A CANNULA OF CHANGEABLE LENGTH AND SHAPE

Abstract: A cannula of changing length and shape, built up of bands linked with each other, which after the end of the cannula separate from each other and immediately after the place of separation, they are folded and inserted into the interior of the cannula, in which they can slide freely toward its beginning or its end. An adjusting device with guiding lamellas is located at the cannula end, the separated sections of the bands pace along the spaces between the lamellas. The elongation of the cannula is effected by pulling and sliding the free parts of the bands by the adjusting device, their arrangement between the guiding lamellas and their pressing and linking in the way predetermined by the location of the lamellas and their fixing in this position are effected by magnetic forces or by meshing the male part and the female part of the bands. The shortening of the cannula is effected by pulling the free parts of the bands toward the beginning of the cannula and the destruction of the cannula from its end.

Description: A CANNULA OF CHANGEABLE LENGTH AND SHAPE Sphere of Technics The invention refers to a cannula of changeable length and shape, which can be used in medical application during the penetration of various devices, e.g. endoscopes, into the living systems as well as other activities, which necessitate the penetration into a medium, vulnerable to mechanical intervention and/or is without well-shaped confining walls. State of Art There are tubes, tubular elements (1-7) and devices., e.g. endoscopes, including tubes and tubular elements (8, 9), which are characterised by the fact that after penetrating into the body along the existing lumens - oesophagus, blood vessels, etc. - they ensure some protection from mechanical traumas to the surrounding tissues during the operation of the devices. A disadvantage of the existing tubes, tubular elements and devices containing tubes and tubular elements is the fact that during their penetration into the living system as well as during their removal, they cause considerable traumas due to the friction between their outside surface and the medium of penetration and particularly to the side pressure exerted by the sections where there are curves. The aim of the invention is to create a cannula of changeable length and shape, which is to penetrate the living system not only through existing orifices and which is to reduce to a minimum the traumas to the surrounding medium e.g. the human body. The task is solved by a device in which the cannula is formed at entering the working medium only through lengthening the front end, which takes the turns in any direction only through growing in the same direction and which in taken out of the surrounding medium only through shortening of the front end, keeping static all the time in respect to the medium and keeping stable its shape. The definition of this task as well as the principle possibility of solving it are subject to patent 1131. Technical character of the invention The task is solved by a cannula 1, built up of bands 2 linked between each other, which can move freely in the sections where they are not linked in the interior of the cannula. The elongation of the cannula 1 is effected by sliding the bands 2 in its interior toward its growing end whereas they bend in such a way that they finish building its walls whereat they link with each other and become static, and fix the shape of the obtained end section of the cannula length 1. The shortening of the cannula 1 is effected by breaking the link between the bands 2 at the end of the cannula along their nex separating and bending, whereat the liberated sections of their length get into the interior of the cannula and slide towards its beginning. The reversible bending of the bands 2 at the point of transition from free into linked state and the creation of links between them is effected by an arranging device, attached to the instrument, e.g. the endoscope 3, for whose penetration into the surrounding medium the cannula is built up. The shape of the cannula 1 is changed by forming turns in the desired direction when the bands at its external side are pulled and included in the walls of the cannula of greater length than the bands at the internal side of the turn. Description of Drawings The advantages of the described cannula are: The cannula 1 is static in respect to the surrounding medium with the exception of its end section where it lengthens or shortens and thus the friction with the medium is eliminated both of the cannula 1 it self and of the endoscope 3 inserted in it. The cannula has a stable shape i.e. it is comparatively solid and therefore at the turns the cannula 1 and the endoscope 3 inserted in it do not press laterally the surrounding medium, i.e. the described cannula 1 does not traumatise the surrounding medium, either by longitudinal friction, or by lateral pressing except at the moment and place of elongation and respectively shortening of the cannula. Examples of Execution Example 1. A cannula 1 of changeable length and shape, shown in figures 1, 2 and 3, consisting of radially arranged and linked with each other bands 2, which at the cannula end are separated from each other and their free parts are loosely located in the space between the cannula and the endoscope 3. The linking of the bands in this example is effected under the influence of magnetic forces, that is why the bands contain particles with constant magnet properties, oriented in such a way that the axis of their poles is perpendicular to their planes whereas in the cannula the bands are