Passive variable-diameter medical cannula and cannula assembly

Abstract

The invention discloses a passive variable-diameter medical cannula and a cannula assembly. The cannula comprises an in-vivo tube and an in-vitro tube which are communicated with each other; the in-vivo pipe can be deformed and compressed along the radial direction of the cross section of the in-vivo pipe, so that the in-vivo pipe is fed into a body by virtue of a pipe feeding component after being deformed and compressed; the in-vivo tube has a shape memory function and can restore to the original shape under the human body temperature condition after the tube feeding component is removed; the in-vivo pipe can be compressed again in the radial direction of the section of the in-vivo pipe by means of the pipe withdrawing component to be withdrawn out of the body. The intubation tube has the advantages that the intubation tube can be conveniently fed into the body and withdrawn out of the body by adjusting the size of the section of the upper in-vivo tube, and the intubation tube is stably positioned in an operation.

Description

Technical Field

[0001] This invention relates to a passive variable-diameter medical cannula and cannulation assembly used as an arterial / venous cannula for extracorporeal life support, belonging to the field of medical cannulation. Background Technology

[0002] In patients with severe cardiopulmonary diseases, extracorporeal life support systems (ECLS) can temporarily or short-term maintain or completely replace heart / lung function, allowing the patient's heart and lungs to rest and recover, or enabling doctors to perform surgical treatments. ECLS works by drawing blood from the body through intravenous cannula (drainage), oxygenating it outside the body (except for extracorporeal ventricular assist devices), and then returning the blood to the body through arterial cannula (perfusion). Therefore, arterial and venous cannulas are crucial medical devices connecting the body to the ECLS, and their core function is to ensure the ECLS maintains a blood flow rate sufficient to meet the patient's needs.

[0003] Arterial and venous catheters are collectively referred to as medical catheters. Currently, the structural design of catheters has been optimized to improve drainage flow rate for venous catheters and perfusion flow rate for arterial catheters: the catheter is composed of three layers of composite materials. Metal is arranged in a spiral pattern around an inner layer of polymer material, which is then covered by an outer layer of polymer material. This achieves thinner walls and a larger lumen size while utilizing the rigidity of the metal material to enhance the catheter's strength. However, existing catheters still have the following problems in use: In ECMO (extracorporeal membrane oxygenation) treatment, the cannula is prone to displacement or loosening. Displacement and loosening can lead to serious complications, such as multi-system dysfunction, including hemodynamic and circulatory disorders, oxygenation and gas exchange disorders, mechanical damage and organ dysfunction.

[0004] Recirculation in VV ECMO (venous-venous extracorporeal membrane oxygenation) refers to the phenomenon where fully oxygenated blood, after passing through the oxygenator, is not returned to the systemic circulation but instead re-enters the ECMO drainage tube, leading to a decrease in oxygen supply efficiency. Recirculation is a complication unique to V-VECMO, and its occurrence is influenced by multiple factors, one of which is cannula placement, such as cannula displacement during operation.

[0005] ECMO cannulas need to be inserted into the body through percutaneous puncture or incision. However, due to the drainage / perfusion flow requirements, the cross-sectional size of the cannula is made very large (e.g., the cross-sectional diameter of the cannula commonly used in adults is 17Fr-25Fr). Therefore, during the insertion of the cannula into the body, the wound site is prone to vascular wall tearing, dissection or perforation.

[0006] In summary, existing intubation cannulas generally suffer from the inability to adjust their cross-sectional dimensions. If the cross-sectional dimensions are designed to be too large, they are prone to causing excessive damage to the incision site during intervention. If the cross-sectional dimensions are designed to be too small, the cannulas may not be properly positioned after intervention, and may easily shift or become dislodged. Summary of the Invention

[0007] The purpose of this invention is to provide a passive variable-diameter medical cannula and cannula assembly, which has the advantages of easy insertion and withdrawal from the body and stable positioning during surgery by adjusting the cross-sectional size of its upper inner tube.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A passive variable-diameter medical cannula includes an internal tube and an external tube that are interconnected. The internal tube can deform and compress along the radial direction of its cross-section, so as to be inserted into the body by means of a cannula delivery component after the internal tube has been deformed and compressed. The internal tube has a shape memory function and can return to its original shape under the condition of body temperature after the cannula delivery component is removed. The internal tube can also be withdrawn to the outside of the body by means of a cannula withdrawal component that can be compressed again along the radial direction of its cross-section.

