Patent Description:
This invention relates to a medical dressing for treating open chest injuries or other injuries that may expose the pleural space or chest cavity.

Chest trauma, including piercing or penetrating chest wounds, can occur as the result of an accidental or deliberate penetration of a foreign object into the body. Risk from chest trauma can be exacerbated if the internal chest volume or lungs are exposed to the external environment, such that atmospheric air enters the internal chest volume. Air entering the chest volume can cause the collapse of the lung(s) in the chest volume. Effective triage of a piercing or penetrating chest wound can be achieved with specifically adapted medical dressings which prevent atmospheric air entering the internal chest volume and thereby reduce the risk of a collapsed lung, also referred to as a pneumothorax.

The lungs are made up of layers of tissue known as pleura and are maintained within an enclosed pleural space. The pleural space is in the internal chest volume and is naturally maintained at a slight, negative pressure as compared to atmospheric pressure. The negative pressure aids in the expansion of the lung during an inhalation of a breath.

When an individual suffers a puncture wound to the chest, the wound may penetrate the chest cavity and expose the pleural space to atmospheric air and thus atmospheric air pressure. Atmospheric air will tend to flow through the puncture wound into the pleura space due to the natural below atmospheric pressure in the pleura space. Because the flow of air through the wound and into the pleural space is typically audible, these types of wounds are commonly referred to as "sucking chest wounds.

If atmospheric air is allowed to flow through the wound into the pleura space, the increased pressure in the pleura space may precipitate a pneumothorax, e.g., a lung collapse. A pneumothorax results from the abnormal buildup of air pressure in the pleural space and may manifest as an uncoupling of the lung from the chest wall. Immediate symptoms typically include a sudden onset of sharp chest pain (general one-sided and localized to the side of the wound opening, and shortness of breath. If left untreated, these symptoms may progress to difficulty breathing, or even death.

Generally, the prescribed treatment to a penetrating chest wound, e.g., a sucking chest wound, is to limit air entry into the pleura space by sealing the wound and evacuate air from the pleura space.

Conventional chest wound dressings include the medical dressing disclosed in <CIT>, which is formed of a base layer and a cover layer fused directly to the base layer to cover an opening in the base layer. One-way air channels are formed between the base and cover layers to allow air to escape from a chest wound and prevent air entering the chest wound.

<CIT> also discloses a wound dressing for patients suffering a chest trauma.

A need developed for a chest wound dressing formed of three or more layers fused together. However, forming air channels between two layers in a dressing creates when there are three or more layers in the dressing. Forming air channels between two layers and fusing all layers appeared to preclude fusing all layers in one fusing step. But, multiple fusing steps would be costly and time consuming. A need arose for a chest wound dressing formed of three or more layers that could be formed by fusing the layers together in a single fusing step, wherein air channels are formed between at least two of the layers.

The invention claimed in claim <NUM> is a medical dressing comprising:
a flexible base layer including a front surface configured to face a skin of a patient and a back surface opposite the front surface, wherein the flexible base layer includes a first opening; an adhesive layer on the front surface of the base layer wherein the adhesive layer extends entirely around the opening; a flexible cover layer entirely covering the opening of the base layer; a flexible intermediate layer sandwiched between the base layer and the cover layer, wherein the intermediate layer includes a second opening aligned with the first opening; the base layer, cover layer and intermediate layer joined together along an annular pattern extending entirely around the first and second openings, wherein the annular pattern joints the base layer to the intermediate layer entirely around the first and second openings, and the annular pattern joins the cover layer, intermediate layer and base layer around the first and second openings except at slots extending beyond an outer edge of the cover layer and ending before an outer edge of the intermediate layer.

<FIG> shows a patient <NUM> with a chest wound, such as a puncture <NUM> that extends through the chest wall. The puncture <NUM> may allow air to flows from the atmosphere into the pleural space <NUM>. The air entering the pleural space can increase the pressure in the space and thereby collapse the lung(s) <NUM>. Immediate and emergency treatment of the chest wound involves the application of a dressing that allows excess air in the pleural space to vent to the atmosphere and prevents additional air from being drawn back into the pleura space.

