Cannula assembly

Abstract

The application discloses a cannula assembly, which comprises a cannula, a dilator and a hemostatic cap connecting the cannula and the dilator. The proximal end of the cannula is provided with a connector, the proximal end of the dilator is provided with a handle, the hemostatic cap is made of flexible material, the distal end of the hemostatic cap is sleeved with the connector, and the proximal end of the hemostatic cap is sleeved with the handle. A first buckle is arranged between the hemostatic cap and the connector, and the first buckle comprises at least two first protrusions arranged on the outer wall of the connector, a first recess and a first flat area arranged on the inner wall of the hemostatic cap. The proximal end first protrusion is in interference fit with the first recess, the distal end first protrusion is in interference fit with the first flat area, and the interference amount of the proximal end first protrusion is greater than that of the distal end first protrusion. When subjected to a bending external force, the proximal end buckle is preferentially detached.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an intubation assembly. Background Technology

[0002] The cannula, a key component for establishing extracorporeal blood circulation, needs to be used in conjunction with a dilator to prevent it from bending or kinking during puncture. The dilator and cannula are detachably secured to prevent the dilator from exiting the cannula during percutaneous insertion into the patient's blood vessel and to remove the dilator from the cannula after insertion is complete.

[0003] The detachable fixation of cannulas and dilators is somewhat similar to that of the sheath, another core component of percutaneous interventional devices. While sheaths and dilators offer relatively mature detachable fixation solutions, such as the threaded locking mechanism of EP2651489A1, the locking connection of US5782807A or WO2024238254A1, and the hook-shaped male-female connector mating connection of US20250041566A1, these solutions are difficult to apply to the detachable fixation of cannulas and dilators. The main reason is the difference in their functions: the sheath's role is to establish a vascular pathway for medical devices (such as catheter pumps, balloons, embolisms, occluders, etc.) to enter the patient's bloodstream. In some cases, the sheath needs to be peeled away after the medical device is successfully positioned in the patient's body. The cannula, on the other hand, establishes an extracorporeal blood circulation loop and needs to be retained after insertion to connect with the extracorporeal circulation tubing. Because both the sheath and the cannula need to prevent blood leakage during insertion into the patient, the proximal end of the sheath is equipped with a flexible hemostatic valve. However, a similar structure cannot be installed in the proximal end of the cannula, as this would block the extracorporeal blood circulation loop. Therefore, the sheath's removability in certain situations requires a secure fixation to the dilator to ensure the hemostatic valve does not shift after being passed through the dilator, thus providing a stable seal. This necessitates a high-strength axial connection between the sheath and the dilator. Conversely, the non-removability of the cannula after insertion and its connection to external circulation lines require the connection to the dilator to maintain good blood sealing while ensuring excellent disassembly capabilities.

[0004] While CN109069792B also provides a threaded locking solution for cannulas and dilators, this method requires relative rotation of the cannulas and dilators. Any operation requiring rotation is undesirable in clinical practice due to its cumbersome and time-consuming nature. Locking connections reduce the rotation angle compared to threaded locking (generally 30-60° is sufficient), but rotation is still unavoidable. Male-female plug-in connections allow for quick connection via end-to-end insertion, but disassembly is more difficult.

[0005] Based on the aforementioned prior art, those skilled in the art have attempted to achieve detachable fixation of the dilator and cannula using an intermediate component—a flexible hemostatic cap. The hemostatic cap secures both during percutaneous insertion and is detached from them after insertion is complete. Furthermore, the hemostatic cap also provides hemostasis during dilator withdrawal, minimizing the risk of blood leakage from the proximal end of the cannula. While the hemostatic cap partially solves the problem of inconvenient installation and removal of the dilator and cannula, it introduces new challenges.

[0006] Because the catheter needs to be left in the puncture site under the patient's skin after insertion, the removal of the hemostatic cap from the catheter requires extreme care. A lower connection strength between the cap and the catheter is desirable to avoid potential inertial injury to the patient when the doctor pulls them apart (during removal, the doctor holds the catheter in place with one hand and pulls the cap outward with the other; a stronger connection could cause the catheter to be suddenly and rapidly moved into the patient's body at the moment the cap is pulled off).

[0007] However, during percutaneous insertion, the cannula always requires the dilator to provide anti-kink strength support. Therefore, a strong connection between the hemostat and the cannula is desirable to prevent the dilator from detaching from the cannula due to easy separation of the hemostat and the cannula.

