HK1131878A - A medical dressing - Google Patents

Description

Medical dressing

Technical Field

The present invention relates to a medical dressing, particularly, but not exclusively, to a medical dressing for treating open chest wounds and other similar injuries.

Background

An open pneumothorax occurs when air is able to enter the chest cavity surrounding the lungs through an open chest wound, such as that resulting from being punctured or shot. Allowing air to enter the chest cavity through the wound in this manner inhibits the breathing process and can therefore be life threatening.

The standard treatment for open pneumothorax is to cover the wound with an occlusive dressing that is adhered to the patient's skin along all four sides to seal the wound and prevent air from entering the chest cavity through the wound. If the wound is effectively sealed, normal breathing can be resumed. However, if the seal is not perfect, more air will be drawn and trapped in the chest cavity, resulting in an increase in the pressure inside the chest cavity. This is known as a tension pneumothorax and is a potentially more severe condition that can rapidly lead to respiratory and heart failure.

Tension pneumothorax also occurs if the patient suffers a lung perforation, as air can escape through the perforation into the chest cavity each time the patient breathes. If the open chest wound is sealed, air entering the chest cavity through the lung puncture is trapped and the pressure inside the chest cavity rises, forcing the lungs to collapse. Once the lungs collapse, the pressure in the chest cavity will increase further so that the collapsed lungs are pressed against the heart and the other lung. If the pressure in the chest cavity increases above normal blood pressure, blood flow from the heart to the lungs may be stopped.

The treatment of a tension pneumothorax with an open wound typically involves the use of an occlusive dressing that is adhered along only three sides so that pressurized air in the pneumothorax can escape through the open sides. However, the conditions that typically address such wounds first make successful application of this type of dressing difficult to achieve in practice.

Patients with open chest wounds will often suffer hemothorax or chest bleeding. The accumulation of blood in the chest cavity inhibits normal lung expansion so that less air is inhaled and the oxygen content of the blood is reduced. Hemothorax is often treated by inserting a chest catheter through a wound and removing blood from the chest cavity through the catheter using suction. Since this is an invasive procedure, it is usually performed in a hospital, rather than on the scene of an accident or in a battlefield environment. This treatment also requires access to the wound, which is not possible when the occlusive dressing is in place.

U.S. patent No.5,160,322 to schermet et al entitled "closed chest seal valve" published on month 11 and 3 1992 discloses a one-way valve for use in emergency closure of an open chest wound. The device includes a one-way valve assembly mounted to a flexible attachment plate having adhesive on one side so that it can be adhered to the skin of a patient over an open wound. The plate has an opening in the center and the valve assembly has a valve seat mounted to the plate to cover the opening. There are a number of holes through the valve seat and a valve member is mounted to the valve seat which allows air and other fluids to exit the wound through the holes in the valve seat but prevents air from being sucked back in. A dome-shaped rigid cover is mounted to the valve seat to cover the valve element and a number of openings are formed around the lower edge of the cover to enable air and other fluids exiting the wound to exit the cover.

The schermet valve is designed to prevent air from being drawn into the chest cavity through an open wound, while allowing pressurized air and other fluids, such as blood, to exit through the valve to relieve a tension pneumothorax or prevent its formation in the first place. However, one significant drawback of the schermet valve is that it prevents access to the wound by medical personnel. Thus, if the patient has a bloodchest, blood may accumulate inside the chest or a blood clot may form at the wound site, blocking or clogging the valve. In this case, it is not possible to remove blood clots from the wound site without removing the valve.

Attempts to overcome the disadvantages of schermet valves and other similar devices are disclosed in Asherman, U.S. patent No.5,478,333 entitled "medical dressing for treating open chest injuries" published on 26.12.1995. The Asherman dressing includes a flexible body with adhesive on one side for attaching the body to the skin of a patient surrounding an open chest wound. The center of the body forms a flexible tubular conduit that projects away from the patient. A flexible one-way valve tubing is mounted to the exterior of the conduit to allow air and other fluids to exit the wound through the conduit, but to prevent air from being drawn back into the wound through the conduit. If the patient has a hemothorax or a collapsed lung, a suction device may be inserted into the flexible valve tubing and the conduit.

The Asherman dressing has a number of drawbacks. The Asherman dressing uses an acrylic adhesive and is reported to have problems adhering the dressing to the skin of the patient. In many cases where urgent treatment of an open wound is required, the patient's skin is covered in blood, sweat and/or oil and the skin may also be covered in hair, all of which present challenges when trying to adhere a dressing to the skin. In addition, because the tubing and valve are flexible, medical personnel must be careful to ensure that it does not collapse and interfere with the proper operation of the valve. For example, medical personnel must ensure that nothing contacts the conduit or valve to cause it to collapse. This can be difficult depending on the location of the wound and the need to cover the patient in a blanket or restrain the patient in a stretcher or other means for transporting the patient. An additional problem with the Asherman dressing is that it obscures the wound from the perspective of the medical practitioner, making assessment of the wound and patient condition difficult.

There is therefore a need for an improved medical dressing for open chest wounds which overcomes or at least alleviates the problems of the prior art arrangements.

In particular, there is a need for an improved medical dressing having a one-way valve mechanism for closing an open chest wound while allowing pressurized air and/or other fluids to exit the chest cavity and allowing access to the wound for inspection and/or allowing air and/or other fluids, such as blood, to be drawn from the wound when the dressing is in place.

There is also a need for an improved medical dressing having a one-way valve mechanism for closing an open chest wound while allowing pressurized air and/or other fluids to exit the chest cavity through the wound that requires less monitoring than prior art arrangements.

There is a further need for an improved medical dressing having a one-way valve mechanism for closing an open chest wound while allowing pressurized air and/or other fluids to exit the chest cavity that adheres more readily to the patient's skin than the prior art.

