Cannula hub for a spinal cannula

Description

[0001] The invention relates to a cannula hub for a spinal cannula, comprising a body extending between a proximal end and a distal end, a fluid channel extending through the body with an observation channel section which can be viewed from the outside through a transparent region of the body, and comprising at least one optical lens arranged in the transparent region, by means of which the observation channel section can be viewed in an optically magnified manner.

[0002] Spinal cannulas are used, for example, during spinal anesthesia to puncture the spinal cord. They consist of a cannula hub and a hollow needle attached to it. During use, the hollow needle is advanced into the cerebrospinal fluid (CSF)-filled space of the spinal cord. To confirm the correct position of the hollow needle, the fluid backflow (flashback) entering the cannula hub is visually monitored.

[0003] A cannula hub designed for optical monitoring is known from US Pat. No. 6,656,161 B2 and comprises a body to whose distal end a hollow needle can be secured. A fluid channel extends between the distal end and a proximal end of the body. The fluid channel has an observation channel section referred to as a chamber. A wall of the body adjacent to the chamber is provided with an optical lens. This is intended to make the chamber visually magnified for an external observer. This is intended to improve the detection of fluid backflow. Furthermore, the aforementioned patent specification teaches that the chamber should have the smallest possible volume.

[0004] Another cannula hub designed for optical inspection is known from US 2011 / 071480 A1. This known cannula hub also has a body with an observation channel section, which can be viewed from the outside through a transparent area of the body. An optical prism is arranged in the observation channel section.

[0005] Furthermore, EP 0 522 737 A1 discloses a cannula hub with a convex lens which serves as a magnifying glass for better visibility of liquid in the cannula hub.

[0006] The object of the invention is to provide a cannula attachment of the type mentioned above which enables improved optical control of the fluid backflow.

[0007] The present invention is defined in independent claim 1. Further embodiments are defined in the dependent claims.

[0008] This object is achieved in that at least one optical prism is present in the observation channel section, which is designed to refract and / or reflect light incident through the optical lens into the observation channel section. The light-refracting and / or reflecting optical properties of the at least one prism result in significantly different optical perceptions and / or images for an observer, depending on whether the observation channel section is filled with air or with liquid. In principle, optical differences also occur without the at least one prism. However, the optical differences are much less apparent without a prism and are therefore more difficult for the observer to perceive. The at least one optical prism therefore makes it possible to determine very clearly whether or not liquid backflow is already taking place in the observation channel section.The inventors recognized that the combination of optical magnification on the one hand and light refraction and / or reflection on the other hand enables particularly reliable and simple optical inspection even under adverse lighting conditions. The cannula hub can also be referred to as a cannula hub or hub for short. The distal end of the body is designed to be connected to a hollow needle of the spinal cannula. Preferably, the proximal end opposite in the longitudinal direction of the body is designed to be connected to another medical component, for example a syringe, a medical tubing or the like. The fluid backflow occurs in the proximal direction. In one embodiment, the at least one optical prism is a component manufactured separately from the body and subsequently inserted into the observation channel section.In other embodiments, the at least one optical prism is integrated in one piece into the body. The same applies analogously with regard to the at least one optical lens. Accordingly, in one embodiment, the at least one optical lens is manufactured as a separate component and subsequently attached to the body. In other embodiments, the at least one optical lens is integrated in one piece into the body. The body is transparent at least in the region of the observation channel section, the at least one optical lens and / or the at least one optical prism. For this purpose, the body is manufactured at least in sections from a transparent material, preferably a plastic.

[0009] In an embodiment of the invention, the at least one optical lens and the at least one optical prism are formed by one and the same transparent wall of the body and are thus integrally connected, wherein the at least one optical lens is assigned to an outer side of the transparent wall and the at least one optical prism is assigned to an inner side of the transparent wall. This results in particular in a simplified structure of the cannula hub. This simplifies manufacture and assembly. By integrating the design of the at least one optical lens and the at least one optical prism into the body, more precisely: its transparent wall, the required number of components of the cannula hub can be reduced. The outer side of the transparent wall faces away from the observation channel section in the radial direction. The inner side of the transparent wall faces the observation channel section in the radial direction.The transparent wall of the body is arranged in its transparent region or forms the transparent region of the body. The outer side of the transparent wall borders on the surrounding area. The inner side of the transparent wall borders on the observation channel section.