[0008] Therefore, how to ensure that the hemostatic cap and the catheter do not easily detach, while also making it easy and quick to separate them when necessary. Summary of the Invention

[0009] This invention proposes an intubation assembly designed to solve the problem of how to ensure the desired connection strength between the hemostatic cap and the intubation tube while facilitating their disassembly.

[0010] To achieve the above objectives, the present invention proposes an intubation assembly comprising: an intubation cannula, a dilator, and a hemostatic cap detachably connecting the intubation cannula and the dilator. The intubation cannula includes a connector at its proximal end. The dilator includes a handle at its proximal end. The hemostatic cap is made of a flexible material and is hollow, with its proximal end detachably press-fitted onto the distal outer wall of the handle, and its distal end detachably press-fitted onto the proximal outer wall of the connector. A first latch is provided between the hemostatic cap and the connector, comprising: a first protrusion on the proximal outer wall of the connector and a first groove on the inner wall of the hemostatic cap. There are at least two first protrusions, and the number of first grooves is less than the number of first protrusions. The inner wall of the hemostatic cap includes: a first concave-convex region and a first flat region located distal to the first concave-convex region. The first groove is formed in the first concave-convex region, and the first flat region does not have any concave-convex structure. When the hemostatic cap and the connector are assembled, at least the first protrusion at the nearest end press-fits with the first groove, and at least the first protrusion at the farthest end press-fits with the first flat region. Furthermore, the first interference fit between any first protrusion and its mating first groove is greater than the second interference fit between any first protrusion and the first flat area. When the hemostatic cap is in the assembled state with the connector and receives an external force, it bends, and at least one pair of first protrusions and first grooves that are in mutual interference fit disengage on the outside of the bend. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the cannulation assembly in this embodiment;

[0012] Figure 2 for Figure 1 Schematic diagram of the middle insertion cannula;

[0013] Figure 3 for Figure 1 Schematic diagram of the expansion device;

[0014] Figure 4 for Figure 1 A cross-sectional view of a hemostatic cap;

[0015] Figure 5 A magnified view of the hemostatic cap and catheter assembly.

[0016] Figure 6 A diagram illustrating the removal of the hemostatic cap and catheter;

[0017] Figure 7 This is a comparative diagram showing the pull-out force of the cannula and hemostatic cap in this embodiment. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The terms "proximal" and "distal" are relative to the physician manipulating the cannulation assembly 100. "Proximal" refers to the portion relatively close to the physician, and "distal" refers to the portion relatively far from the physician. For example, the tube body 12 is located distal to the connector 11, and the handle 21 is located proximal to the dilator catheter 22. It should be understood that these directional terms are defined for ease of description and are not restrictive or absolute.

[0020] Please see Figures 1 to 5 The cannulation assembly 100 includes: a cannula 10, a dilator 20, and a hemostatic cap 30 detachably connecting the cannula 10 and the dilator 20. The cannula 10 includes a connector 11 located proximally and a tube body 12 connected to the distal end of the connector 11. The structure and manufacturing process of the tube body 12 are described in CN119189385A and will not be repeated here. The dilator 20 includes a handle 21 located proximally and a dilator catheter 22 connected to the distal end of the handle 21. The dilator catheter 22 can pass through the hemostatic cap 30 into the cannula 10 (tube body 12), and includes a proximal constant-diameter section 221 with a substantially constant outer diameter and a tapered tip 222 connected to the distal end of the constant-diameter section 221. The hemostatic cap 30 is made of a flexible material and is a hollow cylinder. Its proximal end is detachably press-fitted onto the distal outer wall of the handle 21, and its distal end is detachably press-fitted onto the proximal outer wall of the connector 11. The flexible material of the hemostatic cap 30 allows it to undergo elastic deformation when bent by external force, facilitating the release action. The hemostatic cap 30 forms an intermediate connector between the cannula 10 and the dilator 20, temporarily locking the two into a single unit in the axial direction to prevent the dilator 20 from accidentally dislodging relative to the cannula 10 during insertion.

[0021] A first latch is provided between the hemostatic cap 30 and the connector 11, including: a first protrusion 111 on the proximal outer wall of the connector 11 and a first groove 31 on the inner wall of the hemostatic cap 30. The number of first protrusions 111 is at least two, and the number of first grooves 31 is less than the number of first protrusions 111. In one illustrative embodiment, there are two first protrusions 111 and one first groove 31. Figure 4 As shown, the inner wall of the hemostatic cap 30 includes: a first uneven region 30a and a first flat region 30b located at the distal end of the first uneven region 30a. A first groove 31 is formed in the first uneven region 30a, and the first flat region 30b does not have any uneven structure.

