Adjustable wound flushing device

By designing an adjustable wound flushing device and using lifting components and sliding support plates to achieve automated wound flushing, the fatigue problem caused by manual operation of medical staff is solved, and efficient and comprehensive wound flushing effects are achieved.

CN120643777APending Publication Date: 2025-09-16THE FIRST AFFILIATED HOSPITAL OF ARMY MEDICAL UNIV
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Patent Information

Application Number
CN202511010002.3
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-07-22
Publication Date
2025-09-16

AI Technical Summary

Technical Problem

Existing wound irrigation equipment requires manual operation by medical staff, which causes fatigue and makes it difficult to collect the irrigation fluid. Especially for wounds on the limbs, patients need to support themselves or others, which affects the irrigation effect and efficiency.

Method used

An adjustable wound irrigation device is designed, which includes a lifting assembly, a slidingly connected support plate and an irrigation ring. A drive motor and a ball screw pair are used to realize the lifting and horizontal movement of the support plate and the irrigation ring. The sump collects the irrigation fluid, and the irrigation ring can be adjusted 360° to cover the wound.

Benefits of technology

It realizes automatic flushing without manual operation by medical staff, adapts to different limb lengths, and flushes 360° without dead angles, reducing fatigue of medical staff, improving flushing effect and collecting flushing fluid, thus reducing workload.

✦ Generated by Eureka AI based on patent content.

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Abstract

The invention belongs to the technical field of medical equipment, and particularly relates to an adjustable wound flushing device which comprises a left side plate, a right side plate, a first supporting plate, a second supporting plate and a lifting assembly, the first supporting plate and the second supporting plate are located between the left side plate and the right side plate, and the lifting assembly is used for driving the left side plate and the right side plate to synchronously ascend and descend. The flushing ring is communicated with a liquid inlet hose, a plurality of flushing nozzles are arranged on the inner side of the flushing ring along the circumference, a notch for a wrist joint to penetrate through is formed in the flushing ring, and a water collecting tank is arranged below the flushing ring; the left side plate and the right side plate are both horizontally and slidably connected with sliding blocks, the sliding blocks are fixedly connected with sliding sleeves, the flushing rings are arranged in the sliding sleeves, and the sliding sleeves are provided with slots for the flushing nozzles to pass through. A wounded limb is placed on the first supporting plate and the second supporting plate, the flushing nozzles on the flushing ring surround the wounded limb, and the flushing ring can translate and rotate around the wounded limb, so that 360-degree dead-corner-free flushing of a wound is realized, and the workload of medical staff is reduced.
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Description

Technical Field

[0001] The invention belongs to the technical field of medical equipment, and in particular relates to an adjustable wound flushing device. Background Art

[0002] Wound irrigation is the primary step in treating open wounds after trauma and is one of the most effective means of preventing wound infection. Wound irrigation effectively reduces the pathogenic microbial load within the wound by removing loosely attached cellular debris, pathogenic microorganisms, foreign matter, and wound exudate, thereby reducing the risk of wound infection and promoting wound healing. Currently, manual irrigation is the main method used in clinical practice for wound irrigation. However, manual irrigation is inconvenient and can easily cause the irrigation fluid to flow everywhere, making it difficult to collect the irrigation fluid and increasing the workload of medical staff. Furthermore, if the wound is located on the patient's limbs, the patient's limbs are not supported during irrigation, requiring the patient to lift the injured limb themselves or adjust the injured limb to a suitable position for irrigation with the help of medical staff. To prevent the patient's limbs from being suspended in the air, Chinese Utility Model Patent Publication No. CN214286133U discloses an orthopedic wound irrigation and care device, which is designed with a placement frame 23 for the injured limb to place, preventing the patient's affected limb from being suspended in the air and causing pain during irrigation. However, in this solution, medical staff still need to hold the electric nozzle 43 to flush the patient's wound. Long-term flushing will cause soreness in the hands of the medical staff; and when the wound is located on the lower surface of the affected limb, for example, the wound is located on the calf, the medical staff needs to bend over to check the wound and perform the flushing work in this posture, which makes the medical staff very tired. Summary of the Invention

[0003] The present invention aims to provide an adjustable wound flushing device to solve the problem that existing wound flushing equipment requires medical staff to flush the wound manually.