[0009] Furthermore, the cross-sectional dimension of the internal tube in its original state is larger than the cross-sectional dimension of the patient's wound, while the cross-sectional dimension of the internal tube after deformation and compression is smaller than the cross-sectional dimension of the patient's wound.

[0010] Furthermore, the internal tube includes an inner layer and an outer layer, with reinforcing wires disposed between the inner layer and the outer layer, the reinforcing wires being arranged in a spiral or mesh pattern; the external tube includes a main body layer, the distal end of which branches and connects to the inner layer and the outer layer respectively.

[0011] Furthermore, the outer layer may or may not fill the gaps between adjacent reinforcing wires.

[0012] Furthermore, the main body layer has holes, and the inner layer and the outer layer have corresponding holes, wherein: the insertion tube has multiple sets of holes along its own length direction; each set of holes includes multiple holes, and each hole is evenly distributed circumferentially along the cross-section of the insertion tube.

[0013] Furthermore, the reinforcing wire is made of shape memory alloy or shape memory polymer, wherein: When the reinforcing wire is made of shape memory alloy, the tube removal component includes multiple elastic wires, and adjacent elastic wires are connected by an elastic film. The tube removal component extends from the proximal end of the insertion tube, passes through it, extends outward from the distal end of the insertion tube, rolls outward, and extends along the outer wall of the insertion tube to the connection point where the inner tube and the outer tube are connected, and is then fixed, so that a cavity is formed between the tube removal component and the inner tube. The inner tube is cooled to a predetermined temperature by the coolant filled into the cavity, so that the inner tube is radially deformed and compressed along its own cross-section by pulling the elastic wire at the proximal end of the insertion tube. When the reinforcing wire is made of shape memory polymer, the tube removal component includes multiple elastic wires. Each elastic wire extends from the proximal end of the insertion tube, passes through it, extends outward from the distal end of the insertion tube, rolls outward, and extends along the outer wall of the insertion tube to the connection point where the inner tube and the outer tube are connected, and is then fixed. This allows the inner tube to be radially deformed and compressed along its own cross-section by pulling the elastic wire at the proximal end of the insertion tube.

[0014] Furthermore, a diameter-changing positioning component is provided at the connection between the inner tube and the outer tube. The diameter-changing positioning component includes a diameter-changing part located on one side of the inner tube and a support part located on one side of the outer tube. The diameter-changing part can be compressed and tightly attached to the outer wall of the inner tube so that it can be inserted into the body together with the deformed and compressed inner tube using the tube delivery component. The diameter-changing part has a shape memory function and can return to its original shape together with the inner tube under body temperature conditions after the tube delivery component is removed. The diameter-changing part can also be compressed again by the tube removal component and withdrawn out of the body together with the inner tube. The diameter-changing part is made of the same material as the reinforcing wire. The tube removal component extends through the proximal end of the insertion tube, extends outward from the distal end of the insertion tube, rolls outward, extends along the outer wall of the insertion tube, and is fixed to the diameter-changing part.

[0015] Furthermore, the support portion and the variable diameter portion are annular protrusions surrounding the connecting portion.

[0016] An intubation assembly includes an intubation component, a withdrawal component, and the aforementioned passive variable-diameter medical cannula, wherein: the intubation component is used to fit the internal tube onto the internal tube after deformation and compression, so as to insert the internal tube into the body; the withdrawal component is used to compress the internal tube back to its original shape within the body, so as to withdraw the internal tube from the body.

[0017] Furthermore, the tube delivery component is a tearable sheath.

[0018] The advantages of this invention are: On the one hand, the internal tube of the medical cannula of the present invention is compressed under certain conditions and then delivered into the target physiological structure (such as blood vessels or the right atrium of the heart) with the help of the delivery component. After the delivery component is removed, it returns to its original state and cooperates with the external tube to fix its position, avoiding displacement or loosening. On the other hand, the internal tube of the cannula is compressed by the withdrawal component and smoothly withdrawn to the outside of the body. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the first embodiment of the medical cannula of the present invention.

[0020] Figure 2 This is a schematic diagram of the first embodiment of the medical cannula of the present invention with the cannula delivery component installed.

[0021] Figure 3 This is a schematic diagram of the first embodiment of the medical cannula of the present invention with the cannula removal component installed.

[0022] Figure 4 This is a schematic diagram of the first embodiment of the medical cannula of the present invention, showing how the cross-sectional dimensions are compressed by means of a cannula removal component.

[0023] Figure 5 This is a schematic diagram of the second embodiment of the medical cannula of the present invention.

[0024] Figure 6 This is a schematic diagram of the second embodiment of the medical cannula of the present invention with the cannula delivery component installed.

