Cannula and system

Abstract

The invention relates to a cannula (1), in particular a cannula for bidirectional perfusion, having a distal cannula end (2) for introduction into a blood vessel, for example into a leg artery, a proximal cannula end (3) for connection to an extracorporeal system, for example to a heart-lung machine and / or to an ECMO device, and having a main fluid channel (4) extending from the distal cannula end (2) to the proximal cannula end (3), wherein the main fluid channel (4) is formed by an outer wall (5), wherein a side channel element (6) is formed in and / or on the outer wall (5), wherein the side channel element (6) can be moved between a first position in which it is introduced into and / or onto the outer wall (5) and a second position in which it is removed from the outer wall (5), and wherein the side channel element (6), in the removed, second position, forms a side channel (7), characterised in that at least one fluid pressure channel (8, 9) runs from the proximal cannula end (3) to the side channel element (6) in order to move the side channel element (6) between the first position and the second position by means of a fluid. The invention further relates to a system (14) comprising a cannula (1) and a dilator (15).

Description

[0001] CANNULA AND SYSTEM

[0002] The invention relates to a cannula, in particular a cannula for bidirectional perfusion, with a distal cannula end for insertion into a blood vessel, for example into a leg artery, a proximal cannula end for connection to an extracorporeal system, for example to a heart-lung machine and / or to an ECMO device, and with a main fluid channel extending from the distal cannula end to the proximal cannula end, wherein the main fluid channel is formed by an outer wall, wherein a side channel element is formed in and / or on the outer wall, wherein the side channel element is movable between a first position inserted in and / or on the outer wall and a second position extended from the outer wall, and wherein the side channel element forms a side channel in the extended second position.

[0003] Furthermore, the invention relates to a system comprising a cannula and a dilator.

[0004] Cannulas of this type are used in medicine, particularly to direct fluids, especially solutions, into a blood vessel. If it is a perfusion cannula, it serves, for example, during heart surgery to artificially circulate blood while the heart is being operated on or temporarily stopped, in order to allow for precise intervention. Another well-known application of perfusion cannulas is their use in extracorporeal membrane oxygenation (ECMO). Antegrade leg perfusion is often necessary when, during ECMO or aortic surgery, a cannula is inserted into the femoral artery to pump blood to the body. In this case, blood flow to the leg containing the cannula can be obstructed. This could lead to an insufficient supply of oxygen to the leg, which can cause tissue damage.

[0005] To prevent this, a bidirectional perfusion cannula can be used, which supplies the leg with oxygen-rich blood by maintaining blood flow into the femoral artery towards the foot.

[0006] Corresponding bidirectional perfusion cannulas are shown, for example, in documents WO 2016 / 137212 A1 and US 8,795,253 B2. Furthermore, document US 9,981,119 B2 describes a bidirectional cannula for perfusing blood in two directions. The cannula has a distal opening and a proximal opening connected by a fluid channel. A movable, tubular extension is arranged within the fluid channel, which can be extended and inserted into the channel via a wire, thus enabling antegrade fluid perfusion.

[0007] EP 3 492 133 A1 describes a bidirectional perfusion cannula which, to ensure adequate blood supply to the lower extremity during femoral cannulation, features a special bend (elbow) and a second, backward-facing opening (hole) through which blood can also flow in the opposite direction. A thickening (protuberance) at the bend is intended to stabilize the position of the cannula and keep the artery open. Furthermore, it is described that the bend ("elbow") can be made of flexible material (e.g., PVC, polyurethane, silicone, or rubber) and can be configured so that it could be inflated with an attached balloon. When inflated, this elbow forms the thickening (protuberance), so that the cross-section of the main cannula body is not circular in this area.However, there is a risk that this thickening could injure the arterial walls during implantation and explantation, leading to hematoma formation. Inflating the balloon has no effect on the backward-facing opening (hole), as the balloon and the thickening merely fix the cannula in situ, and the opening in the main body of the cannula, acting as a "hole," directs the flow in the antegrade direction.

[0008] The problem with known devices is that they are structurally complex and complicated to handle.

