Mini midline conduit

Abstract

The utility model discloses a mini midline catheter, which relates to the technical field of medical instruments and comprises a catheter sheath, an expansion sheath and a protective sleeve, the catheter sheath comprises a catheter joint, a protective sleeve and an implantation catheter, the expansion sheath comprises an expansion joint, a locking ring and an expansion catheter, the catheter sheath is wrapped outside the expansion sheath, and the protective sleeve is sleeved outside the expansion sheath. The implantation catheter is wrapped outside the expansion catheter, the length of the expansion catheter is larger than that of the implantation catheter, the catheter connector is connected with the locking ring Luer, and the implantation catheter is made of a material with the biological risk assessment end point reaching the long-term or lasting contact level of circulating blood externally connected into a medical device. The dilation catheter and the dilation joint are connected through an injection molding and rubber coating process, and the implantation catheter and the catheter joint are connected through an injection molding and rubber coating process. The mini midline catheter is convenient, accurate and safe to operate, and the infusion time is prolonged compared with an indwelling needle scheme.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, specifically to a mini midline catheter. Background Technology

[0002] Intravenous infusion is one of the most commonly used treatment methods in clinical practice, delivering medications into the body through peripheral blood vessels to achieve therapeutic goals. Existing short-, medium-, and long-term implantable infusion methods include indwelling needles, peripherally inserted central venous catheters (PICCs), central venous catheters, and implantable drug delivery devices. Comparing the implantation time, indwelling needles can be infused for no more than 7 days, while PICCs, central venous catheters, and implantable drug delivery devices can remain in place for a maximum of a few minutes, but no more than a year. In terms of operation, indwelling needles are convenient and low-risk, and can be performed in a general ward; PICCs, central venous catheters, and implantable drug delivery devices require specialized operating rooms, are complex, and carry higher risks. Among these products, there is a lack of an infusion method with a maximum infusion time longer than indwelling needles but shorter than PICCs, central venous catheters, and implantable drug delivery devices, to meet the need for an infusion time of approximately one month. This method would also be convenient, accurate, and safe. Utility Model Content

[0003] Technical problem to be solved by the utility model

[0004] The technical problem to be solved by this utility model is to provide a mini midline catheter that is easy to operate, accurate and safe, and extends the infusion time compared with the indwelling needle solution.

[0005] Technical solution

[0006] To solve the above problems, the technical solution provided by this utility model is as follows:

[0007] A mini midline catheter includes a catheter sheath, an expansion sheath, and a sheath tube. The catheter sheath includes a catheter connector, a protective sheath, and an implantable catheter. The expansion sheath includes an expansion connector, a locking ring, and an expansion catheter. The catheter sheath wraps around the expansion sheath, and the implantable catheter wraps around the expansion catheter. The length of the expansion catheter is longer than that of the implantable catheter. The catheter connector is Luer-connected to the locking ring. The implantable catheter is made of a material that meets or exceeds the long-term or durable contact level with circulating blood in externally connected medical devices according to biological risk assessment endpoints. The expansion catheter and the expansion connector are connected by an injection molding process, and the implantable catheter and the catheter connector are connected by an injection molding process.

[0008] Improved ease of use and accuracy

[0009] Luer connection and injection molding process: The catheter connector and expansion sheath locking ring adopt a standardized Luer connection to ensure reliable sealing and quick docking. Combined with the injection molding process (expansion catheter-expansion connector, implantation catheter-catheter connector), it eliminates the leakage risk of traditional gluing or welding, simplifies operation steps, and reduces assembly errors.

[0010] Advantages of dilatation catheter length: Dilatation catheters are designed to be longer than implantation catheters, allowing for the establishment of a stable channel during puncture, providing precise guidance for subsequent catheter implantation, and reducing vascular damage caused by repeated adjustments.

[0011] Enhanced safety and complication control

[0012] Biocompatibility Material Guarantee: The implanted catheter is made of materials that meet the standards for long-term or persistent contact with circulating blood, significantly reducing the risks of thrombosis, inflammatory response and biotoxicity, and meeting the needs of long-term indwelling.