[0025] Figure 7 This is a schematic diagram of the second embodiment of the medical cannula of the present invention with the cannula removal component installed.

[0026] Figure 8 This is a schematic diagram of the second embodiment of the medical cannula of the present invention, which uses a cannula removal component to compress the cross-sectional dimensions.

[0027] Figure 9 This is a schematic diagram of one embodiment of the pipe removal component.

[0028] Figure 10 This is a schematic diagram of one embodiment of the reinforcing wire.

[0029] Figure 11 This is a schematic diagram of another embodiment of the reinforcing wire. Detailed Implementation

[0030] like Figures 1 to 11This invention proposes a passive variable-diameter medical cannula, comprising an internal tube 12 and an external tube 11 that are interconnected. Under certain conditions, the internal tube 12 can deform and compress along its own cross-section radially with the aid of relevant tools, so that after the internal tube 12 is deformed and compressed, it can be inserted into the target physiological structure in the body through the wound with the aid of the cannula delivery component 20. The internal tube 12 has a shape memory function, and after the cannula delivery component 20 is removed, it can deform and expand along its own cross-section radially to restore its original shape under the condition of human body temperature, so that the cannula 10 is stably positioned at the wound site. The internal tube 12 can also be withdrawn from the wound to the outside of the body by being compressed again along its own cross-section radially with the aid of the cannula removal component 30.

[0031] In actual design, the cross-sectional size of the uncompressed internal tube 12 in its original state is larger than the cross-sectional size of the patient's wound, while the cross-sectional size of the deformed and compressed internal tube 12 is smaller than the cross-sectional size of the patient's wound. The cross-sectional size of the external tube 11 is also designed to be larger than the cross-sectional size of the patient's wound, so as to cooperate with the internal tube 12 to make the insertion tube 10 more stably positioned on the wound site, without any limitations.

[0032] like Figure 1 The proximal end of the internal tube 12 is connected to the distal end of the external tube 11. Preferably, the cross-sectional dimensions of the external tube 11 gradually decrease from its proximal end to its distal end, while the cross-sectional dimensions of the internal tube 12 in its original state gradually increase from its proximal end to its distal end. When the internal tube 12 is under body temperature conditions, based on shape memory, after the delivery component 20 is removed and the tube is restored to its original shape, the shape of the internal tube 12 should be adapted to the lumen shape of the target physiological structure (such as a vein or artery) into which it is placed. For example, the internal tube 12 is designed to mimic the size of a blood vessel lumen, and the size of the internal tube 12 should be designed according to the required blood drainage / perfusion flow rate. Of course, there should be a certain gap between the internal tube 12 and the blood vessel wall to avoid obstructing blood flow.

[0033] In practical applications, the cross-sectional shape of the cannula 10 should preferably be circular. The radial direction involved in this invention is relative to the cross-section of the cannula 10.

[0034] In the actual design, the inner tube 12 includes an inner layer 121 and an outer layer (not shown in the figure). A reinforcing wire 122 is provided between the inner layer 121 and the outer layer. The reinforcing wire 122 is spiral in shape (e.g., ...). Figure 10 ) or mesh (such as Figure 11 The outer tube 11 includes a main body layer (not shown in the figure), and the distal end of the main body layer branches and connects to the inner layer 121 and the outer layer respectively.

[0035] In actual design, the wall thickness of the inner tube 12 and the outer tube 11 is usually designed to be the same.

[0036] In actual manufacturing, the outer layer may or may not fill the gap between adjacent reinforcing wires 122.

[0037] Furthermore, the main body layer has holes, and the inner layer 121 and the outer layer have corresponding holes. The cannula 10 has multiple sets of holes along its length; each set includes multiple holes, which are evenly distributed circumferentially along the cross-section of the cannula 10. The purpose of these holes is to regulate speed, reduce local pressure at the distal end of the cannula, and improve blood circulation.

[0038] In practical implementation, preferably, the groups of holes on the cannula 10 are evenly distributed at certain intervals, with the distal end face as the reference. Each group of holes can consist of 2 to 4 holes, which are generally circular, and the diameter of the holes should preferably be 0.75 to 2.12 times the minimum outer diameter of the cannula 10. Figure 10 and Figure 11 The figure shows a hole 123 designed on the body tube 12.

[0039] Furthermore, the arrangement of the reinforcing wires 122 is not affected by the holes and is arranged continuously. However, the gaps between adjacent reinforcing wires 122 located at the holes are not filled with the outer layer.