[0009] The present invention is therefore based on the objective of designing and further developing a cannula of the type mentioned above in such a way that reliable use with simple handling is possible using structurally simple means. Furthermore, an improved system consisting of such a cannula and a dilator is to be provided. According to the invention, the aforementioned objective is achieved by the features of claim 1. According to this claim, the cannula in question, in particular a cannula for bidirectional perfusion, has a distal cannula end for insertion into a blood vessel, for example, a leg artery, a proximal cannula end for connection to an extracorporeal system, for example, a heart-lung machine and / or an ECMO device, and a main fluid channel extending from the distal cannula end to the proximal cannula end, wherein the main fluid channel is formed by an outer wall.wherein a side channel element is formed in and / or on the outer wall, wherein the side channel element can be moved between a first position inserted in and / or on the outer wall and a second position extended from the outer wall, and wherein the side channel element forms a side channel in the extended second position, characterized in that at least one fluid pressure channel runs from the proximal cannula end to the side channel element in order to move the side channel element between the first position and the second position by means of a fluid.

[0010] In accordance with the invention, it has first been recognized that the underlying problem can be solved in a surprisingly simple manner by making the side channel element moveable between the first and second positions by means of a fluid. For example, the fluid can be a liquid, in particular comprising water, preferably a saline solution. The liquid could, for example, be introduced into the fluid pressure channel via a syringe connected to the at least one fluid pressure channel, in particular a high-pressure syringe, and / or via a pressure fluid source, for example comprising a compressor, in order to move the side channel element into the second position. For example, the pressure in the deployed side channel element could be in the range of 5 bar to 20 bar. To move the side channel element into the first position, the existing fluid could be drained via the fluid pressure channel.It is conceivable that the fluid is introduced and dispensed via a single fluid pressure channel. Alternatively, two fluid pressure channels could be provided: a first fluid pressure channel for partially extending the side channel element into an intermediate position, allowing the cannula to be positioned in the blood vessel, and a second fluid pressure channel for fully extending the side channel element into the second position. Due to the inventive design of the side channel element, the cannula can be inserted into the body or a blood vessel particularly easily and safely when the side channel element is in the first, inserted position and thus does not protrude from the outer wall. In particular, the side channel element could be flush with the outer wall in the first position or positioned deeper than the outer wall in the direction of the main fluid channel.In other words, the portion of the cannula inserted into the vessel could have a substantially cylindrical, preferably fully cylindrical, outer geometry when the side channel element is in the first position. This would prevent vessel damage during implantation or explantation, as occurs in the prior art. Alternatively or additionally, the portion of the cannula inserted into the vessel could have at least one or more joints or elastic joint areas, allowing for particularly low-impact implantation and explantation of the cannula.

[0011] If necessary, the side channel element can be reliably and easily moved into the second position via the fluid pressure channel, thus enabling bidirectional feeding through the side channel. It should be noted that the statement that the at least one fluid pressure channel "runs from the proximal end of the cannula to the side channel element" is to be understood in the broadest sense. The fluid pressure channel does not have to run directly along the proximal end of the cannula. What is essential is that the fluid pressure channel is accessible when the cannula is inserted into the body in its operating position.Alternatively or additionally, it is conceivable that the at least one fluid pressure channel runs at least partially within the main fluid channel, preferably on the inner wall of the main fluid channel, and / or at least partially outside the main fluid channel, preferably on the outer wall of the main fluid channel, and / or at least partially within the wall of the main fluid channel.

[0012] Within the context of this disclosure, particularly in the claims and the description, the term "side channel element" is to be understood as meaning that, in its deployed, second position, it extends away from the outer wall of the main channel, for example in the form of a tube. This projection in the deployed state distinguishes the side channel element from a mere opening or hole in the main channel, as described in the prior art.

[0013] According to an advantageous embodiment, the side channel element in the deployed second position can have a length in the range of 1 mm to 20 mm, in particular 3 mm to 15 mm, preferably 4 mm to 10 mm, measured from the free end of the side channel element to the end of the side channel element with which it contacts the outer wall. Alternatively or additionally, the side channel element in the deployed state can completely enclose the flowable area in the circumferential direction.

[0014] Advantageously, one wall of the side channel element can be balloon-shaped and be in fluid communication with the at least one fluid pressure channel. This has the advantage that the side channel element can be inflated via the fluid pressure channel to bring the side channel into the working position. A further advantage can be that the side channel element is extremely small in its initial position, so that the main fluid channel is only slightly reduced in diameter by the side channel element. In a particularly preferred embodiment, the side channel element could be designed as a hollow balloon. In other words, the side channel element could have an annular, and in particular circular, cross-section in its deployed state.

