Medical instrument for a peripheral nerve block and cannula for such an instrument
Patent Information
- Application Number
- PCT/EP2026/056660
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-17
- Filing Date
- 2026-03-10
- Publication Date
- 2026-09-24
Smart Images
Figure EP2026056660_24092026_PF_FP_ABST
Abstract
Description
[0001] Medical instrument for peripheral nerve block and cannula for such an instrument
[0002] Description
[0003] Technical field
[0004] This disclosure relates to a medical instrument for performing a peripheral nerve block (PNB) or for administering peripheral local anesthesia. This disclosure further relates to a cannula for such an instrument, which can also be referred to simply as a needle.
[0005] Background of the Revelation
[0006] In medicine, it is known to temporarily block individual nerve pathways using a so-called peripheral nerve block (PNB) to numb specific areas of the body. This type of local anesthesia leads to pain relief (anesthesia) in a limited area of the body through the reversible inhibition of nerve function. The medications used to temporarily block pain signals from the nerve pathways are called local anesthetics.
[0007] State of the art
[0008] It is known from the prior art to insert or puncture a cannula with an internal channel and an opening in the tip into the patient's body and position the tip near the nerve to be blocked (puncture). The local anesthetic is then administered via a tube connected to an opening at the proximal end of the cannula. It emerges from the opening in the tip of the cannula and surrounds the nerve to be blocked.
[0009] So-called pencilpoint or Sprotte needles are known from the prior art. These needles have a conical, closed tip, with an opening for the exit of the local anesthetic located in the immediate vicinity of the conical tip but laterally on the circumference of the needle. Such needles offer, for example, atraumatic puncture in spinal anesthesia.
[0010] The applicant also markets such pencil-point cannulas for spinal anesthesia with a single opening. These cannulas reduce the risk of post-spinal headache.
[0011] The lateral opening is created by removing material radially from the outside inwards until the desired size is achieved in the center of a trough-like depression. The radial depth of the depression defines the width of the opening, and the length of the depression along a longitudinal axis of the cannula defines the length of the opening.
[0012] A disadvantage of such cannulas is that the distribution of the local anesthetic is not even around the cannula. Furthermore, the distribution of the local anesthetic depends on the rotational position of the cannula.
[0013] Brief description of the Revelation
[0014] Therefore, the purpose of this disclosure is to provide a cannula and a corresponding instrument for performing a peripheral nerve block, in which the distribution of the local anesthetic occurs more evenly around the cannula. Furthermore, the distribution of the local anesthetic should be less dependent on the rotational position of the cannula.
[0015] This problem is solved by a cannula having the features of claim 1 and by a medical instrument for performing a peripheral nerve block having the features of claim 14.
[0016] The cannula according to the disclosure is intended, set up and designed to be arranged in a (medical) instrument for performing a peripheral nerve block (PNB), in particular at its central connecting part, and BB2588P-WÖ-0004
[0017] 3 / 15
[0018] to be attached. The cannula is further designed and configured to deliver a local anesthetic from an inlet of the cannula towards a tip section of the cannula, for which purpose the inlet can be connected to a tube in a fluid-tight manner, e.g., via the connecting piece. The cannula has a main section that is formed integrally with the tip section. A channel is formed in the cannula, particularly in the main section, with at least two lateral openings, namely a first opening and a second opening, arranged adjacent to the tip section in the main section. Preferably, a transverse connection formed by the cannula channel is created between the first opening and the second opening, so that the cannula is configured to allow the local anesthetic coming from the channel to exit the cannula via both the first and the second openings.The additional opening(s) compared to the prior art create a cannula for a (medical) instrument used to perform a peripheral nerve block, resulting in a more even distribution of the local anesthetic around the cannula. Furthermore, the distribution of the local anesthetic is less dependent on the cannula's rotational position.
[0019] One, two, or three additional openings are preferred. This results in a total of two, three, or four openings. The more openings, the more even the distribution of the local anesthetic around the cannula. More than four openings can also be provided.