[0022] Please see Figure 5 In the assembled state, the first protrusion 111 located near the connector 11 is embedded in the first groove 31, and the two are interference-fitted to form a snap-fit ​​connection with high bonding strength. Simultaneously, the first protrusion 111 located at the distal end of the connector 11 is interference-fitted with the first flat area 30b. Furthermore, the first interference amount ∆1 between any one of the first protrusions 111 and the first groove 31 is greater than the second interference amount ∆2 between any one of the first protrusions 111 and the first flat area 30b. For example, ∆1 is 0.3~0.4 mm, and ∆2 is 0.15~0.25 mm. In this document, the interference amount refers to the unilateral interference amount, which is obtained by subtracting the inner radius (smaller) of the hemostatic cap 30 at the corresponding location from the outer radius (larger) of the connector 11 and handle 21 at a specified part before assembly.

[0023] like Figure 6 As shown, during disassembly, the doctor typically uses their thumb to press against approximately the middle of the hemostatic cap 30, holding the connector 11 and the hemostatic cap 30 with both hands respectively, and bends the hemostatic cap 30 inward. Although the larger interference ∆1 between the first groove 31 and the proximal first protrusion 111 results in a tighter fit, the engagement point is located on the outer side of the bend (e.g., Figure 6 As shown on the left), it will detach first. The engagement position between the first protrusion 111 at the distal end and the first flat region 30b is approximately located at the bend or even on the inner side of the bend (e.g., on the left side). Figure 6 (As shown on the right side), although they remain partially engaged, the small interference ∆2 between them only provides a low degree of frictional fit. Therefore, with the hemostatic cap 30 bent, applying a slight tension to it allows for easy separation from the connector 11.

[0024] The strong connection between the hemostatic cap 30 and the cannula 10 is mainly achieved through the fit between the first protrusion 111 and the first groove 31. By setting a relatively high interference fit ∆1, the expected connection strength between the hemostatic cap 30 and the cannula 10 can be improved, preventing the dilator 20 from dislodging due to the hemostatic cap 30 breaking off from the cannula 10 during percutaneous insertion. Since the engagement between the first flat area 30b and the first protrusion 111 is less susceptible to the adverse effects of bending and easy disengagement, the relatively low interference fit during percutaneous insertion can at least partially offset any unintended bending of the hemostatic cap 30, thus maintaining their engagement. With the engagement position of the first protrusion 111 and the first groove 31 as a reference, the engagement position of the first protrusion 111 and the first flat area 30b is located on the relatively outer side of the hemostatic cap 30. Therefore, the maintenance of the engagement state between the first protrusion 111 and the first flat area 30b provides favorable protection for the engagement between the first protrusion 111 and the first groove 31 located on the inner side, which contributes to the main connection strength between the hemostatic cap 30 and the cannula 10, and avoids the accidental disengagement of the first protrusion 111 and the first groove 31, thereby maintaining the high connection strength between the hemostatic cap 30 and the cannula 10 during percutaneous insertion.

[0025] Therefore, with the help of the structural design of this embodiment, the clinical expectation for the connection between the hemostatic cap 30 and the cannula 10 is achieved: high axial connection strength to avoid disconnection during percutaneous insertion, and low axial connection strength for easy disassembly.

[0026] To further verify the above effects, the applicant used two of the most common intubation components in clinical practice as comparative examples, and conducted a pull-out force test on the intubation component 100 of this embodiment. Figure 7 As shown, the cannula connectors of the two cannula assemblies are the same as connector 11 in this embodiment, both having two protrusions. However, the inner wall of the hemostatic cap of the cannula assembly in Comparative Example 1 is provided with two grooves that are press-fitted with the two protrusions, while the inner wall of the hemostatic cap of the cannula assembly in Comparative Example 2 is not provided with any grooves, and only relies on its flat inner wall to press-fit with the two protrusions.

[0027] The axial pull-out force is used to characterize the connection strength between the cannula and the hemostat during percutaneous insertion. As described above, a relatively large force is desired. The test method is as follows: a pull gauge is connected to the proximal end of the hemostat, and the cannula connector is fixed with a clamp, keeping the cannula connector and the hemostat basically straight. Then, the pull gauge is pulled proximally until the hemostat detaches from the cannula connector, and the pull force value is read at this point.

