowel.
`
`Serial X-rays typically are used to determine the location
`of the distal end of the tube as it advances by peristaltic
`action through the pylorus to the duodenum,thereby expos-
`ing the patient repeatedly to radiation and increasing the
`costs associated with placement of the tube. For these
`reasons, the use of naturally occurring or pharmaceutically
`enhanced peristalsis provides a sub-optimal method for
`placing a tube in a patient’s small bowel.
`It is known in the art to use magnetic flux or a magnetic
`field in the placement of catheters in the gastrointestinal
`tract. For example, U.S. Pat. No. 3,043,309 to McCarty
`describes the use of a localized magnetic field generated by
`an electrical magnet to manipulate a suction tube having a
`magnetic member at
`its distal end. The suction tube is
`constructed to be manipulated through anintestinal obstruc-
`tion. The electrical magnet enables a medical professional to
`turn off the magnct when using fluoroscopy radiation to
`determine the precise location of the distal end of the tube.
`Without the ability to deactivate the magnetic field in this
`manner, the field would distort the image on the fluoroscopy
`screen, thereby preventing a precise determination of the
`location of the distal end of the tube.
`US. Pat. No. 3,794,041 to Frei, et al. discloses beads of
`a ferromagnetic material constructed to be inserted in a body
`part with a catheter for moving the body part using an
`external magnet. U.S. Pat. No. 3,847,157 to Caillouette, et
`al. discloses the use of a magnetic indicator in a medico-
`surgical tube to identify the location of a tube containing a
`ferromagnetic material. U.S. Pat. No. 3,674,014 to Tillander
`discloses a distal end portion of a catheter having a plurality
`of magnetic tubular elements with ball-shaped ends to allow
`deflection of the sections with respect to each other for
`guidanceof the catheter distal end. U.S. Pat. Nos. 3,961,632
`and 4,077,412 to Moossun disclose a trans-abdominal stom-
`ach catheters of the Foley type used to direct the placement
`of the catheter by way of an external puncture from outside
`the abdomen through the stomach wall. U.S. Pat. No.
`3,358,676 to Frei, et al. shows the use of magnets for
`remotely controlling propulsion of a magnet-containing
`beads through a duct of a human.
`
`;
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`35
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`45
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`50
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`65
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`2
`U.S. Pat. No. 5,431,640 to Gabriel discloses the use an
`external magnetto establish a magneticfield for permeating
`body tissue and enveloping the lesser curvature of the
`stomach for magnetic direction of a distal end of a catheter
`feeding tube having a permanent magnet associated there-
`with. The presence of the permanent magnet on the distal
`end portion of the catheter tube presents the advantage of
`steering the catheter magnet by the external magnet.
`Maneuvering a catheter to the distal duodenum of a
`patient using the magnetic field produced by an external
`magnet requires precise knowledge of the anatomy of the
`stomach and duodenum inrelation to the abdominal surface
`of a patient. This knowledge is necessary sothat the operator
`can maneuver the external magnet over the abdomenofthe
`patient in a precise path resulting in advancement of the
`catheter through the stomach and into the duodenum ofthe
`patient. An operator maneuvering an external magnet cannot
`see through the abdominal wall to decide whether the distal
`end portion of the catheter is continuously captured by the
`magnetic field of the external magnet during the advance-
`ment of the catheter. Thus, an additional procedure is
`required to determine whetherthe distal end of the catheter
`is properly advancing into the patient’s duodenum. One
`methoddiscussed previously and having apparent shortcom-
`ings involves the use of X-ray monitoring to confirm the
`position of the distal end of the catheter. An alternative
`method, described in U.S. Pat. No. 5,431,640, entails the
`aspiration of fluid from the distal end of the catheter and the
`measurement of the pH ofthe aspirated fluid. However, pH
`valucs for a particular individual may vary from cxpected
`values, as occasionally occurs in response to medications,
`thereby resulting in false position information. What
`is
`needed is an apparatus and method for advancing the distal
`end portion of a catheter using the field of an external
`magnet which provides an indication whether the catheter
`distal end is captured by the external magnet,
`thereby
`indicating whether the distal end of the catheter is being
`properly advanced into the patient’s duodenum.