Disclosure of Invention

According to a first aspect of the present invention there is provided a medical dressing for placement over a wound of a patient, the dressing comprising: a flexible plate having an inner surface and an outer surface and defining an opening therethrough, the plate having an adhesive on the inner surface for attaching the plate to the skin of a patient; and a one-way valve assembly mounted to the plate through the opening in the plate, the valve assembly having a valve body defining a first passage through the valve body, the assembly further comprising a valve element configured to allow air and/or other fluid to flow through the first passage only in an outward direction of the valve such that, in use, air and/or other fluid can exit the wound through the first passage but is prevented from entering the wound through the first passage, the valve body further defining a second passage through the valve body, the valve assembly comprising a removable closure element for selectively closing the second passage to prevent fluid flow through the second passage.

In a medical dressing according to the first aspect of the invention, the closure element is removable to allow direct access to the wound through the second passage unobstructed by the valve element. Thus, the second channel may be opened to enable medical personnel to inspect the wound and/or perform invasive procedures without having to remove the dressing. When the closure element is in place, the second passageway is sealed and the dressing acts as an occlusive dressing to prevent air from entering the wound, but to allow pressurized air and/or other fluids to exit the wound through the first passageway.

The first and second passages may extend through the valve body from an inner side configured to be positioned adjacent and proximate to a wound site and an outer side configured to be further from the wound site.

The second passage may extend through a central region of the valve body and the first passage may substantially surround the second passage.

The valve body may include a valve seat and a valve cover mounted to the valve seat, the valve element being mounted to the valve seat and enclosed by the valve cover.

The valve seat may have an inner surface and an outer surface and may define at least one valve opening therethrough, the valve element being mounted to the valve seat for movement between a valve closed position in which the valve element contacts the outer surface of the valve seat to prevent inward flow of air and/or other fluid through the at least one valve opening, and a valve open position in which the valve element is at least partially spaced from the outer surface of the valve seat element such that air and/or other fluid may pass through the at least one valve opening in an outward direction of the valve assembly.

The valve seat may define a further opening through the valve seat, the further opening comprising at least a portion of the second passage, the further opening not being blocked by the valve element.

The further opening comprising at least a portion of the second passage may be defined substantially centrally in the valve seat, and the valve seat may further define at least two valve openings comprising a portion of the first passage, the valve openings being circumferentially spaced around the further opening.

The at least one valve opening and the further opening may be defined in a generally central region of the valve seat, and the valve seat may further comprise an outer flange portion surrounding the central region.

In one embodiment, a generally central portion of the valve seat has a substantially flat outer surface and the valve element is flexible. In the case where the further opening in the valve seat is centrally located, the valve element may be annular.

In an alternative embodiment, the generally central portion of the valve seat comprises an outwardly projecting frustoconical portion and the at least one valve opening is formed in the frustoconical portion. In this embodiment, the further opening in the valve seat may extend centrally through the apex of the frusto-conical portion.

Where the generally central portion of the valve seat comprises a frustoconical portion, the valve element may comprise a frustoconical wall portion and may be movable between a valve closed position in which an inner surface of the frustoconical wall portion of the valve element abuts an outer surface of the frustoconical portion of the valve seat and an open position in which the inner surface of the frustoconical wall portion of the valve element is spaced from the outer surface of the frustoconical portion of the valve seat. The valve element may be rigid.

The valve cover may include a housing portion that encloses the valve element.

The valve cover may have an inner surface and an outer surface and may define at least one valve outlet through a housing portion of the valve cover, wherein the at least one valve outlet forms part of the first passage.

The valve cover may also define another opening through the housing portion of the valve cover that aligns with the other opening through the valve seat to form at least a portion of a second passageway.

An annular projection is provided on the inner surface of the valve cover around the further opening through the valve cover and a corresponding annular projection is provided on the outer surface of the valve seat around the further opening through the valve seat, the corresponding annular projections engaging to define a second passage.

The annular projection on the valve cover may be an inwardly projecting hollow spigot and the annular projection on the valve seat may be a stepped lip, the axial free end of the spigot having a slot which receives a portion of the stepped lip.

The first passage may be defined by the at least one valve opening through the valve seat, a volume defined between the valve cover and the valve seat around the corresponding annular protrusion, and the at least one valve outlet in the valve cover.

The valve cover may have an outer flange portion that covers the flange portion of the valve seat, and a portion of the flexible plate surrounding the opening in the flexible plate is sandwiched between the outer flange portion of the valve cover and the outer flange portion of the valve seat.

Each of the plate, the valve seat, the valve cover, and the valve element may be transparent or translucent.

The valve seat and the valve cover may be secured together by a resilient clip.

The adhesive on the inner surface of the panel may comprise a hydrogel or hydrocolloid adhesive.

A layer of one type of adhesive, such as a hydrogel or hydrocolloid, may be applied to a majority of the central portion of the inner surface of the flexible panel, and a thinner layer of a second adhesive, such as an acrylic adhesive, may be applied to the peripheral border around the inner surface of the central portion.

The valve may be configured for placement around an open chest wound.

According to a second aspect of the present invention, there is provided a medical dressing comprising: a flexible plate having an inner surface and an outer surface and defining an opening therethrough, the flexible plate having an adhesive on the inner surface for attaching the flexible plate to the skin of a patient; and a one-way valve assembly mounted to the flexible plate through the opening in the plate, the valve assembly comprising: a valve seat having a central opening therethrough and a plurality of valve openings circumferentially spaced around the central opening through the valve seat; an annular valve element mounted to the valve seat about the central opening to cover the valve opening at least when the annular valve element is closed, the annular valve element configured to allow air and/or other fluid to flow outwardly through the valve opening while preventing air and/or other fluid from flowing inwardly through the valve opening; a valve housing mounted to the valve seat to enclose the valve element, the valve housing having a central opening aligned with the central opening in the valve seat and a plurality of valve outlets circumferentially spaced around the central opening; the valve assembly may further include a member extending between the central opening in the valve seat and the central opening in the valve cover for defining a continuous, fluid-tight central passage through the valve assembly; and a removable closure element for selectively closing the central passage.