[0040] In this invention, the inner layer 121, the outer layer, and the main body layer are made of polymer materials, such as thermoplastic polyurethane rubber (TPU), silicone, polytetrafluoroethylene (PTFE), or polyethylene terephthalate (PET). Of course, any combination of the above materials is also possible, and the manufacturing method is a well-known technique.

[0041] In this invention, the reinforcing wire 122 should have rigid support and shape memory function, and be made of shape memory alloy or shape memory polymer. The shape memory alloy is, for example, a nickel-titanium alloy, and the shape memory polymer is, for example, shape memory polyurethane, acrylate copolymer, or polyvinyl alcohol-based polymer (such as glutaraldehyde crosslinked polyvinyl alcohol (PVA), carbon nanotube / polyvinyl alcohol (PVA / MWNTS) nanocomposite material). When the reinforcing wire 122 is made of shape memory alloy, the tube removal component 30 includes multiple elastic wires 31. Preferably, each elastic wire 31 is evenly distributed along the circumferential direction of the cross section of the insertion tube 10, and adjacent elastic wires 31 are connected by an elastic film 32. That is, the tube removal component 30 is a tubular structure with a cross section radial dimension that can be stretched. One end of the tube removal component 30 extends from the proximal end of the insertion tube 10, penetrates the insertion tube 10, and then extends outward from the distal end of the insertion tube 10 and extends along the outer wall of the insertion tube 10 to the connection part 13 where the inner tube 12 and the outer tube 11 are connected. Then it is fixed to the connection part 13 so that a cavity is formed between the tube removal component 30 and the inner tube 12. The inner tube 12 is cooled to a predetermined temperature by the coolant filled into the cavity. By pulling the elastic wire 31 at the proximal end of the insertion tube 10, the inner tube 12 is deformed and compressed along its own cross section radially under the pressure of the elastic wire 31 on its own cross section. When the reinforcing filament 122 is made of shape memory polymer, the tube removal component 30 includes multiple elastic filaments 31. Preferably, each elastic filament 31 is evenly distributed circumferentially along the cross-section of the insertion tube 10. Each elastic filament 31 extends from the proximal end of the insertion tube 10, penetrates the insertion tube 10, extends outward from the distal end of the insertion tube 10, rolls outward, and extends along the outer wall of the insertion tube 10 to the connection portion 13 where the inner tube 12 and the outer tube 11 are connected, and is then fixed to the connection portion 13. This allows the inner tube 12 to deform and compress radially along its own cross-section under the pressure of the elastic filament 31 on its own cross-section by pulling the elastic filament 31 at the proximal end of the insertion tube 10. Of course, in this case, the tube removal component 30 may also include an elastic film 32.

[0042] In this invention, the tube-removal component 30 is designed with an elastic film 32, as shown in the example. Figure 9 As shown, the tube removal component 30 without the designed elastic membrane 32 is referenced. Figure 9 To understand.

[0043] In practical implementation, if the reinforcing wire 122 is made of shape memory alloy, compared with the reinforcing wire 122 being made of shape memory polymer, the pulling force applied to the tube removal component 30 can be greatly reduced, that is, it is easy to implement and suitable for promotion.

[0044] It should be noted that the inner tube 12 has a thin wall and a long tube shape, so its cross-section can be deformed and compressed in the radial direction when subjected to compressive force. However, the inner tube 12 is very long, so it will not be deformed and compressed when subjected to compressive force.

[0045] In the actual design, the elastic wire 31 and the elastic film 32 are made of materials that are elastic and have a certain toughness and strength, so as to ensure that the elastic wire 31 will not break when pulled and can exert a top pressure on the inner tube 12 along its radial direction, while the elastic film 32 can withstand the pressure of the injected coolant (such as an ice-water mixture).

[0046] In actual manufacturing, the polymer material can be formed by extrusion, solution deposition, injection molding, weaving, casting, or 3D printing, while the reinforcing filament 122 can be formed by CNC machining, laser engraving, mold forming, or winding. The reinforcing filament 122 can also be formed by weaving, where the woven reinforcing filament is inserted into a mold and then injection molded to form a composite with the inner layer of the polymer material.