`It is an object of the present invention to provide catheters
`which are more easily and accurately positioned than the
`catheters currently available.
`
`SUMMARYOF THE INVENTION
`
`Acatheter having a distal end portion preferably including
`a sensor responsive to the presence of a magnetic field or
`flux of a predetermined strength is provided. Also provided
`is a catheter system which further includes an external
`magnet. The sensor in the distal end portion is selected to
`respond when the distal cnd portion of the catheter is
`exposed to a magnetic field, such as provided bythe external
`magnet, sufficient to capture and maneuverthe distal end of
`the catheter.
`
`The catheter system further includes a catheter having a
`distal end portion that includes a steering portion for maneu-
`vering the distal end of the catheter during intubation of a
`patient. In one embodiment, the steering portion takes the
`form of a portion provided with increased flexibility as
`compared with the flexibility of an adjacent portion of the
`distal end portion of the catheter. In another embodiment,
`the catheter system further includes a catheter having a distal
`end portion that
`includes a steering portion having an
`asymmetrical projection which facilitates advancement of
`the catheter as it encounters surfaces that are substantially
`perpendicularto its direction of advancement.
`Also provided is a method for intubating a patient includ-
`ing the use of a catheter system as disclosed herein with an
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`US 6,173,199 B1
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`3
`external magnet. The catheter is placed in a portion of a
`patient’s body, and the external magnet
`is brought
`into
`proximity of the distal end portion of the catheter such that
`the sensorindicates that the distal end portion of the tube has
`been captured by the external magnet. The external magnet
`is then used to position the distal end portion of the catheter
`in a selected position within the patient’s body. The method
`may also be used with the catheter having a distal end
`portion that includes a steering portion and using the steer-
`ing portion to maneuverthe distal end portion of the catheter
`during intubation of the patient. The catheter may also be
`adapted for insertion within the vasculature of a patient, with
`or without the use of the sensor.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a schematic illustration of the anatomical
`configuration of the stomach and duodenum through which
`the catheter of the present invention is navigated.
`FIG. 2 is a schematic illustration of a patient showing a
`catheter feeding tube in place through the naris of the nose
`to deliver nutrition or medication directly into the small
`intestine.
`
`FIG. 3 is a schematicillustration of a patient showing a
`catheter feeding tube in place through the abdominal wall to
`deliver nutrition or medication directly into the small intes-
`tine.
`
`FIG. 4 is an enlarged plan view, partly in section, of a
`catheter according to the present invention in which the
`distal end portion includes a permanent magnet arranged
`such that lines of flux will travel from a first side of the
`catheter to an opposite side.
`TIG. 5 is an enlarged plan view,partly in section, showing
`the distal end of the catheter of FIG. 4 in the proximity of
`an external magnet.
`FIG. 6 is an enlarged sectional view of the distal end
`portion of a catheter according, the present invention having,
`a permanent magnet in the distal end portion, which is
`differently arranged than the magnet in the catheter tip of
`TIG. 4 such that the lines of flux travel from a generally
`planar face of the magnet adjacent the terminal end of the
`catheter to an opposite generally planar face of the magnet.
`FIG. 7 is an enlarged sectional view of the distal end
`portion of a catheter according to the present
`invention
`having a ferromagnetic tubular member in the distal end
`portion.
`FIG. 8 is an enlarged sectional view of the distal end
`portion of a catheter according to the present invention
`having bits of ferromagnetic material embeddedin the distal
`end portion to magnetically respond to a magneticfield of an
`external magnet.
`FIG. 9 is an enlarged sectional view of the distal end
`portion of a catheter according to the present invention
`which includes a waisted portion having a reduced cross-
`section for increasedflexibilityof a terminalendofthedistal
`end portion and an asymmetrical projection for increased
`maneuverability of the terminal end.