A medical dressing <NUM> is applied to the chest puncture <NUM>. The dressing is applied such that the puncture <NUM> is aligned with the center of the dressing <NUM>. Before the dressing is applied, the wound may be cleaned by removing blood and dirt from the skin surround the wound. An adhesive layer on one side of the dressing seals the dressing to the skin. The dressing covers the puncture <NUM> to prevent water, dirt and other material from entering the wound. The dressing may also assist in stopping further loss of blood from the wound. The dressing also prevents air from being drawn into the puncture <NUM> while also allowing air to vent from the puncture and to the atmosphere. A second medical dressing <NUM> may be applied to the back (not shown) of the patient where there may be an exit (or entrance) wound, especially if the wound is caused by a gunshot.

<FIG> shows a top view of the medical dressing <NUM>, and <FIG> shows an exploded view of the layers of the medical dressing <NUM>.

The principal layers of the medical dressing <NUM> are a base layer <NUM>, an annular intermediate layer(s) <NUM> and a circular disc cover layer <NUM>. Each of these principal layers may be formed of a polyurethane (PU) sheet having a thickness of <NUM> mils to <NUM> mils. The base layer member <NUM> may be thicker, such as by a factor of two, than each of the intermediate and cover layers. The intermediate layer may have the same thickness and the cover layer, or may be thicker than the cover layer if additional firmness is needed to support the cover layer.

The circular disc cover layer <NUM> is the upper layer of the dressing <NUM>, the base layer <NUM> is the bottom layer and the intermediate layer(s) <NUM> are sandwiched between the disc cover layer and the bottom layer. The cover layer <NUM> is a continuous circular sheet that forms a gas impermeable cover over a center opening <NUM> of the base layer. The cover layer prevents gas, liquids and solids from entering the puncture wound <NUM> through the openings <NUM>, <NUM> in the base and intermediate layers.

The opening <NUM> in the base layer may be circular, oval, curvilinear in shape, rectangular or have some other shape. The diameter or other dimension from one side of the opening <NUM> to the other may be one inch, one and one-half inches, two inches, two and one-half inches or other diameter selected to extend around the wound or anticipated wound dimensions. The opening <NUM> should be centered on the wound <NUM> when the dressing <NUM> is applied to the skin on the chest of the patient. The opening <NUM> may have an area sufficiently greater than the puncture so that the edges of the puncture are not coated with the adhesive of the dressing. The opening <NUM> allows air in the pleura space to vent from the wound and through the opening.

The cover layer <NUM> overlaps and covers the opening <NUM> in the base layer. The cover layer <NUM>, intermediate layer <NUM> and base layer <NUM> are fused together such that atmospheric air cannot pass through the layers and that air from the wound can vent through air channels described below. The cover, intermediate and base layers may be transparent or translucent to allow the wound and skin below the dressing <NUM> to be viewed while the dressing is applied to the skin.

The intermediate layer <NUM> includes an opening <NUM> which may have the same diameter or dimensions as the diameter or dimensions of the opening <NUM> in the base layer. The inner edges <NUM> of the intermediate layer <NUM> and base layer <NUM> form the perimeter of the openings <NUM>, <NUM>.

The outer diameter <NUM> of the intermediate layer <NUM> may be in a range of three to four inches, e.g., <NUM> inch. The outer diameter <NUM> of the cover layer <NUM> may be in a range of <NUM> inch to <NUM> inch. The diameter <NUM> of the cover layer is smaller than the diameter <NUM> of the intermediate layer <NUM> by, for example, one half of an inch or in range of <NUM> to <NUM> percent less than the outside diameter <NUM> of the intermediate layer.

The circular disc cover layer <NUM>, intermediate layer(s) <NUM> and the base layer <NUM> are fused together along a fusing template <NUM> that defines the regions of the layers that are fused. Several different methods of fusion may be used to fuse the layers <NUM>, <NUM> and <NUM>. One method of fusing the layers is by welding, e.g., fusing, the layers together with energy such as heat, radio frequencies (RF), other electromagnetic frequencies, and ultrasonic pressure frequencies, such as frequencies in a range of <NUM> to <NUM>. The fused areas are permanent and highly durable. The fusion creates molecular bonds, e.g., fusion, between the layers <NUM>, <NUM>, <NUM>.