[0013] The catheter sheath has a dual-layer protection mechanism: the layered structure of the catheter sheath wrapping the dilation sheath and the implanted catheter wrapping the dilation catheter not only avoids the intrusion of external contamination, but also reduces the risk of catheter breakage or displacement through the protective sleeve. This dual protection enhances the ability to prevent and control infection.

[0014] Extended retention time and functional optimization

[0015] Enhanced structural stability: The injection molding process allows for a seamless connection between the catheter and the connector, resulting in high mechanical strength, excellent tensile and fatigue resistance, and the ability to withstand external forces during patients' daily activities, reducing the risk of accidental catheter dislodgement.

[0016] Optimized blood flow compatibility: The high-grade biomaterial has a smooth surface and is resistant to protein adsorption. Combined with a reasonable tube diameter design, it maintains patency and avoids premature tube removal due to thrombus or fibrous sheath formation. Compared with traditional indwelling needles (which are usually replaced within 72 hours), it significantly extends the infusion cycle to 30 days.

[0017] Alternatively, the implantable catheter may be made of TPU material.

[0018] Meets Class B biocompatibility standards:

[0019] After rigorous purification and formulation optimization, the TPU material meets the Class B requirement (long-term or persistent contact) for "external access devices in contact with circulating blood" in GB / T 16886.1-2022 / ISO10993-1:2018 standard. It has low cytotoxicity, non-sensitizing properties, and excellent blood compatibility, significantly reducing the risk of thrombosis and inflammatory response.

[0020] Surface inertness and resistance to protein adsorption:

[0021] TPU has a dense molecular chain structure, a smooth surface, and stable chemical properties, which can reduce platelet adhesion and fibrinogen deposition, avoid lumen blockage or thrombosis, and prolong the patency time of catheters in blood vessels.

[0022] No plasticizer precipitation:

[0023] Compared to traditional materials such as PVC, TPU does not require the addition of phthalate plasticizers, thus avoiding the release of harmful substances during long-term placement and ensuring patient safety.

[0024] Balance between flexibility and flexural strength:

[0025] TPU combines high elasticity (similar to rubber) with moderate rigidity, allowing the implanted catheter to bend with blood flow without collapsing, while resisting external pressure and deformation, thus reducing the risk of damage to the blood vessel wall.

[0026] Fatigue resistance and durability:

[0027] TPU has excellent resistance to repeated bending (it can withstand millions of bending cycles), adapting to changes in patient limb movement or body position, and reducing catheter rupture or leakage caused by material fatigue.

[0028] Compatible with injection molding overmolding process:

[0029] TPU and conduit connectors are bonded at the molecular level through injection molding, resulting in strong interface sealing. This avoids the aging and detachment problems of traditional adhesives and improves the overall structural reliability.

[0030] Long-term stability:

[0031] TPU has better hydrolysis resistance than ordinary polyurethane and is not easily degraded under long-term blood immersion. Combined with anti-calcification modification (such as adding a hydrophilic coating), it can maintain the mechanical properties of the catheter and support a safe indwelling period of 30 days.

[0032] Improved handling:

[0033] TPU catheters have moderate flexibility, making them easy to pass through bends in blood vessels during puncture, reducing mechanical stimulation to the vascular endothelium, and simplifying catheter placement. They are especially suitable for patients with thin or inelastic blood vessels.

[0034] Image compatibility:

[0035] TPU can be modified by adding contrast agents such as barium sulfate, so that the catheter can be clearly visualized under X-ray, which facilitates intraoperative positioning and postoperative monitoring, and reduces the risk of misplacement or displacement.

[0036] Ease of processing:

[0037] TPU can be formed through conventional processes such as extrusion and injection molding. The layered co-extrusion technology with expansion catheters (such as PEBAX material) is mature and facilitates precise control of catheter wall thickness and flexibility.

[0038] Recyclability:

[0039] TPU material is theoretically recyclable (requires medical-grade purification treatment), which aligns with the trend of green medical development and reduces the environmental burden of long-term use.

[0040] Optionally, the catheter connector is connected to the locking ring via a Luer lock.

[0041] The Luer lock adds a threaded structure to the tapered base, requiring rotation to lock, resulting in a more secure connection. It offers strong anti-loosening properties and is suitable for high-pressure or mobile applications.