[0028] The slight bending pull-out force is used to characterize the connection strength between the cannula and the hemostat during disassembly. As described above, a small force is desired. The test method is as follows: Based on the above test method, a fixture with a bending groove is added to the proximal end of the clamp. The hemostat is housed in the bending groove to limit the bending state of the hemostat. Then, the pull gauge is pulled proximally until the hemostat is disengaged from the cannula connector, and the pull force value is read. Since the friction of the bending groove on the hemostat affects the final pull-out force value, to reduce this adverse effect, a lubricating grease such as silicone oil can be applied to the inner wall of the bending groove and / or the outer wall of the hemostat. However, since the effect of friction is the same for all cannula assemblies, although this will result in the final pull-out force value not being completely accurate, it does not affect the comparison results reflecting the pull-out force of different cannula assemblies.

[0029] Depend on Figure 7 It can be seen that, although the axial pull-out force between the hemostatic cap 30 and the cannula 10 in this embodiment is lower than that in Comparative Example 1, it is slightly higher than that in Comparative Example 2, which meets the requirements for clinical use. Furthermore, the slight bending pull-out force between the hemostatic cap 30 and the cannula 10 in this embodiment is significantly reduced, and the actual tactile feedback during use is consistent with the test results. Therefore, this embodiment, through the above design, makes the pull-out force between the hemostatic cap 30 and the cannula 10 more reasonable, meeting the usage requirements while avoiding excessive tightening.

[0030] In summary, the connector 11 and the hemostatic cap 30 employ a segmented snap-fit ​​structure to ensure a connection strength that meets clinical requirements. When the hemostatic cap 30 is bent under force, the first protrusion 111 and the first groove 31 located on the outer side of the bend will disengage first, at least partially releasing the structure that primarily fixes the connector 11 and the hemostatic cap 30. This allows the cannula 10 to be easily separated from the hemostatic cap 30, preventing the cannula 10 from accidentally and suddenly entering the patient's body due to forcibly pulling the hemostatic cap 30. Thus, both connection reliability and ease of disassembly are considered.

[0031] It should be noted that if the connection strength between the hemostatic cap 30 and the connector 11 is insufficient, it may accidentally detach when the dilator 20 is withdrawn, causing blood leakage. Conversely, if the connection is too strong, it will increase the difficulty of disassembly, and may even lead to the intubation tube 10 being accidentally pushed into the body due to improper operation. Therefore, it is necessary to ensure axial connection strength while also achieving low-resistance disassembly.

[0032] To address the aforementioned issues, in this embodiment, the hemostatic cap 30 and the connector 11 possess a first connection strength that prevents axial separation when they are in an assembled state, and the hemostatic cap 30 and the handle 21 also possess a second connection strength that prevents axial separation when they are in an assembled state. The first connection strength is greater than the second connection strength, so that when the operating handle 21 is pulled out of the expander 20 axially, the hemostatic cap 30 remains fixed to the connector 11.

[0033] The first connection strength refers to the ability of the hemostatic cap 30 and the connector 11 to resist axial separation in the assembled state. It is determined by the mating structure between them, such as the interference fit, contact area, and the presence of a snap-fit ​​mechanism. In this embodiment, by setting the fit between the first protrusion 111 and the first groove 31, combined with an interference fit, the first connection strength reaches a high level, for example, approximately 15N in actual measurements, which is sufficient to maintain a stable connection between the hemostatic cap 30 and the cannula 10 during puncture and insertion. Similarly, the second connection strength refers to the ability of the hemostatic cap 30 and the handle 21 to resist axial separation in the assembled state. The second connection strength is set to be less than the first connection strength to ensure that when the dilator 20 is pulled out axially, the hemostatic cap 30 will not move but will remain fixed on the connector 11.

[0034] By setting the first connection strength between the hemostatic cap 30 and the connector 11 to be greater than the second connection strength between it and the handle 21, the hemostatic cap 30 can only be connected by... Figure 6 The cap 30 is manually detached as shown, and will not be unintentionally pulled away when the expander 20 is pulled out. Thus, the cap 30 remains on the connector 11 throughout the removal of the expander 20, preventing leakage during this process. Simultaneously, the snap-fit ​​structure preferentially releases under bending, reducing the axial pull-out force between the cap 30 and the connector 11, achieving a balance between reliable connection and easy disassembly.