The intermediate layer(s) <NUM> provide added thickness, strength and firmness to an annular region surrounding the opening <NUM> in the base layer. The cover layer <NUM> may be thin and flexible to easily deform, e.g., move up and down, due to a pressure difference between atmospheric pressure and the pressure of the puncture wound, e.g., the pressure in the pleural space. As the cover layer deflects upward due to air being pushed out of the puncture wound, the cover layer <NUM> pulls on the intermediate layer <NUM>. The intermediate layer <NUM> distributes the force applied by the cover layer to the base layer <NUM> to a larger area than only the annular overlap between the cover layer and the base layer. This distribution of force over the larger area of the intermediate layer reduces the concentration of force applied to the base layer and the adhesive between the base layer and the skin around the wound. Reducing the concentration of forces applied to the base layer and adhesive, reduces the tendency of the adhesive to pull away from the skin and form unwanted air channels between the adhesive and the skin.

Fusing the layers is performed simultaneously on all of the layers <NUM>, <NUM> and <NUM>. This one step fusing reduces time and costs in forming the medical dressing <NUM>. The fusion step simultaneously joins the circular disc cover layer <NUM> to the intermediate layer <NUM> and the intermediate layer <NUM> to the base layer <NUM>. If there are multiple intermediate layers, the one step of fusion will also join these intermediate layers together. The energy provided by the fusion tool is sufficient to fuse the layers <NUM>, <NUM> and <NUM> together are the locations on the layers corresponding to the welding tool.

A fusion template <NUM>, e.g., heating template, defines the locations where the layers <NUM>, <NUM>, <NUM> are fused together by a heating element or other tool that fuses the layers together in the area defined by the template. The template <NUM> is a pattern which illustrates the areas of the layers that are fused together. All of the layers <NUM>, <NUM> and <NUM> are fused together at the areas of the template <NUM>. The template <NUM> may be an annular pattern arranged to fuse the layers together and provide air channels <NUM> between the cover layer <NUM> and the intermediate layer <NUM>. To provide for the air channels <NUM>, the template <NUM> has slots <NUM> so that energy is not applied to the portion of the layers which form the air channels and thus the layers are not fused in the area corresponding to the slots <NUM>.

The template <NUM> includes a generally annular first region <NUM> that overlaps the cover layer <NUM> and extends radially outward to just short of the outer diameter <NUM> cover layer <NUM>. The outer radial edge <NUM> of the first region may be at or about <NUM>/<NUM> inch inward of the outer edge <NUM> of the cover layer <NUM>. The first region <NUM> may have a width of in a range of <NUM>/<NUM> to <NUM>/<NUM> of the diameter <NUM> of the cover layer <NUM>. The first region <NUM> seals the layers <NUM>, <NUM> and <NUM> together in a contiguous annular ring interrupted by the slots <NUM>. The first region <NUM> may be sufficient to fuse the layers together such that the regions of the template radially outward of the first region are optional.

The template <NUM> may also have a generally annular second region <NUM>, which is optional. The second region includes fingers <NUM> which extend in a radial direction out from the first region. The second region seals the intermediate later to the base layer <NUM> at regions radially aligned with the slots <NUM>. The fingers extend over the intermediate layers to fuse the intermediate layers to the base layer. The fingers seal the inner later to the base layer in an annular region of the intermediate layer that is radially beyond the cover layer.

The second region also includes bridges <NUM> which are regions radially aligned with the slots <NUM> and the bridges extend transverse to a radial line across the slot. The bridges <NUM> seal the inner layer to the base layer to prevent air channels <NUM> formed by the slots <NUM> and between the intermediate layer <NUM> and the base layer <NUM>. The bridges are optional. Without the bridges, air channels could be formed between the intermediate and base layers, as well as between the cover layer and the intermediate layer. Gaps <NUM> in the template are between adjacent fingers or between a finger and an adjacent bride. The fingers <NUM> and bridges <NUM> secure the intermediate layer to the base layer at regions between these layers that are radially outward of the outer circumference of the cover layer <NUM>. Thus, the fingers and bridges assist in distributing radially outward the force between the cover and intermediate layers due to air being vented from the puncture wound.

