Classifications

• • 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
  • A61B5/14525—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 using microdialysis
  • A61B5/14528—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 using microdialysis invasively
• • 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
  • A61B5/14532—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 glucose, e.g. by tissue impedance measurement
• • 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
  • A61M25/0021—Catheters; Hollow probes characterised by the form of the tubing
  • A61M25/0023—Catheters; Hollow probes characterised by the form of the tubing by the form of the lumen, e.g. cross-section, variable diameter
  • A61M25/0026—Multi-lumen catheters with stationary elements
  • A61M25/003—Multi-lumen catheters with stationary elements characterized by features relating to least one lumen located at the distal part of the catheter, e.g. filters, plugs or valves
• • 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
  • A61M25/0021—Catheters; Hollow probes characterised by the form of the tubing
  • A61M25/0023—Catheters; Hollow probes characterised by the form of the tubing by the form of the lumen, e.g. cross-section, variable diameter
  • A61M25/0026—Multi-lumen catheters with stationary elements
  • A61M25/003—Multi-lumen catheters with stationary elements characterized by features relating to least one lumen located at the distal part of the catheter, e.g. filters, plugs or valves
  • A61M2025/0031—Multi-lumen catheters with stationary elements characterized by features relating to least one lumen located at the distal part of the catheter, e.g. filters, plugs or valves characterized by lumina for withdrawing or delivering, i.e. used for extracorporeal circuit treatment

Definitions

• Catheter for measuring chemical parameters in particular for insertion into biological tissue, liquids or the like
• the invention relates to a catheter of the type mentioned in the preamble of claim 1 for measuring chemical parameters, in particular for insertion into biological tissue, liquids or the like.
• Catheters of the type in question are generally known. They are referred to as microdialysis catheters and are used to use microdialysis to measure certain chemical parameters inside the biological tissue, usually the human body.
• a typical example of such a chemical parameter is the level of blood sugar in the subcutaneous tissue.
• the principle of this measurement, the z. B. is described in DE 40 01 760 C2 and in WO 95/32746, is that a double-lumen probe is inserted through the skin, which has a semi-permeable portion at its tip.
• a rinsing solution is pumped through a channel into the catheter into this probe, flows past the semipermeable membrane, and takes up the blood sugar from the subcutaneous tissue.
• this rinsing solution enriched with blood sugar, is led out of the body again, mixed with a glucose oxidase solution outside the body and fed to a sensor which measures the reaction products of the glucose-oxidase reaction.
• Microdialysis probes for carrying out the measurement described above are known, for example, in US Pat. No. 5,106,365 and WO 95/20983.
• a catheter of the type mentioned in the preamble of claim 1 is known. It is called a dialysis probe there and comprises a dialysis membrane and lines for the perfusion fluid flow through the membrane.
• the dialysis membrane is surrounded by a housing which supports and partially releases the membrane and is more rigid than the membrane itself.
• the lines form diametrically opposed channels in the catheter, which end within the tubular membrane.
• the relatively rigid housing is intended to prevent the catheter from compressing the tubular membrane after insertion into biological tissue and thereby impairing its function and the flow within the tubular membrane.
• This known catheter is complex and expensive to manufacture due to the attachment of the supporting housing and also requires a relatively large diameter. Another disadvantage is that the flushing flow within the tubular membrane does not cover all parts of the membrane in the same way.
• the total volume inside the tubular membrane is relatively large, so that the ratio of exchange surface to volume is low, with the result that the concentration in the outflowing liquid stream is low and the measurement must therefore be carried out at a lower level.
• the invention has for its object to provide a catheter of the type in question, which does not have the disadvantages described in the prior art, which is therefore particularly simple and inexpensive to manufacture, which has a small diameter and dead space and a measurement without a large amount of time Delay and enabled at a higher measurement level.
• the object on which the invention is based is achieved by the teaching specified in the characterizing part of claim 1.
• the basic idea of the invention is to design the supply and return lines in the catheter coaxially and to form the outer wall of the outer channel in the end region of the catheter through the semipermeable tubular membrane. This already results in a small dead volume within the tubular membrane, in that the interior is largely filled by the cross section of the inner wall of the outer channel, which is also the outer wall of the inner channel.
• a further feature of the invention provides that spacing means are provided which cover the walls of the radial external access Support the guide channel or the radially outer return channel against each other.
• a radial breakthrough is provided, so that it is ensured that the outer channel in the area of the tubular membrane is flowed through by the rinsing liquid over its entire length and thereby an effective removal of the the semipermeable membrane from the surrounding tissue is ensured.
• the spacing means can be designed in different ways.
• One embodiment consists in that the spacing means are formed by ribs on the inner wall of the outer feed or return channel.
• the ribs can be produced in a very simple manner when extruding the inner part of the catheter.
• the outer part forming the outer wall of the outer channel can then be pulled or pushed in the form of a tube over the inner part.
• the ribs run in the longitudinal direction of the catheter.
• the ribs run in a helical shape. This ensures intensive wetting of the inner surface of the semipermeable membrane and thus removal of the components that have passed through the semipermeable membrane.
• the helical configuration of the ribs also increases the flow rate of the rinsing liquid, which further enables an effective entrainment of the components that have passed through the semipermeable membrane.
• the ribs expediently fill the entire radial space of the outer channel, so that there is no leakage flow between the outer edges of the ribs and of the neighboring wall.
• the diameter of the tubular membrane can in principle be arbitrary. In particular, it can be larger than the catheter itself, for example when the tubular membrane with its end facing away from the end of the catheter is pushed onto the strand of the catheter and connected there. For practical use, however, it is expedient for the tubular membrane and the catheter to have essentially the same diameter.
• An expedient embodiment of the invention consists in that the outer tubular part consists of membrane material over its entire length and is provided with an impermeable layer except for the front end region of the catheter. This means that there is no gluing between the tubular part 12 and the membrane 16 in the region of the gluing surface 14, and therefore a correspondingly complicated operation. Instead, the outer tubular part is made of membrane material over its entire length, and the only operation still to be carried out is to apply the sealing layer on the inner or outer wall of the outer tubular part, which can be done in a simple manner, for example by a dipping process, can be done.
• Fig. 1 shows a first embodiment of the catheter according to the invention in the region of its end
• Fig. 2 is a section II-II through Fig. 1
• Fig. 3 shows a second embodiment of the
• Fig. 4 shows a section IV-IV through Fig. 3rd
• FIG. 1 shows an inner tubular part 2, in which a return channel 4 for rinsing liquid runs.
• a return channel 4 for rinsing liquid runs on an outer wall 6 of the tubular part 2
• ribs 8 which connect tightly to an inner wall 10 of an outer tubular part 12.
• the ribs 8 are produced by extrusion together with the inner tubular part 2.
• the outer tubular part 12 merges in the area of a conical adhesive surface 14 into a semi-permeable tubular membrane 16, the end 18 of which, like one end 20 of the inner tubular part 2, is glued to a cap 22, which can be formed by an overall drop of adhesive .
• the outer diameter of the outer tubular part is approximately 0.8 mm in this embodiment.
• the return duct 4 is connected via radial openings 24 to a feed duct 26 which is formed in the region of the ribs 8 and is visible in FIG. 2 and shows a section II-II through FIG. 1.
• the part running in the area of the tubular membrane 16 can be referred to as a probe.
• the catheter When used, for example for measuring blood sugar values, the catheter is inserted into the tissue at least with the part of the tubular membrane 16 by means of a cannula. Thereafter, rinsing liquid is supplied through the feed channel 26 and returned through the inner return channel 4. The rinsing liquid flows along the inner surface of the tubular membrane 16, the ribs 8 ensuring a uniform cross-section of the feed channel 26 in the circumferential direction and, in particular, also the semipermeable membrane 16 falling on the tubular membrane 16 or through one due to the external pressure of the fabric Prevent negative pressure generated by the return duct 4.
• Liquid flowing along the membrane entrains constituents that have passed through the membrane 16, which then adhere Return through the return channel 4 can be measured and analyzed.
• FIGS. 3 and 4 show in the same representation as FIGS. 1 and 2 a modification of the exemplary embodiment according to FIGS. 1 and 2.
• the same or corresponding parts are provided with the same reference numerals.
• the difference is that instead of the ribs 8 running in the longitudinal direction according to FIG. 1, a helical rib 28 is provided, which rests firmly on the outer wall 6 of the inner tubular part 2 or forms a part with it.
• a helical feed channel 30 for rinsing liquid is formed, thereby extending its flow path and, for a given delivery volume, also increasing its conveying speed in the area of the tubular membrane 16, which results in a uniform wetting of the inner surface of the tubular membrane 16 by the rinsing liquid and one causes intensive entrainment of the components let through the tubular membrane 16.
• the helical rib 28 can be designed in any manner. You can e.g. B. consist of a helical wire made of metal or plastic, which is pushed onto the inner tubular part 2. The outer tubular part 12 and the tubular membrane 16 are then pushed over it.

