Continuous flushing type intestinal anastomosis metal stent system

Abstract

The utility model provides a continuous flushing type intestinal anastomosis metal stent system which comprises a metal stent, an inner layer membrane, an outer layer membrane, a drainage tube and a stent releasing device, and the metal stent is arranged in the stent releasing device before being released; the metal stent is a full-bare metal stent formed by weaving nickel-titanium alloy wires, is dumbbell-shaped and comprises a head part, a tail part and a body part; the inner-layer film is arranged on the inner surface of the metal stent, the outer-layer film is arranged on the outer surface of the metal stent, and the outer-layer film and the inner-layer film corresponding to the head and the tail are attached to the metal stent into a whole; a space is formed between the inner-layer film and the outer-layer film, and a plurality of through holes communicated with the space are formed in the outer-layer film; the drainage tube is communicated with the space. After the metal support is released, liquid secreted by an intestinal canal anastomotic stoma, intestinal mucosa, blood vessels and leakage tissue can be blocked or supported, the liquid can enter a gap between the outer layer membrane and the inner layer membrane through the through holes and is sucked out by negative pressure, the anastomotic stoma and the leakage can be kept clean, and healing of the anastomotic stoma and the leakage is promoted.

Description

Technical Field

[0001] This utility model relates to the field of medical device technology, and more specifically, to a continuous flushing intestinal anastomosis metal stent system. Background Technology

[0002] Gastrointestinal obstruction is common in clinical practice. According to the location of the obstruction, it can be divided into esophageal obstruction, gastric obstruction, duodenal obstruction, small bowel obstruction, colonic obstruction, and rectal obstruction. According to the benign or malignant nature of the obstruction, it can be analyzed as benign obstruction and malignant obstruction. According to the time of onset, it can be classified as acute obstruction, subacute obstruction, and chronic obstruction. According to the nature of the obstruction, it can be classified as mechanical obstruction, dynamic obstruction, and strangulated obstruction.

[0003] Removing the cause of obstruction, resecting the affected organ, and performing gastrointestinal anastomosis are routine surgical procedures for treating gastrointestinal obstruction. The use of anastomotic devices has greatly simplified organ anastomosis, but complications such as anastomotic leakage and bleeding are still common. For patients in the acute phase, to reduce the incidence of complications, a gastrointestinal stoma is often performed, allowing the anastomosis and reduction of digestive organs to occur after the organ edema subsides. A gastrointestinal stoma not only requires cumbersome nursing care, affecting daily life and work, but the secondary surgery to complete the anastomosis and reduction of digestive organs further increases the patient's financial burden and physical suffering.

[0004] Fully covered nickel-titanium alloy stents have been widely used in the treatment of bile leaks. By sealing the leak through the stent wall, bile leakage can be stopped, thereby promoting wound healing. These stents have also been used to treat gastrointestinal perforations and anastomotic leaks. However, under gastrointestinal peristalsis, cylindrical fully covered stents are prone to displacement, losing their ability to seal the leak and thus limiting their clinical application. To reduce stent displacement, fully covered stents are designed in a dumbbell shape. However, fluid secreted from the gastrointestinal mucosa and the leak tends to accumulate in the central depression of the stent, which not only hinders wound healing but can also lead to further aggravation of the anastomotic leak.

[0005] To facilitate the drainage of secretions accumulated in the recesses of metal stents, VAC Stent Company has applied for a negative pressure suction stent (patent number: WO2024170414A1). This stent is a dumbbell-shaped, fully covered metal stent with a polyurethane foam insert in the recessed area. A vacuum tube connects the foam to the recessed surface of the metal stent. Continuous negative pressure suction through the vacuum tube removes various secretions, inflammatory mediators, and pus filtered by the polyurethane foam, thereby promoting the healing of the leakage site. The aforementioned negative pressure suction stent still has the following problems: 1. The gastrointestinal mucosa is in close contact with the polyurethane sponge, and the friction between the polyurethane sponge and the gastrointestinal mucosa can lead to gastrointestinal mucosal edema and promote the production of secretions; 2. The polyurethane sponge has a filtering effect on the gastrointestinal mucosa and the fluid secreted from the leak, and lumps of necrotic tissue or purulent coating will be deposited on the surface and in the gaps of the polyurethane sponge or block the suction tube, gradually reducing the negative pressure drainage effect; 3. During continuous negative pressure suction, digestive juices in the gastrointestinal tract at both ends of the stent will enter the groove of the metal stent through the gap between the metal stent and the gastrointestinal mucosa. The damage of digestive juices to the leak tissue is not conducive to the closure of the leak; 4. The outer sheath of the stent release device has a raised protective pad, which is not conducive to the application of the stent in surgical procedures. Utility Model Content

