Classifications

• • 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
• • 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
  • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue
  • A61B5/14539—Measuring characteristics of blood in vivo, e.g. gas concentration or pH-value ; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid or cerebral tissue for measuring pH
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B5/00—Measuring for diagnostic purposes; Identification of persons
  • A61B5/42—Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems
  • A61B5/4205—Evaluating swallowing

Definitions

• a catheter for measurement of electrochemical properties of bodily fluids A catheter for measurement of electrochemical properties of bodily fluids
• the invention relates to catheters for measurement of electrochemical properties chiefly in bodily fluids. Namely it is measurement of impedance and /or pH mainly in bodily fluids.
• impedance and /or pH mainly in bodily fluids.
• the pH electrodes register changes in the case of stomach acidic fluids intrusion into esophagus and impedance electrodes register alkalic, duodenal reflux.
• Another known measured electrode consists of metal - a primary copper cylinder galvanically plated by antimony.
• the disadvantage of this electrode is difficult reproducibility during its manufacturing.
• An electrode consists of two conductive metals - copper as a base and an upper layer of antimony. During the contact with digestion fluids the antimony layer is slowly etched down to copper. This happens mostly by microscopic erosions developing around impurities or other irregularities on the surface of conductive layer. There is a mixture potential between exposed copper and surface antimony, which results in an uncontrollable and unpredictable change of resulting potential of electrodes even with constant pH of the measured solution. Measured and displayed pH value drifts - even in identical pH solutions. The electrode produces a lower slope and therefore shows smaller change of potential per pH unit.
• sensing electrode is an electrode from Japanese authors JP 5023360, US 5573798, US 5480534, EP 0472398 and EP 0472396.
• a sensing electrode consists of electrically conductive material with a nonconductive film thereonto. A part of the nonconductive film is removed leaving a layer of pH sensitive film (a mixture of metal, primarily iridium and its oxide) deposited on the exposed surface. Indium and its oxide are in contact with electrically conductive material. In addition, the metal oxide layer could be covered by porous, nonconductive material to protect the oxide layer. Also iridium and its oxide are in some cases deposited directly on nonconductive base, sapphire or ceramics.
• iridium oxide used in these patents as a pH sensitive layer.
• the price of iridium is approx. 55 times more expensive than the price of antimony.
• Sputtering of iridium is problematic because of its non-reactivity.
• Pure oxygen is blasted into the evacuated chamber under a controlled pressure to make a coat of metal and metal oxide at the same time and in a specified narrow ratio.
• a change in the ratio influences the performance of the electrode.
• a coat of porous, nonconductive material can make the access of the measured liquid to the electrode worse. It also worsens the out-washing of measured solution from porous material and slows down the H+ response.
• the fast time response is important for the esophageal application, because evaluation of the procedure is based on the time ratio when pH in the esophagus is over or below pH level of 4.
• CZ patent 299305 is described a sensing electrode for pH measurement mostly in bodily fluids consisting of electrically nonconductive polymeric substance selected from a group consisting of polycarbonate, polyethylene, polypropylene, polystyrene or their copolymers or modified cellulose.
• a pH sensitive antimony layer connected by means of a secondary conductor with a measurement device isolated from the liquid system, in which pH is measured, whereas an nonconductive underlay has a shape of hollow cylinder thickened in its part into a shape of a ring or a sphere.
• a catheter for measurement of bodily fluid properties distinguishing itself as a catheter employing impedance measurement consisting of at least two electrodes in a shape of hollow cylinder, where at least its one part has an electrically conductive surface, which is connected by means of a secondary conductor with a measurement device isolated from the liquid system, in which impedance is measured, whereas in the case of using more electrodes for impedance measurement these electrodes are placed above each other and they are connected with each other by tubing, whereas the secondary conductors are carried out through the cylinder hollow and through the tubing.
• An electrode for impedance measurement can consist of a body in the shape of hollow cylinder of electrically conductive materials selected from the group consisting of metals such as Sn, Ni, Cu, Al, Ag, or its conductive compounds or from the composite polymer materials with electrically conductive - metal or a graphite mixture.
