Cannula with multi-sided cannula tube and retroreflective cannula tip

Abstract

The invention relates to a cannula with a longitudinally extended cannula tube and a distal cannula tip. According to the invention, the cannula tube has a polygonal hollow profile and / or the cannula tip has a retroreflective geometry.

Description

[0001] The invention relates to a cannula with a longitudinally extended cannula tube and a distal cannula tip.

[0002] Cannulas, also known as hollow needles, are used for a wide variety of medical applications, primarily for puncturing body tissue and subsequently injecting or aspirating fluids. They can also be used to insert catheters or other invasive devices, with the cannula tube serving as a delivery channel for the device.

[0003] In many medical applications, precise positioning of the cannula within body tissue is of paramount importance. Therefore, cannulas are often positioned using ultrasound imaging techniques, with the cannula's position being monitored in the ultrasound image. This requires sufficient visibility of the cannula in the ultrasound image. In other words, the cannula must be clearly visible on ultrasound.

[0004] Typical cannulas have a hollow cylindrical profile with an annular cross-section and are made of metal, which usually provides sufficient ultrasound visibility.

[0005] Cannulas are known from the prior art which are intended to achieve improved ultrasonic visibility by modifying the surface properties of the cannula tube.

[0006] The object of the invention is to provide a cannula of the type mentioned above that offers advantages over the prior art. In particular, it aims to enable improved visual differentiation between the cannula tube and the cannula tip in ultrasound images.

[0007] This problem is solved by the cannula tube having a polygonal hollow profile. Alternatively or additionally, the cannula tip has a retroreflective geometry. According to the invention, the cannula tube and the cannula tip exhibit different reflection properties for the ultrasound signals used in position control. The polygonal hollow profile of the cannula tube generates a relatively weak ultrasound echo. The retroreflective geometry of the cannula tip generates a relatively strong ultrasound echo.

[0008] This makes the cannula tip and the cannula tube visible in the ultrasound image with varying degrees of clarity, enabling simple and reliable visual differentiation between them and ultimately improved positional control. In a preferred embodiment, the polygonal hollow profile is a triangular hollow profile with three outer longitudinal edges. In other embodiments, the polygonal hollow profile has more than three outer longitudinal edges, for example, four, five, or more than five. The retroreflective geometry of the cannula tip varies depending on the embodiment. Due to its retroreflective geometry, the cannula tip acts as a retroreflector for the ultrasound signals of the imaging ultrasound procedure. Retroreflectors are well-known as such and are also referred to as retro-reflectors.A retroreflector can be understood as a body or a section of a body that reflects incident waves, especially sound waves, predominantly in the direction from which the waves were emitted, essentially regardless of the direction of incidence with respect to the orientation of the body or body section. This effect is also called retroreflection or back-radiation. Various types of retroreflectors are known, for example, triple mirrors, triple prisms, lens-like devices, and the like.

[0009] In one embodiment of the invention, the polygonal hollow profile is a triangular hollow profile having three longitudinally extending outer edges and three outer surfaces, with each outer surface extending between two of the three outer longitudinal edges. The triangular hollow profile design allows for maximum reduction of the ultrasound echo from the cannula tube. This results in a particularly strong contrast between the cannula tube and the cannula tip in the ultrasound image. Consequently, the cannula tip can be identified with exceptional reliability. Due to the triangular hollow profile design, virtually no ultrasound echo is reflected back to the ultrasound source of the imaging ultrasound system, since, as a rule, none of the three outer surfaces are oriented perpendicular to a sound plane of the ultrasound transducer. Preferably, the three outer surfaces are planar. Preferably, the three outer longitudinal edges are each straight and longitudinally extended.

[0010] In a further embodiment of the invention, the triangular hollow profile has three longitudinally extending inner edges and three inner surfaces, wherein the three inner surfaces each extend between two of the three inner longitudinal edges. In this embodiment of the invention, therefore, not only the outer circumference of the cannula tube is triangular, but also the inner circumference. However, it is also conceivable and possible for the triangular hollow profile to have a circular or otherwise shaped cross-sectional opening.

[0011] In a further embodiment of the invention, the triangular hollow profile is isosceles, whereby the outer surfaces at the outer longitudinal edges and / or the inner surfaces at the inner longitudinal edges each enclose an angle of 60°. The isosceles design of the triangular hollow profile results in a minimal ultrasonic echo that remains constant regardless of the cannula tube's orientation. Furthermore, the manufacturing of the cannula is simplified, thereby reducing costs.