[0035] Please see Figure 3 and Figure 4 A second latch is provided between the hemostatic cap 30 and the handle 21, including: a second groove 211 on the outer wall of the distal end of the handle 21, and a second protrusion 32 on the inner wall of the hemostatic cap 30 for interference fit with the second groove 211. The number of second protrusions 32 and second grooves 211 is equal and less than the number of first protrusions 111. In an illustrative embodiment, the number of second protrusions 32 / second grooves 211 is only one, less than the number of first protrusions 111. In this way, the number of latching contact points between the hemostatic cap 30 and the cannula 10 is more than that between the hemostatic cap 30 and the handle 21, thereby achieving the aforementioned difference in connection strength.

[0036] Furthermore, the height of the first protrusion 111 is greater than the depth of the second groove 211. Therefore, the interference fit between the first protrusion 111 and the first groove 31 is larger, while the fit between the second protrusion 32 and the second groove 211 is relatively shallow, resulting in a smaller axial force. Thus, when the handle 21 is pulled axially to remove the dilator 20, although there is a snap-fit ​​structure between the hemostatic cap 30 and the handle 21, due to its small number and shallow fit, the overall second connection strength is still significantly lower than the first connection strength. Therefore, the hemostatic cap 30 will not be pulled out with the dilator 20, but will remain stably on the connector 11 of the cannula 10, maintaining a seal against the blood. In actual use, after the cannula 10 enters the blood vessel through the puncture site, the doctor holds the handle 21 and pulls it outward. Due to the lower connection strength between the handle 21 and the hemostatic cap 30, the dilator 20 detaches from the hemostatic cap 30, while the hemostatic cap 30 remains on the cannula 10 and is not pulled away. Therefore, the hemostatic cap 30 can continue to perform its hemostatic function.

[0037] By setting a small number of shallowly fitted second clips between the hemostatic cap 30 and the handle 21, both assembly positioning and tactile feedback can be provided, while ensuring that the connection strength is lower than that between the hemostatic cap 30 and the cannula 10. When the dilator 20 is pulled out, the handle 21 and the hemostatic cap 30 separate first, while the hemostatic cap 30 remains reliably fixed to the cannula 10, maintaining a seal against the blood.

[0038] It should be noted that the strength of a connection depends not only on the absolute value of the local interference fit, but also on the number of mating structures, the effective contact area, and the actual stress distribution of the material in the assembled state. Even if a local interference fit is large, if its effective area is limited, the overall connection strength may still be lower than that of a combination of several smaller interference fits.

[0039] Therefore, in this embodiment, any first interference amount ∆1 and second interference amount ∆2 are both less than the third interference amount ∆3 between the second protrusion 32 and the second groove 211, but the sum of all first interference amounts ∆1 and second interference amounts ∆2 is less than the third interference amount ∆3. Numerically, the interference amount ∆3 is greater than the interference amounts ∆1 and ∆2. However, at least two first protrusions 111 are provided between the hemostatic cap 30 and the connector 11, forming two independent interference fit areas with the first groove 31 and the first flat area 30b respectively. The total effective fit length is longer, and the first groove 31 has a radial limiting and axial locking effect on the first protrusion 111, making the overall connection more stable. In contrast, only one pair of second protrusions 32 and second grooves 211 are provided between the hemostatic cap 30 and the handle 21. Although the interference amount is larger, due to the single fit point and small contact area, local elastic release is likely to occur when subjected to axial tension, and the overall anti-detachment ability is weaker.

[0040] Actual testing shows that, under this parameter configuration, the axial pull-out force between the hemostatic cap 30 and the connector 11 is significantly higher than the pull-out force between it and the handle 21. When the doctor pulls out the dilator 20 axially, the connection between the handle 21 and the hemostatic cap 30 separates first, while the hemostatic cap 30 remains firmly attached to the connector 11 of the cannula 10, preventing blood leakage from the proximal interface during the withdrawal of the dilator 20.

[0041] It should be noted that the above interference values ​​were determined under specific material and wall thickness conditions. Because flexible materials are prone to relaxation under large interference, although the interference ∆3 is high, the resulting frictional force decays rapidly over time. Multi-point mating structures can provide a more stable long-term connection. Of course, the specific values ​​of each interference can be adjusted according to material hardness, part size, and clinical needs; the embodiments in this specification do not limit this.