According to a third aspect of the present invention there is provided a medical dressing comprising: a flexible plate having an inner surface and an outer surface and defining an opening therethrough, the flexible plate having an adhesive on the inner surface for attaching the flexible plate to the skin of a patient; and a one-way valve assembly mounted to the flexible plate to control the flow of fluid through the opening; the valve assembly includes: a valve seat having a central portion and an outer flange portion, the valve seat defining at least one valve opening through the central portion of the valve seat, the central portion of the valve seat extending through the opening in the flexible plate while the outer flange portion of the valve seat abuts an inner surface of the flexible plate around the opening in the flexible plate; a valve element mounted to the valve seat to regulate the flow of air and/or other fluids through the at least one valve opening, the valve element configured to allow the outward flow of air and/or other fluids through the at least one valve opening while preventing the inward flow of air and/or other fluids through the at least one valve opening; a valve cover mounted to the valve seat, the valve cover including a housing portion in which the central portion of the valve seat is received and an outer flange portion opposite the flange portion on the valve seat and abutting an outer surface of the flexible plate around the opening in the flexible plate, the housing portion having at least one valve outlet therein through which air and/or fluid flowing outwardly through the at least one valve opening in the valve seat can pass in use to exit the valve assembly; the valve seat and the valve cover defining a further passage through the valve assembly, the further passage being open through the central portion of the valve seat, the further passage being fluidly isolated from the remainder of the valve assembly and unobstructed by a valve element; and the valve assembly comprises a removable closure element for selectively closing the further passage.

Drawings

Several embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

fig. 1 is a perspective view of a first embodiment of a medical dressing according to the present invention;

fig. 2 is a cross-sectional view through the valve assembly forming part of the medical dressing of fig. 1, shown on an enlarged scale;

fig. 3 is an exploded view of the medical dressing of fig. 1;

FIG. 4 is a side elevational view of a cover member forming part of the valve assembly of the medical dressing of FIG. 1;

FIG. 5 is a perspective view of an improved valve assembly for use in the medical dressing of FIG. 1;

FIG. 6 is a perspective view of a valve cover forming part of the valve assembly of FIG. 5;

FIG. 7 is a perspective view of a valve seat forming portion of the valve assembly of FIG. 5;

FIG. 8 is an enlarged cross-sectional view, similar to FIG. 2 but on a slightly smaller scale, of a second embodiment of a valve assembly for a medical dressing in accordance with the present invention; and

fig. 9 is an exploded view of the valve assembly of fig. 8.

Detailed Description

Referring to fig. 1-4, a first embodiment of a medical dressing 10 according to the present invention includes a flexible sheet 12 and a valve assembly 14 mounted to the sheet.

The plate 12 takes the form of a thin sheet of flexible material, in this embodiment generally square in shape. It will be appreciated that the actual shape of the plate is not essential to the invention and the plate may be formed in any suitable shape, for example rectangular or circular. The plate 12 may be made of any suitable material for closing a wound. For example, the panel 12 may be made of a non-woven film of polyurethane, polyurethane foam, or polyethylene foam. The plate is preferably made of a transparent or at least translucent material, but this is not essential.

The plate 12 has an inner surface 16 and an outer surface 18. The inner surface 16 is coated with an adhesive to enable the panel to be adhered to the skin of a patient surrounding an open chest wound. When the dressing is applied, the patient's skin in the area of the wound is likely to be covered in blood, sweat and other contaminants such as oil or the like, and may also be covered in hair. The skin surrounding the wound should be cleaned prior to application of the dressing 10, but this may not be fully effective, particularly under battlefield conditions when the dressing 10 is being applied. It is important that the adhesive used enables the plate to be tightly attached all the way around the wound, even in cases where the skin is not thoroughly cleaned.

Any suitable adhesive may be used, but the adhesive will typically be a transparent or translucent pressure sensitive adhesive. The adhesive may be an acrylic adhesive, but is preferably an aggressive hydrogel or hydrocolloid, both of which have good wet tack and are therefore able to adhere to wet skin and retain their tack over time. A thicker layer of one type of adhesive, such as an aggressive hydrogel or hydrocolloid adhesive, may be applied to the entire inner surface 16 surrounding the valve 14 so that the panel has a uniform thickness. Alternatively, a thicker layer of a first adhesive, such as a hydrogel or hydrocolloid, may be applied to a majority of the central portion of the surface 16 of the panel surrounding the valve 14, while a thinner layer of a second adhesive, such as an acrylic adhesive, is applied to the peripheral boundary of the surface 16. This results in a panel which when adhered to the skin has a low profile at the edges and is therefore less likely to roll up and detach from the skin. The border may extend inwardly about the outer periphery of the plate by about 5-10 mm.

The plate 12 has an opening 12a preferably located in the center of the plate, and a valve assembly 14 is mounted on the plate 12 through the opening 12 a. In use, the plate 12 is attached to the skin of a patient such that the valve assembly 14 is positioned centrally over a wound, the plate being adhered to and sealed with the skin surrounding the wound such that air and/or other fluids, such as blood, can only enter and exit the wound through the valve assembly.