[0047] The following describes the deformation and compression of the inner tube 12 along its own cross-section radial direction under set conditions using relevant tools: When the reinforcing wire 122 is made of shape memory alloy, the shape of the shape memory alloy can be controlled by temperature, exhibiting a one-way shape memory effect. During the manufacturing process of the reinforcing wire 122, the phase transformation temperature of the reinforcing wire 122 is adjusted through a thermoforming process (an existing process), ensuring that its martensitic transformation end temperature (Mf) is below a predetermined temperature (between 0 and 10°C) and its austenitic transformation end temperature (Af) is essentially the same as the human body temperature, between 30 and 36°C. Therefore, utilizing these characteristics, before insertion, the inner tube 12 of the insertion tube 10 is cooled (e.g., placed in a 4°C ice-water mixture), lowering its temperature to Mf. Thus, the inner tube 12, at a predetermined temperature (set condition) below the human body temperature (36-37°C), can be deformed and compressed using relevant tools to reduce its cross-sectional size, allowing the insertion of the tube delivery component 20 to complete the insertion. After insertion is complete and the tube delivery component 20 is removed, due to the heat transfer effect, the inner tube 12 heats up to Af within the tube, thus returning to its original state. Because the shape of shape memory alloys can be controlled by temperature, when the insertion tube 10 needs to be withdrawn, the body tube 12 is cooled down again by the tube withdrawal component 30, so that the temperature drops to Mf. Then the body tube 12 is deformed and compressed by the tube withdrawal component 30, and the cross-sectional size is reduced before it is withdrawn outside the body.

[0048] In the case where the reinforcing wire 122 is made of shape memory polymer, the shape of the shape memory polymer can be controlled through the synthesis process (an existing process), exhibiting a single-pass shape memory effect. Unlike shape memory alloys, the shape of the shape memory polymer is not temperature-controlled, but only temporarily deformed. During the fabrication of the reinforcing wire 122, the polymer chain segment structure is rationally designed to temporarily deform and compress it, and its phase transformation temperature is adjusted so that its austenite transformation end temperature (Af) is basically consistent with the human body temperature. Therefore, utilizing these characteristics, before insertion, the polymer chain segment structure of the inner tube 12 is altered through the synthesis process (setting conditions), causing it to temporarily deform and compress, reducing its cross-sectional size. Then, the tube delivery component 20 is inserted to complete the insertion. After insertion is complete and the tube delivery component 20 is removed, due to the heat transfer effect, the inner tube 12 heats up to Af within the body, thus returning to its original state (permanent shape). Because the shape of the shape memory polymer is not temperature-controlled, when the inserted tube 10 needs to be removed, the inner tube 12 can only be mechanically deformed and compressed by the tube removal component 30 to reduce its cross-sectional size before being removed from the body. Here, the pulling force required for this mechanical method of tube removal component 30 is much greater than the pulling force required by tube removal component 30 for reinforcing wire 122 made of shape memory alloy.

[0049] In practical design, ideally, such as Figure 5The connection 13 between the inner tube 12 and the outer tube 11 is also provided with a diameter-changing positioning component 14. The diameter-changing positioning component 14 includes a diameter-changing part 142 located on one side of the inner tube 12 and a support part 141 located on one side of the outer tube 11. Under set conditions, the diameter-changing part 142 can be compressed and tightly adhered to the outer wall of the inner tube 12 with the aid of relevant tools, so that it can be inserted into the body through the wound together with the deformed and compressed inner tube 12 using the tube delivery component 20. The diameter-changing part 142 has a shape memory function, and when removed... After the insertion component 20 is in place, it can return to its original shape together with the internal tube 12 under the condition of human body temperature, so that the insertion tube 10 is stably positioned at the wound site. The variable diameter part 142 can also be compressed again by the withdrawal component 30 and withdrawn from the wound and out of the body together with the internal tube 12. The variable diameter part 142 is made of the same material as the reinforcing wire 122. The withdrawal component 30 extends from the proximal end of the insertion tube 10, penetrates the insertion tube 10, extends out from the distal end of the insertion tube 10, rolls outward and extends along the outer wall of the insertion tube 10, and is fixed to the variable diameter part 142.

[0050] In actual implementation, the variable diameter section 142 is made of the same material as the reinforcing wire 122. Therefore, the process of inserting the cannula 10 into the body using the insertion member 20 is basically the same as that of inserting the cannula 10 without the variable diameter positioning member 14. The process of withdrawing the cannula 10 from the body using the withdrawal member 30 is also basically the same as that of inserting the cannula 10 without the variable diameter positioning member 14. The only difference is that the withdrawal member 30 is connected to the variable diameter section 142 instead of the connection part 13. Of course, it is also possible for the withdrawal member 30 to be connected to both the variable diameter section 142 and the connection part 13.

[0051] The material of the support part 141 can be the same as or different from that of the variable diameter part 142, without limitation. The support part 141 can be made of ordinary metal material, as long as it can provide a certain support function and is not easily deformed.