[0020] It is particularly preferred if the openings are evenly distributed around the circumference of the main section.
[0021] The cannula, excluding the openings, is preferably rotationally symmetrical about a longitudinal axis. In this case, the main section is circularly cylindrical. The tip can be conical or approximately conical. The tip section can be an irregular cone with a curved outer surface, where the diameter (the increase in diameter) along the longitudinal axis from the absolute tip towards the main section is non-linear. BB2588P-WÖ-0004
[0022] 4 / 15
[0023] A transition from the tip section to the main section can be continuously rounded, especially in the case of a non-linear diameter (profile).
[0024] Preferably at least one of the openings, in particular both openings, each have a first and a second curved edge section, both of which are arranged in the main section, wherein the respective first curved edge section is arranged adjacent to the tip section, and wherein the respective second curved edge section is turned away from the tip section.
[0025] Furthermore, at least one of the openings, in particular both openings, each have a first and a second straight edge section, which are preferably parallel to each other.
[0026] In a specific embodiment of the cannula, the second curved edge section of at least one of the openings has a distance to an absolute tip of the tip section of 2.05 to 2.55 mm, e.g. 2.3 mm.
[0027] In a particularly preferred embodiment, at least one of the openings, and preferably both openings, are surrounded by a respective radial recess opposite an outer surface of the main section. The respective opening can then be easily manufactured by material removal.
[0028] Preferably, the at least one radial recess has, and in particular, both radial recesses each have a first and a second curved edge section, both of which are arranged in the main section, wherein the first curved edge section is adjacent to the tip section, and wherein the second curved edge section faces away from the tip section. Furthermore, at least one of the recesses, and in particular both recesses, each have a first and a second straight edge section, which are preferably parallel to each other.
[0029] A transition from the main section to the depression is preferably continuously rounded, so that the boundary sections, i.e., the two curved boundary sections and the two straight boundary sections, have no edges. BB2588P-WÖ-0004
[0030] 5 / 15
[0031] In a specific embodiment of the cannula, at least one of the recesses has an inclination angle of 23° to 37°, preferably 30°, relative to the longitudinal axis on its two curved edge sections (which are maximally spaced apart from each other along a longitudinal axis of the cannula).
[0032] In a specific embodiment of the cannula, at least one of the openings, preferably both openings, has a width of 0.28 mm to 0.32 mm, e.g. 0.3 mm.
[0033] In a specific embodiment of the cannula, at least one of the openings, preferably both openings, has a length of 0.65 to 0.95 mm, preferably 0.8 mm.
[0034] In a specific embodiment of the cannula, the main section has an outer diameter of 0.71 to 0.75 mm, e.g. 0.73 mm.
[0035] In a specific embodiment of the cannula, the channel has a diameter of 0.51 to 0.55 mm, e.g. 0.53 mm.
[0036] In this specific embodiment, the wall thickness of the main section is, for example, 0.28 mm.
[0037] In a specific embodiment of the cannula, the tip section has a length of 1.0 to 1.5 mm, preferably 1 mm.
[0038] In a known embodiment, the tip section has a rounded edge on its outer surface. In a specific embodiment, the rounded edge has a radius of 2.4 to 2.6 mm, e.g., 2.5 mm.
[0039] Preferably, the cannula is mirror-symmetric about a plane of symmetry that is a median plane defined by the longitudinal axis. Thus, the two openings and, if applicable, also the two recesses are uniformly symmetric about the BB2588P-WÖ-0004
[0040] 6 / 15
[0041] The local anesthetic is distributed around the circumference. Preferably, the cross-sectional area or surface of the first opening is identical to the cross-sectional area or surface of the second opening. Preferably, the first opening is arranged diametrically opposite the second opening. This improves the more uniform distribution of the local anesthetic around the cannula on both sides.
[0042] If the further development with the plane of symmetry also has the depressions, these are also the same, with the first depression being arranged diametrically opposite the second depression.
