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WO2012114219A1 - Cathéter, ensemble comprenant celui-ci et procédé de placement de celui-ci - Google Patents

Cathéter, ensemble comprenant celui-ci et procédé de placement de celui-ci Download PDF

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Publication number
WO2012114219A1
WO2012114219A1 PCT/IB2012/050545 IB2012050545W WO2012114219A1 WO 2012114219 A1 WO2012114219 A1 WO 2012114219A1 IB 2012050545 W IB2012050545 W IB 2012050545W WO 2012114219 A1 WO2012114219 A1 WO 2012114219A1
Authority
WO
WIPO (PCT)
Prior art keywords
catheter
impedance
electrodes
level
guideline
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2012/050545
Other languages
English (en)
Inventor
Pieter Rousseau Fourie
Cornelius Scheffer
Paul Schwartz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Stellenbosch University
Original Assignee
Stellenbosch University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Stellenbosch University filed Critical Stellenbosch University
Publication of WO2012114219A1 publication Critical patent/WO2012114219A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M25/00—Catheters; Hollow probes
    • A61M25/01—Introducing, guiding, advancing, emplacing or holding catheters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
    • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
    • A61B5/0538—Measuring electrical impedance or conductance of a portion of the body invasively, e.g. using a catheter
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/48—Other medical applications
    • A61B5/4887—Locating particular structures in or on the body
    • A61B5/489—Blood vessels
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A61B5/6851—Guide wires
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A61B5/6852—Catheters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6867—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive specially adapted to be attached or implanted in a specific body part
    • A61B5/6876—Blood vessel