[0010] In a further embodiment of the invention, the fluid channel has a total volume, wherein the observation channel section occupies a predominant volume portion of the total volume. In other words, the observation channel section is as large as possible compared to the other dimensions of the fluid channel and / or the body. Accordingly, the observation channel section occupies the predominant volume portion of the total volume of the fluid channel. Due to the comparatively large dimensioning of the observation channel section, a relatively low flow rate of the liquid backflow can be achieved. This is in relation to a comparatively small dimensioned observation channel section. Due to the slower flow rate, an observer has more time to visually perceive an occurring liquid backflow.The inventors recognized that the reduced flow rate is accompanied by even better visual control. The rapid visibility of fluid backflow allows the observer to react more quickly, so less fluid needs to be aspirated. Furthermore, CSF can be prevented from dripping out of the cannula hub. Consequently, the fluid backflow can also be prevented from only being recognized when the fluid starts to drip out, thus preventing fluid loss for the patient. As a result, adverse health effects for the patient can be avoided. In particular, the risk of post-dural puncture headache (PDPH) is reduced.

[0011] In a further embodiment of the invention, the fluid channel has a maximum inner diameter that is a maximum of 45%, preferably a maximum of 10%, larger than a maximum inner diameter of the observation channel section. In other words, in this embodiment, the observation channel section has the largest possible inner diameter in relation to the other diameter dimensions of the fluid channel. The inner diameter of the fluid channel is preferably variable over its longitudinal extent. Accordingly, the fluid channel has channel sections with relatively narrow and relatively wide diameters. The observation channel section has the widest possible diameter. In one embodiment, the maximum inner diameter of the observation channel section simultaneously forms the maximum inner diameter of the entire fluid channel.The relatively large maximum inner diameter of the observation channel section achieves a relatively low flow velocity for the liquid backflow. For the associated advantages, reference is made to the explanations in connection with the previous embodiment. The statements therein also apply mutatis mutandis to this embodiment of the invention. The inner diameter can also be referred to as the hydraulically effective or hydraulic diameter and, in this respect, can have the dimension of a surface.

[0012] In a further embodiment of the invention, the proximal end of the body has a standardized fluid connector with a standardized inner diameter, wherein the maximum inner diameter of the observation channel section is a maximum of 45%, preferably a maximum of 10%, smaller than the standardized inner diameter of the fluid connector. This embodiment also has a comparatively large inner diameter of the observation channel section, wherein the inner diameter is defined in relation to the standardized inner diameter of the standardized fluid connector. This embodiment also enables the lowest possible flow velocity of the fluid backflow within the observation channel section. Regarding the associated advantages, reference is made to the above.In one embodiment, the standardized fluid connector is an NRFit connector according to DIN EN ISO 80369-6, wherein the maximum inner diameter of the observation channel section is a maximum of 20%, preferably a maximum of 15%, particularly preferably a maximum of 10%, smaller than the standardized inner diameter of the NRFit connector. In another embodiment, the fluid connector is a Luer connector according to DIN EN ISO 80369-7, wherein the maximum inner diameter of the observation channel section is a maximum of 45%, preferably a maximum of 30%, smaller than the standardized inner diameter of the Luer connector.

[0013] In a further embodiment of the invention, at least two optical prisms and at least two optical lenses are provided, which are arranged in pairs as lens-prism pairs at an angle to one another in the circumferential direction of the observation channel section. Due to the angularly offset arrangement of several lens-prism pairs, the optical control can be carried out by an observer at different viewing angles relative to the body. In other words, the observer can monitor the fluid backflow not only in a single viewing direction directed towards the body, but also in different viewing directions. This further improves the optical control. If exactly two lens-prism pairs are provided, they are preferably arranged at an angular offset of 90° or 180° to one another.With an angular offset of 90°, the inspection can be performed, for example, in the direction of view of the top and the right and / or left side of the body. With an angular offset of 180°, the inspection can be performed through opposite sides of the body. If more than two lens-prism pairs are present, their angular offset is preferably calculated as the quotient of the 360° circumferential angle of the observation channel section and the number of lens-prism pairs. For example, if there are ten lens-prism pairs, their angular offset is preferably 36°.

