Anti-reflux ostomy bag

Abstract

The present application provides an anti-reflux stoma bag, and relates to the field of medical devices, which comprises a bottom disc, a stoma bag body and a one-way drainage valve bag, the stoma bag is provided with an opening matched with the bottom disc, the bottom disc is buckled at the opening of the stoma bag body; the opening of the stoma bag body is also sealingly connected with a barrier film; the first end of the one-way drainage valve bag is sealingly connected with the stoma, the second end of the one-way drainage valve bag penetrates into the barrier film and extends into the inner cavity of the stoma bag body after being sealingly connected with the barrier film, and the second end of the one-way drainage valve bag is connected with an open first flat adhesive body. The present application can avoid the fecal water refluxing to the intestinal tract at the stoma of the skin, prevent the fecal water from overflowing, avoid the skin from being red and swollen and ulcerated due to the corrosion of the fecal water, reduce the processing time for replacing the stoma bag, block the fecal water and its odor in the stoma bag, prolong the service life of the stoma bag, reduce the medical cost and the cost of the patient, ensure that the clothes, bedding and the like are not polluted by the fecal water, improve the life quality of the patient and reduce the incidence of stoma complications.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an anti-reflux ostomy bag. Background Technology

[0002] Enterostomies are frequently required during colorectal surgery. Common types include terminal ileostomy, transverse colostomy, descending colostomy, and sigmoid colostomy. Currently, the main type of stoma is the prolapsed stoma. Due to incomplete recovery of bowel function and the patient's liquid diet, postoperative stools from the stoma site are primarily watery. In terminal ileostomies, the lack of water-concentrating properties from the colon prevents stool formation, resulting in consistently watery stools postoperatively. Currently, the collection and drainage of excretion around the stoma mainly relies on ostomy bags. However, the following problems frequently arise when using ostomy bags: 1. When changing the ostomy bag, fecal water soaks the area around the stoma and the skin for a long time, causing fecal residue to accumulate around the stoma. Cleaning the area around the stoma during the change can easily cause skin damage and increase the treatment time. 2. The ostomy bag base plate often fails to adhere properly, resulting in leakage of fecal matter. The leaked fecal matter can corrode the surrounding skin and cause complications. The leaked fecal matter can also stain clothing, bedding, etc., causing great inconvenience to the patient's life. 3. When changing the ostomy bag, the fecal water has a strong pungent odor, which reduces the patient's postoperative quality of life and increases the psychological burden on the patient and their family. Summary of the Invention

[0003] This invention proposes an anti-reflux ostomy bag that can prevent fecal water from flowing back to the stoma skin, prevent fecal water from overflowing, reduce the processing time for changing the ostomy bag, and block the odor of fecal water inside the ostomy bag; ensuring that the stoma, the skin around the stoma, clothing, bedding, etc. are not contaminated by fecal water, and reducing the incidence of complications.

[0004] This invention provides an anti-reflux ostomy bag, comprising a base, an ostomy bag body, and a one-way drainage valve bag. The ostomy bag has an opening adapted to the base, and the base is fastened to the opening of the ostomy bag body. A barrier membrane is also sealed to the opening of the ostomy bag body. The first end of the one-way drainage valve bag is sealed to the ostomy opening, and the second end of the one-way drainage valve bag extends into the cavity of the ostomy bag body after passing through the barrier membrane and being sealed to the barrier membrane. The second end of the one-way drainage valve bag is connected to a first flat gel with an opening.

[0005] In an optional embodiment, the first end of the one-way drainage valve bag is surrounded by an inflatable elastic cavity, and the inflatable elastic cavity is provided with an inflation valve.

[0006] In an optional embodiment, the first end of the one-way drainage valve bag is provided with a hollow annular tightening membrane, and a tightening line runs through the hollow annular tightening membrane.

[0007] In an optional embodiment, the tightening thread is a cotton thread or an aluminum core thread.