[0004] In order to achieve the above-mentioned purpose, the solution of the present invention is: an adjustable wound flushing device, comprising a left side plate, a right side plate, a first support plate and a second support plate located between the left side plate and the right side plate, and a lifting assembly for driving the left side plate and the right side plate to rise and fall synchronously, one end of the first support plate and the second support plate is connected to the left side plate, and the other end of the first support plate and the second support plate is connected to the right side plate, a flushing ring is provided between the first support plate and the second support plate, a liquid inlet hose is connected to the flushing ring, a plurality of flushing nozzles are provided along the circumference of the inner side of the flushing ring, a notch is provided on the flushing ring for the wrist joint to pass through, and a water collecting tank is provided below the flushing ring; a slider is horizontally slidably connected to the left side plate and a sliding sleeve is fixedly connected to the slider, the flushing ring is placed in the sliding sleeve, and a slot for the flushing nozzle to pass through is opened on the sliding sleeve.

[0005] The working principle and beneficial effects of this solution are:

[0006] (1) In this solution, the patient places the affected limb on the first support plate and the second support plate. During this process, the wrist of the affected limb enters the flushing ring through the notch on the flushing ring so that the flushing nozzle surrounds the affected limb. Since the slider is horizontally slidably connected to the left and right plates, the flushing ring can be moved horizontally to the vicinity of the wound, and the flushing liquid is sprayed through the flushing nozzle to flush the wound, without the need for medical staff to hold the flushing part to flush the wound. Moreover, even if the wound is located on the lower surface of the affected limb, the flushing nozzle located below the affected limb can flush the wound at that location. In addition, during the flushing process, the flushing ring can slide relative to the sleeve, that is, the flushing ring can rotate around the affected limb, thereby adjusting the position of the flushing ring notch relative to the affected limb, ensuring that the flushing liquid can flush the wound, achieving 360° flushing without dead angles, and improving the flushing effect.

[0007] (2) In this solution, a lifting assembly is used to achieve the lifting and lowering of the first support plate and the second support plate, thereby adjusting the placement height of the affected limb, which has high adaptability.

[0008] (3) The water collection tank in this solution can collect the flushing liquid to prevent it from flowing everywhere. In addition, the left and right panels can prevent the flushing liquid from splashing from the sides, reducing the cleaning work of medical staff.

[0009] Optionally, the left side plate and the right side plate both include a first slide plate and a second slide plate, the first slide plate and the second slide plate are horizontally slidably connected, the slider is horizontally slidably connected to the first slide plate and the second slide plate, the two ends of the first support plate are respectively connected to the two first slide plates, and the two ends of the second support plate are respectively connected to the two second slide plates.

[0010] In this solution, the first slide plate and the second slide plate can slide relative to each other, so that the length of the left plate and the right plate can be adjusted, and the distance between the first support plate and the second support plate can be adjusted, so that the part of the affected limb that is supported can be selected and can adapt to different limb lengths.

[0011] Optionally, the first slide is provided with a locking assembly for locking the first slide and the second slide.

[0012] In this solution, after the first slide plate and the second slide plate slide relative to each other, the locking assembly is used to lock the first slide plate and the second slide plate to prevent them from sliding relative to each other.

[0013] Optionally, the locking assembly includes an internal threaded barrel and a tightening screw, the tightening screw is threadedly connected to the internal threaded barrel, the internal threaded barrel is fixedly connected to the first slide, and the first slide is provided with a through hole for the tightening screw to pass through.

[0014] In this solution, the tightening screw is rotated to move the tightening screw in the axial direction, thereby tightening or disengaging from the second slide, thereby achieving locking or releasing of the first slide and the second slide.

[0015] Optionally, there are four groups of lifting assemblies, each group of lifting assemblies includes a ball screw pair I and a drive motor I for driving the screw of the ball screw pair I to rotate, and the nut of the ball screw pair I is connected to the corresponding first slide and second slide.

[0016] In this solution, the driving motor I and the ball screw pair I are used to realize the synchronous lifting and lowering of the first slide plate and the second slide plate without affecting the relative sliding movement of the first slide plate and the second slide plate.