[0014] In a further embodiment of the invention, a first lens-prism pair is arranged on a first side, preferably an upper side, of the body, and a second lens-prism pair is arranged on a second side, preferably an opposite lower side, of the body. This embodiment of the invention enables optical control from different viewing angles. At the same time, a comparatively large effective inner diameter of the observation channel section can be maintained. The inventors have recognized that arranging as many angularly offset prisms as possible in the observation channel section has a positive effect on optical control. On the other hand, this reduces the effective diameter of the observation channel section. This can lead to a relatively high flow velocity of the liquid backflow, which in turn can have a negative effect on optical control.The design with two lens-prism pairs represents a kind of optimum in this respect.

[0015] In a further embodiment of the invention, the body in the region of the observation channel section has a cuboid shape with pairs of opposite outer sides, with the at least one optical lens being assigned to one of the outer sides. The cuboid shape of the body in the region of the observation channel section allows the latter to be dimensioned comparatively large. Furthermore, the cuboid shape supports the handling of the cannula hub, since the pairs of opposite outer sides can be ergonomically grasped between the fingers of one hand. Furthermore, the cuboid shape allows for easy visual inspection of the angular orientation of the cannula hub. To further simplify this inspection, the body can have a marking section on one of its outer sides, preferably its upper side. This can be designed, for example, in the form of a recess, a projection, or the like.

[0016] In a further embodiment of the invention, the body is made in one piece from a transparent plastic. This simplifies manufacturing, as different materials are no longer required for different sections of the body. Furthermore, the completely transparent design of the body facilitates the penetration of light into the observation channel section. This allows for even better visual monitoring of fluid backflow.

[0017] The invention also relates to a spinal cannula with a cannula hub according to the preceding description and with a hollow needle attached to the cannula hub. The hollow needle is attached to the distal end of the cannula hub. The hollow needle is elongated between a ground distal end and a proximal end in a manner known to those skilled in the art and has a continuous lumen. The lumen of the hollow needle is fluidically connected to the fluid channel of the cannula hub in a manner known in principle.

[0018] Further advantages and features of the invention emerge from the claims and from the following description of a preferred embodiment of the invention, which is illustrated with reference to the drawings. Fig. 1 shows a schematic top view of an embodiment of a spinal cannula according to the invention with an embodiment of a cannula hub according to the invention and with a hollow needle fixed to the cannula hub, Fig. 2 shows a schematic perspective view of the cannula hub with a view towards a distal end, Fig. 3 shows a further schematic perspective view of the cannula hub with a view towards a proximal end, Fig. 4 shows a schematic rear view of the cannula hub with a distal view, Fig. 5 shows a schematic side view of the cannula hub, Fig. 6 shows a schematic longitudinal section of the cannula hub along a section VI-VI according to Fig. 5 , Fig. 7 a schematic plan view of the cannula hub and Fig. 8 a further longitudinal sectional view of the cannula hub along a section VIII-VIII.

[0019] According to Fig. 1 A spinal cannula S is intended for use in spinal anesthesia and has a hollow needle K and a cannula hub 1.

[0020] The hollow needle K is designed in a manner known to those skilled in the art and is intended for puncturing the spinal cord. In this respect, the hollow needle K is elongated between a proximal end (not further designated) and a distal end E, the latter being provided with a sharpened cannula tip. The proximal end of the hollow needle K is received in a receiving recess A ( Fig. 6 , 8 ) of the cannula hub 1. For example, the proximal end of the hollow needle K can be glued into the receiving recess A.

[0021] The cannula hub 1 can also be referred to as a cannula hub or hub and has a body 2 that extends between a proximal end 3 and a distal end 4. Furthermore, the cannula hub 1 has a fluid channel 5 extending through the body 2 with an observation channel section 6. The observation channel section 6 is surrounded by a transparent area 7 ( Fig. 2 ) of the body 2. Furthermore, the cannula hub 1 has at least one optical lens 8 arranged in the transparent region 7. By means of the optical lens 8, the observation channel section 6 can be viewed from the outside in an optically magnified manner.

[0022] When using the spinal cannula S, the spinal cord is punctured using the hollow needle K. To check the correct position of the distal end E in the region of the spinal cord, cerebrospinal fluid (CSF) is aspirated through the hollow needle K into the cannula hub 1. As soon as a corresponding fluid backflow in the proximal direction occurs, the correct position of the distal end E can be assumed. The observation channel section 6 arranged in the transparent area 7 allows optical monitoring of said fluid backflow. The at least one optical lens 8 supports the optical monitoring by optically magnifying the observation channel section 6.