[0015] Advantageously, the outer wall can be flexible and / or made of plastic, preferably a metal-reinforced plastic. Alternatively or additionally, the outer wall can have a curved section, and the side channel element can be arranged in this curved section. This has the advantage that the cannula can be securely positioned in a blood vessel and that the flow direction of the side channel element in its extended second position and the flow direction of the main fluid channel are at least substantially opposite, thus enabling bidirectional perfusion. Alternatively or additionally, the main fluid channel can have a diameter in the range of 2 mm to 10 mm. This ensures reliable patient care.According to an advantageous embodiment, the side channel element can be applied layer by layer, so that the inner diameter of the side channel can be adjusted via the pressure in the fluid pressure channel. Thus, the inner diameter can be adapted to the requirements for optimal patient treatment. It is conceivable that the inner diameter of the side channel could be in a range of 1 mm to 8 mm.

[0016] Advantageously, a positioning device with at least one positioning element can be arranged to determine the position of the side channel element relative to a blood vessel lumen. Further advantageously, the positioning element can be arranged between the proximal end of the cannula and the side channel element. The positioning device enables the operator to determine the position of the positioning element, and thus of the side channel element, relative to the blood vessel. This ensures that the side channel element is only moved into its second, deployed position when it is correctly positioned relative to the blood vessel.

[0017] According to an advantageous embodiment, two positioning elements can be arranged one behind the other in the direction of flow of the main fluid channel, preferably at a distance of 1 mm to 5 mm. Such a design allows the position of the side channel element to be determined particularly precisely, namely when it is recognized that one positioning element lies inside the blood vessel and the other positioning element lies outside the blood vessel.

[0018] Advantageously, the sensor device can have at least one sensor fluid channel, preferably two. The at least one sensor fluid channel can extend from the proximal end of the cannula to the area of ​​the outer wall where the side channel element is located, with the proximal end of the sensor fluid channel forming the at least one positioning element. Such a design provides a simple and precise way to determine whether the positioning element is located within the blood vessel, as this will result in blood flow from the side channel element. If the positioning element is located outside the blood vessel, however, the blood flow will be minimal or absent. It should be noted that the phrase "extends from the proximal end of the cannula" is to be understood in the broadest sense. The sensor fluid channel need not run directly along the proximal end of the cannula.It is essential that the sensor fluid channel is accessible when the cannula is inserted into the body in the operating position. Alternatively or additionally, it is conceivable that the at least one sensor fluid channel runs at least partially within the main fluid channel, preferably on the inner wall of the main fluid channel, and / or at least partially outside the main fluid channel, preferably on the outer wall of the main fluid channel, and / or at least partially within the wall of the main fluid channel.

[0019] Advantageously, the positioning element can be configured as a marking element, with at least one marking element being formed on the area of ​​the outer wall where the side channel element is located. Such a marking element could, for example, be configured to be visible using an imaging technique, particularly ultrasound.

[0020] Advantageously, the positioning element can be designed as a sensor element, with the at least one sensor element being located on the area of ​​the outer wall where the side channel element is arranged. This has the advantage that reliable position determination, possibly computer-aided, is possible.

[0021] Advantageously, the outer wall can be made of a metal, in particular nitinol, and / or of a plastic, in particular polypropylene. Alternatively or additionally, the side channel element can be made of a plastic, in particular nylon, and / or reinforced with a metal, in particular nitinol.

[0022] According to a further advantageous embodiment, the cannula could be formed, at least partially, from a double-walled base body, preferably made of plastic, wherein a spiral element, preferably made of metal, runs within the double-walled base body. The outer surface of the double-walled base body can form the outer wall of the cannula. Such a design is particularly stable and easy to insert into the vessel.

[0023] Advantageously, the distal end of the cannula could be tapered. This allows the cannula to be used with a standard dilator. Alternatively or additionally, at least one, preferably several, passages, in the side wall of the cannula, could be formed at the distal end. This ensures sufficient flow. If multiple passages are provided, it can be ensured that a sufficient flow rate is achievable even if one or more passages are blocked because the distal end of the cannula is in contact with a vessel wall. The multiple passages could, in particular, be arranged equidistant from one another.

[0024] With regard to the system, the underlying problem is solved by the features of claim 11. This claims a system comprising a cannula according to any one of claims 1 to 10 and a dilator, wherein in a working position the dilator is inserted into the cannula, the dilator having a dilator tip for insertion into a blood vessel at a distal dilator end and a handle at a proximal dilator end.