The dressing 10 is typically provided with a non-stick protective backing (not shown) that covers the adhesive and can be peeled away when the dressing is applied. A strip 20 of additional non-stick protective material is positioned on the inner surface 16 along one edge of the panel so that the panel can be grasped along that edge to remove it from the protective backing and position it around the wound. Once the panel is correctly positioned, the strip 20 of additional material is peeled off so that the area of the panel covered by the strip can also adhere to the skin of the patient.

The valve assembly 14 can best be seen in fig. 2-4 and includes a valve seat 22 and a valve cover 24 which together comprise a valve body generally designated 26.

The valve seat 22 is a generally disk-shaped member having a thin annular flange portion 28 surrounding a thicker central portion 30. Five arcuate valve openings 32 are formed through the central portion 30, dividing the central portion into an inner ring 34 and an outer ring 36. The arcuate valve openings 32 are circumferentially spaced about the central portion and are separated by radial spokes connecting an inner ring 34 and an outer ring 36. A bore 42 extends through the inner ring 34 and forms another opening through the central portion 30. A stepped annular lip 44 projects outwardly (that is, away from the wound site in use) from a radially inner edge of the outer surface of the inner ring 34 for reasons which will be discussed below.

The valve cover 24 is circular in plan view, having an inner dome-shaped housing portion 46 and an outer annular flange portion 48 extending radially outwardly around the circumference of the dome-shaped portion 46. The dome-shaped portion 46 has a flat annular wall portion 50 at its bottom, a flattened upper surface 52 and a generally arcuate wall portion 54 between the flat annular wall portion 50 and the upper surface. A series of openings 56 are spaced circumferentially around the arcuate wall portion 54. The opening 56 forms a fluid outlet of the valve assembly, as will be described in more detail subsequently.

The inner diameter of the annular wall region 50 is slightly larger than the outer diameter of the raised central portion 30 of the valve seat 22 so that the central portion 30 of the valve seat 22 is received within the dome-shaped portion 46 of the cap 24 when the cap and valve seat are assembled together. A hollow spigot 58 projects inwardly from the centre of the flattened upper surface 52 for engagement with the stepped lip 44 on the valve seat. An annular notch 60 is formed around the inner surface of the free end of the spigot 58 in which the outer portion 44a of the stepped lip is located by an interference or snap fit to secure the cover 24 and base 22 together. When the base 22 and cover are assembled, the free axial end surface 62 of the spigot 58 abuts the inner portion 44b of the stepped lip and the flange portion 48 of the cover 24 overlies the flange portion 28 of the base 22.

Both the valve seat 22 and the valve cover 24 are fabricated from a substantially rigid material, such as a rigid polymeric material. Preferably, the valve seat 22 and valve cover 24 are made from a transparent or translucent polymeric material, such as polypropylene, acetyl, or any other suitable material, and may be manufactured by means of, for example, injection molding.

A flat annular valve member 64 is mounted to the central portion 30 of the valve seat 22 about the lip 44. The valve member 64 has an outer diameter equal to the outer diameter of the raised central portion 30 of the valve seat and an inner diameter slightly larger than the inner portion 44b of the lip such that the valve member covers the entire valve opening 32 and at least a portion of each of the inner ring 34 and the outer ring 36. In this embodiment, when the cover 24 is assembled to the valve seat 22, the axially free end 62 of the central spigot 58 on the cover overlies the inner diameter portion of the valve element 64 to secure it in position against the inner ring 34 of the valve seat. However, in an alternative arrangement, the inner diameter of the valve element may be slightly larger than the outer diameter of the adapter 58, such that the valve element is able to slide along the outer surface of the adapter 58. The valve element 64 is made of a flexible material, such as a flexible polymer (e.g., silicon), which is preferably transparent or at least translucent.

To mount the valve assembly 14 to the plate 12, the area of the plate 12 surrounding the central opening 12a is sandwiched between the annular flange portion 28 of the valve seat 22 and the annular flange portion 48 of the cover 24. During assembly of the dressing 10, the raised central portion 30 of the valve seat 22 is inserted into the plate through the opening 12a such that the area of the plate surrounding the opening 12a is positioned over the annular flange portion 28 of the valve seat. With the flexible valve member 64 in place on the central raised portion 30 of the valve base 22, the valve cover 24 is assembled to the valve base 22 such that the notch 60 in the nipple 58 engages the annular lip 44 and the area of the plate 12 surrounding the central opening 12a is sandwiched between the annular flange portion 48 of the cover 24 and the annular flange portion 28 of the valve base. The cover 24 and base 22 may be secured together simply by frictional engagement of the lip 44 in the slot 60 or they may be adhered together using a suitable adhesive or welded together, for example by means of ultrasonic welding. Adhesive may also be used to bond the annular flange portions 28, 48 of the valve seat and lid to the plate 12 to ensure that an air-tight seal is formed between the plate and the flange portions.

Where the base 22 and cover 24 are bonded together using an adhesive or ultrasonic welding, the notch 60 and stepped lip 44 may be omitted and the inner end of the spigot 58 may have a flat surface that abuts a corresponding flat surface on the base around the central bore 42.

With the dressing 10 assembled as described above, the arcuate opening 32 in the valve seat 22, the volume between the valve seat 22 and the inner surface of the cover 24 surrounding the central joint 58, and the opening 56 in the arcuate wall portion of the cover form a first passage 66 extending through the valve body and through which air and/or other fluids may flow under the control of the valve element 64.

The diameter of the bore 42 in the inner ring and the inner diameter in the hollow nipple 58 are substantially the same such that when the valve seat 22 and cover 24 are assembled, the inner ring 34 and hollow nipple 58 define a continuous second passage 68 extending through the center of the valve body 26. The connection between the nipple 58 and the lip 44 on the inner ring 34 is such that air and/or other fluids are prevented from leaking between the connections, such that the second channel 68 is fluidly isolated from the first channel 66. The second passage 68 is not blocked by the valve element 64.