[0042] Please continue reading. Figure 3 and Figure 4 The inner wall of the hemostatic cap 30 includes a second concave-convex region 30c and a second flat region 30d located proximal to the second concave-convex region 30c. A second protrusion 32 is formed in the second concave-convex region 30c, while the second flat region 30d does not have any concave-convex structure. Correspondingly, the distal outer wall of the handle 21 includes a third concave-convex region 21a and a third flat region 21b located proximal to the third concave-convex region 21a. A second groove 211 is formed in the third concave-convex region 21a, while the third flat region 21b does not have any concave-convex structure. When the hemostatic cap 30 and the connector 11 are assembled, the second protrusion 32 and the second groove 211 are in an interference fit, and the second flat region 30d and the third flat region 21b are in an interference fit. The third interference amount ∆3 is less than the fourth interference amount ∆4 between the second flat region 30d and the third flat region 21b.

[0043] Although the fourth interference fit ∆4 is larger, the mating area is a continuous flat surface lacking an axial restraint structure. Under tension, it relies primarily on friction to maintain the connection, making it prone to slippage. While the second protrusion 32 and the second groove 211 have smaller interference fits, their snap-fit ​​design provides initial positioning and tactile feedback. In contrast, the mating between the hemostatic cap 30 and the connector 11 includes at least two first protrusions 111, which respectively mate with the first groove 31 and the first flat area 30b. The first groove 31 circumferentially wraps around and axially blocks the first protrusions 111, resulting in stronger resistance to pull-out even when the local interference fit is smaller than ∆4.

[0044] Therefore, when the dilator 20 is pulled out, although a large interference fit ∆4 is provided between the handle 21 and the hemostat 30, the overall connection strength is still lower than that between the hemostat 30 and the connector 11 due to the lack of a locking mechanism. The hemostat 30 can be stably retained on the cannula 10 to prevent blood leakage.

[0045] Of course, the interference fit, length, and surface treatment of each region can be adjusted according to material properties and sealing requirements. For example, the axial length of the second uneven region 30c can be increased to improve the connection stability of the handle 21, or a rough texture can be added to the third flat region 21b to adjust the coefficient of friction. This specification does not limit the specific implementation form, as long as the overall connection strength gradient is met.

[0046] Furthermore, the sum of the interference fits ∆1 and ∆2 is less than the interference fit ∆4. This seemingly makes the fit between the handle 21 and the cap 30 tighter, but in reality, the area containing the interference fit ∆4 is a flat surface without any concave or convex limiting structures. Its main function is to prevent blood leakage during the insertion of the expander 20. Although the interference fit in this area is large, it is prone to overall slippage under axial tension. Conversely, although the individual interference fits between the cap 30 and the connector 11 are small, and the sum is still lower than the interference fit ∆4, the presence of at least two first protrusions 111, with the proximal first protrusion 111 embedded in the first groove 31 to form a snap-fit ​​connection, provides a clear axial blocking effect, making it difficult to dislodge even under greater tension. Thus, the combination of geometric limiting and moderate interference results in higher connection strength in actual testing.

[0047] Therefore, although the interference amount ∆4 is the largest, even exceeding the sum of the interference amounts on the cannula 10 side, its effect on the axial connection strength is limited due to the lack of structural locking. Meanwhile, the multi-point limiting structure on the cannula 10 side ensures that the hemostatic cap 30 remains stably attached to the connector 11 when the dilator 20 is withdrawn.

[0048] Of course, the specific values ​​of the above interference fits can be adjusted according to the material elasticity, wall thickness, and manufacturing tolerances. This specification does not limit the unique value, as long as the sum of the first interference fit ∆1 and the second interference fit ∆2 is less than the fourth interference fit ∆4 and the overall connection strength gradient is reasonable.

[0049] To further optimize the connection stability and sealing performance of the cannulation assembly 100, ensuring reliable fixation of the hemostatic cap 30 and effective prevention of blood leakage during clinical operations, in one embodiment, the interference fit length between the hemostatic cap 30 and the connector is greater than the interference fit length between the hemostatic cap 30 and the handle 21. It is understood that the fit length affects the contact area and frictional resistance, thus affecting the axial connection strength. A longer fit length means a larger mating area, resulting in higher pull-out resistance for the same interference fit. This difference ensures that when the dilator 20 is withdrawn, the hemostatic cap 30 is more likely to remain on the connector 11 rather than being pulled out with the handle 21, thereby maintaining the integrity of the proximal interface.