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`Catheters
`In a preferred embodiment of the catheter disclosed
`herein, the distal portion of the catheter must be navigated
`through the stomach and placed in the duodenum so that
`nutrition or medication can be delivered directly into the
`small intestine. The anatomical configuration of the stomach
`
`35
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`50
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`60
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`65
`
`4
`is illustrated in FIG. 1, with salient features of the stomach
`and associated esophagus and duodenum labeled.
`One embodiment of the catheter system is illustrated in
`FIG. 2, wherein catheter 10 has a catheter body portion 12
`whichis elongated and extendsto a distal end portion 14 for
`delivery of nutrition or medication. It will be appreciated
`that catheter 10 can be used to deliver various fluids to a
`variety of locations within a patient’s body. I'or the purposes
`of this disclosure, reference will be made to use of catheter
`10 to deliver an enteral nutritional product to a patient’s
`duodenum. However, it will be appreciated that the present
`invention is not limited to this application; other embodi-
`ments are described below.
`The distal end portion 14 of the catheter 10 is introduced
`through the naris 16 of the nose and advanced by the
`application of a longitudinally compressive force to the
`catheter 10, thus urging distal end portion 14 in the direction
`of the backwardportion of the patient’s head and thence to
`the esophagus 18. Preferably, the distal end portion 14 of the
`catheter 10 is coated with a lubricant while a numbing agent
`is applied to the nasal mucosa. The passagewayof the
`csophagus atfords ample guidance to the distal cnd portion
`14 ofthe catheter 10 when it enters the stomach bodyportion
`20 of the stomach 22 at the lower portion of the fundus 24.
`The movement of the distal end portion 14 along the
`esophagus and into the body of the stomach occurs within
`the left upper quadrant (“LUQ”).
`The stomach 22 has a generally J-shaped configuration.
`The largest transverse anatomical size of stomach 22 is
`located at
`the cardiac orifice, ie.,
`the sile al which the
`esophagus enters the stomach. The transverse dimension of
`the stomach narrows moving away from the cardiac orifice
`in the direction of the normal passage of food through the
`gastrointestinal tract. An angular notch 26 is present at the
`border between the left upper quadrant (““LUQ”) and the
`right upper quadrant (“RUQ”). From the angular notch,
`there commences a smaller transverse dimension at
`the
`pyloric part 28 typically residing in the right upper quadrant
`(“RUQ’”)with pyloric sphincter 30. The pyloric sphincter 30
`is a muscular closure which dilates to permit the passage of
`food from the stomach 22 into the small bowel 32. The small
`bowel 32 includes a duodenum 34 andthe distal duodenum
`36. Food passes through the pyloric sphincter 30 into the
`duodenum 34, the duodenum 34 extending to the night lower
`quadrant (“RT.Q”) and then in a general horizontal direction
`into the left
`lower quadrant
`(“LLQ”) where the distal
`duodenum 36 of the small intestine is situated.
`The generally J-shaped configuration of the stomach 22 is
`arranged with the longer limb ofthe “J” lying to the left of
`the median plane and the major part
`in the left upper
`quadrant (“LUQ”). The long axis of the stomach passes
`downwardly, forwardly, and then to the right and finally
`backwardly and slightly upwardly. The size and shape ofthe
`stomach 22 vary greatly from patientto patient, for example,
`in short, obese persons the stomach is high and transverse
`whereasin tall persons the stomachis elongated. It is known
`that in a given patient the shape of the stomach depends on
`whether the stomach is empty or full, the position of the
`patient, and the phase of respiration. At the cardiac orifice,
`an acute angle is formed which tends to misdirect the distal
`end of the catheter toward the fundus 24 rather than toward
`the pyloric part 28 as the catheter is urged through the
`stomach.
`An alternative entry site to the stomach 22 for the catheter
`10 is illustrated in FIG. 3. The distal end of the catheter
`enters through a stomatract in the patient’s abdominal wall
`38 to the stomach body portion 20 of the stomach 22 rather
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`5
`than through the naris of the nose. This stomach formation
`technique is well known in the art and is referred to as
`percutaneous endoscopic gastrostomy (“PEG”).