The valve assembly also comprises a closure member 70 for the second passage, which is shown only in fig. 1, 3 and 4. The closure member 70 comprises a plastic plug that is removably inserted into the bore of the hollow connector 58 to seal the second passage 68 against the flow of air and/or other fluids. The plug 70 is preferably attached to the lid by means of a strip 72 of flexible material forming a lanyard. In this embodiment, the lanyard 72 and the plug 70 are formed integrally with the lid 24 and the lanyard projects from the outer edge of the flange portion 48 of the lid. As can be seen in fig. 4, the lanyard is formed with a series of grooves 72a extending across its width to assist in flexing of the lanyard. The plug 70 is hollow with an annular wall portion 70a defining a blind bore. When the plug is inserted into the fitting 58, the annular wall portion 70a is resiliently compressed so that it forms an effective seal to prevent air and/or other fluids from passing through the second passage. The lanyard 72 enables the plug 70 to be removed from the second channel while remaining connected to the lid 24, as shown in fig. 4.

Preferably, the plug 70, lanyard 72 and lid 24 are formed as one piece as an injection molding. However, the plug 70 and lanyard 72 may be formed separately from the lid 24 with the end of the lanyard secured to the lid by any suitable mechanism. For example, the free end of the lanyard 72 may be inserted through an opening or slot in the cover and have a flexible tab arranged such that it can be inserted through the opening or slot in one direction, but does not easily retract from the opening or slot in the opposite direction. It will be appreciated that other methods of attaching the lanyard 72 to the cover 24 may be used.

In use, the dressing 10 is attached to a patient having an open chest wound with the valve assembly 14 positioned directly over the wound and the inner surface 16 of the panel 12 adhered to the patient's skin surrounding the wound to form an air-tight seal. With the dressing in place and the closure element 70 located in the bore of the hollow spigot 58, air and/or other fluid can only leave the wound through the first passage 66 under the control of the valve element 64. When the pressure of the ambient air acting on the outer surface 78 of the valve member 64 is greater than the pressure of air and/or other fluid, such as blood, in the chest cavity acting on the inner surface 80 of the valve member 64, the valve member is pressed against the outer face of the raised central portion 30 of the valve seat 22, thereby closing the arcuate opening 32 and preventing air from being drawn into the chest cavity through the valve assembly and wound. However, if the pressure of the air and/or other fluid in the chest cavity exceeds the ambient air pressure, the flexible valve member 64 is lifted at least partially away from the outer surface of the central elevated portion 30 of the valve seat. This allows the pressurized air and/or other fluid in the chest cavity to flow outwardly through the arcuate openings 32 in the valve seat, through the space between the valve seat and the inner surface of the valve cover 24 surrounding the central joint 58, and out through the openings 56 in the arcuate wall portion of the valve cover. The ability of the pressurized air and/or blood to escape from the chest cavity through the first passage 68 in the valve assembly facilitates the management and, in some cases, prevents the occurrence of a tension pneumothorax and/or a hemothorax.

As described above, with the second passage 68 in the valve body closed, the medical dressing 10 according to the present invention acts as a one-way valve to prevent air from being drawn into the chest cavity through the wound, while allowing pressurized air, blood, and/or other fluids to flow out of the chest cavity. However, by removing the closure element 70, direct access to the wound may be provided via the second channel 68 without the need to remove the dressing 10. The open second channel 68 may be used to perform visual inspection of the wound and/or to enable an invasive procedure to be performed therethrough without removing the dressing 10. For example, a chest drain may be introduced into the chest cavity through a second channel to draw blood or other fluid from the chest cavity in the case of a patient suffering from a hemothorax or to draw air from the chest cavity in the case of a tension pneumothorax. If the first channel 66 becomes occluded with clotted blood, suction through the second channel 68 may be used to remove the clot and restore air and fluid flow through the first channel 66.

The plate 12 and various components of the valve assembly 14 are preferably made of a transparent or at least translucent material in order to assist the user in accurately placing the dressing 10 while having the valve assembly centrally positioned over the wound. The transparent nature of the dressing also makes it easier to visually monitor the wound.

The rigid cover portion 14 of the valve assembly protects the valve member 64 and will not readily collapse in the manner of the flexible tubing and valve member of the prior art Asherman dressing. As a result, the dressing 10 according to the present invention requires less monitoring and attention by medical personnel.

Figures 5-7 show an improved valve assembly 14 for the dressing 10. In the improved valve assembly 14, the valve seat 22 is secured to the valve cover 24 by means of four resilient clips 85. As best seen in fig. 7, the clips project axially and radially outwardly from the outer surface of outer ring 36. The distal end of the clip 85 has an enlarged head 87 which engages in a notch or indentation 89 in the inner surface of the opening 56 in the valve cover to secure the valve seat and cover together. To assemble the valve, the central portion 30 of the valve seat 22 is inserted through an opening in the flexible plate 12. The cover 24 is pressed down over the valve seat and pushed inwardly as the head portion 87 of the clip enters the dome-shaped portion 46 of the housing. Once the cover 24 is tightly pressed against the valve seat, the head portions 87 spring radially outward into the notches and clamp the cover to the valve seat, with the flexible panel 12 secured between the flange portion 28 of the valve seat and the flange portion 48 of the valve cover. The head portion 87 of the clip has a tapered outer surface 87a to assist in deflecting the clip inwardly when the cap 24 is assembled.

In the improved valve assembly 14, the lip 44 is not stepped and the larger diameter inner portion 44b is omitted from the valve seat. In this arrangement, the inner diameter of the valve element 64 is sandwiched between the axially free end 62 of the central spigot 58 on the cover and the inner ring 34 of the valve seat.