[0050] It should be noted that the above two technical means can be used alone or in combination. For example, in a preferred embodiment, the connection strength is improved by increasing the sleeve length between the hemostatic cap 30 and the connector 11, and a reliable seal is achieved using the constant diameter section 221 of the dilator catheter 22. Of course, the specific value of the sleeve length, the length of the constant diameter section 221, and the interference fit can be adjusted according to the material properties, the size of the cannula 10, and clinical needs. This specification does not limit the implementation to a single method; any method that can enhance connection stability or improve sealing effect falls within the scope of protection of this application.

[0051] The outer wall of the proximal constant diameter section 221 is press-fitted with the inner wall of the hemostatic cap 30. Specifically, the inner wall of the hemostatic cap 30 has a radially inward first protrusion 33, which is a continuous ring with an inner diameter slightly smaller than the outer diameter of the proximal constant diameter section 221, forming a press-fit. Thus, after the dilator 20 is inserted into place, the first protrusion 33 wraps around the outer wall of the constant diameter section 221, blocking blood leakage along the gap between the outer wall of the dilator conduit 22 and the inner wall of the hemostatic cap 30, thereby providing a blood seal during the withdrawal of the dilator 20. Because the outer diameter of the proximal constant diameter section 221 is uniform, the force is stable during assembly, and local stress concentration or seal failure is less likely to occur due to taper changes.

[0052] The first concave-convex region 30a is located at the distal end of the first protrusion 33. This region is used to mate with the first protrusion 111 on the connector 11 to form the main connection structure between the hemostatic cap 30 and the connector 11, thereby providing axial limiting and pull-out resistance. Since it is located at the distal end of the first protrusion 33, the snap-fit ​​connection is completed first during assembly, and then it is pushed to the sealing position, which is conducive to step-by-step positioning.

[0053] The outer wall of the hemostatic cap 30 has a second protrusion 34 that protrudes radially outward, and its axial position is substantially aligned with the first protrusion 33 on the inner wall. The second protrusion 34 does not participate in internal connection or sealing, but mainly provides radial high elasticity to resist outward expansion deformation when the first protrusion 33 is interference-fitted with the constant diameter section 221, thereby improving blood sealing. The second concave-convex region 30c for mating with the handle 21 is located near the proximal end of the second protrusion 34, which facilitates initial alignment and tactile feedback when assembling the handle 21.

[0054] Thus, the axially partitioned design allows the inner wall of the hemostatic cap 30 to perform three functions sequentially from distal to proximal: connecting and securing the cannula 10, sealing the dilator 20, and temporarily positioning the handle 21. Each area operates independently and responds in the expected sequence under force. For example, when the dilator 20 is withdrawn, the second latch on the handle 21 disengages first, allowing the dilator catheter 22 to slide over the first protrusion 33 for blood sealing. The hemostatic cap 30, however, remains firmly connected to the cannula 10 due to the first latch at its distal end and will not be removed with the dilator 20. This design ensures a reliable connection between the hemostatic cap 30 and the cannula 10, while preventing blood leakage during the withdrawal of the dilator 20, thus effectively meeting clinical needs for sealing, connection stability, and step-by-step disassembly.

[0055] To improve the smoothness of insertion of the dilator catheter 22 into the hemostatic cap 30, the tapered tip 222, whose outer diameter gradually decreases from proximal to distal, can be centered and guide the dilator 20 smoothly into the cannula 10 during insertion, reducing jamming caused by deflection or excessive resistance. To complement this structure, a proximal guide bevel 331 is provided at the proximal end of the first protrusion 33 to guide the tapered tip 222 into the first protrusion 33. The guide bevel 331 extends from the outer edge of the first protrusion 33 towards the central axis and slopes axially towards the proximal end, guiding the tapered tip 222 as it approaches, allowing it to smoothly glide through the inner hole of the first protrusion 33, avoiding scraping or sudden obstruction, thereby improving assembly feel and sealing consistency. The angle of the proximal guide bevel 331 can be matched according to the taper of the tapered tip 222, for example, from 5° to 20°.

[0056] The cannula 10 (cannula body 12) is fitted with a suture ring 4, which is used to fix the cannula 10 to the skin with sutures after it is inserted into the blood vessel, thereby preventing displacement of the cannula 10. The suture ring 4 is a non-closed ring with circumferential slits. On the one hand, its inner wall is smooth, which allows it to better adhere to the outer wall of the cannula 10; on the other hand, because it has an opening, the non-closed ring can be flexibly adjusted to the optimal fixation position on the cannula 10 after it has been inserted and positioned. In this way, the operation is convenient and can be adapted to the needs of different puncture depths.