[0043] In a simplified, user-friendly version of the device, colored markings are provided around the main section to indicate the depth of insertion. This visualizes the insertion depth when placing the cannula.
[0044] In a preferred, simplified version of the cannula, a (physical) structure, e.g., in the form of grooves and / or notches, is arranged on the main section. This makes the cannula suitable for ultrasound guidance during placement.
[0045] In a preferred, simplified embodiment, an electrically conductive area is provided on the main section adjacent to the two openings, preferably defined by a break in a coating (e.g., polymer) of the cannula. This makes the cannula suitable for guidance by nerve stimulation during placement.
[0046] The medical instrument disclosed comprises a cannula as previously described or disclosed, wherein the cannula's opening is fluid-tightly connected to a connecting piece (e.g., inserted into it). A tube for administering the local anesthetic can be fluid-tightly connected, or preferably is connected, to the connecting piece on the side facing away from the cannula. The instrument has the advantage of a second opening in the cannula, compared to the prior art, that the distribution of the local anesthetic around the cannula is more uniform. Furthermore, the distribution of the local anesthetic is less dependent on the rotational position of the cannula or the instrument.
[0047] In a further development of the medical instrument, an electrical stimulation cable is attached to the connecting part, which can be electrically connected to or is connected to the electrically conductive point. This makes the instrument suitable for supporting nerve stimulation.
[0048] In a particularly flexible further development of the instrument, the electrical stimulation cable can be optionally detached from and attached to the connecting part.
[0049] Brief description of the characters
[0050] Figure 1 shows an instrument according to one embodiment;
[0051] Figure 2 shows an essential part of an instrument according to a second embodiment;
[0052] Figure 3 shows a view of the tip of a cannula of both embodiments from Figures 1 and 2; and
[0053] Figure 4 shows the tip of the cannula of both embodiments from Figures 1 and 2 in a different view.
[0054] Description of the exemplary implementations
[0055] Below, two embodiments of the instrument 20; 120 according to the disclosure for performing a peripheral nerve block and two cannulas 42; 142 are described based on the accompanying figures. Figure 1 shows an instrument 20 according to a first embodiment. It serves to perform a peripheral nerve block or local anesthesia by stimulation of nerve pathways (stimulation-assisted) and by imaging using ultrasound (ultrasound-assisted).
[0056] The instrument 20 comprises as its essential components a cannula 42, often referred to simply as a needle, a connecting piece 22, and a tube 24. The tube 24 can be connected via a coupling 25 to a container (not shown) for a local anesthetic. The four components mentioned—the coupling 25, the tube 24, the connecting piece 22, and the cannula 42—are fluid-tightly connected to one another, so that the local anesthetic is conveyed without leakage from the coupling 25 through the tube 24, through the connecting piece 22, and through a channel 8 of the cannula 42 (visible only in Figure 4) to or near a tip section 4 of the cannula 42, where it exits from two openings 10 (visible only in Figure 4).
[0057] To visualize the insertion depth of the cannula 42 for the doctor, circumferential color rings 28 are provided on the outer sheath of the cannula 42.
[0058] To aid orientation and positioning for the physician, the cannula 42 is provided with an electrically non-conductive coating, which has a gap or interruption only at the tip section 4. This gap is electrically connected via the metallic cannula 42 and a stimulation cable 26 attached to the connecting part 22 to a plug 27, so that the physician can infer the position of the tip section 4 by means of low voltage pulses and the corresponding reaction of the nerve pathway.
[0059] For supplementary or alternative support by ultrasound, a structure in the form of an X-pattern is provided on the outer sheath of the cannula 42 (not shown).
[0060] Figure 2 shows a substantial part of an instrument 120 according to a second embodiment. Only a short portion of the hose 24 is shown, and the BB2588P-WÖ-0004
[0061] 9 / 15
[0062] The coupling was omitted. The main differences from the first embodiment are that the cannula 142 is longer and that the connecting part 122 is simplified, since no stimulation cable is provided.