`Alternatively, the catheter 10 can be placed through a stoma
`tract in the patient’s abdominal wall 38 directly into the
`patient’s duodenumor jejunum. The apparatus and method
`of placementof the present inventionare particularly suited
`for use in placing a feeding tube through a stomatract
`formed through the patient’s abdominal wall by a PEG
`procedure and in placing a feeding tube through the patient’s
`nose.
`One embodimentof the catheter disclosed herein is shown
`in FIG. 4, enlargedto illustrate catheter 10 in greater detail.
`Whenthe catheter 10 is configured as a feeding tube, the
`catheter 10 is about 50 incheslong. Catheter bodyportion 12
`typically has a diameter of about 3 mm and can be con-
`structed in wholeor in part of a radiopaque material in order
`to facilitate identification thereof using known X-ray tech-
`niques. The distal end portion 14 of the catheter 10 typically
`has an outside diameter of about 5 mm. The distal end
`portion 14 can be integrally form ed with the remainder of
`catheter body portion 12. Alternatively, distal end portion 14
`can be mounted mechanically on, or chemically bondedto,
`the remainderof catheter body portion 12. A lumen40 in the
`catheter body portion 12 is in fluid communication with an
`external environmentof distal end portion 14 through one or
`more apertures. The aperture can be defined as an axial
`orifice 42A at the terminal end ofdistal end portion 14. The
`apertures also can be defined through the walls of distal end
`portion 14 as eyelets 42B. The apertures allow a fluid to be
`directed through lumen 40 and into the site in which the
`distal end portion 14 of catheter 10 is positioned.
`Magnetically Responsive Elements
`The catheter is provided with a magnetically responsive
`membcrat distal cnd portion 14. In a firstembodimentof the
`present
`invention,
`the magnetically responsive member
`includes a cylindrically shaped permanent magnet 44 posi-
`tioned in distal end portion 14 of catheter 10. The magneti-
`cally responsive membercan alternatively be constructed of
`a ferromagnetic material, i.c., a material in which a magnetic
`state can be induced. Permanent magnet 44 in the embodi-
`ment of FIG. 4 has a diameter of about 5 mm and a length
`of about 6 mm. A slight bulge 46 in the lumen 40 occurs
`when the permanent magnet 44 is inserted through axial
`orifice 42A. In analternative configuration, permanent mag-
`net 44 is placed on an exterior wallof distal end portion 14.
`The permanent magnet 44 can include opposite, hemi-
`cylindrical pole faces 44A and 44B which cxhibit polariza-
`tion across a diameter 44C such that lines of magnetic flux
`travel from hemi-cylindrical pole 44A to hemi-cylindrical
`pole 44B.
`An external magnet 48 is illustrated in FIG. 5 in a
`proximal relation with the distal end portion 14 of the
`catheter which encounters the magnetic field of the external
`magnet. The wall of the stomach 22 and the abdominal wall
`38 are between the distal end portion 14 of the catheter 10
`and the external magnet 48. The inclusion of the permanent
`magnet 44 polarized along the diameter, as illustrated,
`results in the orientation of the distal end portion 14 trans-
`versely with respect to the external magnet 48 when thefield
`of the extcrnal magnct has captured the permanent magnet
`44 inthe distal end portion 14. This is favorable for guiding
`the catheter through the curves of the gastrointestinaltract.
`In an alternative embodiment, the magnetically respon-
`sive member is a permanent magnet 50 arrangedinthe distal
`end portion 14 of the catheter 10 as illustrated in FIG. 6.