arranged in such a way that the contact surfaces are with alternatively changeable magnet poles. The transition of the bands 2 from their free state in the interior of the cannula toward their arranged state in the cannula 1 is effected in the adjusting device in the endoscope head 4, which consists of the adjusting lamellas which are in the endoscope head, which has a shape allowing the turning of the band direction at 180°. At the endoscope head the lamellas are most apart front each other both with their neighbours and with those opposite the diameter D, whereas in the farthest place from the transition point the lamellas are closest to each other along the diameter D 2 , whereat D, greater than D 2 . This allows the bands to move apart and their transition from free end loose location in the interior of the cannula 1 to their arrangement in a radial direction and linkage in the cannula 1 it self, which is effected because of the arrangement of the bands and their contact after passing the lamellas ends. The elongation of the cannula 1 is effected by moving the endoscope 3 and respectively its head 4 in the direction of its penetration into the surrounding medium, whereas at the point of transition around the lamellas 5 as a result of the friction in the rounded channels, in which these lamellas are placed, the bands 2 slide in respect to the endoscope 39, bend at 180°, arrange themselves between the lamellas 5 and after passing the place where these lamellas are the narrowest and are located closest to each other, they turn out to be pressed and linked with each other and included in the end newly-built section of the cannula, which is of stable shape due to the regular arrangement of the bands and the presence of linkage forces. The shortening of the cannula is effected by moving the endoscope 3 in the opposite direction and pulling the freely located bands 2 from the beginning of the endoscope outside the surrounding mediums, at which at the point of transition in the cannula end the bands 2 get separated because of moving apart from each other and getting between the adjusting lamellas 5, they turn at 180° at the point of transition and in a free state they are pulled in the direction of the beginning of the endoscope. The turns of the cannula are formed by bending the endoscope head 4 in the desired directions at which the bands 2 at the external side of the turn are pulled with a higher speed and a greater length than the bands at the internal side of the turn, and with such different length they are included in the cannula structure, therefore it turns to have a fixed stable curve at the place of the turn. In order to prevent the linking of the bands 2 in the interior of the cannula, in which they should slide freely in respect to each other, they should be arranged in such a way that their contact surfaces have the same pole of magnetising, that is why they will not attract each other, but will be apart to the limit. Example 2. A cannula 1, shown in figures 4, 5 and 6, similar to that described in Example 1, in which the bands, building up the cannula, are with tangentially located planes at their wide side. One of the two narrow sides of each band is formed with a protruding lodge like a male part 6, while the other side is with a recess like a male part 7. The bands are linked with each other with their narrow side by clipping the male part 6 of each band with the female part 7 of the next band. The linking of the bands in this way is effected at the moment of their maximum tangential closeness on leaving the point of transition, whereat the adjusting lamellae are closest to each other along the diameter D 2 , along which their narrow ends are located, is the smallest. In the interior of the cannula the bands are also with tangentially located surfaces of their wide aides but, because of the smaller diameter of the hollow they are in, they overlap each other with some part of their width. At the point of transition the bands are bent at 180° without charging their tangential location of their surfaces along their wide side. The advantages of this cannula are: Due to the tangential location of the bands 2, the thickness of the cannula is small and a larger free interior section (lumen) remains for moving the endoscope 3. The linking of the bands 2 with each other is effected in an ordinary, safe, feasible and easy to master way, the elements to be linked do not interact, while the bands in the interior of the cannula are in a free state. Example 3. A cannula 1, shown in fig. 7, similar to that described in Example 2, in which the bands building the cannula are linked with each other by clipping the male part 6 of each narrow side with the female part 7 of the other narrow side of each side, whereat the male part is the unchanged narrow part of the flat band, and the female part is obtained. The penetration of the male part of one band into the female part of the next band causes the opening of the cone, forms the female part, while the tension of the link between the two sides of the cone causes pressing of the male part. This pressing, together with the wide sides of the cone ensure the stability of the link between neighbouring bands. The Advantages of this cannula are: The simplicity of linking neighbouring lands, which does not require a special element for opening the female part of the band on meshing, and does not require considerable error for pressing the bands at the moment of their meshing. The possibility of realising and maintaining the link between the bands with varying within certain limits the distance between them. The minimal thickness of