Patent Publication Number: US-2022218533-A1

Title: Medical dressing to treat sucking chest wound

Description:
TECHNICAL FIELD 
     This invention relates to a medical dressing for treating open chest injuries or other injuries that may expose the pleural space or chest cavity. 
     BACKGROUND 
     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 U.S. Pat. No. 10,639,207, 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. 
     BRIEF DESCRIPTION 
     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 may be embodied as 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. 
     The invention may be embodied as 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 and overlapping at least a portion of the main membrane; 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 a 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. 
     The invention may be embodied as a method to form a medical dressing comprising: overlaying a cover layer on an intermediate layer and the intermediate layer on a base layer such that openings in the intermediate and base layers are aligned and the cover layer overlays the openings; fusing together the cover layer, the intermediate layer and the base layer by applying an annular welding tool face to at least one of the cover layer and base layer and applying welding energy to the template, wherein the annular tool face extends entirely around the first and second openings and fuses the base layer to the intermediate layer entirely around the first and second openings and fuses the cover layer, intermediate layer and base layer around the first and second openings except slots extend beyond an outer edge of the cover layer and end before an outer edge of the intermediate layer, and applying an adhesive layer on a side the base layer opposite to the intermediate layer, wherein the adhesive layer extends entirely around the opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a view of a patient with a medical dressing applied to the lower chest or abdomen. 
         FIG. 2  is a top view of the medical dressing. 
         FIG. 3  is an exploded view of the medical dressing showing the layers of the dressing. 
         FIG. 4  is a bottom view of the medical dressing. 
         FIG. 5  is a perspective view of the bottom of the medical dressing, showing the release liner partially peeled from the base layer. 
         FIG. 6  illustrates a method for fusing the base, intermediate and cover layers. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  shows a patient  100  with a chest wound, such as a puncture  102  that extends through the chest wall. The puncture  102  may allow air to flows from the atmosphere into the pleural space  104 . The air entering the pleural space can increase the pressure in the space and thereby collapse the lung(s)  106 . 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  10  is applied to the chest puncture  102 . The dressing is applied such that the puncture  102  is aligned with the center of the dressing  10 . 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  102  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  102  while also allowing air to vent from the puncture and to the atmosphere. A second medical dressing  10  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. 2  shows a top view of the medical dressing  10 , and  FIG. 3  shows an exploded view of the layers of the medical dressing  10 . 
     The principal layers of the medical dressing  10  are a base layer  12 , an annular intermediate layer(s)  14  and a circular disc cover layer  16 . Each of these principal layers may be formed of a polyurethane (PU) sheet having a thickness of 10 mils to 5 mils. The base layer member  12  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  16  is the upper layer of the dressing  10 , the base layer  12  is the bottom layer and the intermediate layer(s)  14  are sandwiched between the disc cover layer and the bottom layer. The cover layer  16  is a continuous circular sheet that forms a gas impermeable cover over a center opening  18  of the base layer. The cover layer prevents gas, liquids and solids from entering the puncture wound  102  through the openings  18 ,  20  in the base and intermediate layers. 
     The opening  18  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  18  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  18  should be centered on the wound  102  when the dressing  10  is applied to the skin on the chest of the patient. The opening  18  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  18  allows air in the pleura space to vent from the wound and through the opening. 
     The cover layer  16  overlaps and covers the opening  18  in the base layer. The cover layer  16 , intermediate layer  14  and base layer  12  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  10  to be viewed while the dressing is applied to the skin. 
     The intermediate layer  14  includes an opening  20  which may have the same diameter or dimensions as the diameter or dimensions of the opening  18  in the base layer. The inner edges  21  of the intermediate layer  14  and base layer  12  form the perimeter of the openings  18 ,  20 . 