[0017] Optionally, a horizontal driving assembly for driving the slider to slide horizontally is installed on the left plate and / or the right plate, and a sliding groove for the slider to slide horizontally is provided on the first slide plate and the second slide plate.

[0018] In this solution, a horizontal driving assembly is used to achieve horizontal reciprocating sliding of the slider, thereby driving the flushing ring to move horizontally back and forth, and then flushing the wound on the affected limb back and forth.

[0019] Optionally, the horizontal drive assembly includes a ball screw pair II and a drive motor II for driving the screw of the ball screw pair II to rotate, and the nut of the ball screw pair II is connected to the slider.

[0020] In this solution, the drive motor II and the ball screw pair II are used to realize the horizontal reciprocating sliding of the slider, thereby realizing the horizontal reciprocating movement of the flushing ring.

[0021] Optionally, a bottom plate is provided below the water collecting tank, and the driving motor I corresponding to the second slide plate is horizontally slidably connected to the bottom plate.

[0022] In this solution, during the sliding of the second slide relative to the first slide, the drive motor I corresponding to the second slide slides on the bottom plate, and the friction resistance is small, which makes it easier for medical staff to adjust the position of the second support plate.

[0023] Optionally, the first support plate and the second support plate each include an arc-shaped support portion and a horizontal portion, and the arc-shaped support portion and / or the horizontal portion are provided with a strip groove for the strap to pass through.

[0024] In this solution, a strap (to be called Velcro) is used to pass through the strip groove to fix the affected limb on the arc-shaped support part, so as to prevent the patient from unconsciously moving the affected limb due to pain during the flushing process, thereby ensuring a smooth flushing process.

[0025] Optionally, the water collecting trough is fixedly connected to the second slide plate, a mirror panel is hinged on the inner side wall of the water collecting trough, a mirror is provided on the mirror panel, and a pushing screw for pushing the mirror panel is threadedly connected on the side wall of the water collecting trough.

[0026] In this solution, the push screw is rotated to push the mirror panel, thereby adjusting the inclination angle of the mirror panel so that medical staff can observe the flushing of the wound on the lower surface of the affected limb through the mirror without lifting the affected limb for inspection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic structural diagram of an adjustable wound flushing device in Example 1 of the present invention;

[0028] Figure 2 This is a front view of an adjustable wound flushing device in Example 1 of the present invention;

[0029] Figure 3 This is a top view of an adjustable wound flushing device in Example 1 of the present invention;

[0030] Figure 4 It is a longitudinal cross-sectional view of the water collecting tank in the second embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following is further described in detail through specific implementation methods:

[0032] The marks in the drawings of the specification include: base plate 1, left side plate 2, right side plate 3, first slide plate 2301, second slide plate 2302, first support plate 4, second support plate 5, arc-shaped support part 4501, horizontal part 4502, lifting assembly 6, ball screw pair I 601, drive motor I 602, locking assembly 7, internal threaded cylinder 701, tightening screw 702, strip groove 8, flushing ring 9, liquid inlet hose 10, flushing nozzle 11, slider 12, slide groove 13, sliding sleeve 14, horizontal drive assembly 15, ball screw pair II 1501, drive motor II 1502, connecting part 16, limit sleeve I 17, limit sleeve II 18, water collection tank 19, drain hose 20, mirror panel 21, mirror 22, and push screw 23.

[0033] Example 1

[0034] This embodiment is basically as Figure 1 、 Figure 2 and Figure 3As shown: An adjustable wound flushing device includes a base plate 1, a left side plate 2, a right side plate 3, a first support plate 4 and a second support plate 5 located between the left side plate 2 and the right side plate 3, and a lifting assembly 6 for driving the left side plate 2 and the right side plate 3 to rise and fall synchronously. The left side plate 2 and the right side plate 3 each include a first slide plate 2301 and a second slide plate 2302, which are horizontally slidably connected to each other. The first slide plate 2301 is provided with a locking assembly 7 for locking the first slide plate 2301 and the second slide plate 2302. In this embodiment, the locking assembly 7 includes an internally threaded barrel 701 and a tightening screw 702. The tightening screw 702 is threadedly connected to the internally threaded barrel 701. The internally threaded barrel 701 is fixedly connected to the first slide plate 2301, and the first slide plate 2301 is provided with a through hole for the tightening screw 702 to pass through.