`Permanent magnet 50 is constructed with a cylindrical
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`surface between opposing planar pole faces. The permanent
`magnet 50 is supported in the lumen 40 with the cylindrical
`surface producing a slight bulge identified by reference
`numeral 52. The permanent magnet 50 inserted through
`axialorifice 42A is distinctly polarized when compared with
`the permanent magnet 44 illustrated in FIGS. 4 and 5. The
`lines of flux of permanent magnet 50 in FIG. 6 extend from
`a first generally planar pole face 50A adjacent a terminal end
`of the catheter to an opposite second generally planar pole
`face 50B. As described hereinbefore,
`the magnetically
`responsive member can take the form of a ferromagnetic
`insert 54 in the distal end portion 14 of the catheter as
`illustrated in FIG. 7. According to this embodimentof the
`catheter system disclosed herein, the ferromagneticinsert 54
`is tubular in cross-section. The insert can be encapsulated
`within the catheter wall at the distal end portion 14 or can be
`providedon an interior surface of lumen 40 or an external
`surface of distal end portion 14. It has been found that the
`selection of an external magnet can be madeso as to provide
`a magnetic field strength sufficient to induce magnetization
`in the ferromagnetic insert 54. The induced magnetization
`provides a magnetic coupling between the external magnet
`and the ferromagnetic insert 54, thus allowing the distal end
`portion 14 to be manipulated by movementof the external
`magnet.
`The material comprising ferromagnetic insert 54 can be
`an alloy which is defined as a ferromagnetic alloy that
`becomes magnetized readily upon application of a field and
`that resumes practically a nonmagnetic condition when a
`field is removed. Suitable ferromagnetic materials include,
`but are not necessarily limited to, permandure, iron, iron
`silicone steel, iron cobalt alloys, and iron nickel alloys. The
`magnetization of ferromagnetic insert 54 which occursin the
`presence of the applied field by the external magnet
`is
`defined as the induccd magnetization and is distinguished
`from permanent magnetization which is present without an
`applied field. Sensors
`Sensor 56 is positioned at distal end portion 14 of the
`catheter 10. Sensor 56 can be integral with or attached to
`catheter 10, or can be positioned on a stylet 68 inserted into
`catheter 10. The sensor56 is preferably constructed to detect
`the presence of a magnetic field of a predetermined magni-
`tude. The magnetic field can be either the result of the
`magnetic flux of the external magnet 48 or the induced
`magnetism of ferromagnetic insert 54, or a combination
`thereof. The predetermined magnitude of the magneticfield
`is selected to be sufficient to ensure that permanent magnet
`44, 50 or ferromagnetic insert 54 is magnctically coupled to
`the external magnet. Sensor 56 preferably is constructed to
`provide an audio, visual, or tactile indication through indi-
`cator 58 whenthe threshold magnetic field is presentatdistal
`end portion 14. In the embodiments in which permanent
`magnets 44 and 50 are provided on distal end portion 14 of
`the catheter 10, sensor 56 is constructed suchthatit does not
`respond to the magnetic field or magnetic flux density of
`permanent magnets 44 and 50. In FIGS. 5 and6, sensor 56
`is spaced [rom the permanent magnet 44 and 50 in the distal
`end portion 14 of the catheter in order to avoid false
`triggering of sensor 56. Sensor 56 can have anyofa variety
`of formsutilizing principles of operation well knownin the
`art
`to respond to the presence of a magnetic ficld or a
`magnetic flux of a predetermined magnitude.
