Surgery – Endoscope – Having auxiliary channel
Reexamination Certificate
2001-09-13
2003-05-20
Dvorak, Linda C. M. (Department: 3739)
Surgery
Endoscope
Having auxiliary channel
C600S139000, C600S140000
Reexamination Certificate
active
06565507
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Art
This invention relates to a flexible tube which is particularly useful, for example, as a biopsy channel or guide tube to be incorporated into an endoscopic insertion instrument or as a catheter or the like, and a method for manufacturing such guide tubes.
2. Prior Art
Generally, endoscopes which are in use in medical fields are constituted by a manipulating head assembly to be gripped by an operator and an insertion instrument which is extended forward from the manipulating head assembly for insertion into a patient's body cavity. By way of properties, an endoscopic insertion instrument can be divided into three sections, i.e., a rigid tip end section which is provided at a fore distal end of the insertion instrument, an angle section which is connected to a proximal end of the rigid tip end section, and an elongated flexible body section which is connected between a proximal end of the angle section and the manipulating head assembly. Endoscopic observation means are provided on the rigid distal end section for observation of intracavitary portions, including an illumination window or windows having a light emitting end of a light guide fitted therein for projecting illumination light, and an observation window having an optical lens system fitted therein for picking up optical images of intracavitary portions. Further, an exit hole of a biopsy channel is opened in the rigid tip end section for projecting forceps or other biopsy or surgical instrument into a body cavity therethrough.
The angle section is a part which can be flexibly bent into an angular form by remote control from the manipulating head assembly. The flexible body section has a flexible structure which is bendable in arbitrary directions along a path of insertion into a body cavity. Various component parts which are fitted in or threaded through the flexible body section should also be flexible in bending directions of the insertion instrument. In this connection, the biopsy channel is extended coextensively through the insertion instrument, more specifically, from a fore distal end of the insertion instrument up to an entrance hole or an entrance way which is provided on the manipulating head assembly. Forceps or other instruments which are introduced into the biopsy channel through the entrance hole are projected into a body cavity through the exit hole which is formed in the rigid tip end section of the insertion instrument to make a necessary treatment. Therefore, the biopsy channel is required to be flexible in bending directions and is usually constituted by a flexible tube. The biopsy channel which is fundamentally provided for insertion of biopsy instruments is also used as a suction passage at the time of sucking out body fluids or the like. In addition to a biopsy channel, a flexible tube of similar nature is also fitted in the endoscopic insertion instrument to serve as an air/water feed tube for the purpose of washing the observation window.
In addition to the afore-mentioned flexibility, the flexible tubes which are used in medical treatments as endoscopic biopsy channels or for other purposes are required to have satisfactory properties in shape retainability including anti-crushing strength, anti-kinking strength, anti-rupturing strength, air tightness, water tightness, resistance to chemicals, feasibility of disinfection by washing, biotic suitability or safety etc. Especially, a flexible tube to be use as an endoscopic biopsy channel should be formed of a material which is slippery and of low frictional coefficient in order to ensure smooth insertion of various instruments. The inside diameter of an endoscopic biopsy channel is determined depending upon outside diameters of endoscopically inserting instruments, and is normally in the range of 1 mm to 5 mm. Besides, in order to make the outside diameter as small as possible, a flexible tube for a biopsy channel is usually arranged to have a minimum necessary wall thickness.
For instance, disclosed in Japanese Patent Publication H7-45219 is a flexible tube which was developed to meet the above-mentioned requirements in properties. This known flexible tube is of a laminated structure consisting of an inner layer and an outer layer. The inner layer is formed by extruding a crystalline polymer resin consisting of a fluorine resin or the like into a tubular form. This inner layer is particularly so arranged as to have properties which are required of the inner layer of the biopsy channel, namely, to have suitable properties in slipperiness, low friction coefficient, resistance to chemicals, feasibility of disinfection by washing and biotic safety, in addition to air- and water-tightness. However, the crystalline polymer resin itself is inferior flexibility. Therefore, the thickness of the inner layer is reduced as much as possible for the purpose of imparting flexibility thereto, at the sacrifice of strength. For these reasons, the outer layer needs to be imparted with necessary properties in strength, including shape retainability and anti-rupturing strength, in addition to flexibility. Therefore, the outer layer is formed of a thermoplastic resin, desirably urethane resin. In order to enhance the strength of the outer layer, a reinforcing layer is embedded in urethane resin or a reinforcing layer is sandwiched between urethane resin layers. Mesh-like knit fabric of metal fiber is used as a reinforcing layer for the purpose of ensuring flexibility in bending directions.
The arrangement of above-described prior art flexible tube can be advantageously used as an endoscopic biopsy channel. However, this prior art flexible tube still has a number of problems. One problem relates to the wall thickness of the flexible tube. The use of the outer layer, having a reinforcing layer sandwiched between urethane resin layers, makes reductions in wall thickness very difficult. In addition, reductions in wall thickness are also difficult with regard to the inner layer which is formed by extrusion molding. Thus, the prior art flexible tube has limits in reducing the wall thickness of the flexible tube as a whole.
In the case of an endoscope which is designed for medical use, it is desirable for the insertion instrument to be as thin as possible from the standpoint of reducing pains on the part of patients and facilitating passage through a narrow duct. Recently, the insertion instrument itself of an endoscope as well as internally fitted members of the insertion instrument are reduced in diameter almost to ultimate limits. Nevertheless, regarding the biopsy channel which occupies a relatively large space within the endoscopic insertion instrument, use of a flexible tube which is thinned down in wall thickness and in diameter and yet can meet the above-mentioned requirements in properties can contribute significantly in further reducing diameters of endoscopic insertion instruments.
On the other hand, as for a flexible tube which is intended for use as an endoscopic biopsy channel or for other medical use, Laid-Open Japanese Utility Model H4-47402 discloses a flexible tube construction having an inner layer or inner tube of fluororesin wrapped in a helical metal wire winding, and an outer layer of urethane resin which is laminated around the inner layer. In the case of this prior art flexible tube having a reinforcing layer formed directly around the outer periphery of the inner layer, the outer layer can be constituted by a single urethane resin layer. Therefore, since the properties such as anti-kinking strength, shape retainability and anti-rupturing strength can be covered by the outer layer, it becomes possible to reduce the wall thickness almost to an ultimate limit. However, the use of a helical metal wire winding as a reinforcing layer is insufficient in guaranteeing required shape retainability and strength of the biopsy channel particularly when a load is exerted in a twisting direction.
Further, the above-mentioned properties such as air tightness, water tightness, slipperiness, low friction coeffici
Akiba Haruo
Kamata Kouichi
Kimura Masanori
Muraki Kouichi
Dvorak Linda C. M.
Fuji Photo Optical Co., Ltd.
Schopfer Kenneth G
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