[0052] Specifically, when the reinforcing wire 122 and the variable diameter part 142 are made of shape memory alloy, the tube removal component 30 includes a plurality of elastic wires 31. Preferably, each elastic wire 31 is evenly distributed circumferentially along the cross section of the insertion tube 10, and an elastic film 32 is connected between adjacent elastic wires 31. One end of the tube removal component 30 extends from the proximal end of the insertion tube 10, penetrates the insertion tube 10, and then extends outward from the distal end of the insertion tube 10 and rolls out along the outer wall of the insertion tube 10, and is connected and fixed to the variable diameter part 142, so that a cavity is formed between the tube removal component 30, the inner tube 12, and the variable diameter part 142. Thus, the inner tube 12 and the variable diameter part 142 are cooled to a predetermined temperature by the coolant filled into the cavity, so that by pulling the elastic wire 31 at the proximal end of the insertion tube 10, the inner tube 12 and the variable diameter part 142 are deformed and compressed in the radial direction of the cross section of the insertion tube 10 under the action of the elastic wire 31.

[0053] When the reinforcing wire 122 and the diameter-changing part 142 are made of shape memory polymer, the tube removal component 30 includes a plurality of elastic wires 31. Preferably, each elastic wire 31 is evenly distributed circumferentially along the cross-section of the insertion tube 10. Each elastic wire 31 extends from the proximal end of the insertion tube 10, penetrates the insertion tube 10, extends outward from the distal end of the insertion tube 10, rolls outward, and extends along the outer wall of the insertion tube 10, and is connected and fixed to the diameter-changing part 142, so that by pulling the elastic wire 31 at the proximal end of the insertion tube 10, the inner tube 12 and the diameter-changing part 142 are deformed and compressed radially along the cross-section of the insertion tube 10 under the action of the elastic wire 31.

[0054] In practical design, the support portion 141 and the variable diameter portion 142 are annular protrusions surrounding the connecting portion 13, with arc-shaped or straight cross-sections, without limitation. Preferably, the support portion 141 and the variable diameter portion 142 are symmetrically arranged on the connecting portion 13. The support portion 141 and the variable diameter portion 142 can be sheet bodies with arc-shaped cross-sections, for example... Figure 5 As shown. The support portion 141 and the reducing portion 142 can also be designed in the shape of flanges. Alternatively, the support portion 141 and the reducing portion 142 can be designed as flanges with a certain volume; the flanges can be solid or hollow. Of course, the support portion 141 and the reducing portion 142 can also be an asymmetrical structure. The cross-sectional dimensions of the support portion 141 and the reducing portion 142 should be larger than the wound area or cross-sectional dimensions to better block blood flow out of the wound. The support portion 141 and the reducing portion 142 can be made of the same or different materials.

[0055] In practical applications, since the medical cannula 10 of the present invention needs to be closely attached to the skin and blood vessels at the wound site to assist in positioning, the support part 141 and the diameter-changing part 142 should have good fit, that is, they should be soft, smooth and elastic.

[0056] In this invention, all materials used in the above-mentioned components are well-known materials that are available and can be purchased directly from the market. Furthermore, the parts that come into contact with human physiological structures, blood, etc., should have good biocompatibility and good fatigue resistance, wear resistance, and other properties.

[0057] The present invention also proposes an intubation assembly, which includes an intubation component 20, an intubation component 30, and the passive variable diameter medical cannula 10 of the present invention described above, wherein: the intubation component 20 is used to fit over the intubation tube 12 after deformation and compression, so as to insert the intubation tube 12 into the body through the wound; the intubation component 30 is used to compress the intubation tube 12 again to restore its original shape, so as to withdraw the intubation tube 12 from the wound to the outside of the body.

[0058] In this invention, the tube delivery component 20 is an existing tearable sheath.

[0059] For the medical cannula 10 of the present invention that does not have a variable diameter positioning component 14, when using it, refer to... Figure 1 and Figure 2Under set conditions, the internal tube 12 of the intubation cannula 10 is deformed and compressed radially along its cross-section using relevant tools. The delivery component 20 is then inserted and kept compressed before being inserted through the patient's wound. The delivery component 20 is then removed. The internal tube 12 is positioned within the lumen of the target physiological structure (such as veins, arteries, or the right atrium of the heart) and returns to its original shape. The external tube 11 remains outside the body, with the connection point 13 positioned at the wound site. The proximal end of the external tube 11 is used to connect to an external life support system, while the distal end of the internal tube 12 serves as the target location for drainage or perfusion. At this point, the intubation cannula 10 is stably positioned at the wound site, ready for surgical use.