[0006] In response to the aforementioned technical problems, a continuous flushing intestinal anastomosis metal stent system is provided.

[0007] The technical means adopted in this utility model are as follows:

[0008] A continuous flushing intestinal anastomosis metal stent system includes: a metal stent, an inner membrane, an outer membrane, a drainage tube, and a stent release device, wherein the metal stent is disposed within the stent release device before release;

[0009] The metal support is a bare metal support woven from nickel-titanium alloy wire. The metal support is dumbbell-shaped, including a head and a tail at both ends and a body in the middle. The head and tail are raised relative to the body, and the body is a groove between the head and the tail.

[0010] The inner membrane is disposed on the inner surface of the metal support, and the outer membrane is disposed on the outer surface of the metal support. The outer membrane and inner membrane corresponding to the head and tail are bonded together with the metal support to form a whole.

[0011] There is a space between the inner membrane and the outer membrane, and the outer membrane corresponding to the body is provided with multiple through holes, which are connected to the space.

[0012] The drainage tube is connected to the space.

[0013] Furthermore, both the head and tail are equipped with a retrieval loop.

[0014] Furthermore, the inner surface of the inner membrane is smooth, and the outer surface of the inner membrane corresponding to the body may or may not have a first protrusion.

[0015] Furthermore, the outer surface of the outer membrane is smooth, the plurality of through holes are arranged in a crisscross pattern, and the inner surface of the outer membrane may or may not have a second protrusion, the second protrusion being located between two adjacent through holes.

[0016] Furthermore, the drainage tube enters through the interior of a raised section on one side of the metal support, passes through the raised section into the space, and fits against the inner and / or outer surfaces of the metal support; the drainage tube located in the space is arranged along the length of the entire groove.

[0017] Furthermore, the drainage tube may be a single tube or two tubes.

[0018] Furthermore, the single drainage tube is a suction tube, which is located in the space and is attached to the outer surface of the metal support. The lead end of the suction tube is connected to an external negative pressure device through a negative pressure suction connector. The tube wall of the suction tube is provided with multiple first side holes, which are used to connect the suction tube and the space.

[0019] Furthermore, the single drainage tube is a dual-channel tube, located within the space and attached to the outer surface of the metal support. The interior of the dual-channel tube is provided with a suction channel and a water injection channel. The tube wall of the dual-channel tube is provided with multiple second side holes and multiple third side holes. The multiple second side holes communicate with the suction channel and the space, and the multiple third side holes communicate with the water injection channel and the space. The outlet end of the dual-channel tube is connected to a negative pressure suction connector and an air injection connector. The negative pressure suction connector communicates with the suction channel and is connected to an external negative pressure device, and the air injection connector communicates with the water injection channel and is connected to an external water injection pipe.

[0020] Furthermore, the drainage tube is a double tube, which includes a suction tube and a flushing tube. Both the suction tube and the flushing tube are single-channel tubes. The suction tube is connected to an external negative pressure device through a negative pressure suction connector, and the flushing tube is connected to an external water injection pipe through an air injection connector. The suction tube has multiple fourth side holes on its wall, which are used to connect the suction tube and the space. The flushing tube has multiple fifth side holes on its wall, which are used to connect the flushing tube and the space.

[0021] Inside the space, the suction tube is attached to the inner surface of the metal support, and the flushing tube is attached to the outer surface of the metal support; or the suction tube is attached to the outer surface of the metal support, and the flushing tube is attached to the inner surface of the metal support; the suction tube and the flushing tube are distributed on both sides of the metal support in the diametrical direction.