[0035] There are four sets of lifting assemblies 6. Each set of lifting assemblies 6 includes a ball screw pair I 601 and a drive motor I 602 for driving the screw of the ball screw pair I 601. The nut of the ball screw pair I 601 is fixedly connected to the corresponding first slide 2301 and second slide 2302. The drive motor I 602 corresponding to the two first slides 2301 is fixedly mounted on the base plate 1, and the drive motor I 602 corresponding to the two second slides 2302 is horizontally slidably connected to the base plate 1. To ensure the stable operation of the screw of the ball screw pair I 601, a frame can be set on the base plate 1, and a stabilizing sleeve (such as a bearing) can be provided on the frame to fix the top and bottom ends of the screw. In addition, in another embodiment, rollers are fixedly mounted on the bottom surface of the base plate 1 to facilitate the movement of the entire device.

[0036] One end of the first support plate 4 is fixedly connected to the first slide plate 2301 of the left side panel 2, and the other end of the first support plate 4 is fixedly connected to the first slide plate 2301 of the right side panel 3. One end of the second support plate 5 is fixedly connected to the second slide plate 2302 of the left side panel 2, and the other end of the second support plate 5 is fixedly connected to the second slide plate 2302 of the right side panel 3. The first support plate 4 and the second support plate 5 each include an arcuate support portion 4501 and a horizontal portion 4502, each of which is provided with a strip groove 8 for the strap to pass through.

[0037] A flushing ring 9 is provided between the first support plate 4 and the second support plate 5. A liquid inlet hose 10 is connected to the flushing ring 9. Several flushing nozzles 11 are arranged along the inner circumference of the flushing ring 9. The flushing ring 9 also has a notch for the wrist joint to pass through. Sliders 12 are connected to both the left and right plates 2 and 3 for horizontal sliding. Specifically, the first and second slides 2301 and 2302 each have a groove 13 for the horizontal sliding of the sliders 12. A sleeve 14 is fixedly connected to the slider 12. The curvature of the sleeve 14 matches that of the flushing ring 9. The flushing ring 9 is placed within the sleeve 14, which has a slot for the flushing nozzles 11 to pass through. This allows the flushing ring 9 to slide relative to the sleeve 14. A horizontal drive assembly 15 for driving the slider 12 to slide horizontally is mounted on the right side plate 3. The horizontal drive assembly 15 includes a ball screw pair II 1501 and a drive motor II 1502 for driving the screw of the ball screw pair II 1501. The nut of the ball screw pair II 1501 is fixedly connected to the slider 12 via a connector 16. Furthermore, to ensure stable operation of the screw of the ball screw pair II 1501, a limit sleeve I 17 is fixedly mounted on the first slide plate 2301 of the right side plate 3, and a limit sleeve II 18 is fixedly mounted on the second slide plate 2302 of the right side plate 3. Both the limit sleeve I 17 and the limit sleeve II 18 have limit holes for the screw of the ball screw pair II 1501 to pass through.

[0038] A water collection trough 19 is provided below the flushing ring 9, the bottom of which is connected to a drain hose 20. Furthermore, in this embodiment, the top of the left side wall of the water collection trough 19 is fixedly connected to the second slide 2302 of the left side panel 2, and the top of the right side wall of the water collection trough 19 is fixedly connected to the second slide 2302 of the right side panel 3.

[0039] During use, the height of the first and second support plates 4, 5 is adjusted based on the patient's condition. Specifically, the drive motor I 602 is activated, driving the screw of the ball screw assembly I 601, thereby causing the nut of the ball screw assembly I 601 to rise and fall, thereby simultaneously driving the left and right plates 2, 3 to rise and fall. When the first and second support plates 4, 5 are at the appropriate height, the drive motor I 602 is deactivated. The spacing between the first and second support plates 4, 5 is then adjusted based on the length of the affected limb. Specifically, the second slide plate 2302 is pushed left or right, causing the drive motor I 602 corresponding to the second slide plate 2302 to slide horizontally on the base plate 1. Once the spacing between the first and second support plates 4, 5 is adjusted, the medical professional rotates the locking screw 702, causing the end of the locking screw 702 to abut against the second slide plate 2302, thereby locking the first and second slide plates 2301, 2302, and preventing relative sliding between them.

