A CANNULA OF CHANGEABLE LENGTH AND SHAPE

Abstract: A cannula for movement along determined trajectory, consisting of numerous longitudinal bands, connected with cross links, which allow their sliding in respect to each other. The movement of the cannula is effected by abrupt strokes longitudinally upon one separate band, whereat it slides at a definite distance in respect to its neighbouring bands, whereas the remaining bands remain linked and static in respect to each other, followed by the same strokes, consecutively upon each of the remaining bands and repeated repetition of the cycle until the movement at the desired distance is achieved. The immobility of the numerous bands with the exception of one, ensures the mechanical memory of the cannula for its location in the different sections of space and its movement along a determined trajectory.

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 patent /13/ proposes a new principle of action of a three-dimensional controllable cannula according to which the leading instrument is placed in a lumen of the cannula itself. The lumen is formed during the penetration into the body without having to use ready natural ways and operates on the principle of snail horns - protruding and retracting The patents however, does not propose a construction working on this principle, neither the moving force which will open and close the cannula. 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 the 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 by lengthening the front end, which takes the turns in any direction only through growing in the same direction and which is taken out of the surrounding medium only by shortening of the front ends, keeping static all the time and keeping stable its shape. The task of the invention is to create a cannula, which is to penetrate into the surrounding medium and to be taken out of it along a predetermined trajectory, keeping its shape in the sections, in which It has penetrated. Technical Character of the Invention A cannula 1 has been created, built up of parallel to its axis bands 2, which are linked laterally with each other with links, which allow their sliding in respect to each other. At the end of the cannula 1, with which it penetrates into the surrounding medium, the bands 2 have ledges, covered by caps 4, and these ledges allow each of them to slide past its neighbours only to a definite limited distance. The penetration or the removal of the cannula 1 is effected by abrupt strokes upon one separate band 2 in the direction of the movement of cannula 1 as a whole, whereat this band 2 slides to a certain distance in respect to the bands it touches and by consecutive as abrupt strokes upon each of the remaining bands, each of them slides irrespective of the others in respect to its neighbours, until all the bands 2 move in the desired direction, and the cannula 1 as a whole is moved too. At the moment of sliding of each of the bands 2, the remaining bands keep their position between each other and in this way the cannula 1 keeps the shape, obtained before in each section. That is why after moving the cannula 1 in one or another direction, it keeps its shape in each of the sections of the space it has penetrated. The direction of the penetration of the cannula 1 in the new sections of spaces hence the shape of the cannula 1 in the new section can be changed when from the exterior side of the turn the bands 2 move at a higher degree than the bands 2 from the internal side of the turn, and the stage of movement of the intermediate bands smoothly changes between two extreme vales. Since the ends of the bands 2 are covered by their common cap 4, which has a fixed diameter, the unequal movement of the bands results in forming a turn with an exterior side from the side of the bands, which are moved at a higher degree. The advantages of the cannula 1 consist of: During the penetration and the removal of the cannula 1, its friction with the surrounding medium is minimum, as at each separate moment only one of its numerous narrow bands 2 moves only a short distance. After that this band remains static until all the remaining bands 2 move. This makes possible the relaxation of even minimal tensions created in any point of the surrounding medium, which is in contact with this band. The side pressure during the penetration into and the removal from the cannula 1 is eliminated completely in spite of the curves of its shape, because all the sections of the cannula move only along the trajectory, traced by the cannula end during its penetration into the surrounding medium. This is due to the mechanical memory for their location in space of numerous static bands in the cannula wall at the moment of the sharp and short movement of only one band from its wall at a short distance. The wall of the cannula is free from any additional parts, devices and instruments, therefore the diameter of the lumen of this cannula is maximal. Examples of Execution Example 1. A cannula for movement along determined trajectory shown in fig. 1, whose wall is built up of bands 2, which are located parallelly to its axis and are linked laterally with each other by meshing a male and a female part, located respectively on each side of the band. At the end of the bands, from the end of the cannula by which it penetrates into the surrounding medium, from the external wall of the cannula, the bands have limiting ledges 3, covered by a cap 4. The penetration into or the removal from the surrounding medium is effected by abrupt strokes in the direction of the cannula movement as a whole upon one of all bands of this cannula, whereat this band slides a short distance in respect to its neighbouring bands, the distance being determined by the limiting ledges at the end of each band covered by the cap. Analogous, consecutive in time strokes follow upon each of the remaining bands, whereby the movement of the cannula as a whole is achieved. The repeated repetition of this cycle results in the penetration of the cannula as a whole at the desired distance in the surrounding medium. During the abrupt, brief and short sliding of each separate bands, the remaining bands, static at this moment, ensure the mechanical memory of the cannula and it keeps its shape without alterations in the sections, it has already penetrated, although it still continues to penetrate or is being removed from the surrounding medium. The sequence of alternating the movement of the separate bands is arbitrary within each cycle, but in order to achieve maximum relaxation of the tensions- a result of the friction with the surrounding medium and between the bands, it is better to alternate bands opposite to the cannula diameter. The end of the cannula moves along a straight line when all bands move the same distance within each consecutive cycle, and it turns in the desired direction, forming a turn, when from the external side of the turn the movement of the bands is greater than the movement from the internal side of the turn and the necessary deformation of the bands is ensured by the cap in the same end. Literature 1. Author's certificate CCCP SU 1477371 Al (11.05.86) 2. Author's certificate CCCP SU 1480806 Al (06.07.87) 3. Author's certificate CCCP SU 1819566 Al (17.04.91) 4. Author's certificate CCCP SU 1099949 Al (25.02.82) 5. Author's certificate CCCP SU 1819567 Al (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 ( 12.04.95) 12. Patent USA 5645520 (08.07.97) 13. Swedish patent 9604792-3 Description of attached figures Fig. 1 - AXONOMETRIC PROJECTION OF THE CANNULA 1. Cannula 2. Bands Fig, 2 - LONGITUDINAL SECTION 1. Cannula 2. Limiting ledges (stops) 4. Cap

Claims: Patent clams 1. A cannula 1 for movement along determined trajectory, whose wall is built up of bands 2, which are longitudinally located, and characterised by the fact that the bands are laterally connected with links, allowing them to slide in respect to each other, and at the end of the cannula, by which it penetrates into the surrounding medium, the bands have limiting ledges 3, covered by a cap 4, which allow the movement of each band in respect to its neighbouring bands to occur only at a definite, limited distance. 2. A cannula, according to Claim 1, characterised by the fact that its penetration into, or its removal from the surrounding medium is effected by abrupt strokes longitudinally along one of all the bands of this cannula, whereat this band slides in respect to its neighbouring bands, at a distance, determined by the limiting ledges (stops) and the cap covering them, followed by the same strokes upon each of the remaining bands, whereby movement of the cannula as a whole is achieved and by repeating this cycle of strokes many times the movement of the cannula at the desired distance is achieved, whereat the cannula end moves in a straight line when all the bands move the same distance within each consecutive cycle, and turns in the desired direction forming a turn, when from the external side of the turn the movement of the bands is greater than the movement from the internal side of the turn, and the necessary deformation of the bands is ensured by the cap at the same end, while the abrupt, brief and short- distanced sliding of each separate band in respect to its neighbouring bands, while the remaining bands remain linked and static at the same moment, ensures the mechanical memory of the cannula and it keeps its shape without alteration in the section, it has penetrated, although it continues to penetrate or is being removed from the surrounding medium.

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