The fingers <NUM> may have uniform dimensions and shapes such that all fingers have the same shape and size. The fingers may have a substantially rectangular shape when viewed from above, except that the sides of each finger may be aligned along racial lines and thus diverge slightly as the finger extends radially outward. The length along a radial direction of each finger may be in a range of <NUM> to <NUM> inch. Each finger <NUM> may have radially inward end that mergers with the first annular region <NUM> of the template <NUM> and be substantially aligned with the outer edge <NUM> of the cover layer. Each finger may extend from the outer edge <NUM> of the cover layer over the intermediate layer, and a short distance, e.g., <NUM> to <NUM> inch, past the outer edge <NUM> of the intermediate layer. Each finger may have a width in an arc direction of <NUM> to <NUM> inch at its greatest width. The width of each finger may increase <NUM>% to <NUM>% in a radial direction along its length.

The bridges <NUM> may each have a width in an arc direction in a range of <NUM> to <NUM> inch and a length of <NUM> to <NUM> inch, which is substantially the same length as the fingers. The width of the slot <NUM> in each bridge may be <NUM> to <NUM> inch. The slot extends radially entirely through the inner annular ring <NUM> and beyond the edge <NUM> of the cover layer to <NUM> to <NUM>% of the radial distance between the edge of the cover layer and the edge <NUM> of the inner layer. This distance may be in a range of <NUM> to <NUM> inch. Further, there may be two or three fingers for each bridge and slot arrangement. The ratio of length to width of the slots may be selected to balance the needs to prevent air or blood entering the wound through the channel, allowing air and blood to vent from the wound and reducing the risk that the air channel becomes clogged with blood or other material. A ratio length to width in a range of <NUM> to <NUM>, such as <NUM>, may be optimal for balancing these needs.

The air channels <NUM> each define air passages extending between the cover layer <NUM> and the intermediate layer <NUM> that exhausts to the atmosphere at the outer edge <NUM> of the cover layer. The air channels <NUM> have a radially inward entrance at an annular region <NUM> between the cover and intermediate layers, and radially inward of the welded area corresponding to the template <NUM>.

When gases and liquid, e.g., air and blood, flow out of the wound and into the gap between the skin and the cover layer, the pressure of these gases and liquids is greater than atmospheric air. This pressure deforms the cover layer away from the skin which opens the annular region <NUM> and the air channels <NUM> to allow the gasses and liquids to flow away from the wound and out through the dressing <NUM>. When the pressure between the wound and the cover layer drops, atmospheric pressure pushes the cover layer against the intermediate layer and closes the air channels <NUM> and the annular region <NUM>.

The number of air channels <NUM> may be five, six or more. Because of the large number of air channels, one or more of the air channels may clog, such as with blood, while other air channels continue to expand and allow venting of air from the chest wound. The width and length of each air channel, such as the radial length of the slot <NUM>, may be selected to be sufficiently long and narrow to ensure that the passage collapses and prevents air conveyance when the air pressure at the wound is at or below atmospheric pressure. A competing and contrary requirement is that the air channel should be short and wide to avoid being clogged with blood and debris and to air readily vent from the wound with minimal resistance due to the air channel. Balancing these competing requirements is preferred to achieve an optimal air channel.

As shown in <FIG>, the front surface (skin side) of the base layer <NUM> is configured to face a chest of a patient. The back surface of the base layer is opposite the front surface and is fused to the intermediate layer <NUM>. The front surface is substantially coated in its entirety with an adhesive layer <NUM>. The adhesive layer includes an outer edge <NUM> and an inner edge <NUM>. The inner edge is radially outward of the inner edges <NUM> of the base layer and the intermediate layer due to an annular ring <NUM> on the front surface of the base layer.

The adhesive layer <NUM> may be a biocompatible adhesive disposed for securing the dressing <NUM> to a patient's skin. Suitable adhesives for adhering the flange body to the patient's skin include hydro gel, acrylic, silicone gel, silicone PSA or hydrocolloid. The adhesive layer <NUM> may include a substrate layer that is coated on both sides with adhesives. The substrate provides support for the adhesives.