[0023] In order to enable further improved optical control, the cannula hub 1 also has at least one optical prism 9, which is Fig. 4 , 6 and 8is shown. The optical prism 9 is arranged in the observation channel section 6 and is designed to refract and / or reflect light incident through the transparent area 7 and / or the optical lens 8 into the observation channel section 6. Due to its light-refracting and / or reflecting properties, the prism 9 allows for significantly improved optical control of the liquid backflow. This is because, depending on whether the observation channel section 6 is filled with air or liquid, the optical perceptions for the observer are significantly different. Of course, the liquid backflow is in principle also perceptible without the prism 9, but to a significantly reduced extent. The present combination of optical prism 9 and optical lens 8 allows reliable control of the liquid backflow even under adverse optical conditions, for example in poor lighting conditions.

[0024] Further spatial-physical and functional features of the cannula hub 1 are explained below. Despite their potential advantages, the features explained below are not necessarily to be considered essential with regard to the present invention.

[0025] In the embodiment shown, the optical lens 8 and the optical prism 9 are formed by one and the same transparent wall 10 of the body 2. This is shown in detail with reference to Fig. 8 shown. As a result, the optical lens 8 and the optical lens 9 are formed integrally. The optical lens 8 is assigned to an outer side 11 of the transparent wall 10. The optical prism 9 is assigned to an inner side 12 of the transparent wall 10. The outer side 11 faces an unspecified surrounding area. The inner side 12 faces the observation channel section 6.

[0026] In the present case, the body 2 is made in one piece from a transparent plastic T. Therefore, the body 2 is transparent not only in the transparent region 7, but also beyond it. In embodiments not illustrated in the drawings, a multi-part construction may be provided instead of a one-piece design of the body. Furthermore, in other embodiments, the body is transparent only in its transparent region.

[0027] The fluid channel 5 is elongated between the proximal end 3 and the distal end 4. Starting from the proximal end 3, the fluid channel 5 initially has a proximal channel section 13, which opens in the proximal direction into a proximal channel opening 14. In the distal direction, the proximal channel section 13 opens into the observation channel section 6. The observation channel section 6 opens in the distal direction into the receiving recess A. The fluid channel 5 is in the area of the Fig. 6 and 8 The proximal channel section 13 and the observation channel section 6 are subdivided by the dashed line shown in the figure. This subdivision is to be understood as exemplary. In any case, the observation channel section 6 is defined by the top view ( Fig. 1 , 7 ) directly below the optical lens 8 extending portion of the fluid channel 5.

[0028] The fluid channel 5 has a total volume V1, V2. In the embodiment shown, the total volume V1, V2 is composed of a first volume portion V1 of the observation channel section 6 and a second volume portion V2 of the proximal channel section 13. In other words, the total volume V1, V2 in this case results from the sum of the first volume portion V1 and the second volume portion V2. In the embodiment shown, the first volume portion V1 of the observation channel section 6 is dimensioned as large as possible in relation to the second volume portion V2. In preferred embodiments, the first volume portion V1 takes up a large part of the total volume V1, V2. By dimensioning the first volume portion V1 as large as possible, a relatively low flow velocity of the liquid backflow upon entering the observation channel section 6 is achieved. This has proven particularly advantageous for various reasons.

[0029] Further with reference to Fig. 6 In the embodiment shown, the fluid channel 5 has a maximum inner diameter D2. This is located in the area of the proximal channel section 13, more precisely: in the area of the channel opening 14. The observation channel section 6 has a maximum inner diameter D1. In the embodiment shown, the maximum inner diameter D1 of the observation channel section 6 corresponds approximately to the maximum inner diameter D2 in the area of the proximal channel section 13. Accordingly, the inner diameter, or hydraulic diameter, of the observation channel section 6 is dimensioned as large as possible in relation to the inner diameter, or hydraulic diameter, of the fluid channel 5. This supports a reduction in the flow velocity of the fluid backflow in the area of the observation channel section 6. The maximum inner diameter D1 of the observation channel section 6 in the embodiment shown is in the Fig. 6 In a longitudinal section plane rotated by 90° according to Fig. 8 This results in a different inner diameter. This is due to the at least one prism 9. With regard to the aforementioned reduction in flow velocity, a narrowing in one plane is not decisive. Rather, it is more important that the observation channel section 6 has the largest possible effective hydraulic diameter.

[0030] In preferred embodiments, the maximum hydraulic diameter of the observation channel section is a maximum of 45%, particularly preferably a maximum of 10%, smaller than a maximum hydraulic diameter of the proximal channel section 13.