[0022] The flushing pipe is either straight or circular.

[0023] Furthermore, the stent release device includes an outer sheath and a pusher, the pusher being inserted into the interior of the outer sheath, and the metal stent being sleeved on the pusher and located inside the outer sheath before release;

[0024] The head end of the outer sheath may or may not be covered with a silicone protective ring, and the tail end of the outer sheath is provided with a first handle;

[0025] The head end of the pusher has a conical structure, and a limiting structure is provided on the tube wall of the pusher. Before the metal bracket is released, it is sleeved between the conical structure and the limiting structure. The tail end of the pusher is provided with a second handle.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. The continuous flushing intestinal anastomosis metal stent system provided by this utility model has a biofilm attached to the inner and outer surfaces of the bare metal stent, which simplifies the structure and manufacturing process.

[0028] 2. The continuous flushing intestinal anastomosis metal stent system provided by this utility model has a smooth outer membrane, which can reduce irritation to the digestive tract mucosa and reduce the production of secretions.

[0029] 3. The continuous flushing intestinal anastomosis metal stent system provided by this utility model has pores on the outer membrane, through which the fluid secreted by the gastrointestinal mucosa and the leak can enter the gap between the outer and inner membranes and be suctioned out by the negative pressure drainage tube, which can promote the healing of the anastomosis and the leak.

[0030] 4. The continuous flushing intestinal anastomosis metal stent system provided by this utility model forms a closed space between the outer membrane and the inner membrane, which can promote the entry of large pieces of pus and necrotic tissue into the closed space through the pores on the outer membrane, resulting in higher drainage efficiency.

[0031] 5. The continuous flushing intestinal anastomosis metal stent system provided by this utility model has multiple protrusions on the inner surface of the outer membrane and the outer surface of the inner membrane. Under the compression of the gastrointestinal mucosa against the outer membrane and the compression of the intestinal contents against the inner membrane, there is still a large gap between the outer and inner membranes, resulting in high negative pressure drainage efficiency. The flushing fluid can enter the suction tube through the gap, avoiding the accumulation of flushing fluid.

[0032] 6. The continuous flushing intestinal anastomosis metal stent system provided by this utility model has retrieval loops at both ends of the metal stent. The metal stent can be removed through the digestive tract by pulling the retrieval loops under endoscopy.

[0033] Based on the above reasons, this utility model can be widely promoted in fields such as medicine. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is a schematic diagram of the structure of the system of this utility model.

[0036] Figure 2 This is a schematic diagram of the structure of the metal support, inner membrane, outer membrane and drainage tube of this utility model.

[0037] Figure 3 for Figure 2 A sectional view.

[0038] Figure 4 This is a schematic diagram of the inner membrane structure of the present invention, which has a first protrusion.

[0039] Figure 5 This is a schematic diagram of the outer membrane structure of the present invention, which has a through hole and a second protrusion.

[0040] In the diagram: 1. Metal support; 21. Outer sheath; 22. Pusher; 23. Silicone protective ring; 3. Inner membrane; 31. First protrusion; 4. Outer membrane; 41. Through hole; 42. Second protrusion; 5. Drainage tube. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0042] This invention provides a continuous flushing intestinal anastomosis metal stent system, comprising: a metal stent 1, an inner membrane 3, an outer membrane 4, a drainage tube 5, and a stent release device. Before release, the metal stent 1 is placed within the stent release device. The metal stent 1 is a completely bare metal stent 1 woven from nickel-titanium alloy wire. The metal stent 1 is dumbbell-shaped, including a head and a tail at both ends and a body in the middle. The head and tail are raised relative to the body, and the body is a groove between the head and tail. The inner membrane 3 is disposed on the inner surface of the metal stent 1, and the outer membrane 4 is disposed on the outer surface of the metal stent 1. The outer membrane 4 corresponding to the head and tail and the inner membrane 3 are bonded together with the metal stent 1 to form a whole. There is a space between the inner membrane 3 and the outer membrane 4. The outer membrane 4 corresponding to the body has multiple through holes 41 communicating with the space. The drainage tube 5 communicates with the space.