`As described above, sensor 56 preferably is constructed to
`provide an indication of the presence of a threshold mag-
`netic flux orfield at distal end portion 14. In the embodiment
`of the catheter system depicted in FIG. 4, sensor 56 is
`connected to an audio or visual signal generator 58 and a
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`tially the entire length of the lumen 40. The stylet 68 adds
`powersupply 60.In this embodiment, sensor 56 includes an
`a desired degree of stiffness andrigidily to the catheter to
`envelope 62 forming a protective housing containing elec-
`facilitate the placement procedure. After placement of the
`trically conductive limbs consisting of leaf-like reeds 64
`catheter is completed, the cap is used for extracting thestylet
`having a predetermined elasticity such that the electrical
`68 from the catheter body portion 12. The lumen 40 can then
`state of the sensor 56 changes in response to the presence of
`be used for the supply of nutrients or medication for the
`the magnetic field or flux at the predetermined threshold
`patient. The cap 72 is fitted to a cavity formedin a fixture 74
`level. The electrically conductive leaf-like reeds 64 extend
`whichis joined to the proximal cnd of the catheter which is
`from opposite ends of the envelope 62 in a spaced apart and
`opposite the distal end portion 14. The fixture 74 is provided
`overlying relation. In the embodimentof FIG. 4,the leaf-like
`with an additional duct section 76 having a removable
`reeds are constructed such that they are out of electrical
`closure cap 78 [or access to the lumen whenit is desired t
`contact with one another in the absence of a magnetic field
`o introduce fluids into the lumen of the catheter. It is also
`or magnetic flux of a predetermined magnitude. However,
`possible for a syringe to be connectable to the duct section
`the leaf-like reeds are elastically forced into electrical con-
`76 in a fluid tight manner, as is well knowninthe art, should
`tact with one another in the presence of a magneticfield or
`it be desired to withdraw fluid from the lumen.
`magnetic flux of sufficient strength to provide a magnetic
`An alternative embodiment of the catheter disclosed
`coupling between the external magnet and the distal end
`herein is illustrated in I'IG. 9, showing distal end portion 82.
`portion 14, thereby allowing electricity to flow through the
`The construction of the distal end portion 82 provides
`sensor 56 and actuate a signal generator 58. Movementof
`the leaf-like reeds 64 between their electrical contact and
`increased flexibility of one portion of the catheter as com-
`paredwith the flexibility of an adjacent distal end portion of
`separated positions is responsive to the presence or absence
`the catheter. In the depicted embodiment, the first portion of
`of a magnetic field or magnetic flux.
`the distal end portion 14 of catheter 10 has a different
`Signal Generators
`diameter resulting in greater clasticity and thereby inercascd
`Signal gencrator 58 prcfcrably is positioned cxternal to
`flexibility when compared to the adjacent distal end portion
`the patient during placement of catheter 10. ‘The requisite
`of catheter 10. Preferably the increased flexibility at the
`electrical connection between sensor 56 and signal generator
`distal end of the catheter is provided bya waisted portion 84
`58 can be achieved using a variety of known technologies.
`
`For example, electrically insulated wire 66 can be wrapped extending along the distal end portion fromafirst location
`around stylet 68, with wire 66 providing an electrical
`86 to a second location 88. The waisted portion 84 has a
`reduced cross-sectional dimension at an intermediate loca-
`coupling between sensor 56 and signal generator 58. In an
`alternative embodiment, stylet 68 can be formed of an
`tion 90 with respect to the dimensionsatthe first and second
`electrically conductive material which provides the requisite
`locations 86 and 88. This results in increasedflexibility of a
`electrical coupling, between sensor 56 and signal generator
`terminal end portion 92 of the distal end portion 82 in
`58. Electrical
`insulators preferably are provided around
`comparison with a catheter having a similarly thick distal
`stylet 68 in order to prevent the inadvertent delivery of an
`end portion of the same material in which the cross section
`electrical shock to the patient.
`dimension of the distal end portion remains unchanged
`The signal gencrator 58 is prefcrably a light bulb or other
`throughout. Such increased ficxibility provides increased
`visual signal which provides a detectable signal indicating
`maneuverability for the terminal end portion 92. If desired,
`that sensor 56 is detecting a threshold level of a magnetic
`more than one waisted portion 84 may be provided.
`field or magnetic flux. A physician is thereby informed that
`The distal end portion 82 illustrated in FIG. 9 provides a
`distal end portion 14 of catheter 10 has been captured by
`second feature for increasing the maneuverability of the
`external magnet 48 and that the external magnet 48 can be
`distal end portion by providing a projection 94 which is
`used for manipulating the distal end portion 14 of the
`asymmetrical with respect to a central axis 96 of the distal
`catheter 10. An audible signal emitted by a buzzerorbell, for
`end portion 82. The projection 94 provides greater maneu-
`example, may be used instead of a light bulb without
`verability due to