     The outer diameter  22  of the intermediate layer  14  may be in a range of three to four inches, e.g., 3.5 inch. The outer diameter  24  of the cover layer  16  may be in a range of 2.5 inch to 3.5 inch. The diameter  24  of the cover layer is smaller than the diameter  22  of the intermediate layer  14  by, for example, one half of an inch or in range of 12 to 17 percent less than the outside diameter  22  of the intermediate layer. 
     The circular disc cover layer  16 , intermediate layer(s)  14  and the base layer  12  are fused together along a fusing template  26  that defines the regions of the layers that are fused. Several different methods of fusion may be used to fuse the layers  12 ,  14  and  16 . 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 10 to 100 MHz. The fused areas are permanent and highly durable. The fusion creates molecular bonds, e.g., fusion, between the layers  12 ,  14 ,  16 . 
     The intermediate layer(s)  14  provide added thickness, strength and firmness to an annular region surrounding the opening  18  in the base layer. The cover layer  16  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  16  pulls on the intermediate layer  14 . The intermediate layer  14  distributes the force applied by the cover layer to the base layer  12  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  12 ,  14  and  16 . This one step fusing reduces time and costs in forming the medical dressing  10 . The fusion step simultaneously joins the circular disc cover layer  16  to the intermediate layer  14  and the intermediate layer  14  to the base layer  12 . 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  12 ,  14  and  16  together are the locations on the layers corresponding to the welding tool. 
     A fusion template  26 , e.g., heating template, defines the locations where the layers  12 ,  14 ,  16  are fused together by a heating element or other tool that fuses the layers together in the area defined by the template. The template  26  is a pattern which illustrates the areas of the layers that are fused together. All of the layers  12 ,  14  and  16  are fused together at the areas of the template  26 . The template  26  may be an annular pattern arranged to fuse the layers together and provide air channels  28  between the cover layer  16  and the intermediate layer  14 . To provide for the air channels  28 , the template  26  has slots  30  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  30 . 
     The template  26  includes a generally annular first region  32  that overlaps the cover layer  16  and extends radially outward to just short of the outer diameter  24  cover layer  16 . The outer radial edge  34  of the first region may be at or about 1/16 inch inward of the outer edge  54  of the cover layer  16 . The first region  32  may have a width of in a range of 1/16 to 1/10 of the diameter  24  of the cover layer  16 . The first region  32  seals the layers  12 ,  14  and  16  together in a contiguous annular ring interrupted by the slots  30 . The first region  34  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  26  may also have a generally annular second region  36 , which is optional. The second region includes fingers  38  which extend in a radial direction out from the first region. The second region seals the intermediate later to the base layer  12  at regions radially aligned with the slots  30 . 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  40  which are regions radially aligned with the slots  40  and the bridges extend transverse to a radial line across the slot. The bridges  40  seal the inner layer to the base layer to prevent air channels  28  formed by the slots  30  and between the intermediate layer  14  and the base layer  12 . 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  41  in the template are between adjacent fingers or between a finger and an adjacent bride. The fingers  38  and bridges  40  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  16 . 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  38  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 0.3 to 0.5 inch. Each finger  38  may have radially inward end that mergers with the first annular region  32  of the template  26  and be substantially aligned with the outer edge  54  of the cover layer. Each finger may extend from the outer edge  54  of the cover layer over the intermediate layer, and a short distance, e.g., 0.1 to 0.2 inch, past the outer edge  56  of the intermediate layer. Each finger may have a width in an arc direction of 0.2 to 0.25 inch at its greatest width. The width of each finger may increase 20% to 40% in a radial direction along its length. 
     The bridges  40  may each have a width in an arc direction in a range of 1.0 to 1.4 inch and a length of 0.3 to 0.5 inch, which is substantially the same length as the fingers. The width of the slot  30  in each bridge may be 0.25 to 0.5 inch. The slot extends radially entirely through the inner annular ring  46  and beyond the edge  54  of the cover layer to 0.5 to 0.8% of the radial distance between the edge of the cover layer and the edge  56  of the inner layer. This distance may be in a range of 0.15 to 0.25 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 2 to 8, such as 4, may be optimal for balancing these needs. 