[0063] Thus, the second embodiment of the instrument 120 according to the disclosure is designed for performing peripheral nerve blocks with the support of ultrasound by means of the (not shown) structure in the form of an X-pattern on the outer sheath of the cannula 142.
[0064] Figure 3 shows a section of the cannulas 42; 142 of both embodiments from Figures 1 and 2 in a single view. The cannulas 42; 142 thus consist essentially of a circular cylindrical tubular main section 2, of which only a shorter part is shown in Figure 2, and the approximately conical tip section 4 formed integrally with it. The tip section 4 has an absolute point 4a. The main section 2 is tubular, so that the channel 8 (shown in Figure 4) is formed inside it. The main section 2 with the channel 8 and the tip section 4 with the absolute point 4a are essentially rotationally symmetric about a longitudinal axis 6.
[0065] On the side of the cannula 42; 142 facing the viewer, an opening 10 shaped like an elongated hole is provided in the main section 2. According to the disclosure, a similar opening 10 is also provided on the side of the main section 2 facing away from the viewer. The two openings 10 are thus arranged diametrically opposite each other. A transverse connection formed by the channel 8 of the cannula 42 is formed between the two openings 10. Accordingly, local anesthetic coming from the channel 8 of the cannula 42; 142 can exit the cannula 42; 142 through either of the two openings 10.
[0066] The two openings 10 each have a width B 10, which in the illustrated embodiment is 0.3 mm.
[0067] Each opening 10 extends along the longitudinal axis 6 from a first curved edge section 14 to a second curved edge section 15.BB2588P-WÖ-0004
[0068] 10 / 15
[0069] In the illustrated embodiment, the two openings 10 have a distance between their respective two curved edge sections 14, 15 and thus a length L10 along the longitudinal axis 6 of 0.8 mm.
[0070] Each opening 10 is fully encircled and surrounded by a recess 11, which was produced by machining. The opening 10 was produced by machining the recess 11. Each recess 11 has an approximately oval, continuous rim that is rounded towards the outer surface of the main section 2, with a first curved rim section 12 facing the tip section 4 and a second curved rim section 13 facing away from the tip section 4.
[0071] The tip section 4 has a length L4, which is 1 mm in the illustrated embodiment. Furthermore, the outer surface of the tip section 3 is rounded with a radius R, which is 2.5 mm in the illustrated embodiment.
[0072] Figure 4 shows a section of the cannula 42; 142 of both embodiments from Figures 1 and 2 in a sectional view. The viewing direction is rotated by 90° compared to that shown in Figure 3. This makes the two opposing recesses 11 particularly visible.
[0073] Each recess 11 has a slope a to the longitudinal axis 6 or to the plane of symmetry 7, which in the illustrated embodiment is 30°.
[0074] Furthermore, it can be seen that the main section 2 has a diameter D2, which is 0.73 mm in the illustrated embodiment. Finally, it is shown that the channel 8 has a diameter D8, which is 0.53 mm in the illustrated embodiment. BB2588P-WÖ-0004
[0075] 11 / 15 List of reference symbols:
[0076] 2 Main Section
[0077] 4 Top section
[0078] 4a absolute top
[0079] 6 Longitudinal axis
[0080] 7. Plane of symmetry
[0081] 8-channel
[0082] 10 Opening
[0083] 11 In-depth study
[0084] 12 First curved edge section (recess) 13 Second curved edge section (recess) 14 First curved edge section (opening) 15 Second curved edge section (opening) 20; 120 Instrument
[0085] 22; 122 Connecting part
[0086] 24 hose
[0087] 25 Clutch
[0088] 26 stimulation cables
[0089] 27 plugs
[0090] 28 Marking / Color ring
[0091] 42; 142 cannula
[0092] A distance
[0093] B10 width
[0094] D2 outer diameter
[0095] D8 diameter
[0096] L4 length
[0097] L10 length
[0098] R radius
[0099] a slope angle
Claims
BB2588P-WÖ-0004 12 / 15 Claims 1. Cannula (42; 142) which is designed, configured and configured to deliver a local anesthetic from an inlet of the cannula (42; 142) towards a tip section (4) of the cannula (42; 142), wherein the cannula (42; 142) has a main section (2) which is integrally formed with the tip section (4), wherein a channel (8) is formed in the cannula (42; 142), and wherein at least two lateral openings (10), namely a first opening (10) and a second opening (10), are arranged in the main section (2) adjacent to the tip section (4).