As shown in fig. 7, four openings 91 are formed in the flange portion 28 of the valve seat, one adjacent each spring clip. The opening 91 allows the injection gate to enter and retract during molding of the valve seat. To ensure that there is no leakage through the opening 91 when the dressing 10 is in use, a ring of double sided tape is secured to the inner surface of the flange 28. The strap helps secure the valve assembly to the patient and seals the opening 91.

In a further refinement, the annular wall 70a of the plug 70 is not resiliently compressed when inserted into the bore of the hollow fitting but is designed to be a close sliding fit in the bore. To hold the plug in place, an annular rib 70b extends around the annular wall 70a for snap-fit engagement with a corresponding groove 58a in the bore of the hollow spigot 58. This allows for consistent assembly and provides a more reliable pull force value to remove the plug 70. The rib 70b may be continuous as shown in fig. 5 or discontinuous as shown in fig. 6, wherein the rib 70b is divided into four sections. The annular wall 70a may be tapered inwardly towards its distal end to ease assembly while ensuring that the second channel is sealed when the stopper 70 is fully inserted. Four vertical ribs 70c extend from the enlarged head region of the plug 70 to limit the extent to which the plug can be inserted into the second passage. This again helps with consistency of assembly and ensures that there is sufficient clearance between the head of the bung 70 and the valve cover to enable the bung to be gripped for removal.

The improved valve assembly 14 shown in fig. 5-7 is otherwise identical to that described above with reference to fig. 1-4. The modifications described with respect to fig. 5-7 may be applied to the valve assembly shown in fig. 1-4.

Fig. 8 and 9 illustrate an alternative embodiment of a valve assembly 114 that may be used with a dressing 10 according to the present invention.

In the following description, the same reference numerals, increased by 100, will be used to indicate the same or equivalent features as the first embodiment described above with reference to fig. 1-7.

The valve assembly 114 of the second embodiment is similar in construction and operation to the first embodiment and includes a valve seat 122 and a valve cover 124 (which together define a valve body 126) and a valve member 164.

The valve seat 122 includes an outer annular flange portion 128 and an increased thickness central portion 130. The central portion 130 in this embodiment comprises a frusto-conical wall portion 130A which extends outwardly from the valve seat, i.e. away from the wound site in use. A series of circumferentially spaced openings 132 are formed through the frustoconical wall portion 130A to provide access to the first fluid passageway 166 of the valve assembly 114.

An expanded, stepped annular lip 144 is provided at a radially inner or upper edge as shown of the frustoconical wall portion 130A and includes an outer portion 144a of smaller diameter and an inner portion 144b of larger diameter. The inner portion 114b in this embodiment has an increased length compared to the lip 44 in the first embodiment. The lip 44 defines a central bore or opening 142 through the valve seat and which opens into the interior of the frustoconical wall portion 130A.

The valve cover 124 in the second embodiment is similar to the valve cover 24 in the first embodiment and has a dome-shaped portion 146 and an annular flange portion 148 projecting radially outwardly around the circumference of the dome-shaped portion. However, the cover 124 in the second embodiment does not have a hollow fitting 58 but rather has a circular opening 190 in the center of the flattened upper surface 152. The diameter of the opening 190 is substantially the same as the diameter of the bore 142 through the lip 144 of the valve seat 122. An annular flange 192 projects inwardly from the inner surface of the cap. The flange 192 is spaced from the opening 190 in the cover and is configured to engage the stepped lip 144 on the base, as shown in fig. 5. Thus, in the second embodiment, the bore 142 defined by the lip 144 in the base 122 and the opening 190 in the cover together define the second passageway 168 through the valve body.

The valve member 164 is rigid and may be made of any suitable material, such as a rigid polymeric material. The valve element 164 has a frustoconical portion 164A that corresponds to the frustoconical wall portion 130A on the valve seat. An annular wall region 164B projects radially inwardly from the outer end (or upper end as shown) of the frustoconical portion 164A for sliding engagement about the expanded inner portion 144B of the lip 144. This arrangement enables the valve element 164 to move in the axial direction of the valve assembly between a valve open position as shown in fig. 5 and a valve closed position.

In the valve open position, the annular wall region 164B of the valve member is positioned toward the outer end (or upper end as shown) of the enlarged inner lip portion 144B and the inner surface 180 of the frustoconical portion 164A of the valve member 164 is spaced from the frustoconical wall portion 130A of the valve seat. With the valve element 164 in this position, air and/or other fluid exits through the opening 132 in the valve seat, the space between the valve seat 122 and the inner surface of the cover 114, and through the opening 156 in the cover. In the valve closed position, the valve member 164 is slid inwardly towards the wound site so that the inner surface 180 of its frustoconical portion contacts the outer surface of the frustoconical wall portion 130A of the valve seat. In this position, the valve element closes the opening 132 in the valve seat to prevent air and/or other fluid from flowing through the opening 132 in an inward direction.

Although not shown in the figures, the valve assembly 114 has a removable closure member similar to the closure member or plug 70 of the first embodiment. The closure member is adapted to be inserted into the opening 190 in the cover and/or the bore 142 in the valve seat to close the second passage. The closure element 70 may be constructed as described with respect to the first embodiment shown in fig. 1-4 or as described with respect to the modified embodiment shown in fig. 5-7.

In use, when second passageway 168 is closed by the closure member, valve member 164 moves in response to a pressure differential across the valve member. If the pressure of the air and/or other fluid in the chest cavity acting on the inner surface 180 of the valve member through the opening 132 in the valve seat is higher than the ambient air pressure acting on the outer surface 178 of the valve member, the valve member 164 will move to the valve open position to allow pressurized air and/or other fluid to flow outwardly through the valve body. However, if the ambient air pressure is higher than the pressure of the air and/or other fluid in the chest cavity, the valve member 164 is held in the valve closed position, preventing air from being drawn into the chest cavity through the first passage 166. As with the first embodiment, the closure element for the second fluid channel 168 may be removed to provide direct access to the chest wound through the unobstructed second channel.