[0025] Advantageously, the distal end of the dilator and the proximal end of the dilator can be connected to each other via a central element, wherein in the working position the dilator tip can protrude at least partially from the distal end of the cannula and the handle can protrude at least partially from the proximal end of the dilator.

[0026] According to the invention, it has been found that the cannula can be safely inserted, particularly into a blood vessel, if a corresponding dilator is provided. In the working position, i.e., the position in which it is inserted into the body, the dilator is arranged within the cannula, with the dilator tip protruding from the distal end of the cannula. The dilator can be manipulated via the handle, which also protrudes from the proximal end of the cannula in the working position. Advantageously, the dilator tip can be formed in two parts, and a first part of the dilator tip can be moved between a puncture position and a movement position via the handle. Specifically, in the puncture position, the dilator tip can at least substantially close off the proximal end of the cannula.Alternatively or additionally, the first dilator tip part can be positioned at least partially on or under the second dilator tip part in the movement position, so that the dilator tip can be guided past the side channel element when inserted into and withdrawn from the cannula without being blocked by it.

[0027] In a further advantageous manner, the dilator can have a passage extending between the distal end of the dilator and the proximal end of the dilator, which can be used, for example, to accommodate a guide wire.

[0028] There are now various ways to advantageously elaborate and further develop the teaching of the present invention. For this purpose, reference should be made, on the one hand, to the claims subordinate to claims 1 and 11, and on the other hand, to the following explanation of preferred embodiments of the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and further developments of the teaching are also explained. The drawing shows

[0029] Fig. 1 in a schematic representation, a perspective view of a cannula according to the invention in a first position,

[0030] Fig. 2 in a schematic representation, a perspective view of a proximal cannula end of the cannula according to Fig. 1 ,

[0031] Fig. 3 in a schematic representation, a sectional view of the proximal end of the cannula according to Fig. 1 ,

[0032] Fig. 4 in a schematic representation, a sectional view of a

[0033] Part of the cannula according to Fig. 1 in a second position, Fig. 5 in a schematic representation, a perspective view of part of the cannula according to Fig. 1 in a second position,

[0034] Fig. 6 in a schematic representation, a sectional view of a

[0035] Part of the cannula according to Fig. 1 ,

[0036] Fig. 7 in a schematic representation, a partially cutaway

[0037] Side view of a system according to the invention, wherein the cannula and the dilator are in a first position,

[0038] Fig. 8 in a schematic representation, a partially cutaway

[0039] Side view of the system according to Fig. 7, wherein the cannula is in a first position and the dilator is in a second position with a reduced dilator tip, and

[0040] Fig. 9 in a schematic representation, a partially cutaway

[0041] Side view of the system according to Fig. 7, with the cannula in a first position and the dilator removed.

[0042] Figures 1 to 6 show an embodiment of a cannula 1 according to the invention, which is designed as a bidirectional perfusion cannula.

[0043] The cannula 1 has a distal cannula end 2 for insertion into a blood vessel, a proximal cannula end 3 for connection to an extracorporeal system, and a main fluid channel 4 extending from the distal cannula end 2 to the proximal cannula end 3. The main fluid channel 4 is formed by an outer wall 5.

[0044] Furthermore, Fig. 4 shows that a side channel element 6 is formed in or on the outer wall 5. Fig. 4 shows the side channel element 6 in its second position extending from the outer wall 5, in which the side channel element 6 forms a side channel 7. Bidirectional perfusion is possible through the side channel 7. In Fig. 1, the side channel element 6 is in its first, inserted position. In this position, the side channel element 6 is embedded in the outer wall, so that the cannula 1 can be inserted into a blood vessel particularly easily without the side channel element 6 obstructing the insertion. Advantageously, the side channel element 6 is designed in a balloon-like shape.

[0045] Furthermore, two fluid pressure channels 8 and 9 are visible, extending from the proximal cannula end 3 to the side channel element 6. The first fluid pressure channel 8 serves to move the side channel element 6 from its initial, first position to an intermediate position, i.e., partially into the deployed second position, via a fluid, in particular a liquid. The fluid can be introduced under high pressure via the second fluid pressure channel 9 to fully deploy the side channel element 6 into the second position. Thus, the side channel element 6 can be partially deployed via the first fluid pressure channel 8 and fully deployed via the second fluid pressure channel 9. It is also conceivable that only a single fluid pressure channel is used to control the position of the side channel element 6.