[0060] When the surgery is completed and the intubation tube needs to be removed, refer to [reference needed]. Figure 3 and Figure 4 The tube removal component 30 is installed on the intubation tube 10 from outside the body using relevant tools. Then, the elastic wire 31 located outside the body and near the end of the intubation tube 10 is pulled by relevant equipment (if the reinforcing wire 122 is a shape memory alloy, it also needs to be filled with coolant to cool it down), so that the elastic wire 31 presses against the inner tube 12 radially along the inner tube 12, thereby compressing the cross-sectional size of the inner tube 12, and the intubation tube 10, together with the tube removal component 30, is withdrawn from the wound to the outside body.

[0061] For the medical cannula 10 of the present invention equipped with the variable diameter positioning component 14, when using it, refer to... Figure 5 and Figure 6 Under set conditions, the internal tube 12 and the reducing section 142 of the intubation cannula 10 are deformed and compressed radially along their cross-section using relevant tools. The delivery component 20 is then inserted and kept compressed before being inserted through the patient's wound. The delivery component 20 is then removed. The internal tube 12 is positioned within the lumen of the target physiological structure (such as a vein, artery, or the right atrium of the heart). The internal tube 12 and the reducing section 142 return to their original positions. The external tube 11 is outside the body, and the connection point 13 is at the wound site. The proximal end of the external tube 11 is used to connect to an external life support system, and the distal end of the internal tube 12 serves as the target location for drainage or perfusion. The physiological structure at the wound site is located between the external support section 141 and the internal reducing section 142. At this point, the intubation cannula 10 is stably positioned at the wound site, ready for surgical use.

[0062] When the surgery is completed and the intubation tube needs to be removed, refer to [reference needed]. Figure 7 and Figure 8The withdrawal component 30 is installed on the cannula 10 from outside the body using relevant tools. Then, the elastic wire 31 located outside the body and near the end of the cannula 10 is pulled using relevant equipment (if the reinforcing wire 122 and the diameter-changing part 142 are shape memory alloys, coolant is also required for cooling). This causes the elastic wire 31 to radially press against the inner tube 12 and pull the diameter-changing part 142, thereby compressing the cross-sectional dimensions of the inner tube 12. The diameter-changing part 142 is then pressed tightly against the outer wall of the inner tube 12, and the cannula 10, along with the withdrawal component 30, is withdrawn from the wound to the outside body.

[0063] In this invention, the end closer to the doctor is the proximal end, and the end closer to the patient is the distal end. For example, during surgery, when the doctor operates the intubation tube 10, the end of the intubation tube 10 first inserted into the patient is the distal end, and the end inserted later into the patient, i.e., the end closer to the doctor, is the proximal end. Figure 1 , Figure 5 As shown. For the cannula delivery member 20 and the cannula withdrawal member 30, their distal and proximal ends are defined as described above for the cannula 10.

[0064] Here, since the radial diameter change of the medical cannula 10 of the present invention is inseparable from external components (cannula delivery component, cannula withdrawal component), it is defined as passive. The main function of the cannula delivery component is to maintain the diameter change state of the cannula, which is also regarded as a radial change of the cross-sectional size of the cannula 10.

[0065] The present invention has the following beneficial effects: The medical cannula of this invention can be used as an arterial cannula or a venous cannula, providing extracorporeal life support. The internal tube on the cannula maintains its cross-sectional size through the cannula delivery component and changes its cross-sectional size through the cannula withdrawal component, thereby enabling the cannula to be smoothly delivered into the body, positioned, and withdrawn.

[0066] Regardless of whether a variable diameter positioning component is designed, the variable diameter design of the medical cannula of this invention is less likely to cause excessive damage to the wound during insertion into the body, greatly reducing the size of the wound used for cannula insertion, which is conducive to vascular closure after cannula removal and reduces trauma to the patient. In addition, the cannula can be positioned at the patient's wound site to avoid complications. Furthermore, the large cross-sectional size of the tube within the target physiological structure can well meet the drainage flow requirements when used as a venous cannula and the perfusion flow requirements when used as an arterial cannula.

[0067] The medical cannula of the present invention, which is designed with a variable diameter positioning component, also has the effect of blocking blood flow in the body (preventing blood flow from the wound), and the positioning effect of the cannula at the patient's wound site is better.

[0068] The above description describes the preferred embodiments of the present invention and the technical principles applied thereto. For those skilled in the art, any obvious changes such as equivalent transformations or simple substitutions based on the technical solutions of the present invention, without departing from the spirit and scope of the present invention, shall fall within the protection scope of the present invention.