[0043] Preferably, both the head and tail are equipped with retraction loops.

[0044] Preferably, the inner surface of the inner membrane 3 is smooth, and the outer surface of the inner membrane 3 corresponding to the body is provided with or not provided with the first protrusion 31.

[0045] Preferably, the outer surface of the outer membrane 4 is smooth, and the multiple through holes 41 are arranged in a crisscross pattern. The inner surface of the outer membrane 4 may or may not have a second protrusion 42, and the second protrusion 42 is located between two adjacent through holes 41.

[0046] Preferably, the drainage tube 5 enters through the interior of a raised section on one side of the metal bracket 1, passes through the raised section into the space, and fits against the inner and / or outer surfaces of the metal bracket 1; the drainage tube 5 located in the space is arranged along the length of the entire groove.

[0047] Preferably, the drainage tube 5 is a single tube or a double tube.

[0048] Preferably, the single drainage tube 5 is a suction tube, which is located in the space and is attached to the outer surface of the metal support 1 (the drainage tube can enter through the inside of the head on the right side of the metal support, perforate the inner membrane and metal mesh of the metal support, and be attached to the outside of the metal mesh body). The outlet end of the suction tube is connected to the external negative pressure equipment through a negative pressure suction connector. The tube wall of the suction tube is provided with multiple first side holes, which are used to connect the suction tube and the space.

[0049] Preferably, the single drainage tube 5 is a dual-channel tube. The dual-channel tube located in the space is attached to the outer surface of the metal support 1. The interior of the dual-channel tube is provided with a suction channel and a water injection channel. The tube wall of the dual-channel tube is provided with multiple second side holes and multiple third side holes. The multiple second side holes are connected to the suction channel and the space, and the multiple third side holes are connected to the water injection channel and the space. The outlet end of the dual-channel tube is connected to a negative pressure suction connector and an air injection connector. The negative pressure suction connector is connected to the suction channel and to an external negative pressure device, and the air injection connector is connected to the water injection channel and to an external water injection pipe.

[0050] Preferably, the drainage tube 5 is a double tube, which includes a suction tube and a flushing tube. Both the suction tube and the flushing tube are single-channel tubes. The suction tube is connected to an external negative pressure device through a negative pressure suction connector, and the flushing tube is connected to an external water injection pipe through an air injection connector. The suction tube has multiple fourth side holes on its wall, which are used to connect the suction tube and the space. The flushing tube has multiple fifth side holes on its wall, which are used to connect the flushing tube and the space.

[0051] Inside the space, the suction tube is attached to the inner surface of the metal support 1, and the flushing tube is attached to the outer surface of the metal support 1; or the suction tube is attached to the outer surface of the metal support 1, and the flushing tube is attached to the inner surface of the metal support 1; the suction tube and the flushing tube are distributed on both sides of the diameter direction of the metal support 1, and are arranged approximately symmetrically; the flushing tube is straight or ring-shaped.

[0052] Preferably, the stent release device includes an outer sheath 21 and a pusher 22. The pusher 22 is inserted into the interior of the outer sheath 21. Before release, the metal stent 1 is fitted onto the pusher 22 and located inside the outer sheath 21. The head end of the outer sheath 21 may or may not be fitted with a silicone protective ring 23, and the tail end of the outer sheath 21 is provided with a first handle. The head end of the pusher 22 has a conical structure, and the tube wall of the pusher 22 is provided with a limiting structure (an existing limiting structure can be used). Before release, the metal stent 1 is fitted between the conical structure and the limiting structure, and the tail end of the pusher 22 is provided with a second handle.

[0053] After release, the metal stent of this invention can block intestinal leaks or support intestinal anastomoses. Fluids secreted by the intestinal mucosa, blood vessels, and leak tissue can enter the gap between the outer and inner membranes through pores on the outer membrane and be suctioned out by negative pressure, keeping the anastomosis and leak clean and promoting their healing. By continuously injecting saline or air into the gap between the outer and inner membranes, the anastomosis mucosa and leak are constantly flushed, which not only promotes the discharge of inflammatory mediators secreted by the anastomosis and leak but also reduces the blockage rate of the negative pressure drainage tube, thereby accelerating the healing of the anastomosis and leak. The gap between the protrusions on the inner surface of the outer membrane and the protrusions on the outer surface of the inner membrane maintains unobstructed drainage between the outer and inner membranes.