[0008] In an optional embodiment, the barrier film is a polyethylene elastic film, and the barrier film is fixedly connected to the one-way drainage valve bag.

[0009] In an optional embodiment, the lower part of the barrier membrane has an opening, and the one-way drainage valve bag is fixedly connected to the opening and extends obliquely downward into the ostomy bag body so that the drainage direction is downward.

[0010] In an optional embodiment, the inflation valve includes an outer tube, a valve core fitted inside the outer tube, a cap, a spring, and a washer; a retaining ring is fixed in the middle of the valve core, the spring is fitted below the retaining ring on the valve core, and the washer is fitted above the retaining ring on the valve core; the valve core is triangular prism-shaped above the retaining ring, and the cap covers the top of the valve core at a predetermined distance from the washer; a boss is provided on the inner wall of the outer tube, and the outer diameter of the washer is larger than the inner diameter of the boss to ensure a sealed connection between the valve core and the outer tube; wherein the top of the cap is semi-open and semi-closed.

[0011] In an optional embodiment, a one-way flushing valve is provided on the ostomy bag body, and the one-way flushing valve is inserted into a second flat gel with an open end inside the ostomy bag body.

[0012] In an optional embodiment, the one-way drainage valve bag is further provided with an inner one-way valve.

[0013] In an optional embodiment, the chassis includes an adhesive film and a ring buckle, the adhesive film being fixedly connected to the ring buckle; the ring buckle is provided with a hook to hang the chassis on the stoma abdominal binder; the stoma bag body is also provided with a gas filter.

[0014] The beneficial effects of this invention are as follows: The anti-reflux ostomy bag of this invention has a barrier membrane sealed at the opening of the ostomy bag body, and a one-way drainage valve bag is also sealed on the barrier membrane; the first end of the one-way drainage valve bag is sealed to the stoma, and the second end extends into the inner cavity of the ostomy bag body. The one-way drainage valve bag is used to drain fecal matter from the stoma into the ostomy bag body; since the second end of the one-way drainage valve bag is an open, flat colloid, it can prevent fecal matter in the ostomy bag body from flowing back to the stoma, thus avoiding contamination of the stoma and the skin around the stoma; at the same time, since the barrier membrane is connected to both the one-way drainage valve and the opening of the ostomy bag body... The sealed connection further prevents fecal matter from flowing into the ostomy bag body, preventing leakage. This invention avoids fecal matter reflux into the intestines at the stoma site on the skin, preventing leakage and skin redness, swelling, and ulceration due to fecal matter corrosion. It reduces the processing time for changing the ostomy bag, trapping fecal matter and its odor inside the bag. It increases the adhesion time between the ostomy bag base and the skin, extending the lifespan of the ostomy bag and reducing medical costs and patient expenses. It ensures that the stoma, surrounding skin, clothing, bedding, etc., are not contaminated by fecal matter, improving the patient's quality of life and reducing the incidence of stoma complications.

[0015] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained in accordance with the structures particularly pointed out in the description, claims and drawings.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the rear structure of the present invention; Figure 2 This is a front view of the present invention. Figure 3 This is a schematic diagram of the chassis structure of the present invention; Figure 4 This is a schematic diagram of the inflation valve of the present invention; Figure 5 This is a schematic diagram of the structure of the cap and valve core of the present invention; Figure 6This is a schematic diagram of the one-way flushing valve of the present invention; Figure 7 This is a schematic diagram of the structure of the end of the one-way drainage valve bag of the present invention.

[0019] In the diagram: 1—Ostomy bag body; 2—Base plate; 21—Hanging ring; 22—Fixing ring; 23—Adhesive film; 24—Ring buckle; 3—One-way drainage valve bag; 31—Inflatable elastic cavity; 32—Hollow ring tightening film; 33—Inflating valve; 331—Outer tube; 332—Valve core; 333—Cap; 334—Retaining ring; 335—Washer; 336—Spring; 337—Boss; 34—First flat gel; 4—Barrier film; 5—One-way flushing valve; 51—Tube cap; 52—Tube body; 53—Second flat gel; 61—Hook and loop fastener; 62—Hook and loop fastener. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To facilitate understanding of this embodiment, the following detailed description of an anti-reflux ostomy bag disclosed in this invention will be provided through embodiments.