• a catheter for measurement of bodily fluid properties especially a catheter using impedance for pH measurement consists of at least two electrodes for impedance measurement in a shape of hollow cylinder, where at least its one part has electrically conductive surface, which is connected by means of a secondary conductor with measurement device isolated from the liquid system in which impedance is measured; and from at least one pH electrode consisting from electrically nonconductive underlay in a shape of hollow cylinder with pH sensitive layer deposited onto, which is connected by means of a secondary conductor with the measurement isolated from the liquid system in which impedance and pH is measured, where measurement device is a combined conductivity-meter and voltmeter to which one reference electrode is connected, whereas measurement electrodes are placed above each other and they are connected with each other by tubing, whereas the secondary conductors are carried out through the cylinder hollow and through the tubing.
• An electrode for impedance measurement can consist of electrically nonconductive polymeric underlay with electrically active surface, which is selected from the group consisting of metals such as Sn, Ni, Cu, Al, Ag 1 or its conductive compounds such as silverchloride (AgCI).
• An electrically active surface can be also an electric conductor from the group of doped conjugated polymers such as polythiofene, polyaniline, polypyrrole, polyfenylene or poly(p-fenylenvinylene).
• An underlay of electrode for impedance measurement can be completelly electrically conductive as a whole, and can consist of acrylonitril/butadiene/styrene with graphite admixture.
• An underlay of an electrode for impedance or pH measurement is preferably from electrically nonconductive polymeric substance and it is selected from the group consisting of polycarbonate, acrylonitril/butadiene/styrene, polyethylene, polypropylene, polystyrene or their copolymers or polymeric gells or modified cellulose.
• An underlay of electrode for impedance or pH measurement preferably a hollow cylinder shape where its central part is widened into a shape of a ring or a sphere.
• An underlay body of the electrode for impedance measurement, or an electrically active surface on the underlay, or a pH sensitive layer on the underlay are connected with a secondary conductor in a place, which is distal to the measured liquid, by means of pressure from a conductive spring, adhered by conductive glue, by metal plating or by a combination of tese methods.
• a pH sensitive layer or an electrically active surface is preferably placed on a widened part of underlay.
• a pH sensitive layer or electrically active surface is deposited onto nonconductive underlay by a metal deposition method, where a metal is evaporated under a vacuum - sputtering, magnetron sputtering, radiofrequency sputtering, diode plasma sputtering, cathodic arc evaporation, ion plating, ionization-assisted evaporation, ion implantation, or laser alloying.
• a pH sensitive layer and/ or electrically active surface of a thickness greater than 1 micrometer is deposited by magnetron sputtering onto the underlay in vacuum in an inert gas environment consisting mostly of argon.
• An electrically active surface is deposited onto conductive underlay electrochemically or by a metal deposition method, where a metal is evaporated under a vacuum - sputtering, magnetron sputtering, radiofrequency sputtering, diode plasma sputtering, cathodic arc evaporation, ion plating, ionization-assisted evaporation, ion implantation, or laser alloying.
• An electrically active surface consisting from electrically conductive doped conjugated polymer is deposited on the underlay from water colloid dispersion.
• a secondary conductor is selected from electrically conductive materials selected from the group consisting of Cu, Al 1 Ni, Ag 1 Au, Pt in the shape of an insulated wire, or by an insulated carbon fiber.
• Impedance and pH electrodes preferably have the same shape while combined into one catheter. They consist from an underlay in a shape of a hollow cylinder, where its central part is preferably widened into a shape of a ring or a sphere.
• the material of an underlay can be either polymeric nonconductor analogous to the pH electrode, or it can be composite conductive plastic such as ABS (acrylonitril/butadiene/styrene) with graphite admixture, or the impedance electrode can form a hollow cylinder shaped body created directly from the electrically conductive metal.
• the impedance electrode is provided by electrically active surface from noble, rustproof metal in the case of polymeric underlay either conductive or nonconductive.
• This metal can be. Sn, Ni, Cu, Ag, R, Al or its conductive compounds e.g. silver chloride (AgCI).
• the electrically active surface of a conductor can be also formed by doped conjugated polymers, such as doped polythiofene, polyaniline, polypyrrole, polyfenylene or poly(p- fenylenvinylene).
• a secondary conductor is carried out through the hollow center of the cylinder.
• the first end of a secondary conductor is connected with electrically active surface of an underlay and the second end goes through the underlay hollow and up the tubing towards the measurement device.
• An electrically active surface of the underlay is either a directly conductive underlay body, or it is an active coating deposited on the underlay surface.
• the outer part of an underlay with an electrically active surface is covered by flexible elastic tubing. This covering prevents penetration of measured liquid to contact area of secondary conductor and electrically active surface of an underlay.