[0040] The patient then places the injured limb on the curved support portion 4501 of the first and second support plates 4, 5. A healthcare professional secures the injured limb to the first and second support plates 4, 5, using a strap through the strip groove 8. During placement, the wrist (or ankle) of the injured limb passes through the notch in the irrigation ring 9, allowing the limb to enter the irrigation ring 9, where the irrigation nozzles 11 surround the limb. The entire device is movable. To properly support the injured limb, the healthcare professional can move the base plate 1, thereby moving the entire device relative to the patient, allowing the irrigation ring 9 to be moved closer to the wound on the affected limb.

[0041] Next, the medical staff determines the irrigation range based on factors such as the location of the wound and the area of ​​the wound, and adjusts the notch on the irrigation ring 9 according to the irrigation range so that the notch is away from the wound. Specifically, the medical staff pinches the irrigation ring 9 and applies force to it, so that the irrigation ring 9 rotates around the affected limb until the notch is away from the wound.

[0042] The flushing liquid enters the flushing ring 9 through the liquid inlet hose 10 and is then sprayed toward the affected limb through the flushing nozzle 11. Simultaneously, the drive motor II 1502 is activated, driving the screw of the ball screw pair II 1501 to rotate. The nut of the ball screw pair II 1501 drives the slider 12 to slide horizontally, thereby driving the flushing ring 9 to move horizontally to the wound site to flush the wound. Furthermore, when the wound area is large, the flushing ring 9 is driven by the drive motor II 1502 to move back and forth horizontally, and the flushing range covers the entire wound area. Furthermore, during the flushing process, medical staff can apply force to the flushing ring 9 to rotate it around the affected limb, thereby adjusting the position of the flushing nozzle 11 on the flushing ring 9 relative to the affected limb, thereby achieving 360° flushing without blind spots and achieving better flushing results.

[0043] During the flushing process, the flushing liquid is collected in the sump 19 and discharged through the drain hose 20. Furthermore, the left and right panels 2 and 3 prevent the flushing liquid from splashing out from the sides. The flushing liquid droplets blocked by the left and right panels 2 and 3 flow into the sump 19 under the action of gravity. After the flushing is completed, the flushing ring 9 is moved to the wrist of the affected limb, the straps securing the affected limb are released, and the patient can remove the affected limb.

[0044] To sum up, in this embodiment, the position of the second support plate 5 is adjustable, the position of the flushing ring 9 is adjustable, and the flushing ring 9 can rotate around the affected limb (the circumferential position of the flushing nozzle 11 relative to the affected limb is adjustable), so that the device can adapt to affected limbs of different lengths, and perform 360° no-dead-angle flushing on the wound on the affected limb, as well as flushing the wound back and forth, with a good flushing effect.

[0045] Example 2

[0046] The difference between this embodiment and the first embodiment is that: Figure 4As shown, in this embodiment, a mirror panel 21 is hingedly connected to the inner wall of the water collection tank 19, and a mirror 22 is bonded to the mirror panel 21. A push screw 23 for pushing the mirror panel 21 is threadedly connected to the side wall of the water collection tank 19. When the wound is located on the lower surface of the affected limb, there is often no way to observe the wound during the flushing process. Therefore, in this embodiment, after the affected limb is fixed to the first support plate 4 and the second support plate 5, the medical staff rotates the push screw 23 so that the push screw 23 pushes the mirror panel 21 to flip relative to the side wall of the water collection tank 19, changing the inclination angle of the mirror panel 21 until the medical staff can observe the wound through the mirror 22. In this way, during the flushing process, the spraying of the flushing liquid can be suspended so that the medical staff can observe the flushing status of the wound through the mirror 22, without having to lift the affected limb to observe the wound.