Definitions

  • This invention relates to a catheter that is to communicate with the interior of a blood vessel, especially an artery; to a catheter assembly including same; and to a method of placement thereof.
  • an intra-arterial catheter especially in the aortal or femoral arteries, can be extremely difficult for the medical practitioner and traumatic for the patient.
  • the difficulty is created by the fact that a medical practitioner trying to place a catheter that communicates properly with the interior of a blood vessel cannot be certain that the inner end of the catheter is properly located within the blood vessel. It is possible that the blood vessel is not easily visible in which instance it is difficult to gauge when and if the open end of the catheter is positioned within the blood vessel.
  • the problems are particularly pronounced in the instance of an artery which contains relatively high-pressure blood. Multiple attempts to achieve proper placement of a catheter are traumatic for the patient and even injurious and also increase the risk of infection.
  • a catheter assembly comprising a catheter having a removable guideline passing through the catheter for assisting in its placement, and an impedance measuring apparatus for measuring the impedance between at least two electrodes provided in an inner end region of the catheter assembly and communicating by way of conductors extending along at least a part of the length of the catheter assembly, wherein the at least two electrodes are provided on the catheter or guideline, or both in the region of the operatively inner end thereof with conductors communicating with said at least two electrodes extending along at least an appropriate part of the length of the catheter or guideline or both, and wherein the impedance measuring apparatus is set up to detect a first level of impedances commensurate with the presence of the electrodes in the tissue of a patient and a second level of impedances commensurate with the presence of the electrodes within the blood in a blood vessel of the patient and means for communicating the transition from the former level to the latter level to a medical practitioner.
  • the guideline is an electrically conductive guide wire and the wire itself may form one electrode and its associated conductor.
  • said two or more electrodes could be provided on the outer surface of the catheter towards its operatively inner end and the conductors may be electrically conductive material applied onto the outer surface of the catheter with an insulating coating around the major part of the length of the electrode to allow only the tip of the electrode nearest the tip of the catheter to be exposed and therefore in electrical contact with its surroundings.
  • said two or more electrodes could be provided on the outer surface of the guideline in which instance the guideline would typically be electrically insulating.
  • the electrodes could simply be exposed inner ends of the conductors.
  • an impedance measuring apparatus adapted to detect impedance between two electrodes of a catheter assembly as defined above and having means for communicating to an operator a transition from a first level of impedance commensurate with the presence of the electrodes of the catheter assembly in the tissue of a patient and a second level of impedance commensurate with the presence of the electrodes within the blood in a blood vessel of the patient.
  • the impedance measuring apparatus is preferably provided with audible or visible means for communicating to a medical practitioner a transition between a first level of impedance and a second level of impedance as indicated above.
  • the impedance measuring apparatus may be of any commercially available type that is suitable for the purpose or that may be especially adapted for this purpose.
  • an impedance measuring apparatus may be especially designed and produced for the purposes of this invention and therefore be dedicated to the practice of placement of catheters.
  • the frequency range of the AC signal used to produce the impedance will generally be in the range of 10 to 100 kHz, while the slumping frequency used to identify the impedance [using A/D conversion] will generally be in the region of 50 MHz.
  • a method of placing a catheter comprising progressively introducing a catheter into a patient and monitoring the output from impedance measuring apparatus such that placement can be considered to have been achieved once an output from the impedance measuring apparatus corresponds to a second level of impedance as indicated above.
  • the invention also provides catheters that are especially configured to form part of an assembly as defined above and to be used in a method as defined above.
  • catheters could also be provided with other sensors and detectors for monitoring other conditions such as blood flow, temperature, oxygen saturation and the like.
  • Figure 1 is a schematic isometric illustration of one form of catheter assembly according to the invention.
  • Figure 2 is a schematic isometric illustration of another form of catheter assembly according to the invention
  • Figure 3 is a schematic diagram illustrating the composite apparatus of the invention ;
  • Figure 4 is a schematic section taken through a blood vessel on a patient and showing the catheter in use;
  • Figure 5 is a schematic circuit diagram of one arrangement of catheter monitoring circuit that has been used in tests of the functioning of the invention.
  • a catheter assembly as illustrated in Figure 1 and indicated generally by numeral [1 ], comprises a catheter [2] having a removable guideline in the form of a hypodermic style of needle [3] passing through the catheter for assisting in its placement.
  • two spaced electrodes [4] are provided at the inner end region of the catheter with conductors [5] that communicate with them extending along at least part of the length of the catheter assembly and electrically insulated from each other and from the outside along the major length of the catheter so that only the spaced electrodes are exposed to their surroundings.
  • the catheter (1 1 ) has a single electrode (12) with its associated conductor (13) extending along the catheter and wherein the electrically conductive guideline that may again be in the form of a hypodermic style of needle (14) serves as the second electrode and its associated conductor.
  • the hypodermic style of needle has an electrical conductor (15) in electrical contact with it so that the two conductors (13, 15) can be connected to the impedance measuring apparatus that is further described below.
  • Impedance measuring apparatus [21 ] is provided for measuring the impedance between the two electrodes, in each instance, with the apparatus being adapted to detect a first level of impedances commensurate with the presence of the electrodes in the tissue of a patient and a second level of impedances commensurate with the presence of the electrodes within the blood in a blood vessel of the patient.
  • the impedance measuring apparatus is preferably provided with both audible (22) and visible (23, 24) indicators of the fact when the impedance measured changes from the first level to the second level.
  • audible (22) and visible (23, 24) indicators of the fact when the impedance measured changes from the first level to the second level.
  • a visible indicator could simply be a suitable LED arrangement, such as a red LED [23] and a green LED [24] with the red LED being illuminated when the electrodes are positioned within the tissue of the patient and the green LED becoming illuminated when the electrodes are positioned in the blood vessel.
  • the apparatus may also have a screen [28] enabling a graphic output of impedance and changes therein to be displayed and visually observed.
  • a catheter (1 1 ) according to Figure 2 was fabricated from a 0,4mm (diamater) standard intra arterial catheter with a conductor (13) in the form of a copper thread wound around the canule (exterior part) of the arterial catheter.
  • the copper thread was held in place by an electrically insulating non-toxic resin with the last distal 0,5mm being left un-insulated by the resin so as to leave it exposed in order to serve as the electrode (12).
  • the proximal end of the cannula was attached to a conductor (16) by means of silver adhesive paint and the conductor was attached to the signal processing device that is further described below.
  • the hypodermic needle (14) of the arterial catheter assembly was electrically connected by means of silver adhesive paint to the conductor (15), at the proximal end of the needle and this conductor was also connected to the signal processing device.
  • the device that was the subject of testing had a signal processing device in the form of a combination of a signal generator (31 ) (to produce the reference signal and the signal to induce the impedance), a PC oscilloscope (32) (used to analyze the reference and output signals) and a laptop style of processor (33), running MS Excel 2010, used to interpret the data from the PC oscilloscope (taking A/D measurements, sampling at 50MHz), record the information and to give feedback during the testing.
  • a signal processing device in the form of a combination of a signal generator (31 ) (to produce the reference signal and the signal to induce the impedance), a PC oscilloscope (32) (used to analyze the reference and output signals) and a laptop style of processor (33), running MS Excel 2010, used to interpret the data from the PC oscilloscope (taking A/D measurements, sampling at 50MHz), record the information and to give feedback during the testing.
  • the signal generator used produced a signal with a peak-to-peak amplitude of 8V at a frequency of 30kHz.
  • a reference resistor (34) of 1 ,2kQ was used to calculate the measured impedance, using the reference signal, the output signal and the reference resistor.
  • the copper thread wrapped around the canule is to be replaced by a gold or silver thread which is to be embedded into the canule by heating the canule appropriately.
  • the 0,5mm distal end of the thread is to be exposed to form the one electrode (12).
  • a plastic housing (37) fitted on the proximal end of the arterial line is to keep all conductors and electronics together and function as a grip for a practitioner using the device.
  • the housing may also house the LED's responsible for user feedback, possibly an RGB LED displaying colours that depend on impedance levels detected, preferably avoiding the colours red and green to accommodate users who are colour blind.
  • the signal generator may be one that produces a 5V peak-to-peak voltage at 30kHz.
  • An ICL 8038 chip may be used to produce this signal and a series of op amps may be used to modify the signal around 2,5V, giving it a maximum of 5V and a minimum of 0V.
  • the Arduno board will compare the present impedance with stored impedances and determine under which group the present impedance falls; that is, the associated impedance level for tissue or blood.
  • the apparatus of this invention is intended to be active whilst the catheter is being placed rather than only after the catheter has been properly placed.
  • both electrodes could be carried by the guideline provided they are adequately electrically insulated from each other.
  • both electrodes could be carried by the guideline provided they are adequately electrically insulated from each other.