2. Cannula (42; 142) according to claim 1, wherein at least one, preferably both, of the openings (10) each has a first and a second curved edge section (14, 15), both of which are arranged in the main section (2), wherein the first curved edge section (14) is arranged adjacent to the tip section, and wherein the second curved edge section (15) is turned away from the tip section (4), and wherein at least one, preferably both, of the openings (10) has a first and a second straight edge section, which are preferably parallel to each other.
3. Cannula (42; 142) according to claim 2, wherein the second curved edge section (15) has a distance (A) to an absolute tip (4a) of the tip section (4) of 2.05 to 2.55 mm from at least one of the openings (10), preferably both openings (10).
4. Cannula (42; 142) according to one of the preceding claims, wherein at least one of the openings (10), preferably both openings (10), is surrounded by a radial recess (11) opposite an outer shell of the main section (2).
5. Cannula (42; 142) according to claim 4, wherein the at least one radial depression (11) has a first and a second curved edge section (12, 13), which BB2588P-WÖ-0004 13 / 15 both are arranged in the main section (2), wherein the first curved edge section (12) is arranged adjacent to the tip section (4), and wherein the second curved edge section (13) is turned away from the tip section (4), and wherein the at least one radial recess (11) has a first and a second straight edge section which are preferably parallel to each other.
6. Cannula (42; 142) according to claim 5, wherein the at least one recess (11 ) has an inclination angle (a) of 23° to 37° on its two curved edge sections (12, 13) relative to a longitudinal axis (6) of the cannula (42; 142).
7. Cannula (42; 142) according to one of the preceding claims, wherein at least one of the openings (10), preferably both openings (10), has a width (B10) of 0.28 mm to 0.32 mm, and / or wherein at least one of the openings (10), preferably both openings (10), has a length (L10) of 0.65 to 0.95 mm.
8. Cannula (42; 142) according to one of the preceding claims, wherein the main section (2) has an outer diameter (D2) of 0.71 to 0.75 mm, and / or wherein the channel (8) has a diameter (D8) of 0.51 to 0.55 mm.
9. Cannula (42; 142) according to one of the preceding claims, wherein the tip section (4) has a length (L4) of 1.0 to 1.5 mm, and / or wherein the tip section (4) has a rounding on its outer shell preferably with a radius (R) of 2.4 to 2.6 mm.
10. Cannula (42; 142) according to one of the preceding claims, which is mirror-symmetric about a plane of symmetry (7), whereby the two openings (10) are the same, and wherein the first opening (10) is arranged diametrically opposite the second opening (10).
11. Cannula (42; 142) according to one of the preceding claims, wherein colour markings (28) are provided on the main section (2) for depth grading.
12. Cannula (42; 142) according to one of the preceding claims, wherein a structure is arranged on the main section (2).
13. Cannula (42; 142) according to one of the preceding claims, wherein an electrically conductive location adjacent to the two openings (10) is provided on the main section (2), which is preferably formed and defined by a discontinuity in a coating of the cannula (42; 142).
14. Medical instrument (20; 120) with a cannula (42; 142) according to one of the preceding claims, wherein the inlet of the cannula (42; 142) is fluid-tight connected to a connecting part (22; 122) to which a hose (24) for supplying the local anesthetic can be fluid-tightly connected or is connected.
15. Medical instrument (20) according to claim 14 with a cannula (42) according to claim 13, wherein an electrical stimulation cable (26) is attached to the connecting part (22; 122) which can be electrically connected or is connected to the electrically conductive part of the cannula (42).