[0042] Optionally, the inner wall of the locking ring is provided with a threaded groove, and the outer side of the conduit connector is provided with a thread that mates with the threaded groove.

[0043] The threaded groove and thread engagement design conforms to the Luer Lock standard. Compared to the traditional Luer Slip connection, it forms a mechanical interlock structure through rotational locking, which can resist accidental dislodgement caused by external force or patient movement. It is especially suitable for scenarios with fluctuating infusion pressure or frequent limb movement. Torsional and tensile resistance: The threaded engagement surface distributes force evenly, dispersing external stress and avoiding joint breakage or seal failure caused by single-point stress concentration, significantly improving the stability of the catheter system in complex mechanical environments.

[0044] Optionally, the locking ring is fitted over the expansion joint, and the expansion joint has an expansion ring protrusion on its periphery that elastically engages with the inner wall of the locking ring.

[0045] The expansion ring protrusion on the periphery of the expansion joint forms an elastic interference fit with the inner wall of the locking ring, and realizes "press and lock" by utilizing the elastic deformation of the material, replacing the traditional threading or adhesive fixing, reducing connection steps (no rotation action required), and is especially suitable for one-handed operation or emergency tube placement scenarios.

[0046] Optionally, the expansion joint is provided with a rotating annular protrusion, and friction ribs are provided on the outside of the rotating annular protrusion.

[0047] The rotating annular protrusion helps the expansion joint rotate, and the expansion sheath's expansion Luer interface has a Luer lock structure, which facilitates control of the connection with other components after rotation.

[0048] Optionally, the outer side of the conduit connector is provided with reinforcing ribs.

[0049] Reinforcing ribs can significantly increase the structural strength of conduit joints and prevent deformation under high pressure or high load conditions.

[0050] Optionally, the locking ring is provided with reinforcing ribs on its outer side.

[0051] Reinforcing ribs can significantly increase the structural strength of the locking ring and prevent deformation under high pressure or high load conditions.

[0052] Optionally, a protective sleeve is provided to seal the connection between the catheter connector and the implanted catheter.

[0053] The protective sleeve can isolate contaminants from the external environment, preventing bacteria, viruses or other impurities from entering the catheter system. The protective sleeve can buffer external impacts or friction, reducing damage to the connection caused by external forces. The design of the protective sleeve can make the transition between the catheter and the connector smoother, reducing stimulation or damage to surrounding tissues (such as blood vessel walls). By wrapping the connection, the protective sleeve can further fix the relative position of the catheter and the connector, preventing loosening.

[0054] Optionally, the end of the expansion joint is provided with an expansion Luer interface.

[0055] The Luer connector is a standardized connector widely used in medical and industrial fields, offering excellent compatibility and reliability. By configuring an expansion Luer connector, seamless interfacing with other Luer connector devices can be ensured.

[0056] Beneficial effects

[0057] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0058] The technical solution provided by this utility model achieves safe catheter placement through modular Luer interfaces, upgraded biomaterials, and precision manufacturing processes. Simultaneously, its structural innovation balances flexibility, durability, and biocompatibility, offering an efficient and low-risk solution for medium- to long-term intravenous infusion therapy. It improves ease of operation and accuracy, enhances safety and complication control, extends indwelling time, and optimizes function. Attached Figure Description

[0059] Figure 1 A cross-sectional view of a mini midline conduit provided for an embodiment of this utility model;

[0060] Figure 2 A schematic diagram of the structure of a mini midline catheter sheath provided for an embodiment of this utility model;

[0061] Figure 3 A cross-sectional view of the structure of a mini midline catheter sheath provided for an embodiment of this utility model;

[0062] Figure 4 A schematic diagram of the structure of an expansion sheath for a mini midline catheter, as proposed in an embodiment of this utility model;

[0063] Figure 5 A cross-sectional view of the structure of an expansion sheath for a mini midline catheter, as proposed in an embodiment of this utility model;

[0064] 1. Catheter sheath; 11. Catheter connector; 12. Protective sleeve; 13. Implanted catheter; 2. Dilation sheath; 21. Dilation connector; 211. Rotating ring protrusion; 212. Dilation Luer interface; 213. Dilation ring protrusion; 22. Locking ring; 23. Dilation catheter; 3. Sheath tube. Detailed Implementation