The valve assembly 114 of the second embodiment may be mounted to the plate 12 in a manner similar to that described above with respect to the first embodiment. Thus, the central portion 130 of the valve seat is inserted through the opening 12a in the plate, and the valve element 164 and cover are mounted to the valve seat such that the area of the plate surrounding the opening 12a is sandwiched between the flange portion 128 of the valve seat 122 and the flange portion 148 of the cover 124.

The valve seat 122 and cover 124 may be modified to be held together by resilient clips in a manner similar to that disclosed above with respect to fig. 5-7.

In all embodiments of the dressing 10 of the present invention, the valve body 26, 126 defines two separate passages 66, 68 extending through the body from the inner side 94, 194 to the outer side 96, 196; 166. 168, the inner side being positioned adjacent and proximal to the wound in use, and the outer side being positioned further from the wound in use. Valve element 64, 164 is operable in the first passage such that air and/or other fluids may only pass through first passage 66, 166 in an outward direction from the inner side to the outer side. The second channel 68, 168 is unobstructed and allows direct access to the wound in use, but may be sealed by the closure element 70 when direct access is not required. When the second passage is sealed, the dressing occludes the wound to prevent air from being drawn into the chest cavity through the wound while allowing pressurized air and/or other fluids to escape from the chest cavity through the first passage. It can therefore be seen that the medical dressing 10 according to the present invention provides an effective and easy way to use a dressing for an open chest wound that is simple in design and reliable in operation.

While the dressing is particularly advantageous in treating open chest wounds, it may have other applications, for example, the dressing may be used to attach a drain to a patient, whether in the chest cavity or elsewhere.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed arrangements, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. For example, the second passage may be defined by means of a hollow nipple projecting outwardly from the valve seat about the central opening, the nipple extending through the opening in the cap. Furthermore, it will be appreciated that while it is advantageous to form the second channel in the centre of the valve assembly so that it is positioned over the centre of the wound, this is not essential. The first and second channels may be aligned side-by-side, for example. It will also be appreciated that even where the second channel is located centrally of the valve assembly, this need not be formed at the actual geometric centre of the assembly, as long as the dressing can be positioned with the second channel aligned with the wound opening.

Where the term "comprises" is used in this specification, it should be understood that it is intended to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

Claims (30)

1. A medical dressing for placement over a wound of a patient, the dressing comprising:

a flexible plate having an inner surface and an outer surface and defining an opening therethrough, the flexible plate having an adhesive on the inner surface for attaching the flexible plate to the skin of a patient; and

a one-way valve assembly mounted to the flexible plate through the opening in the flexible plate, the one-way valve assembly having a valve body defining a first passage through the valve body, the one-way valve assembly further comprising a valve element configured to allow air and/or other fluid to flow through the first passage only in an outward direction of the valve element such that, in use, air and/or other fluid can exit a wound through the first passage but is prevented from entering the wound through the first passage, the valve body further defining a second passage through the valve body, the one-way valve assembly comprising a removable closure element for selectively closing the second passage to prevent fluid flow through the second passage.

2. A medical dressing as claimed in claim 1, in which the second passageway is unobstructed when the closure element is removed to provide, in use, direct access to a wound covered by the dressing.

3. A medical dressing as claimed in claim 1 or claim 2, in which the first and second passages extend through the valve body between an inner side configured to be positioned adjacent a wound in use and an outer side configured to be remote from a wound in use.

4. A medical dressing as claimed in any one of claims 1 to 3, in which the second passage extends through a central region of the valve body and the first passage substantially surrounds the second passage.

5. A medical dressing as claimed in any one of claims 1 to 4, in which the valve body comprises a valve seat and a valve cover mounted to the valve seat, the valve element being mounted to the valve seat and enclosed by the valve cover.

6. A medical dressing as claimed in claim 5, in which the valve seat has an inner surface which faces the wound site in use and an outer surface which faces away from the wound site in use, the valve seat defining at least one valve opening through the valve seat, the valve element being mounted to the valve seat for movement between a valve closed position in which the valve element contacts the outer surface of the valve seat to prevent inward flow of air and/or other fluid through the at least one valve opening, and a valve open position in which the valve element is at least partially spaced from the outer surface of the valve seat such that air and/or other fluid can pass through the at least one valve opening in an outward direction of the valve assembly.

7. A medical dressing as claimed in claim 6, in which the valve seat defines a further opening through the valve seat, the further opening comprising at least part of the second passageway, the further opening being unobstructed by the valve element.

8. A medical dressing as claimed in claim 7, in which the further opening is defined substantially centrally of the valve seat and the valve seat defines at least two valve openings which are circumferentially spaced around the further opening.

9. A medical dressing as claimed in any one of claims 6 to 8, in which the at least one valve opening and the further opening are defined in a central region of the valve seat and the valve seat further comprises an outer flange portion surrounding the central region.

10. A medical dressing as claimed in claim 9, in which the central portion of the valve seat has a generally flat outer surface and the valve element is flexible.

11. A medical dressing as claimed in claim 10 when dependent on claim 8, in which the valve element is annular.

12. A medical dressing as claimed in claim 9, in which the central portion of the valve seat comprises an outwardly projecting frusto-conical portion and the at least one valve opening is formed in the frusto-conical portion.

13. A medical dressing as claimed in claim 12, in which the further opening in the valve seat extends centrally through the apex of the frusto-conical portion.