[0046] It is also clearly visible that the outer wall 5 has a curved area in which the side channel element 6 is arranged. This ensures that the flow paths of the side channel element 6 and the main fluid channel 4 run in essentially opposite directions for bidirectional perfusion.

[0047] To determine the position of the cannula 1 or the side channel element 6 in the blood vessel, a sensor device is provided, comprising two sensor fluid channels 10, 11. The sensor fluid channels 10, 11 extend from the proximal cannula end 3 to the region of the outer wall 5, which is located more proximal than the side channel element 6, with sensor fluid channel 10 being connected to the distal sensor fluid channel end 12 and sensor fluid channel 11 to the distal sensor fluid channel end 13. The distal sensor fluid channel ends 12, 13 form the positioning elements of the sensor device. Viewed in the direction of flow of the main fluid channel 4, the distal sensor fluid channel ends 12, 13 are arranged one behind the other and downstream of the side channel element 6. Once the cannula 1 is inserted into the blood vessel, it can be withdrawn until no blood or much less blood flows from the posterior sensor fluid channel 10, i.e.that the posterior distal sensor fluid channel end 12 is located outside the blood vessel. If a stronger blood flow is still detectable from the anterior sensor fluid channel 11, the anterior distal sensor fluid channel end 13 is located inside the blood vessel. Thus, the position is determined with sufficient clarity to move the side channel element 6 into the second position. Alternatively or additionally, marker elements and / or sensor elements can be used as positioning elements.

[0048] Figures 7 to 9 show an embodiment of a system 14 according to the invention. This system comprises a cannula 1 according to the invention and a dilator 15. The cannula 1 can, for example, be designed according to the embodiment shown in Figures 1 to 6, so reference is made to the corresponding description.

[0049] The dilator 15 has a dilator tip 17 at its distal dilator end 16 for insertion into a blood vessel. A handle 19, designed here as a rotary handle, is provided at the proximal dilator end 18. The distal dilator end 16 and the proximal dilator end 18 are connected to each other via a central element 20.

[0050] Figure 7 shows the system in its working position, in which the dilator tip 17 protrudes at least partially from the distal cannula end 2 and the handle 19 protrudes at least partially from the proximal dilator end 3. In this position, the system can be inserted into the body or a blood vessel.

[0051] Fig. 8 shows the system in the position in which the dilator 15 can be withdrawn from the cannula 1. It can be seen that the dilator tip 17 and the handle 19 are designed in two parts. Via a correspondingly designed central element 20, the first dilator tip part 21 can be adjusted between a puncture position (Fig. 7) and a movement position (Fig. 8) using the handle 19. In the movement position according to Fig. 8, the first dilator tip part 21 is positioned at least partially above or below the second dilator tip part 22, so that when the dilator 15 is withdrawn from the cannula 1, the dilator tip 17 is not blocked by the side channel element 6, which is in the first position. The dilator 15 is inserted into the cannula 1 in the same way.Furthermore, the dilator 15 can have a passage 23 extending between the distal dilator end 15 and the proximal dilator end 18, which can be used, for example, to accommodate a guide wire.

[0052] Fig. 9 shows the cannula 1 with the dilator 15 removed.

[0053] Regarding further advantageous embodiments of the teaching according to the invention, reference is made to the general part of the description and to the attached claims in order to avoid repetition.

[0054] Finally, it should be expressly pointed out that the exemplary embodiments of the teaching described above serve only to discuss the claimed teaching, but do not limit it to these exemplary embodiments.