[0022] Reference Figure 1 This invention provides an anti-reflux ostomy bag, including a base plate 2, an ostomy bag body 1, and a one-way drainage valve bag 3. The ostomy bag has an opening adapted to the base plate 2, and the base plate 2 is fastened to the opening of the ostomy bag body 1. A barrier membrane 4 is also sealed to the opening of the ostomy bag body 1. The first end of the one-way drainage valve bag 3 is sealed to the ostomy opening, and the second end of the one-way drainage valve bag 3 passes through the barrier membrane 4 and is sealed to the barrier membrane 4 before extending into the inner cavity of the ostomy bag body 1. The second end of the one-way drainage valve bag 3 is connected to a first flat gel 34 with an opening.

[0023] Specifically, the anti-reflux ostomy bag in this embodiment is a two-piece design, with the base plate 2 separate from the ostomy bag body 1; the base plate 2 is generally circular, and the opening is provided with a fixing ring 22 that is adapted to the base plate 2; in use, the base plate 2 is pasted onto the skin around the stoma, and then the fixing ring 22 is fastened to the base plate 2.

[0024] The barrier membrane 4 is sealed to the opening, such as... Figure 2 As shown (it should be noted that, Figure 2The dotted lines in the front structural diagram represent the internal structure of the ostomy bag body 1 as seen from the front (this does not indicate that the structure shown in the dotted lines is installed on the front of the ostomy bag body 1). The diaphragm 4 is annular, with a diameter larger than the fixing ring 22, to seal the fixing ring 22 installed on the ostomy bag body 1. An opening is provided below the diaphragm 4, and the second end of the one-way drainage valve bag 3 extends into the inner cavity of the ostomy body 1 through the opening below the diaphragm 4. At the same time, the connection between the one-way drainage valve and the diaphragm 4 is sealed to prevent fecal matter from overflowing from the connection.

[0025] The first end of the one-way drainage valve bag 3 is sealed to the stoma, draining fecal matter from the stoma into the stoma bag body 1; the second end of the one-way drainage valve bag 3 has an opening to allow fecal matter to flow into the stoma bag body 1. Specifically... Figure 7 As shown, a first flat colloid 34 is provided at the second end of the one-way drainage valve bag 3 at a distance of about 1 cm from the barrier membrane. Figure 7 The dashed line in the middle marks the boundary between the first flat silicone body 34 and the one-way drainage valve bag 3. The first flat silicone body 34 has a flat shape with upper and lower sheets. Since the one-way drainage valve bag 3 is a polyurethane elastic film, its thickness is relatively thin, while the first flat silicone body 34 is relatively thick. The first flat silicone body 34 can be made of PVC, PP, rubber, or silicone materials.

[0026] The flattened first flat colloid 34 ensures that fecal matter can flow into the ostomy bag body 1 while preventing fecal matter in the ostomy bag body 1 from flowing back into the stoma, thus enhancing the anti-reflux effect.

[0027] Here, the barrier membrane 4, the sealing connection structure between the barrier membrane 4 and the opening of the one-way drainage valve bag 3, and the opening of the first flat colloid 34 of the one-way drainage valve bag 3 together play an anti-backflow role, preventing fecal water from flowing back. Even if the base plate 2 is not firmly attached, fecal water will not overflow from the ostomy bag body 1 due to the barrier membrane 4. This embodiment helps to keep the stoma and its surrounding area clean, prevents fecal water from contaminating clothing, reduces the risk of fecal water overflow corroding the skin around the stoma, and avoids complications caused by fecal water overflow. At the same time, this utility model can also be applied to the collection and anti-backflow application of drainage fluids such as drainage tubes, preventing pollution and corrosion caused by drainage fluids.