14. A medical dressing as claimed in claim 12 or claim 13, in which the valve element includes a frusto-conical wall portion and is movable between a valve closed position in which an inner surface of the frusto-conical wall portion of the valve element abuts an outer surface of the frusto-conical portion of the valve seat and an open position in which the inner surface of the frusto-conical wall portion of the valve element is spaced from the outer surface of the frusto-conical portion of the valve seat.

15. A medical dressing as claimed in claim 14, in which the valve element is rigid.

16. A medical dressing as claimed in any one of claims 5 to 15, in which the valve cover comprises a housing portion which encloses the valve element.

17. A medical dressing as set forth in claim 16, wherein said valve cover has an inner surface and an outer surface and defines at least one valve outlet through a housing portion of said valve cover, said at least one valve outlet forming a portion of said first passageway.

18. A medical dressing as claimed in claim 17 when dependent on claim 7 or claim 8, in which the valve cover defines a further opening through the housing portion of the valve cover which is aligned with the further opening through the valve seat to form at least part of the second passageway.

19. A medical dressing as claimed in claim 18, in which an annular projection is provided on the inner surface of the valve cover around the further opening through the valve cover, and a corresponding annular projection is provided on the outer surface of the valve base around the further opening through the valve base, the respective annular projections engaging with one another to define the second passageway.

20. A medical dressing as claimed in claim 19, in which the annular projection on the valve cover is an inwardly projecting hollow spigot and the annular projection on the valve base is a stepped lip, the axial free end of the spigot having a slot which receives a portion of the stepped lip.

21. A medical dressing as claimed in claim 19 or claim 20, in which the first passage comprises the at least one valve opening through the valve base, a volume defined between the valve cover and the valve base around the corresponding annular protrusion and the at least one valve outlet in the valve cover.

22. A medical dressing as claimed in claim 9 or any one of claims 10 to 21 when dependent on claim 9, in which the valve cover has an outer flange portion which overlies the outer flange portion of the valve seat, the portion of the flexible sheet surrounding the opening in the flexible sheet being sandwiched between the outer flange portion of the valve seat and the outer flange portion of the valve cover.

23. The medical dressing of any one of claims 5-22, wherein the flexible sheet, the valve seat, the valve cover, and the valve element are all transparent or translucent.

24. A medical dressing as claimed in any one of claims 5 to 23, in which the valve seat and valve cover are secured together by resilient clips.

25. The medical dressing of any one of the preceding claims, wherein the adhesive on the inner surface of the flexible sheet comprises a hydrogel or hydrocolloid adhesive.

26. A medical dressing as claimed in any one of the preceding claims, in which a layer of one type of adhesive, for example a hydrogel or hydrocolloid, is applied to a major central portion of the inner surface of the flexible sheet and a thinner layer of a second adhesive, for example an acrylic adhesive, is applied to the peripheral border around the inner surface of the central portion.

27. The medical dressing of any one of the preceding claims, wherein the dressing is configured for placement over an open chest wound of a patient.

28. A medical dressing, comprising:

a flexible panel having an inner surface and an outer surface and defining an opening therethrough, the flexible panel having an adhesive on the inner surface for attaching the flexible panel to the skin of a patient; and

a one-way valve assembly mounted to said flexible plate through said opening in said flexible plate, said one-way valve assembly comprising:

a valve seat having a central opening therethrough and a plurality of valve openings circumferentially spaced around the central opening through the valve seat;

an annular valve element mounted to the valve seat about the central opening so as to cover the valve opening at least when the annular valve element is closed, the annular valve element being configured to allow air and/or other fluid to flow outwardly through the valve opening while preventing air and/or other fluid from flowing inwardly through the valve opening;

a valve housing mounted to the valve seat to enclose the valve element, the valve housing having a central opening aligned with the central opening in the valve seat and a plurality of valve outlets circumferentially spaced around the central opening;

a member extending between said central opening in said valve seat and said central opening in said valve cover for defining a continuous, fluid-tight central passageway through said valve assembly; and

a removable closure element for selectively closing the central passage.

29. A medical dressing, comprising:

a flexible plate having an inner surface and an outer surface and defining an opening therethrough, the flexible plate having an adhesive on the inner surface for attaching the flexible plate to the skin of a patient; and

a one-way valve assembly mounted to the flexible plate to control the flow of air and/or other fluids through the opening; the one-way valve assembly includes:

a valve seat having a central portion and an outer flange portion, the valve seat defining at least one valve opening through the central portion of the valve seat, the central portion of the valve seat extending through the opening of the flexible plate while the outer flange portion of the valve seat abuts an inner surface of the flexible plate around the opening in the flexible plate;

a valve element mounted to the valve seat to regulate flow of air and/or other fluids through the at least one valve opening, the valve element configured to allow the outward flow of air and/or other fluids through the at least one valve opening while preventing the inward flow of air and/or other fluids through the at least one valve opening;

a valve cover mounted to the valve seat, the valve cover including a housing portion in which the central portion of the valve seat is received and an outer flange portion opposite the outer flange portion on the valve seat and abutting an outer surface of the flexible plate around the opening in the flexible plate, the housing portion having at least one valve outlet in the housing portion through which air and/or other fluid flowing outwardly through the at least one valve opening in the valve seat can pass in use to exit the valve assembly;

the valve seat and the valve cover defining a further passage through the valve assembly, the further passage being open through the central portion of the valve seat, the further passage being fluidly isolated from the remainder of the valve assembly and unobstructed by the valve element; and

the one-way valve assembly includes a removable closure member for selectively closing the other passageway.

30. A medical dressing substantially as hereinbefore described with reference to and as shown in figures 1 to 4 or figures 5 or 6 of the accompanying drawings.