     The air channels  28  each define air passages extending between the cover layer  16  and the intermediate layer  14  that exhausts to the atmosphere at the outer edge  54  of the cover layer. The air channels  28  have a radially inward entrance at an annular region  58  between the cover and intermediate layers, and radially inward of the welded area corresponding to the template  26 . 
     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  58  and the air channels  28  to allow the gasses and liquids to flow away from the wound and out through the dressing  10 . 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  28  and the annular region  58 . 
     The number of air channels  28  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  30 , 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  FIGS. 4 and 5 , the front surface (skin side) of the base layer  12  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  14 . The front surface is substantially coated in its entirety with an adhesive layer  42 . The adhesive layer includes an outer edge  43  and an inner edge  45 . The inner edge is radially outward of the inner edges  19  of the base layer and the intermediate layer due to an annular ring  46  on the front surface of the base layer. 
     The adhesive layer  42  may be a biocompatible adhesive disposed for securing the dressing  10  to a patient&#39;s skin. Suitable adhesives for adhering the flange body to the patient&#39;s skin include hydro gel, acrylic, silicone gel, silicone PSA or hydrocolloid. The adhesive layer  42  may include a substrate layer that is coated on both sides with adhesives. The substrate provides support for the adhesives. 
     A release liner (membrane)  44  covers the adhesive layer  42  until the medical dressing  10  is to be applied to the skin of the chest. Immediately before the medical dressing  10  is applied to the skin, the release liner  44  is peeled from the dressing adhesive layer  42 . 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  18  is centered on the wound  102 . 
     An inner annular ring  46  on the front surface of the base layer is devoid of adhesive and extends from the outer perimeter of the opening  18  to the inner edge  43  of the adhesive layer  42 . The inner annular ring  46  assists in preventing adhesive from creeping around the edge of the opening  18  and between the cover layer  16  and intermediate layer  14 . Such adhesive creep could seal one or more of the air channels  28 . The inner annular ring  46  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  48  on the front surface (skin side) of the base layer  12  is also devoid of adhesive  42 . The outer annular ring extends from the outer edge  49  of the adhesive layer  42  to the outer wedge of the base layer  12 . The outer annular ring may have a width of 0.3 to 0.7 of an inch, such as 0.5 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  48  also facilitates dressing  10  removal by providing a lip that can be grasped to pull the dressing off the skin. 
     A rectangular tab  50  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  50  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  44 . 
       FIG. 6  illustrates a manufacturing process for fusing, e.g., welding, together the base layer  12 , the intermediate layer  14  and the cover layer  16 . These layers are assembled by placing the base layer on a flat substrate  60 , 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  60 . The layers  12 ,  14 ,  16 , are brought together such that the openings  18  and  20  of the based and intermediate layers are aligned, and the cover layer is centered on these openings. A heating or ultrasonic tool  62  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  26 . A source of heat or ultrasonic energy  64  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  42  may be applied to the side of the base layer not facing the intermediate layer. The release liner  44  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  10 . The completed wound dressing  10  may be enclosed in a package, such as an airtight package, for safe keeping until the wound dressing is needed to treat a wound. 
     While at least one exemplary embodiment of the present invention(s) is disclosed herein, it should be understood that modifications, substitutions and alternatives may be apparent to one of ordinary skill in the art and can be made without departing from the scope of this disclosure. This disclosure is intended to cover any adaptations or variations of the exemplary embodiment(s). In addition, in this disclosure, the terms “comprise” or “comprising” do not exclude other elements or steps, the terms “a” or “one” do not exclude a plural number, and the term “or” means either or both. Furthermore, characteristics or steps which have been described may also be used in combination with other characteristics or steps and in any order unless the disclosure or context suggests otherwise. This disclosure hereby incorporates by reference the complete disclosure of any patent or application from which it claims benefit or priority.