[0031] The body 2 is configured in the region of a proximal end 3 for detachable connection to a fluid-conducting medical component, such as a syringe, a medical tubing, or the like. For this purpose, the body 2 has a standardized fluid connector N at its proximal end 3. The fluid connector N is an NRFit connector known to those skilled in the art. This connector has connecting elements 15, 16 arranged at an angle to one another in the circumferential direction of the proximal end 3. The connecting elements 15, 16 are configured for detachable, positive-locking connection with complementary connecting elements of a correspondingly complementary NRFit connector. The fluid connector N complies with the standard DIN EN ISO 80369-6. The standardization covers not only the shape of the connecting elements 15, 16, but also the design of the proximal channel section 13, more precisely: its inner diameter D2 and / or inner contour.Further with regard to . Fig. 6 It can be seen that the observation channel section 6 merges in the proximal direction into the dimensionally standardized proximal channel section 13 without, or without, a practically significant reduction in cross-section. Due to manufacturing reasons, a draft angle of approximately 1° to 3° may be present.

[0032] In an embodiment not shown in the drawing, the fluid connector is a Luer connector, more precisely a Luer-Lock connector, according to DIN EN ISO 80369-7. The version with a Luer connector may have a slightly larger cross-sectional reduction.

[0033] The optical lens 8 has in the area of the outer side 11 of the transparent wall 10 ( Fig. 8 ) different lens sections 81, 82, 83. These can also be referred to as central section 18, medial section 82 and lateral section 83. The central section 81 has a flat outer contour, so that there is no curvature, particularly in the longitudinal direction of the observation channel section 6. The central section 81 also has no curvature in the transverse direction. In contrast, the medial section 82 and the lateral section 83 are inclined and / or curved in the transverse direction. The inclination and / or curvature is directed inwards from the central section 81 in the radial direction of the observation channel section 6.

[0034] In the embodiment shown, the optical lens 8 extends at least substantially, preferably completely, over the entire length of the observation channel section 6. In further embodiments, the optical lens 8 has a different design.

[0035] In the embodiment shown, the optical prism 9 is designed as a roof prism P. The optical prism 9 has a triangular cross-sectional area and / or prism surfaces 91, 92 that converge inwardly in the radial direction of the observation channel section 6, which can also be referred to as the first prism surface 91 and the second prism surface 92. The prism surfaces 91, 92 form boundary surfaces of the observation channel section 6. The prism 9 has front ends 93, 94 that are arranged opposite one another in the longitudinal direction of the observation channel section 6. In the region of the front ends 93, 94, the prism 9 is flattened at an acute angle. In embodiments not shown in the drawings, the at least one prism has a different design. For example, the prism can be designed as a triple prism.

[0036] In the embodiment shown, the longitudinal extent of prism 9 corresponds to the longitudinal extent of lens 8. Prism 9 is arranged in the radial direction of observation channel 6 below the central portion 81 of lens 8. In the transverse direction of the central portion 81, prism 9 is centrally aligned. A common edge of the prism surfaces 91, 92 is located centrally below the central portion 81.

[0037] In the embodiment shown, the cannula hub 1 has two optical prisms 9, 9' ( Fig. 4 ) and two optical lenses 8, 8' on ( Fig. 5 ). These can also be referred to as first lens 8, second lens 8', and first prism 9 and second prism 9'. In the embodiment shown, the prisms 9, 9' and the lenses 8, 8' form a first lens-prism pair 8, 9 and a second lens-prism pair 8', 9'.

[0038] With regard to the design and function of the second lens 8' and the second prism 9', what has already been said about the first lens 8 and the first prism 9 applies mutatis mutandis. Further explanations in this regard are unnecessary.

[0039] The first lens-prism pair 8, 9 and the second lens-prism pair 8', 9' are arranged at an angular offset from one another in the circumferential direction of the observation channel section 6. In the embodiment shown, the angular offset is 180°, so that said pairs are arranged diametrically opposite one another with respect to the observation channel section 6.

[0040] In one embodiment not shown in the drawing, only a single lens-prism pair is present. Other embodiments include more than two, in particular three, four, five, six, or more lens-prism pairs. Furthermore, in another embodiment, an angular offset of 90° is provided instead of the 180° shown here.