the bands both in the cannula structure and in their free state, in which the sides of the female part touch each other and ensure in this way the maximum lumen of the cannula and the simplicity of sinking the bands. Literature 1. Author's certificate CCCP SU 1477371A1 (11.05.66) 2. Author's certificate CCCP SU 1480806A1 (06.07.87) 3. Author's certificate CCCP SU 1819566A1 (17.04.91) 4. Author's certificate CCCP SU 1099949A1 (25.02.82) 5. Author's certificate CCCP SU 1819567A1 (28.06.91) 6. Patent USA 5643174 (01.07.97) 7. Patent USA 5620408 (15.04.97) 8. Author's certificate CCCP 925310 (15.01.79) 9. Patent PF RU 2022518 Cl (13.02.91) 10. Patent USA 5558665 (24.09.96) 11. Patent USA 5448989 (02.04.95) 12. Patent USA 5645520 (08.07.97) 13. Swedish patent 9604792-3 Description of attached figures Fig. 1 - LONGITUDINAL SECTION 1. Cannula 2. Bands 3. Endoscope 4. Endoscope head 5. Lamellae Fig. 2 - CROSS SECTION ALONG AB 2. Bands 3. Endoscope 4. Endoscope head 5. Lamellae Fig. 3 - CROSS SECTION ALONG BG 1. Cannula 2. Bands 3. Endoscope 4. Endoscope head Fig. 4 - LONGITUDINAL SECTION 1. Cannula 2. Bands 3. Endoscope 4. Endoscope head 5. Lamellae Fig. 5 - CROSS SECTION ALONG AB 2. Bands 3. Endoscope 4. Endoscope head 5. Lamellae 6. Male part of the bands 7. Female part of the bands Fig. 6 The same Fig.7 The same

Claims: Patent Claims 1. A cannula of changing length and shape (1), built up of bands linked with each other (2), characterised by the fact that at the end of the cannula these bands are separated from each other and immediately after the place of their separation they are bent and inserted in the interior of the cannula, in which they can, irrespective of each other, slide towards the beginning or the end of the cannula as well as in respect to the instrument, e.g. the endoscope (3), for whose penetration in the surrounding medium this cannula is constructed. 2. A cannula, according to claim 1, characterised by the fact that the transition from free bands to bands linked into the cannula is affected in the end part of the endoscope, in its head (4), which contains guiding lamellas (5), in the space between which the bands are located and which from their one side lead the free sections of the bonds to the end of the cannula in the same way in which they are located in the structure of the cannula itself, while from the other side they lead them toward the interior of the cannula so that they are free from each other, but on overlapping they take a minimal total volume of the cannula interior. 3. A cannula, according to claims 1 and 2, characterised by the fact that the distances between the lamellas and the free spaces between them, in which the bands are located, grow in the direction of the cannula end toward the tip of the endoscope head and in this way ensure the moving apart of the bands from the end of the cannula in the direction of the point of their transition, from arranged to free state and thus provide the possibility for the bands to pass from free into arranged state and vice versa. 4. A cannula, according to claims 1, 2 and 3, characterised by the fact that the bands in the cannula are arranged radially in the walls of this cannula. 5. A cannula. according to claims 1 and 4, characterised by the fact that the bands in the cannula wall are linked by magnetic forces, due to the fact that the bands are constant magnets with a direction of the axis of the poles perpendicular to the wide side of the bands, and the bands are arranged in such a way that the north pole of the one touches the south pole of its neighbouring band. 6. A cannula, according to claims 1, 2 and 3, characterised by the fact that the bands in the cannula are arranged tangentially in the walls of this cannula. 7. A cannula, according to claims 1 and 6, characterised by the fact that the bands have a male part (6) on one of their narrow sides and a female part (7) on the other narrow side. In the cannula wall the bands are linked by clicking the male part of each band with the female part of its neighbouring band. 8. A cannula, according to claims 1, 2 and 3, characterised by the fact that it elongates when the endoscope moves forward in the surrounding medium, whereat the free parts of the bands slide in the direction of the transition from free to arranged and linked state and after this transition they get included in the cannula wall in a way predetermined by the location of the guiding lamellas and the spaces between them, and if the endoscope head moves along a curved line, the bonds, front the external side of the turn are pulled with a higher speed and with a greater length, while from the internal side of the turn they are pulled with a lower speed and a shorter length and with these lengths they are included in the cannula wall and because of the linking of these bands with each other, the constructed cannula has a stable shape, obtained at the moment of its construction, while the shortening of the cannula is effected when the endoscope is taken out of the surrounding medium, and a gradual destruction of the cannula occurs at its end when the bands move apart and the links between them break apart at the point of transition and the bands of which the cannula is built up pass from linked into a free state and slide toward the beginning of the endoscope by pulling the endoscope out of the surrounding medium.

Inventors: STEFANOV ALEXANDER R, STEFANOV IVAN R, STEFANOV, ALEXANDER R., STEFANOV, IVAN R.
Applicants: STEFANOV ALEXANDER R, STEFANOV IVAN R, STEFANOV, ALEXANDER R., STEFANOV, IVAN R.
Application year: 1999
Main classification: A61B1
IPC codes: A61B1, A61B17, A61M25