[0065] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0066] Example

[0067] Combined with appendix Figure 1-4 A mini midline catheter includes a catheter sheath 1, an expansion sheath 2, and a sheath 3. The catheter sheath 1 includes a catheter connector 11, a protective sheath 12, and an implantable catheter 13. The expansion sheath 2 includes an expansion connector 21, a locking ring 22, and an expansion catheter 23. The catheter sheath 1 is wrapped around the expansion sheath 2, and the implantable catheter 13 is wrapped around the expansion catheter 23. The expansion catheter 23 is longer than the implantable catheter 13. The catheter connector 11 is Luer-connected to the locking ring 22 via a Luer lock. The inner wall of the locking ring 22 has a threaded groove, and the outer side of the catheter connector 11 has threads that mate with the threaded groove. The locking ring 22 is fitted over the expansion connector 21, and the periphery of the expansion connector 21 has an expansion ring protrusion 213 that elastically engages with the inner wall of the locking ring 22.

[0068] The implantable catheter 13 is made of a material that meets or exceeds Grade B (long-term or persistent contact) of the circulating blood in the externally connected medical device in the biological risk assessment endpoint. The expansion catheter 23 and the expansion connector 21 are connected by injection molding and the implantable catheter 13 and the catheter connector 11 are connected by injection molding and the expansion connector 21.

[0069] The implantable catheter 13 is made of TPU material. The catheter connector 11 is injection molded from medical-grade polycarbonate (PC), with Luer lock threads matching the locking ring 22 and radially distributed reinforcing ribs on the outside. The reinforcing ribs are 0.8 mm high and 2 mm wide, and the surface is knurled to enhance grip friction. The catheter connector 11 and the implantable catheter 13 are seamlessly connected through an injection molding overmolding process. An annular groove with a depth of 0.3 mm is added to the overmolding interface to improve the bonding strength between the TPU material and the PC connector.

[0070] The implantable catheter 13 is made of high-purity medical-grade TPU (thermoplastic polyurethane) material, meeting the Class B requirements for circulating blood contact in GB / T 16886.1—2022 / ISO10993-1:2018 standard. It has an outer diameter of 1.6 mm and an inner diameter of 1.0 mm, and its surface is treated with a hydrophilic coating to reduce frictional resistance. The distal end of the catheter is pre-shaped with a 15° constriction for easy directional advancement within the blood vessel.

[0071] The protective sleeve 12 is made of transparent silicone and is fitted onto the connection between the catheter connector 11 and the implanted catheter 13. It forms an airtight package through an adhesive process, effectively protecting the catheter 13 and preventing backflow of body fluids or bacterial invasion.

[0072] The dilator catheter 23 is made of PEBAX® 7233 material (hardness 72D), is 5cm longer than the implanted catheter 13, has an outer diameter of 2.0mm, and is coated with a PTFE lubricating layer in the inner lumen to guide the guidewire into the blood vessel.

[0073] The expansion connector 21 has a POM body and an integrated expansion Luer interface 212 at the end (compliant with ISO 80369-7 standard). It also has an expansion annular protrusion 213 (0.5mm high, 40° angle) on its periphery, which elastically engages with the inner wall of the locking ring 22. An integrated rotating annular protrusion 211 is located on its outer side, with wavy friction ribs distributed on its surface for easy tightening.

[0074] The locking ring 22 is made of PP material, with a double-headed threaded groove (5mm pitch) on the inner wall and axial reinforcing ribs (distributed at 90° intervals) on the outer side. After being screwed into the thread of the conduit connector 11, it forms a Luer locking structure.

[0075] The sheath 3 is made of transparent PE material and its length matches that of the catheter sheath 1. It is used to pre-encapsulate the catheter sheath 1 and the dilation sheath 2 assembly to avoid contamination during transportation or storage.

[0076] The expansion joint 21 is provided with a rotating annular protrusion 211, and friction ribs are provided on the outside of the rotating annular protrusion 211.

[0077] The outer side of the conduit connector 11 is provided with a reinforcing rib. The outer side of the locking ring 22 is provided with a reinforcing rib.