[0028] Preferably, the first end of the one-way drainage valve bag 3 is surrounded by an inflatable elastic cavity 31, and an inflation valve 33 is provided on the inflatable elastic cavity 31.

[0029] Here, the inflatable elastic cavity 31 is a hollow structure composed of two layers of polyurethane elastic film. The film made of polyurethane-based materials is soft, transparent, and elastic, making it an excellent material for preparing medical dressings. A one-way inflation valve 33 is provided on the outer surface of the inflatable elastic cavity 31. In use, the one-way inflation valve 33 is aligned with the stoma and wrapped around it; air is injected into the inflatable elastic cavity 31 through the one-way inflation valve 33, causing it to expand and tightly wrap around the stoma, thus effectively preventing fecal matter from overflowing from the stoma. Because it expands and wraps around the stoma through inflation, it will not damage the stoma, making it highly practical.

[0030] In this embodiment, the inflation valve 33 is a compression type inflation valve 33, which has an internal spring 336. Gas is injected using a syringe; after the syringe is removed, the spring 336 rebounds, and the gas cannot be expelled on its own. In addition, pressing down on the spring 336 with the syringe can also extract the gas.

[0031] Preferably, the first end of the one-way drainage valve bag 3 is provided with a hollow annular tightening membrane 32, and a tightening line runs through the hollow annular tightening membrane 32.

[0032] Furthermore, the tightening thread is made of cotton thread or aluminum core thread.

[0033] Here, as Figure 1 As shown, a hollow annular tightening membrane 32 is connected to the front end of the inflatable elastic cavity 31. Tightening is achieved via a tightening thread, allowing for tightening near the skin after stoma prolapse to restrict fecal leakage. When using cotton thread as the tightening thread, both ends of the thread can be threaded through the hollow cavity of the annular tightening membrane 32 and tightened by binding the ends. When using aluminum core wire as the tightening thread, the aluminum core wire can be designed as a closed annular structure; it can be tightened by hand during wear.

[0034] It should be noted that the inflatable elastic cavity 31 and the hollow annular tightening membrane 32 are set independently. In specific implementation, the hollow annular tightening membrane 32 is set at the top of the one-way drainage valve bag 3, that is, at the front end of the inflatable elastic cavity 31.

[0035] In addition, the tightening thread can also be set as an elastic stretch ring and attached to the skin around the stoma.

[0036] Preferably, the barrier membrane 4 is a polyethylene elastic membrane, and the barrier membrane 4 is fixedly connected to the one-way drainage valve bag 3.

[0037] Here, the barrier membrane 4 is made of elastic polyethylene material, and the one-way drainage valve bag 3 is fixedly connected to the barrier membrane 4. This fixed structure allows the relatively soft and elastic barrier membrane 4 to keep the one-way drainage valve bag 3 in an expanded state at the point where it enters the barrier membrane 4. At the same time, due to the fixed structure, it can avoid pulling on the stoma.

[0038] Optionally, the lower part of the barrier membrane 4 has an opening, and the one-way drainage valve bag 3 is fixedly connected to the opening and extends obliquely downward into the ostomy bag body 1 so that the drainage direction is downward.

[0039] Here, the one-way drainage valve bag 3 is fixedly connected to the opening of the barrier membrane 4, and the one-way drainage valve bag 3 is inserted obliquely downward into the ostomy bag body 1. This ensures that the drainage direction of the fecal water is downward, further draining the fecal water to a lower position, which is conducive to the smooth entry of the fecal water into the ostomy bag body 1.