Claims

1. A passive variable-diameter medical cannula, characterized in that, It includes an internal tube and an external tube that are interconnected; the internal tube can deform and compress along the radial direction of its own cross-section, so as to be sent into the body by means of a tube delivery component after the internal tube is deformed and compressed; the internal tube has a shape memory function and can return to its original shape under the condition of human body temperature after the tube delivery component is removed; the internal tube can also be re-compressed along the radial direction of its own cross-section by means of a tube removal component and withdrawn to the outside of the body.

2. The passive variable-diameter medical cannula as described in claim 1, characterized in that, The cross-sectional dimensions of the internal tube in its original state are larger than the cross-sectional dimensions of the patient's wound, while the cross-sectional dimensions of the internal tube after deformation and compression are smaller than the cross-sectional dimensions of the patient's wound.

3. The passive variable-diameter medical cannula as described in claim 1, characterized in that, The inner tube includes an inner layer and an outer layer, with reinforcing wires arranged in a spiral or mesh pattern between the inner and outer layers; the outer tube includes a main body layer, with the distal end of the main body layer branching off and connecting to the inner and outer layers respectively.

4. The passive variable-diameter medical cannula as described in claim 3, characterized in that, The outer layer may or may not be filled into the gaps between adjacent reinforcing wires.

5. The passive variable-diameter medical cannula as described in claim 3, characterized in that, The main body layer has holes, and the inner layer and the outer layer have corresponding holes. The insertion tube has multiple sets of holes along its length. Each set of holes includes multiple holes, and each hole is evenly distributed circumferentially along the cross-section of the insertion tube.

6. The passive variable-diameter medical cannula as described in claim 3, characterized in that, The reinforcing wire is made of shape memory alloy or shape memory polymer, wherein: When the reinforcing wire is made of shape memory alloy, the tube removal component includes multiple elastic wires, and adjacent elastic wires are connected by an elastic film. The tube removal component extends from the proximal end of the insertion tube, passes through it, extends outward from the distal end of the insertion tube, rolls outward, and extends along the outer wall of the insertion tube to the connection point where the inner tube and the outer tube are connected, and is then fixed, so that a cavity is formed between the tube removal component and the inner tube. The inner tube is cooled to a predetermined temperature by the coolant filled into the cavity, so that the inner tube is radially deformed and compressed along its own cross-section by pulling the elastic wire at the proximal end of the insertion tube. When the reinforcing wire is made of shape memory polymer, the tube removal component includes multiple elastic wires. Each elastic wire extends from the proximal end of the insertion tube, passes through it, extends outward from the distal end of the insertion tube, rolls outward, and extends along the outer wall of the insertion tube to the connection point where the inner tube and the outer tube are connected, and is then fixed. This allows the inner tube to be radially deformed and compressed along its own cross-section by pulling the elastic wire at the proximal end of the insertion tube.

7. The passive variable-diameter medical cannula as described in any one of claims 1 to 6, characterized in that, A variable diameter positioning component is provided at the connection between the inner tube and the outer tube. The variable diameter positioning component includes a variable diameter portion on one side of the inner tube and a support portion on one side of the outer tube. The variable diameter portion can be compressed and tightly adhered to the outer wall of the inner tube so that it can be inserted into the body together with the deformed and compressed inner tube using the tube delivery component. The variable diameter portion has a shape memory function and can return to its original shape together with the inner tube under body temperature conditions after the tube delivery component is removed. The variable diameter portion can also be compressed again by the tube removal component and withdrawn out of the body together with the inner tube. The variable diameter portion is made of the same material as the reinforcing wire. The tube removal component extends through the proximal end of the insertion tube, extends outward from the distal end of the insertion tube, rolls outward, extends along the outer wall of the insertion tube, and is fixed to the variable diameter portion.

8. The passive variable-diameter medical cannula as described in claim 7, characterized in that, The support portion and the variable diameter portion are annular protrusions surrounding the connection portion.

9. A cannulation assembly, characterized in that, The device includes a cannula delivery component, a cannula removal component, and a passive variable-diameter medical cannula as described in any one of claims 1 to 8, wherein: the cannula delivery component is used to fit the internal tube onto the internal tube after deformation and compression, so as to deliver the internal tube into the body; the cannula removal component is used to compress the internal tube again to restore its original shape, so as to remove the internal tube from the body.

10. The cannulation assembly as claimed in claim 9, characterized in that, The delivery tube component is a tearable sheath.

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