[0054] Use of this utility model:

[0055] 1. Treatment of gastrointestinal perforation or anastomotic leakage

[0056] If a gastroscopy or colonoscopy reveals a perforation in the digestive tract or anastomotic leakage, a guidewire is inserted and advanced into the distal digestive tract. Under guidewire guidance, this stent system is placed. The stent pusher of the stent release device is fixed, and the outer sheath is pulled back. The metal stent is gradually released from the outer sheath until it is completely released. The drainage tube is fixed, and the stent release device is pulled back until the drainage tube separates from the stent release device.

[0057] 1.1 Single suction tube

[0058] The suction tube is connected to negative pressure, which can intermittently or continuously suction out secretions that have entered between the outer and inner membranes.

[0059] 1.2 Single-channel dual-channel flushing drainage tube

[0060] The dual-channel drainage tube connection connector allows air or water to be injected through the air injection connector, allowing the air or water to enter the cavity between the inner and outer membranes; the negative pressure suction tube is connected through the negative pressure suction connector to intermittently or continuously suction out the air, water, and secretions between the inner and outer membranes.

[0061] 1.3, Dual single-channel flushing drainage tubes

[0062] An air or water is injected into a drainage tube through an air injection connector. The air or water flows into the cavity between the inner membrane and the outer mesh through the side hole of the drainage tube. A negative pressure suction tube is connected through a negative pressure suction connector to intermittently or continuously suction out the water and secretions in the cavity between the inner membrane and the outer membrane.

[0063] 2. Acute phase intestinal anastomosis

[0064] For patients with acute intestinal obstruction, after resection of necrotic and stenotic intestinal segments, enterostomy is unnecessary; the edematous intestinal segments are directly anastomosed end-to-end. The intestinal wall is incised away from the anastomosis, and the stent system is inserted through the incision, with the anastomosis located in the middle of the stent. The intestinal segments at both ends of the anastomosis are squeezed towards the middle of the stent, and the stent pusher of the stent release device is fixed, while the outer sheath is pulled back. The metal stent is gradually released from the outer sheath until it is completely released. The drainage tube is fixed, and the stent release device is pulled back until it separates from the stent release device. At this point, the intestinal wall on the groove of the metal stent is folded, and the anastomosis is tension-free. Absorbable sutures are used to fix the intestinal wall to the raised tube walls at both ends of the metal stent to prevent stent displacement. The entire intestinal wall incision and the depressor muscle layer are sutured with absorbable sutures and fixed to the drainage tube, which runs parallel to the intestinal wall and is wrapped with seromuscular sutures. Finally, the drainage tube is brought out through a puncture in the abdominal wall and sutured to the abdominal wall to fix it in place. By using negative pressure suction, secretions in the gap between the inner and outer membranes can be intermittently or continuously drawn out. Alternatively, air or water can be continuously injected into the gap between the inner and outer membranes to dilute the secretions and promote their expulsion.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A continuous flushing intestinal anastomosis metal stent system, characterized in that, include: The metal stent (1), inner membrane (3), outer membrane (4), drainage tube (5) and stent release device are provided, wherein the metal stent (1) is placed in the stent release device before being released; The metal support (1) is a bare metal support (1) woven from nickel-titanium alloy wire. The metal support (1) is dumbbell-shaped, including a head and a tail at both ends and a body in the middle. The head and tail are raised relative to the body. The body is a groove between the head and the tail. The inner membrane (3) is disposed on the inner surface of the metal support (1), and the outer membrane (4) is disposed on the outer surface of the metal support (1). The outer membrane (4) and the inner membrane (3) corresponding to the head and tail are bonded together with the metal support (1) to form a whole. There is a space between the inner membrane (3) and the outer membrane (4), and the outer membrane (4) corresponding to the body is provided with a plurality of through holes (41), which are connected to the space; The drainage tube (5) is connected to the space.