[0040] Furthermore, the inflation valve 33 includes an outer tube 331, a valve core 332 fitted inside the outer tube 331, a cap 333, a spring 336, and a washer 335; a retaining ring 334 is fixed in the middle of the valve core 332, the spring 336 is fitted below the retaining ring 334 on the valve core 332, and the washer 335 is fitted above the retaining ring 334 on the valve core 332; the upper part of the valve core 332 is triangular prism-shaped, and the cap 333 covers the top of the valve core 332 and is a predetermined distance away from the washer 335; a boss 337 is provided on the inner wall of the outer tube 331, and the outer diameter of the washer 335 is larger than the inner diameter of the boss 337 so that the valve core 332 and the outer tube 331 are sealed together; wherein, the top of the cap 333 is semi-open and semi-closed.

[0041] Specifically, such as Figure 4 As shown, the valve core 332, cap 333, spring 336, and washer 335 are all located inside the outer tube 331, and the outer tube 331 is sealed to the ostomy bag body 1. Figure 5 As shown, the valve core 332 is a triangular prism, and the cap 333 is a hollow cylinder. The cap 333 covers the top of the valve core 332, and the lower edge of the cap 333 is a preset distance from the washer 335. This allows airflow to flow in through the gap between the cap 333 and the valve core 332 during inflation.

[0042] The washer 335 is a colloid with a certain degree of elasticity, such as a rubber ring or a latex ring. A boss 337 is provided on the inner wall of the outer tube 331. In the initial state, the spring 336 is in the relaxed state, and the washer 335 contacts the boss 337 to block airflow. When the cap 333 is pressed down, the spring 336 is compressed, and a gap appears between the washer 335 and the boss 337. The airflow from between the cap 333 and the valve core 332 flows into the inflatable elastic cavity 31 through this gap.

[0043] In use, use a syringe to inject airflow through the cap 333. The cap 333 is set to be half closed and half open to ensure the airtightness of the inflation valve 33 when airflow is injected.

[0044] Optionally, a one-way flushing valve 5 is provided on the ostomy bag body 1, and the one-way flushing valve 5 is inserted into a second flat gel 53 with one end open inside the ostomy bag body 1.

[0045] Here, as Figure 6 As shown, the one-way flushing valve 5 includes a cap 51, a tube body 52, and a gel. The first end of the second flat gel 53 is connected to the tube body 52, and the second end is flattened. The second end of the second flat gel 53 is located inside the ostomy bag body 1. Here, the cap 51, tube body 52, and gel can all be made of PVC, PP, rubber, or silicone. The cap 51 is used to seal the one-way flushing valve 5, and the flattened structure of the second flat gel 53 prevents fecal matter from flowing back from inside the second flat gel 53 to outside the ostomy bag.

[0046] In this embodiment, the one-way flushing valve 5 can be positioned above the ostomy bag body 1. It has a simple structure and low cost, and can flush fecal matter inside the ostomy bag body 1 without causing it to overflow. This keeps the ostomy bag clean and increases its lifespan. Furthermore, because the one-way flushing valve 5 has an open end (the second flat colloid 53) that penetrates into the ostomy bag body 1, it prevents fecal matter from flowing out.

[0047] Preferably, the one-way drainage valve bag 3 is also provided with an inner cavity one-way valve.

[0048] In this embodiment, an inner cavity check valve is also provided inside the one-way drainage valve bag 3, such as at the junction of the one-way drainage valve bag 3 and the barrier membrane 4. The provision of this inner cavity check valve can further enhance the anti-backflow effect.

[0049] Furthermore, the chassis 2 includes an adhesive film 23 and a ring buckle 24, with the adhesive film 23 and the ring buckle 24 fixedly connected; the ring buckle 24 is provided with a hook to hang the chassis 2 on the stoma abdominal binder; the ostomy bag body 1 is also provided with a gas filter.