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • Biophysics (AREA)
  • Engineering & Computer Science (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • General Health & Medical Sciences (AREA)
  • Pathology (AREA)
  • Surgery (AREA)
  • Molecular Biology (AREA)
  • Medical Informatics (AREA)
  • Physics & Mathematics (AREA)
  • Vascular Medicine (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Radiology & Medical Imaging (AREA)
  • Pulmonology (AREA)
  • Anesthesiology (AREA)
  • Hematology (AREA)
  • Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
  • Media Introduction/Drainage Providing Device (AREA)

Abstract

La présente invention concerne un ensemble de cathéter dans lequel un cathéter a une ligne de guidage amovible traversant celui-ci pour faciliter son placement. Un appareil de mesure d'impédance mesure l'impédance entre au moins deux électrodes disposées dans une région d'extrémité interne de l'ensemble de cathéter et communiquant au moyen de conducteurs s'étendant le long d'au moins une partie de la longueur de l'ensemble de cathéter. Lesdits au moins deux électrodes sont disposées sur le cathéter ou la ligne de guidage, ou les deux dans la région de l'extrémité fonctionnellement interne de celui-ci. L'appareil de mesure d'impédance est configuré pour détecter un premier niveau d'impédance proportionné avec la présence des électrodes dans le tissu d'un patient et un deuxième niveau d'impédance proportionné avec la présence des électrodes dans le sang dans un vaisseau sanguin du patient. Des moyens sont disposés pour communiquer la transition du premier niveau au deuxième niveau à un praticien médical.
PCT/IB2012/050545 2011-02-22 2012-02-07 Cathéter, ensemble comprenant celui-ci et procédé de placement de celui-ci Ceased WO2012114219A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ZA201101384 2011-02-22
ZA2011/01384 2011-02-22

Publications (1)

Publication Number Publication Date
WO2012114219A1 true WO2012114219A1 (fr) 2012-08-30

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Family Applications (1)

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PCT/IB2012/050545 Ceased WO2012114219A1 (fr) 2011-02-22 2012-02-07 Cathéter, ensemble comprenant celui-ci et procédé de placement de celui-ci

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Country Link
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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022266501A1 (fr) * 2021-06-18 2022-12-22 Bard Access Systems, Inc. Systèmes médicaux de détermination d'impédance
US11759268B2 (en) 2012-04-05 2023-09-19 C. R. Bard, Inc. Apparatus and methods relating to intravascular positioning of distal end of catheter
US12029539B2 (en) 2003-02-21 2024-07-09 3Dt Holdings, Llc Systems, devices, and methods for mapping organ profiles
US12343091B2 (en) 2012-04-05 2025-07-01 C. R. Bard, Inc. Apparatus and methods relating to intravascular positioning of distal end of catheter

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5078714A (en) * 1990-03-02 1992-01-07 Jefferson Katims Method and apparatus for placement of a probe in the body and the medical procedure for guiding and locating a catheter or probe in the body
US20040249295A1 (en) * 2003-03-28 2004-12-09 Terumo Kabushiki Kaisha Catheter with puncture sensor
US20090036794A1 (en) * 2005-12-29 2009-02-05 Rikshospitalet-Radiumhospitalet Hf Method and apparatus for determining local tissue impedance for positioning of a needle

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5078714A (en) * 1990-03-02 1992-01-07 Jefferson Katims Method and apparatus for placement of a probe in the body and the medical procedure for guiding and locating a catheter or probe in the body
US20040249295A1 (en) * 2003-03-28 2004-12-09 Terumo Kabushiki Kaisha Catheter with puncture sensor
US20090036794A1 (en) * 2005-12-29 2009-02-05 Rikshospitalet-Radiumhospitalet Hf Method and apparatus for determining local tissue impedance for positioning of a needle

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US12029539B2 (en) 2003-02-21 2024-07-09 3Dt Holdings, Llc Systems, devices, and methods for mapping organ profiles
US11759268B2 (en) 2012-04-05 2023-09-19 C. R. Bard, Inc. Apparatus and methods relating to intravascular positioning of distal end of catheter
US12343091B2 (en) 2012-04-05 2025-07-01 C. R. Bard, Inc. Apparatus and methods relating to intravascular positioning of distal end of catheter
WO2022266501A1 (fr) * 2021-06-18 2022-12-22 Bard Access Systems, Inc. Systèmes médicaux de détermination d'impédance

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