[0078] A protective sleeve 12 is provided to seal the connection between the catheter connector 11 and the implanted catheter 13.

[0079] The end of the expansion connector 21 is provided with an expansion Luer interface 212.

[0080] Integrated locking design: The catheter connector 11 and the locking ring 22 are locked by a threaded Luer lock and a self-locking Luer cone surface. The tightening torque is ≤0.5N·m and the pull-out force is ≥15N, which takes into account both operational efficiency and resistance to accidental separation.

[0081] Biocompatibility assurance: The TPU implanted catheter 13 was tested for cytotoxicity (MTT assay) and met the requirements for medium- to long-term placement.

[0082] Structural reliability: Peel strength at the injection molding overmolding interface ≥25N / cm.

[0083] Operating procedures:

[0084] Puncture and guidewire placement:

[0085] Using an 18G needle, the target blood vessel (such as the basilic vein) is percutaneously punctured. After confirming blood return, a 0.018-inch guide wire is inserted into the blood vessel through the needle and then withdrawn.

[0086] If the skin at the puncture site is thick, make a 2mm incision along the guidewire with a scalpel to reduce the resistance to the catheter passage.

[0087] Catheter insertion:

[0088] Remove the sheath 3, and slowly advance the catheter sheath 1 and dilation sheath 2 assembly along the guide wire. Use the rigid tip of the dilation catheter 23 to dilate the subcutaneous tissue and blood vessel wall until the catheter sheath 1 enters the blood vessel to the predetermined depth (usually 10-15cm).

[0089] With one hand, squeeze the outer side of the locking ring 22 to disengage the dilation ring protrusion 213 from the inner wall of the locking ring 22. Rotate the catheter connector 11 in the opposite direction to unlock the Luer thread, and pull out the guide wire and dilation sheath 2, leaving only the catheter sheath 1 in the blood vessel.

[0090] Catheter fixation and connection:

[0091] Wipe away any blood from the puncture site and secure the catheter with a sterile dressing and catheter fixation device, which includes catheter fixation adhesive tape and catheter sheath 1.

[0092] Tightly connect the infusion device (such as a positive pressure connector) to the catheter connector 11, flush the tubing with saline to confirm patency, and then begin the infusion.

[0093] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A mini midline catheter, characterized by, The application relates to a catheter sheath, a dilatation sheath and a sheath tube, the catheter sheath comprising a catheter joint, a protective sleeve and an implant catheter, the dilatation sheath comprising a dilatation joint, a locking ring and a dilatation catheter, the catheter sheath being wrapped outside the dilatation sheath, the implant catheter being wrapped outside the dilatation catheter, the dilatation catheter being longer than the implant catheter, the catheter joint being connected with the locking ring through a luer connection, the implant catheter being made of a material reaching a long-term or persistent contact level of a circulation blood of an external access medical instrument above a biological risk assessment endpoint, the dilatation catheter and the dilatation joint being connected through an injection molding process, and the implant catheter and the catheter joint being connected through an injection molding process.

2. The mini-cord catheter of claim 1, wherein, The implant catheter is made of a TPU material.

3. The mini-cord catheter of claim 1, wherein, The catheter joint is connected with the locking ring through a luer lock.

4. The mini-cord catheter of claim 3, wherein, An inner wall of the locking ring is provided with a threaded groove, and an outer side of the catheter joint is provided with a thread matched with the threaded groove.

5. The mini-core wire catheter of claim 1 or 3, wherein, The locking ring is sleeved outside the dilatation joint, and a circumferential side of the dilatation joint is provided with a dilatation ring convex which is elastically clamped with the inner wall of the locking ring.

6. The mini-rail catheter of claim 1, wherein, The dilatation joint is provided with a rotating ring convex, and the rotating ring convex is provided with a friction rib outside.

7. The mini-rail catheter of claim 1, wherein, The catheter joint is provided with a reinforcing rib outside.

8. The mini-rail catheter of claim 1, wherein, The locking ring is provided with a reinforcing rib outside.

9. The mini-rail catheter of claim 1, wherein, The joint of the catheter joint and the implant catheter is provided with a protective sleeve.

10. The mini-rail catheter of claim 1, wherein, An end of the dilatation joint is provided with a dilatation luer interface.

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