[0012] In a further embodiment of the invention, the polygonal hollow profile is rounded at its outer longitudinal edges with an outer radius. This embodiment of the invention is based on the consideration that unrounded outer longitudinal edges pose a potential risk of injury if the cannula rotates within body tissue. Rounding the outer longitudinal edges with an outer radius prevents such injuries. The ultrasound echo of the polygonal hollow profile is not amplified by the outer radii, or at most only to a practically negligible extent.

[0013] In a further embodiment of the invention, the retroreflective geometry of the cannula tip is formed by material removal, in particular by beveling, of the polygonal hollow profile. To form the retroreflective geometry, a distal end of the cannula tube can be beveled, in particular by beveling. In this case, the beveled material removal and / or beveling of the polygonal hollow profile forms the retroreflective geometry of the cannula tip.

[0014] In a further embodiment of the invention, the retroreflective geometry comprises at least a first surface, a second surface, and a third surface, wherein the first surface is oriented perpendicular to the second surface and perpendicular to the third surface, and wherein the second and third surfaces face each other. The ultrasound echo of the cannula tip can be further maximized by the first, second, and third surfaces and their orientations relative to each other. Preferably, the second and third surfaces are directly opposite each other. In other words, preferably, the second and third surfaces are at the same height with respect to the first surface. Preferably, the first, second, and third surfaces are each planar.

[0015] In a further embodiment of the invention, the first surface is formed by a section of an inner surface of the polygonal hollow profile, and the second and third surfaces are each formed by a section of a wall surface, the wall surfaces extending between an inner surface and an outer surface of the polygonal hollow profile. In this embodiment of the invention, the second and third surfaces are preferably exposed by material removal and / or grinding of the distal cannula tube.

[0016] Further advantages and features of the invention will become apparent from the claims and from the following description of a preferred embodiment of the invention, which is illustrated with reference to the drawings.

[0017] They show: Fig. 1 In a schematically simplified, proximally truncated side view, an embodiment of a cannula according to the invention with a cannula tube and a distal cannula tip, Fig. 2 the cannula tube of the cannula after Fig. 1 in a cross-section along a section line II-II according to Fig. 1, Fig. 3 the cannula tip of the cannula after Fig. 1 in a cross-section along a section line III-III according to Fig. 1, Fig. 4 A schematically simplified exemplary usage situation of the cannula according to Fig. 1 to illustrate the reduced ultrasonic visibility of the cannula tube, Fig. 5 in one of the Fig. 4. In the corresponding representation, a cannula tube known from the prior art with an annular hollow profile, which exhibits a comparatively strong ultrasonic echo, Fig. 6 a schematic representation of another exemplary use situation of the cannula according to Fig. 1 to illustrate the retroreflective properties of the cannula tip, with the cannula taking a first orientation in relation to an imaging ultrasound source, Fig. 7 a schematic representation of another exemplary usage situation accordingly Fig. 6, wherein the cannula assumes a second orientation with respect to the ultrasound source, and Fig. 8 in simplified and cropped perspective view the cannula after Fig. 1 in the area of ​​the distal cannula tip.

[0018] According to Fig. 1 has a cannula 1, a longitudinally extended cannula tube 2 and a distal cannula tip 3.

[0019] Cannula 1, also known as a hollow needle, is used for puncturing body tissue for subsequent injection and / or aspiration of fluid. Alternatively or additionally, cannula 1 can be used to insert invasive components, such as guide wires or catheters, into a patient's body.

[0020] The cannula tube 2 is extended straight along a longitudinal axis L. In Fig. Figure 1 shows the cannula tube 2 cut off proximally. The cannula tip 3 is located at a distal end of the cannula tube 2. In other words, the cannula tip 3 forms the distal end of the cannula tube 2.

[0021] The cannula tube 2 has a polygonal hollow profile M, the cross-section of which is shown in detail in Fig. Figure 2 shows the cannula tip 3, which has a retroreflective geometry G, the cross-section of which is shown in detail in Figure 2. Fig. 3 is shown.

[0022] The polygonal hollow profile M exhibits a weak ultrasound echo compared to the retroreflective geometry G. Conversely, the retroreflective geometry G exhibits a strong ultrasound echo compared to the polygonal hollow profile M. When the cannula 1 is positioned in body tissue using an ultrasound imaging technique, the medical personnel can easily and reliably differentiate between the cannula tube 2 and the cannula tip 3 in the resulting ultrasound image. This allows for improved positioning of the cannula 1.

[0023] In the embodiment shown, the polygonal hollow profile M is a triangular hollow profile D (see Fig. 2) The triangular hollow profile D has three longitudinally extending outer edges 4, 5, 6 and three outer surfaces 7, 8, 9. The outer edges 4, 5, 6 can also be referred to as the first outer edge 4, second outer edge 5 and third outer edge 6. The outer surfaces 7, 8, 9 can also be referred to as the first outer surface 7, second outer surface 8 and third outer surface 9.