[0041] In the present case, the body 2 has a cuboid shape in the area of the observation channel section 6 with pairwise opposite outer sides A1, A2 ( Fig. 5 ) and A3, A4 on ( Fig. 7). It is understood that this is not an exact cuboid shape, but merely a basically cuboid design. The outer sides A1 to A4 can also be referred to as top side A1, bottom side A2 as well as medial side A3 and lateral side A4. The first lens-prism pair 8, 9 is assigned to the top side A1. The second lens-prism pair 8', 9' is assigned to the bottom side A2. The medial side A3 and the lateral side A4 are each provided with a knurling 18 having a plurality of projections 17. The knurling 18 makes it easier to grip and manipulate the cannula hub 1 between the fingers of one hand.

[0042] In the embodiment shown, the body 2 has a plate 20. The plate 20 is arranged in the longitudinal direction of the fluid channel 5 in the region of the aforementioned subdivision between the observation channel section 6 and the proximal channel section 13. The plate 20 protrudes radially outward from the fluid connector N. The plate 20 can serve, for example, as an axial stop for a complementary fluid connector and can accordingly also be referred to as a stop plate. Whether a stop is formed naturally also depends on the specific design of the complementary fluid connector.

[0043] The body 2 further comprises a marking section 19 that marks an orientation oriented around the longitudinal axis of the body 2. In this case, the marking section 19 is assigned to the upper side A1. Furthermore, the marking section 19 is formed as a radially inwardly recessed notch (not further specified) on the plate 20.

Claims

1. Cannula attachment (1) for a spinal cannula (S), comprising a body (2) which extends between a proximal end (3) and a distal end (4), a fluid channel (5) which extends through the body (2) and which has an observation channel section (6) visible from the outside through a transparent region (7) of the body (2), and comprising at least one optical lens (8) which is arranged in the transparent region (7) and by means of which the observation channel section (6) is visible with optical magnification, characterized in that at least one optical prism (9) is present in the observation channel section (6) and configured for refraction and / or reflection of light incident into the observation channel section (6) through the optical lens (8).

2. Cannula attachment (1) as claimed in claim 1, characterized in that the at least one optical lens (8) and the at least one optical prism (9) are formed by the same transparent wall (10) of the body (2) and are thus integrally joined, the at least one optical lens (8) being assigned to an outer face (11) of the transparent wall (10) and the at least one optical prism (9) being assigned to an inner face (12) of the transparent wall (10).

3. Cannula attachment (1) as claimed in claim 1 or 2, characterized in that the fluid channel (5) has a total volume (V1, V2), the observation channel section (6) occupying a predominant volume fraction (V1) of the total volume (V1, V2).

4. Cannula attachment (1) as claimed in any of the preceding claims, characterized in that the fluid channel (5) has a maximum internal diameter (D2) which is not more than 45%, preferably not more than 10%, greater than a maximum internal diameter (D1) of the observation channel section (6).

5. Cannula attachment (1) as claimed in any of the preceding claims, characterized in that the proximal end (3) of the body (2) has a standardized fluid connector (N) having a standardized internal diameter (D2), a maximum internal diameter (D1) of the observation channel section (6) being not more than 45%, preferably not more than 10%, smaller than the standardized internal diameter (D2) of the fluid connector (N).

6. Cannula attachment (1) as claimed in any of the preceding claims, characterized in that at least two optical prisms (9, 9') and at least two optical lenses (8, 8'), pairs of which in the form of lens-prism pairs (8, 9; 8', 9') are arranged angularly offset to each other in the circumferential direction of the observation channel section (6), are present.

7. Cannula attachment (1) as claimed in claim 6, characterized in that a first lens-prism pair (8, 9) is arranged on a first face (A1), preferably an upper face, of the body (2) and a second lens-prism pair (8', 9') is arranged on a second face (A2), preferably an opposite lower face, of the body (2).

8. Cannula attachment (1) as claimed in any of the preceding claims, characterized in that the body in the region of the observation channel section (6) has a cuboid shape (G) with pairs of opposite outer faces (A1, A2, A3, A4), the at least one optical lens (8) being assigned to one of the outer faces (A1, A2, A3, A4).

9. Cannula attachment (1) as claimed in any of the preceding claims, characterized in that the body (2) is made of a transparent plastic material (T) in one piece.

10. Spinal cannula (S) comprising a cannula attachment (1) as claimed in any of the preceding claims and comprising a hollow needle (K) fixed to the cannula attachment (1).