[0057] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A cannulation assembly, characterized in that... Includes: a cannula, a dilator, and a hemostatic cap that detachably connects the cannula and the dilator; wherein, The cannula includes a connector located at the proximal end; The expander includes a handle located at the proximal end; The hemostatic cap is made of flexible material and is hollow. Its proximal end is detachably press-fitted onto the distal outer wall of the handle, and its distal end is detachably press-fitted onto the proximal outer wall of the connector. A first latch is provided between the hemostatic cap and the connector, including: a first protrusion on the proximal outer wall of the connector and a first groove on the inner wall of the hemostatic cap; The number of first protrusions is at least two, and the number of first grooves is less than the number of first protrusions; The inner wall of the hemostatic cap includes: a first concave-convex region and a first flat region located at the distal end of the first concave-convex region; a first groove is formed in the first concave-convex region, and the first flat region does not have any concave-convex structure; When the hemostatic cap and the connector are assembled, at least the first protrusion at the nearest end is in an interference fit with the first groove, and at least the first protrusion at the farthest end is in an interference fit with the first flat area; Furthermore, the first interference fit between any first protrusion and its mating first groove is greater than the second interference fit between any first protrusion and the first flat area; The hemostatic cap is configured to bend when it receives an external force while in an assembled state with the connector, and at least one pair of first protrusions and first grooves that are in an interference fit with each other disengage on the outside of the bend.

2. The cannulation assembly as described in claim 1, characterized in that... The hemostatic cap and the connector have a first connection strength that prevents axial separation when they are assembled; similarly, the hemostatic cap and the handle have a second connection strength that prevents axial separation when they are assembled. The first connection strength is greater than the second connection strength, so that the hemostatic cap remains fixed to the cannula connector when the operating handle is pulled out axially from the dilator.

3. The cannulation assembly as described in claim 2, characterized in that... A second latch is provided between the hemostatic cap and the handle, including: a second groove on the outer wall of the distal end of the handle, and a second protrusion on the inner wall of the hemostatic cap for interference fit with the second groove; The number of second protrusions is equal to the number of second grooves, and the number of first protrusions is less. The height of the first protrusion is greater than the depth of the second groove.

4. The cannulation assembly as described in claim 3, characterized in that... Any first interference and second interference are both less than the third interference between the second protrusion and the second groove, but the sum of all first interferences and second interferences is less than the third interference.

5. The cannulation assembly as described in claim 4, characterized in that... The inner wall of the hemostatic cap includes: a second convex-concave region and a second flat region located proximal to the second convex-concave region; a second protrusion is formed in the second convex-concave region, and the second flat region does not have any convex-concave structure; The distal outer wall of the handle includes: a third concave-convex region and a third flat region located near the proximal end of the third concave-convex region; a second groove is formed in the third concave-convex region, and the third flat region has no concave-convex structure; When the hemostatic cap and the connector are assembled, the second protrusion and the second groove are interference-fitted, and the second flat area and the third flat area are interference-fitted. The third interference is less than the fourth interference between the second and third flat regions.

6. The cannulation assembly as described in claim 5, characterized in that... The sum of the first and second over-excess amounts is less than the fourth over-excess amount.

7. The cannulation assembly as described in claim 1 or 2, characterized in that... The interference fit length between the hemostatic cap and the connector is greater than the interference fit length between the hemostatic cap and the handle.

8. The cannulation assembly as described in claim 1 or 2, characterized in that... The dilator also includes a dilator catheter connected to the distal end of the handle, which can pass through the hemostatic cap into the cannula, including a proximal constant diameter section with a substantially constant outer diameter; the inner wall of the hemostatic cap has a radially inward first protrusion, which is interference-fitted with the outer wall of the constant diameter section.

9. The cannulation assembly as claimed in claim 8, characterized in that... The outer wall of the hemostatic cap has a second protrusion that is radially outward and substantially aligned with the first protrusion.

10. The cannulation assembly as claimed in claim 8, characterized in that... The dilator catheter also includes a tapered tip connected to the distal end of the constant diameter section; a proximal guide bevel is provided at the proximal end of the first protrusion to guide the tapered tip through the first protrusion.

11. The cannulation assembly as claimed in claim 1, characterized in that... The cannula is fitted with a suture ring, which is a non-closed ring with circumferential slits.

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