[0047] The above are only embodiments of the present invention. The invention is not limited to the fields involved in this implementation case. Common knowledge such as the known specific structures and characteristics in the scheme is not described in detail here. Ordinary technicians in the relevant field are aware of all the common technical knowledge in the technical field to which the invention belongs before the application date or priority date, can obtain all the existing technologies in the field, and have the ability to apply conventional experimental means before that date. Ordinary technicians in the relevant field can improve and implement this scheme in combination with their own abilities under the inspiration given by this application. Some typical known structures or known methods should not become obstacles for ordinary technicians in the relevant field to implement this application. It should be pointed out that for those skilled in the art, without departing from the structure of the present invention, several variations and improvements can be made, which should also be regarded as the scope of protection of the present invention. These will not affect the effect of the implementation of the present invention and the practicality of the present invention. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. An adjustable wound flushing device, characterized by: It includes a left side plate, a right side plate, a first support plate and a second support plate located between the left side plate and the right side plate, and a lifting assembly for driving the left side plate and the right side plate to rise and fall synchronously, one end of the first support plate and the second support plate is connected to the left side plate, and the other end of the first support plate and the second support plate is connected to the right side plate, a flushing ring is provided between the first support plate and the second support plate, a liquid inlet hose is connected to the flushing ring, a plurality of flushing nozzles are provided along the circumference of the inner side of the flushing ring, a notch is provided on the flushing ring for the wrist joint to pass through, and a water collecting tank is provided under the flushing ring; sliders are horizontally slidably connected to the left side plate and a sliding sleeve is fixedly connected to the slider, the flushing ring is placed in the sliding sleeve, and a slot for the flushing nozzle to pass through is provided on the sliding sleeve.

2. The adjustable wound irrigation device according to claim 1, characterized in that: The left side plate and the right side plate each include a first slide plate and a second slide plate, the first slide plate and the second slide plate are horizontally slidably connected, the slider is horizontally slidably connected to the first slide plate and the second slide plate, the two ends of the first support plate are respectively connected to the two first slide plates, and the two ends of the second support plate are respectively connected to the two second slide plates.

3. The adjustable wound irrigation device according to claim 2, characterized in that: The first slide plate is provided with a locking assembly for locking the first slide plate and the second slide plate.

4. The adjustable wound irrigation device according to claim 3, characterized in that: The locking assembly includes an internal threaded barrel and a tightening screw, the tightening screw is threadedly connected to the internal threaded barrel, the internal threaded barrel is fixedly connected to the first slide, and the first slide is provided with a through hole for the tightening screw to pass through.

5. The adjustable wound irrigation device according to claim 2 or 3, characterized in that: There are four groups of lifting assemblies, each group of lifting assemblies includes a ball screw pair I and a drive motor I for driving the screw of the ball screw pair I to rotate, and the nut of the ball screw pair I is connected to the corresponding first slide and second slide.

6. The adjustable wound irrigation device according to claim 2 or 3, characterized in that: The left plate and / or the right plate are provided with a horizontal driving assembly for driving the slider to slide horizontally, and the first slide plate and the second slide plate are both provided with a sliding groove for the slider to slide horizontally.

7. The adjustable wound irrigation device according to claim 6, characterized in that: The horizontal drive assembly includes a ball screw pair II and a drive motor II for driving the screw of the ball screw pair II to rotate. The nut of the ball screw pair II is connected to the slider.

8. The adjustable wound irrigation device according to claim 5, characterized in that: A bottom plate is provided below the water collecting tank, and a driving motor I corresponding to the second slide plate is horizontally slidably connected to the bottom plate.

9. The adjustable wound irrigation device according to claim 1, characterized in that: The first support plate and the second support plate each include an arc-shaped support portion and a horizontal portion, and the arc-shaped support portion and / or the horizontal portion are provided with a strip groove for the strap to pass through.

10. The adjustable wound irrigation device according to claim 2, characterized in that: The water collecting trough is fixedly connected to the second slide plate, a mirror panel is hinged on the inner side wall of the water collecting trough, a mirror is provided on the mirror panel, and a pushing screw for pushing the mirror panel is threadedly connected on the side wall of the water collecting trough.

Citation Information

Patent Citations

  • Orthopedic wound flushing and nursing device

    CN214286133U

  • Pulse flusher with positioning function

    CN116236637A

  • Multifunctional debridement nursing frame for operating room

    CN213190832U

  • Multifunctional bed dressing change frame for dressing change of affected limb

    CN215081300U