[0055] Reference sign list

[0056] 1 cannula

[0057] 2 distal cannula end

[0058] 3 proximal cannula end

[0059] 4 Main fluid channel

[0060] 5 Exterior wall

[0061] 6 side channel element

[0062] 7 side channel

[0063] 8 first fluid pressure channel

[0064] 9 second fluid pressure channel

[0065] 10 sensor fluid channels

[0066] 11 Sensor fluid channel

[0067] 12 Sensor fluid channel end

[0068] 13 Sensor fluid channel end

[0069] 14 System

[0070] 15 Dilator

[0071] 16 distal dilator ends

[0072] 17 Dilator tip

[0073] 18 proximal dilator end

[0074] 19 Handle

[0075] 20 Middle element

[0076] 21 first dilator tip part

[0077] 22 second dilator tip part

[0078] 23rd round

Claims

A n s p r ü c h e 1. Cannula (1), in particular a cannula for bidirectional perfusion, with a distal cannula end (2) for insertion into a blood vessel, for example an artery, a proximal cannula end (3) for connection to an extracorporeal system, for example a heart-lung machine and / or an ECMO device, and with a main fluid channel (4) extending from the distal cannula end (2) to the proximal cannula end (3), wherein the main fluid channel (4) is formed by an outer wall (5), wherein a side channel element (6) is formed in and / or on the outer wall (5), wherein the side channel element (6) is movable between a first position inserted in and / or on the outer wall (5) and a second position extended from the outer wall (5), and wherein the side channel element (6) forms a side channel (7) in the extended second position, characterized in that at least one fluid pressure channel (8, 9),from the proximal cannula end (3) to the side channel element (6) in order to move the side channel element (6) between the first position and the second position by means of a fluid.

2. Cannula (1 ) according to claim 1 , characterized in that a wall of the seitan canal element is balloon-shaped and is in fluid communication with the at least one fluid pressure channel (8, 9).

3. Cannula (1 ) according to claim 1 or 2, characterized in that the outer wall (5) has a curved area and that the side channel element (6) is arranged in the curved area, and / or that the side channel element (6) is flexible and / or is made of plastic, preferably a metal-reinforced plastic, and / or that the main fluid channel (4) has a diameter in the range of 2 mm to 10 mm.

4. Cannula (1) according to one of claims 1 to 3, characterized in that the side channel element (6) can be applied layer by layer, so that a The inner diameter of the side channel (7) is adjustable via the pressure in the fluid pressure channel (8, 9), preferably in a range of 1 mm to 8 mm.

5. Cannula (1 ) according to one of claims 1 to 4, characterized in that a positioning device with at least one positioning element is arranged to determine a position of the side channel element (6) relative to a blood vessel lumen, preferably wherein the positioning element is arranged between the proximal cannula end (3) and the side channel element (6).

6. Cannula (1 ) according to claim 5, characterized in that two positioning elements are arranged one behind the other in the direction of flow of the main fluid channel (4), preferably at a distance of 1 mm to 5 mm.

7. Cannula (1 ) according to claim 5 or 6, characterized in that the sensor device has at least one sensor fluid channel (10, 11 ), preferably two sensor fluid channels, wherein the at least one sensor fluid channel (10, 11 ) extends from the proximal cannula end (3) to the area of ​​the outer wall (5) in which the side channel element (6) is arranged and wherein the proximal sensor fluid channel end (12, 13) forms the at least one positioning element.

8. Cannula (1 ) according to one of claims 5 to 7, characterized in that the positioning element is designed as a marking element, wherein at least one marking element is formed on the area of ​​the outer wall (5) in which the side channel element (6) is arranged.

9. Cannula (1 ) according to one of claims 5 to 8, characterized in that the positioning element is designed as a sensor element, wherein the at least one sensor element is formed on the area of ​​the outer wall (5) in which the side channel element (6) is arranged.

10. Cannula (1 ) according to one of claims 1 to 9, characterized in that the outer wall (5) is made of a metal, in particular nitinol, and / or of a plastic, in particular of polypropylene or other material, and / or the side channel element (6) is made of a metal, in particular nitinol, and / or of a plastic, in particular of nylon.

11. System (14) comprising a cannula (1) according to one of claims 1 to 10 and a dilator (15), wherein in a working position the dilator (15) is inserted into the cannula (1), wherein the dilator (15) has at a distal dilator end (16) a dilator tip (17) for insertion into a blood vessel and at a proximal dilator end (18) a handle (19).

12. System according to claim 11, characterized in that the distal dilator end (16) and the proximal dilator end (18) are connected to each other via a central element (20) and wherein, in the working position, the dilator tip (17) protrudes at least partially from the distal cannula end (2) and the handle (19) protrudes at least partially from the proximal dilator end (18).

13. System (14) according to claim 12, characterized in that the dilator tip (17) is formed in two parts and that a first dilator tip part (21) can be moved between a puncturing position and a movement position via the handle (19).

14. System (14) according to claim 13, characterized in that the dilator tip (17) in the puncture position at least substantially closes off the proximal cannula end (3).

15. System (14) according to claim 13 or 14, characterized in that the first dilator tip part (21 ) is arranged at least partially on or under the second dilator tip part (22) in the movement position, so that the dilator tip (17) can be guided past the side channel element (6) when being inserted into and removed from the cannula (1 ).

Images