• the part of electrically active surface which is in contact with measured liquid preferably on the widened part of an underlay.
• the second end of a secondary conductor going through the underlay hollow is together with the end of the underlay in the shape of cylinder compressed in another flexible elastic tube. A secondary conductor is then carried inside of this flexible elastic tube towards the measurement device or.conductivity-meter.in the case of impedance measurement.
• Flexible elastic tubes are preferably glued to an underlay. Individual electrodes can be linked by flexible elastic tubes. Separated secondary conductors go through these tubes towards the measurement device. A combined voltmeter and conductivity-meter is preferred for combined monitoring of pH and impedance. Each meter is then connected to its data logger.
• a catheter for measurement of electrochemical properties mainly the impedance and pH of bodily fluids according to the invention consists of any number of measuring electrodes placed sequencialy where each of them is connected to a measuring device by means of a secondary conductor.
• This modular solution greatly simplifies catheter assembly and reduces manufacturing cost when compared to current technologies.
• Electrodes are not placed outside of one long catheter, but on the contrary, partly inside.
• a catheter consisting of of flexible elastic tubing, is placed outside on the narrowed ends of measuring electrodes.
• a flexible body of a catheter is pulled over a contact part of an electrode and one end of a secondary conductor, and presses on this contact.
• a contact is secured not only by means of a conductive glue, but also by the pressure of an electrode against a flexible elastic tube on the catheter. pH and/or impedance electrodes are added in successive steps at the end of a catheter.
• One secondary conductor, going through inside of a catheter, is easily pulled out of a catheter. An advantage is easy manipulation with secondary conductors without breaking.
• Secondary conductors are easily taken out in the lenghtwise direction of a catheter through the length of the inside diameter, which is much bigger than traditional small perforations placed upright on the side wall of current catheters. This prevents possible twisting of a secondary conductor, or possible accidental removal of two or more secondary conductors and their back pushing in a catheter. Drastic bending of a secondary conductor in a small area is eliminated . Also a secondary conductor can be easily pulled out of a catheter in its longitudinal axis when the functionality of the secondary conductor is in question without bending or jepordizing the functionality of other secondary conductors placed inside of a catheter.
• Manufacturing of catheters according to this invention is, in comparison with current methods, simplified,, easily reproduced and economical. It enables miniaturization of an electrode.
• Conductive and nonconductive underlay from plastic can be easily molded in molds of a desired shape.
• a conductive metal can be deposited on a small plastic pressing/casting by a method such as vacuum sputtering, where each sputtering batche can be over a hundred thousand pieces.
• a catheter in accordance with this invention is capable of measuring impedance and pH both separetely and simultaneously.
• Fig. 1- illustrates design of a catheter, which consists from two types of shape identical electrodes in a shape of a hollow cylinder for impedance measuring. Two electrodes consist of an underlay with electrically active surface and one is made from a body of an electrically active material.
• Fig. 2 - illustrates design of a combined catheter which consists from one pH electrode and multiple electrodes for impedance measurement manufactured from nonconductive and/or conductive plastic underlays with electrically active surface.
• Design examples Fig. 1- design of a catheter, which consists of three electrodes for impedance measuring.
• Two electrodes consist of an electrically nonconductive underlay 1, in form of a hollow polycarbonate cylinder 7 mm long. The cylinder is wider in the middle. The diameter of this middle section is 2 mm and length is 3 mm and represents about 1/3 of the total cylinder length.
• the third electrode consists of a body 10 of the same shape made from copper, Cu.
• the thicker middle part in the shape of cylinder or sphere has the best surface to volume ratio. A current density is higher, which results in a stable reading at measuring device 6.
• An electrode with a thicker middle part in the shape of a sphere does not suffer from false reading due to an attachment to an esophagus wall, which an electrode with flat sensitive area may exhibit, when a measured liquid cannot reach the sensitive surface.
• An electrically active surface 9 is connected - clamped and glued - to a secondary wire conductor 3, which goes down through an underlay hollow 1 and its non-insulated tip touches on distal, narrowed part of an underlay 1 with an electrically active surface 9 ⁇
• a flexible polyurethane tube 4J. of outer diameter 2mm is pulled over this underlay 1 end and presses a secondary conductor 3 against an electrically active surface 9.
• the flexible polyurethane tube 4,3 is connected to a proximal (close to the measuring device 6) end of an underlay 1.
• a secondary conductor 3 goes through this flexible polyurethane tube 4 ⁇ 3 towards a measuring device 6.
• Tubes AA x A_2 and 4J3 are glued to an underlay %.