A release liner (membrane) <NUM> covers the adhesive layer <NUM> until the medical dressing <NUM> is to be applied to the skin of the chest. Immediately before the medical dressing <NUM> is applied to the skin, the release liner <NUM> is peeled from the dressing adhesive layer <NUM>. The exposed adhesive layer and the rest of the medical dressing are applied to the skin as the dressing is pressed to the skin. The dressing is applied such that the opening <NUM> is centered on the wound <NUM>.

An inner annular ring <NUM> on the front surface of the base layer is devoid of adhesive and extends from the outer perimeter of the opening <NUM> to the inner edge of the adhesive layer <NUM>. The inner annular ring <NUM> assists in preventing adhesive from creeping around the edge of the opening <NUM> and between the cover layer <NUM> and intermediate layer <NUM>. Such adhesive creep could seal one or more of the air channels <NUM>. The inner annular ring <NUM> may have a width (from the opening to the adhesive layer) of one-eighth of an inch to one-quarter of an inch. The annular inner ring is a region of the base layer, but alternatively may be a structural ring having minimal height, e.g., less than one-eighth of an inch.

An outer annular ring <NUM> on the front surface (skin side) of the base layer <NUM> is also devoid of adhesive <NUM>. The outer annular ring may have a width of <NUM> to <NUM> of an inch, such as <NUM> inch. The annular perimeter region may assist in preventing adhesive from creeping from between the intermediate layer and the cover layer, and limits contact between the adhesive and potential contaminants that may be present around the application area. The outer annular ring <NUM> also facilitates dressing <NUM> removal by providing a lip that can be grasped to pull the dressing off the skin.

A rectangular tab <NUM> on the front side of the base layer main and the adhesive layer provides a grip for removing the medical dressing from the skin. A back surface of the tab <NUM> may adhere to the adhesive layer, and the front side may be a non-adhesive coating or layer that does not adhere to the skin or to the release liner <NUM>.

<FIG> illustrates a manufacturing process for fusing, e.g., welding, together the base layer <NUM>, the intermediate layer <NUM> and the cover layer <NUM>. These layers are assembled by placing the base layer on a flat substrate <NUM>, e.g. metal table. The intermediate layer is laid on the base layer and the cover layer is laid on the intermediate layer. Alternatively, the base, intermediate and cover layers may be placed as an assembly on the substrate <NUM>. The layers <NUM>, <NUM>, <NUM>, are brought together such that the openings <NUM> and <NUM> of the based and intermediate layers are aligned, and the cover layer is centered on these openings. A heating or ultrasonic tool <NUM> moves towards the layers and presses the layers between the tool and the substrate. A front surface of the tool in contact with the layers, e.g., the cover layer, has a shape corresponding to the template <NUM>. A source of heat or ultrasonic energy <NUM> applies the energy to the front surface of the tool to cause the layers to be fused together at the areas corresponding to the template. Alternatively, other types of energy may be applied to the layers, such as radio frequencies welding and laser through-transmission welding, or other modes of welding such as chemical adhesives may be used to join the base, intermediate and cover layers in the designed pattern.

After the layers are fused together, the adhesive layer <NUM> may be applied to the side of the base layer not facing the intermediate layer. The release liner <NUM> is applied to the adhesive layer, if not already applied when the adhesive layer is applied to the base layer, to complete the wound dressing <NUM>. The completed wound dressing <NUM> may be enclosed in a package, such as an airtight package, for safe keeping until the wound dressing is needed to treat a wound.

Claim 1:
A medical dressing comprising:
a flexible base layer including a front surface configured to face a skin of a patient and a back surface opposite the front surface, wherein the flexible base layer includes a first opening;
an adhesive layer on the front surface of the base layer wherein the adhesive layer extends entirely around the opening;
a flexible cover layer entirely covering the opening of the base layer;
a flexible intermediate layer sandwiched between the base layer and the cover layer, wherein the intermediate layer includes a second opening aligned with the first opening; and
an annular pattern joining the base layer and intermediate layer entirely around the first and second openings and the pattern joins the cover layer, intermediate layer and base layer around the first and second openings except at slots extending beyond an outer edge of the cover layer and ending before an outer edge of the intermediate layer.