2. The continuous flushing intestinal anastomosis metal stent system according to claim 1, characterized in that, Both the head and tail are equipped with retraction loops.

3. The continuous flushing intestinal anastomosis metal stent system according to claim 1, characterized in that, The inner surface of the inner membrane (3) is smooth, and the outer surface of the inner membrane (3) corresponding to the body is provided with or not provided with a first protrusion (31).

4. The continuous flushing intestinal anastomosis metal stent system according to claim 1, characterized in that, The outer surface of the outer membrane (4) is smooth, the plurality of through holes (41) are arranged in a crisscross pattern, and the inner surface of the outer membrane (4) may or may not have a second protrusion (42), the second protrusion (42) being located between two adjacent through holes (41).

5. The continuous flushing intestinal anastomosis metal stent system according to claim 1, characterized in that, The drainage tube (5) enters through the interior of the bulge on one side of the metal bracket (1), passes through the bulge on one side and enters the space, and fits against the inner and / or outer surfaces of the metal bracket (1). The drainage tube (5) located in the space is arranged along the length of the entire groove.

6. The continuous flushing intestinal anastomosis metal stent system according to claim 1, characterized in that, The drainage tube (5) can be a single tube or two tubes.

7. The continuous flushing intestinal anastomosis metal stent system according to claim 6, characterized in that, The single drainage tube (5) is a suction tube. The suction tube located in the space is attached to the outer surface of the metal bracket (1). The lead end of the suction tube is connected to the external negative pressure equipment through the negative pressure suction connector. The tube wall of the suction tube is provided with multiple first side holes, which are used to connect the suction tube and the space.

8. The continuous flushing intestinal anastomosis metal stent system according to claim 6, characterized in that, The single drainage tube (5) is a dual-channel tube. The dual-channel tube located in the space is attached to the outer surface of the metal bracket (1). The interior of the dual-channel tube is provided with a suction channel and a water injection channel. The tube wall of the dual-channel tube is provided with multiple second side holes and multiple third side holes. The multiple second side holes are connected to the suction channel and the space, and the multiple third side holes are connected to the water injection channel and the space. The outlet end of the dual-channel tube is connected to a negative pressure suction connector and an air injection connector. The negative pressure suction connector is connected to the suction channel and to an external negative pressure device. The air injection connector is connected to the water injection channel and to an external water injection pipe.

9. The continuous flushing intestinal anastomosis metal stent system according to claim 6, characterized in that, The drainage tube (5) is a double tube, which includes a suction tube and a flushing tube. Both the suction tube and the flushing tube are single-channel tubes. The suction tube is connected to an external negative pressure device through a negative pressure suction connector. The flushing tube is connected to an external water injection pipe through an air injection connector. The suction tube has multiple fourth side holes on its wall. The multiple fourth side holes are used to connect the suction tube and the space. The flushing tube has multiple fifth side holes on its wall. The multiple fifth side holes are used to connect the flushing tube and the space. Inside the space, the suction tube is attached to the inner surface of the metal bracket (1), and the flushing tube is attached to the outer surface of the metal bracket (1). Alternatively, the suction tube may be attached to the outer surface of the metal support (1), and the flushing tube may be attached to the inner surface of the metal support (1); the suction tube and the flushing tube may be distributed on both sides of the diameter direction of the metal support (1); The flushing pipe is either straight or circular.

10. The continuous flushing intestinal anastomosis metal stent system according to claim 1, characterized in that, The stent release device includes an outer sheath (21) and a pusher (22). The pusher (22) is inserted into the interior of the outer sheath (21). Before release, the metal stent (1) is sleeved on the pusher (22) and located inside the outer sheath (21). The head end of the outer sheath (21) may or may not be covered by a silicone protective ring (23), and the tail end of the outer sheath (21) is provided with a first handle; The head end of the pusher (22) is tapered, and a limiting structure is provided on the tube wall of the pusher (22). Before the metal bracket (1) is released, it is sleeved between the tapered structure and the limiting structure. The tail end of the pusher (22) is provided with a second handle.

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