[0024] The outer surfaces 7, 8, 9 are each flat. In an embodiment not shown in the figures, the outer surfaces are each concave. Alternatively, the outer surfaces can be convex.

[0025] The first outer surface 7 extends between the first outer longitudinal edge 4 and the second outer longitudinal edge 5. The second outer surface 8 extends between the second outer longitudinal edge 5 and the third outer longitudinal edge 6. The third outer surface 9 extends between the third outer longitudinal edge 6 and the first outer longitudinal edge 1.

[0026] In the embodiment shown, the outer longitudinal edges 7, 8, 9 each extended along the longitudinal axis L over the entire length of the cannula tube 2.

[0027] In the embodiment shown, the triangular hollow profile D has three longitudinally extending inner longitudinal edges 10, 11, 12 and three inner surfaces 13, 14, 15. In other words, both an outer circumference and an inner circumference of the cannula tube 2 are triangular or triangular in shape.

[0028] In an embodiment not shown in the figures, the inner circumference differs from the outer circumference in that it is round, in particular circular or oval. In a further embodiment, the inner circumference has a polygonal shape with more than three inner longitudinal edges, for example four, five, six or more than six inner longitudinal edges.

[0029] The inner longitudinal edges 10, 11, 12 can also be referred to as the first inner longitudinal edge 10, the second inner longitudinal edge 11, and the third inner longitudinal edge 12. The inner surfaces 13, 14, 15 can also be referred to as the first inner surface 13, the second inner surface 14, and the third inner surface 15.

[0030] The first inner surface 13 extends between the first inner longitudinal edge 10 and the second inner longitudinal edge 11. The second inner surface 14 extends between the second inner longitudinal edge 11 and the third inner longitudinal edge 12. The third inner surface 15 extends between the third inner longitudinal edge 12 and the first inner longitudinal edge 10.

[0031] The inner surfaces 13, 14, 15 are each flat. In this case, the inner surfaces 13, 14, 15 extend longitudinally along the longitudinal axis L over the entire length of the cannula tube 2.

[0032] The first outer surface 7 and the first inner surface 13 are parallel to each other. The same applies, mutatis mutandis, to the second outer surface 8 and the second inner surface 14, as well as to the third outer surface 9 and the third inner surface 15.

[0033] In the embodiment shown, the triangular hollow profile D is isosceles. Accordingly, the outer surfaces 7, 8, 9 are oriented at an angle of 60° to each other at the outer longitudinal edges 4, 5, 6 and the inner surfaces 13, 14, 15 are oriented at the inner longitudinal edges 10, 11, 12.

[0034] In the embodiment shown, the triangular hollow profile D is rounded at its outer longitudinal edges 4, 5, 6 with an outer radius R. The outer radius R is in Fig. 2 is only indicated graphically with regard to the third outer longitudinal edge 6.

[0035] In the illustrated embodiment, the retroreflective geometry G is formed by removing material S from the polygonal hollow profile M. In this case, the material removal S is a bevel. The cannula tip 3 is therefore formed by beveling the distal end of the cannula tube 2.

[0036] In the embodiment shown, the retroreflective geometry G has at least a first surface 141, a second surface 131 and a third surface 151 (see Fig. 3) The first surface 141 is oriented at right angles to the second surface 131 and at right angles to the third surface 151. The in Fig. The three drawn angles α and β therefore each correspond to 90°. The second surface 131 and the third surface 151 face each other. The second surface 131 and the third surface 151 are directly opposite each other. With respect to the first surface 141, the second surface 131 and the third surface 151 are at the same height.

[0037] In the embodiment shown, the first surface 141, the second surface 131 and the third surface 151 are each flat.

[0038] In the illustrated embodiment, the first surface 141 is formed by a section of the third inner surface 14. The second surface 131 and the third surface 151 are each formed by a section of a wall surface W, W', which extends between the inner and outer surfaces of the polygonal hollow profile M. The second surface 131 extends between the first inner surface 13 and the first outer surface 7. The third surface 151 extends between the third inner surface 15 and the third outer surface 9. The wall surfaces W, W', and thus the second surface 131 and the third surface 151, are exposed by the aforementioned material removal S.

[0039] The in the Fig. 3, Fig. 6, Fig. The design of the retroreflective geometry G shown in Figures 7 and 8 is to be understood as schematic. In embodiments not shown in the figures, the retroreflective geometry has a different design, in particular, with more or fewer surfaces and different orientations of the surfaces. In other words, the cannula tip 3 can be designed as a retroreflector in different ways. The design shown in the figures is to be understood as purely exemplary.