Landscapes

• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• Biophysics (AREA)
• General Health & Medical Sciences (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Animal Behavior & Ethology (AREA)
• Surgery (AREA)
• Molecular Biology (AREA)
• Medical Informatics (AREA)
• Pathology (AREA)
• Optics & Photonics (AREA)
• Anesthesiology (AREA)
• Pulmonology (AREA)
• Emergency Medicine (AREA)
• Hematology (AREA)
• Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
• External Artificial Organs (AREA)
• Measuring And Recording Apparatus For Diagnosis (AREA)
• Media Introduction/Drainage Providing Device (AREA)
• Infusion, Injection, And Reservoir Apparatuses (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (1)

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Citations (9)

Family Cites Families (10)

• 1997
  • 1997-04-09 DE DE19714572A patent/DE19714572C1/de not_active Expired - Fee Related
• 1998
  • 1998-04-02 EP EP98921414A patent/EP0973573B1/de not_active Expired - Lifetime
  • 1998-04-02 WO PCT/EP1998/001906 patent/WO1998044978A1/de not_active Ceased
  • 1998-04-02 ES ES98921414T patent/ES2256938T3/es not_active Expired - Lifetime
  • 1998-04-02 JP JP54235398A patent/JP3892050B2/ja not_active Expired - Fee Related
  • 1998-04-02 AT AT98921414T patent/ATE318631T1/de not_active IP Right Cessation
  • 1998-04-02 DE DE59813418T patent/DE59813418D1/de not_active Expired - Fee Related
  • 1998-04-02 AU AU74282/98A patent/AU7428298A/en not_active Abandoned
  • 1998-04-02 US US09/402,342 patent/US6616625B2/en not_active Expired - Fee Related

Patent Citations (10)

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