[0050] Specifically, such as Figure 3 As shown, the base 2 is provided with an adhesive film 23, on which a release sticker is applied. In use, the release sticker is peeled off, and the base 2 is fixed to the skin around the stoma. A ring-shaped buckle 24 is fixed to the adhesive film. The ring-shaped buckle 24 is used to fasten the base 2 to the fixing ring 22 located at the opening of the stoma bag body 1. Hooks are fixed on both sides of the ring opening. The size of the hooks matches the hanging ring 21 on the stoma abdominal binder, so that the stoma bag body 1 can be hung on the stoma abdominal binder.

[0051] This embodiment increases the support for the chassis 2 by setting hooks, allowing the chassis 2 to be hung on the stoma abdominal binder, further increasing the adhesion and usage time of the chassis 2, reducing medical costs, and at the same time, the use of the stoma abdominal binder can delay the onset of parastomal hernia.

[0052] like Figure 2As shown, in this embodiment, the gas filter can be disposed on the upper front of the ostomy bag body 1. This embodiment filters gas by providing a gas filter.

[0053] Additionally, a Velcro closure is located at the bottom of the ostomy bag body 1, which can be folded back and fastened when not in use for the patient's convenience. Figure 1 As shown, the Velcro side 61 is located near the ostomy bag's wastewater outlet and can be rolled up and folded when not in use. Figure 2 The hook and loop fasteners on the middle side (62) are used for attaching and curling for secure fastening.

[0054] In practice, the barrier membrane 4 and the one-way drainage valve bag 3 can be an integral structure, and the barrier membrane 4 and the ostomy bag body 1 can also be set as an integral structure.

[0055] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0056] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An anti-reflux ostomy bag, characterized in that, The device includes a base, an ostomy bag body, and a one-way drainage valve bag. The ostomy bag has an opening adapted to the base, and the base is fastened to the opening of the ostomy bag body. A barrier membrane is also sealed to the opening of the ostomy bag body. The first end of the one-way drainage valve bag is sealed to the stoma, and the second end of the one-way drainage valve bag passes through the barrier membrane and is sealed to it before extending into the inner cavity of the ostomy bag body. The second end of the one-way drainage valve bag is connected to an open first flat gel. An inflatable elastic cavity surrounds the first end of the one-way drainage valve bag, and an inflation valve is provided on the inflatable elastic cavity. The inflation valve includes an outer tube, a valve core fitted inside the outer tube, a cap, a spring, and a washer. A valve core is fixed in the middle. A retaining ring is provided, with the spring sleeved below the retaining ring on the valve core and the washer sleeved above the retaining ring on the valve core. The valve core is triangular prism-shaped at the upper part of the retaining ring, and a cap covers the top of the valve core at a predetermined distance from the washer. A boss is provided on the inner wall of the outer tube, and the outer diameter of the washer is larger than the inner diameter of the boss to ensure a sealed connection between the valve core and the outer tube. The top of the cap is semi-open and semi-closed. A hollow annular tightening membrane is provided at the first end of the one-way drainage valve bag, and a tightening line runs through the hollow annular tightening membrane. The tightening line is made of cotton thread or aluminum core thread. A one-way flushing valve is provided on the ostomy bag body, and the end of the one-way flushing valve that enters the ostomy bag body is an open second flat gel.

2. The anti-reflux ostomy bag according to claim 1, characterized in that, The barrier membrane is a polyethylene elastic membrane, and the barrier membrane is fixedly connected to the one-way drainage valve bag.

3. The anti-reflux ostomy bag according to claim 1, characterized in that, The lower part of the barrier membrane has an opening, and the one-way drainage valve bag is fixedly connected to the opening and extends obliquely downward into the ostomy bag body so that the drainage direction is downward.

4. The anti-reflux ostomy bag according to claim 1, characterized in that, The one-way drainage valve bag is also equipped with an inner cavity one-way valve.

5. The anti-reflux ostomy bag according to claim 1, characterized in that, The chassis includes an adhesive film and a ring buckle, the adhesive film being fixedly connected to the ring buckle; the ring buckle is provided with a hook to hang the chassis on the stoma abdominal binder; the stoma bag body is also provided with a gas filter.

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