• Another impedance electrode consisting of an underlay 1 and an electrically active surface 9_ is connected to the bottom end of the first flexible elastic tube 4J ⁇ .
• Another impedance electrode consisting only from a body 10 from Cu is connected to the bottom end of this flexible elastic tube A ⁇ _.
• a secondary conductor 3 is connected/ glued to a surface of body Ij) and this connection is secured by tube 4 ⁇ 2, with dead end, which prevents of access of measured liquid inside of a catheter. All secondary conductors are made of insulated wire such as copper.
• Fig. 2 pictures the design of a combined catheter enabling simultaneous measurement of impedance and pH.
• Underlays 1 of impedance electrodes are made from polymeric substances either electrically nonconductive or conductive.
• An underlay 1 of a pH electrode is made from polymeric electrically nonconductive material, polycarbonate.
• the first underlay 1 of pH electrode (in the picture at the top part under measuring devices 6) is equipped with pH sensitive layer 2.
• Four secondary conductors 3 and one conductor 7 from reference electrode come through an underlay 1 hollow.
• One secondary conductor 3 is taken out of an underlay 1 hollow and it is connected with a part of pH sensitive layer 2j on the surface of an underiay_J..
• This contact area of underlay 1 is covered by the first flexible elastic tube 4J., which prevents of penetration of measured liquid to junction of secondary conductor 3 and pH sensitive layer 2.
• the upper end of underlay 1 hollow of pH electrode is covered by third flexible elastic tube 4 ⁇ 3 going to measurement device 6.
• the lower end of the first tube 4J. is pulled over another end of underlay 1 of impedance electrode.
• first flexible elastic tube 4J which prevents penetration of measured liquid to junction of secondary conductor 3 and an electrically active surface 9, which is deposited on this underlay 1 of impedance electrode.
• Another pH electrode is attached to the lower end of this first flexible elastic tubing 4J..
• the second flexible elastic tube 42 is pulled over the lower end of this impedance electrode.
• This secondary flexible elastic tube 42 is closed and contains an Ag/AgCI reference electrode preferably of the same shape as the pH and impedance electrodes, but it can have any shape.
• Secondary conductors 3 and reference electrode conductor 7 are pulled through all tubes and electrode hollow centers. The second ends of secondary conductors 3, connected with impedance electrodes, are linked to conductivity-meter. A secondary conductor 3 of pH electrode and reference electrode conductor 7 are connected to a voltmeter. A reference electrode 5 can be an external one - placed entirely outside of a catheter.
• an underlay 1 for pH measurement is covered by an electrically conductive, pH sensitive layer 2 of antimony.
• the antimony layer of 99.99% purity and 9 micrometer thickness is sputtered in a planar magnetron with double rotation in argon inert atmosphere of pressure 100 militorr and cathode potential -1kV.
• the pH sensitive layer 2 of antimony forms metal/oxide equilibrium spontaneously after the deposition when placed in free air or during the first minutes of measurement in a solution.
• a layer of Sn was sputtered on an underlay 1, for impedance measurement, made of acrylonitril/butadiene/styrene (ABS) with a graphite mixture in the same way.
• ABS acrylonitril/butadiene/styrene
• this system of modular catheter allows the important advantage of easy assembly and a price for a multiple-electrode catheter that is similar to the price of a single-electrode catheter. It will also be possible to make special catheters fitted to a patient from prepared modules - electrodes, easily connected linked together, according to a doctor's specifications.
• One benefit for the patient is the use of a low-costmodular multiple- electrode catheter within the first 24 hours.
• Presently the basic 24 hours measurement of esophageal reflux is carried on by a catheter with one pH electrode placed 5 cm above the esophageal sphincter, because of its lower price.
• An electrode according to invention can be used mainly for continuous measurement of pH and impedance in the case of esophageal reflux. In light of its possible miniaturization and possibility to building-in catheters, it is suitable for using in medicine, for pH and impedance measurement of bodily fluids.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Surgery (AREA)
• General Health & Medical Sciences (AREA)
• Biophysics (AREA)
• Pathology (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Medical Informatics (AREA)
• Molecular Biology (AREA)
• Veterinary Medicine (AREA)
• Animal Behavior & Ethology (AREA)
• Public Health (AREA)
• Radiology & Medical Imaging (AREA)
• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
• Endocrinology (AREA)
• Gastroenterology & Hepatology (AREA)
• Physiology (AREA)
• Optics & Photonics (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
• Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=42084567

Family Applications (1)

Country Status (2)

Cited By (3)

Citations (11)

Family Cites Families (5)

• 2008
  • 2008-12-08 CZ CZ20080792A patent/CZ302036B6/cs not_active IP Right Cessation
• 2009
  • 2009-11-30 WO PCT/CZ2009/000142 patent/WO2010066208A1/en active Application Filing

Patent Citations (13)

Also Published As

Similar Documents

Legal Events