[0040] In Fig. Figure 4 shows a cross-section of the cannula tube 2 together with an ultrasound transducer 100 of an ultrasound imaging system in an exemplary usage situation. The ultrasound transducer 100 emits ultrasound signals that are reflected by the cannula tube 2. The emitted ultrasound signals are in Fig. 4 is designated with the reference symbol E. The reflected ultrasound signals are designated with the reference symbol F. Due to the design of the cannula tube 2 as a polygonal hollow profile M, specifically as a triangular hollow profile D, the transmitted ultrasound signals E are reflected in a direction-leading manner by the ultrasound transducer 100 in the application shown. Because of its specific design, the cannula tube 2 does not produce an ultrasound echo detectable by the ultrasound transducer 100. Consequently, the cannula tube 2 exhibits no or only very low ultrasound visibility.

[0041] In contrast, in Fig. Figure 5 shows a cannula tube 200 with an annular cross-section known from the prior art. Due to the annular shape of the cannula tube 200, the transmitted ultrasound signals E are reflected back, at least partially, towards the ultrasound transducer 100. The reflected ultrasound signals F can be received by the ultrasound transducer 100. The cannula tube 200 known from the prior art therefore exhibits a stronger ultrasound echo and thus a clearer ultrasound visibility than the cannula tube 2 according to the Fig. 1 to 4.

[0042] In Fig. Figure 6 shows the cannula tip 3 in cross-section together with the ultrasound transducer 100. The retroreflective geometry G of the cannula tip 3 causes the transmitted ultrasound signals E to be reflected back towards the ultrasound transducer 100 as completely as possible. The reflected ultrasound signals F result in a comparatively strong ultrasound echo and thus clear ultrasound visibility of the cannula tip 3. In the Fig. In the application shown in Figure 6, the first surface 141 of the retroreflective geometry G is positioned directly below and approximately parallel to the ultrasound transducer 100. The reflected ultrasound signals F are primarily reflected back towards the ultrasound transducer 100 via the first surface 141.

[0043] In Fig. 7 is cannula 1 relative to the one in Fig.The position shown in Figure 6 is rotated counterclockwise around its longitudinal axis L. This results in a different orientation of the retroreflective geometry G and its surfaces 141, 131, 151 relative to the ultrasound probe 100. Largely independent of this different rotational position, a strong ultrasound echo from the cannula tip 3 is still produced. This is due to its design as a retroreflector. In the application shown, ultrasound signals E are reflected from the first surface 141 towards the second surface 131 and from there back to the ultrasound probe 100.

Claims

[1] Cannula (1) with a longitudinally extended cannula tube (2) and a distal cannula tip (3), characterized by , that the cannula tube (2) has a polygonal hollow profile (M), and / or that the cannula tip (3) has a retroreflective geometry (G). [2] Cannula (1) according to claim 1, wherein the polygonal hollow profile (M) is a triangular hollow profile (D) having three longitudinally extended outer longitudinal edges (4, 5, 6) and three outer surfaces (7, 8, 9) extending between each of the three outer longitudinal edges (4, 5, 6). [3] Cannula (1) according to claim 2, wherein the triangular hollow profile (D) has three longitudinally extended inner longitudinal edges (10, 11, 12) and three inner surfaces (13, 14, 15) which each extend between two of the three inner longitudinal edges (10, 11, 12). [4] Cannula (1) according to claim 2 or 3, wherein the triangular hollow profile (D) is isosceles, whereby the outer surfaces (7, 8, 9) at the outer longitudinal edges (4, 5, 6) and / or the inner surfaces (13, 14, 15) at the inner longitudinal edges (10, 11, 12) each enclose an angle of 60°. [5] Cannula (1) according to one of the preceding claims, wherein the polygonal hollow profile (M) is rounded at its outer longitudinal edges (4, 5, 6) with an outer radius (R). [6] Cannula (1) according to one of the preceding claims, wherein the retroreflective geometry (G) of the cannula tip (3) is formed by material removal (S), in particular a bevel, of the polygonal hollow profile (M). [7] Cannula (1) according to one of the preceding claims, wherein the retroreflective geometry (G) has at least a first surface (141), a second surface (131) and a third surface (151), wherein the first surface (141) is oriented perpendicular to the second surface (131) and perpendicular to the third surface (151), and wherein the second surface (131) and the third surface (151) are facing each other. [8] Cannula (1) according to claim 7, wherein the first surface (141) is formed by a surface section of an inner surface (14) of the polygonal hollow profile (M), and wherein the second surface (131) and the third surface (151) are each formed by a surface section of a wall surface (W, W') extending between an inner surface (13, 15) and an outer surface (7, 9).

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