Patent Publication Number: US-2012046582-A1

Title: Chest seal bandage and other medical devices for night use

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of the filing date of U.S. Provisional Patent Application Ser. No. 61/401,643, filed Aug. 17, 2010. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to medical devices such as a medical bandage or dressing for treating open chest wounds and other injuries, and to use of such medical devices in darkness. 
     An open pneumothorax occurs when air is able to enter the chest cavity surrounding the lungs through an open chest wound, such as may be sustained as a result of being stabbed or shot. The admission of air into the chest cavity through a wound in this manner inhibits the normal breathing process and so can be life threatening. 
     Standard treatment for an open pneumothorax is to cover the wound with an occlusive dressing which is taped to the patient&#39;s skin along all sides so as to seal the wound and prevent air from entering the chest cavity through the wound. If the wound is effectively sealed then normal breathing can be restored. However, if the seal is not perfect, more air may be drawn into and trapped in the chest cavity, causing an increase in pressure inside the chest cavity. This is known as a tension pneumothorax and is a potentially more serious condition which can quickly lead to respiratory and heart failure. 
     Tension pneumothorax can also occur if the patient has suffered a punctured lung, as air can escape from the lung through the puncture into the chest cavity each time the patient breathes. If the open chest wound has been sealed, the air entering the chest cavity through the lung puncture is trapped and the pressure inside the chest cavity rises, forcing the lung to collapse. Once the lung has collapsed, the pressure in the chest cavity will increase further so that the collapsed lung is pressed against the heart and the other lung. The blood flow from the heart to the lungs may be stopped if the pressure in the chest cavity increases above normal blood pressure. 
     Treatment of a tension pneumothorax with an open wound typically comprises using an occlusive dressing which is taped along only three sides so that pressurized air in the chest cavity can escape through an open fourth side. However, the conditions in which such wounds are typically first treated make the successful application of this type of dressing difficult to achieve in practice. 
     Chest seal dressings including one-way valves to promote escape of fluids, including air, from a punctured chest are disclosed in, for example, Kauth et al. U.S. Pat. No. 7,429,687. 
     In battlefield conditions such as may be found in the Middle East, sand carried by the wind of sandstorms, or generated by helicopter rotor wash or raised by machinery movements, may contaminate a one-way valve in known chest seal dressings, preventing complete valve closure and allowing air or sand to enter the chest cavity. 
     Some previously known chest seal bandages are of transparent material. In battlefield conditions at night correct placement of such chest seal bandages is difficult without use of illumination by visible light which may attract enemy attention. While they are not transparent, other medical articles such as splints are also difficult to use most advantageously without illumination by visible light. 
     It is somewhat awkward to place currently used chest seal bandages into a preferred location to treat an open chest wound, although some such bandages do include a handle in the form of an ear at an end or corner of such a dressing. 
     There is a need, therefore, for an improved medical dressing particularly for an open chest wound, which overcomes or at least mitigates the problems of the prior art arrangements. 
     In particular, there is a need for an improved medical dressing having a one-way valve for occluding an open chest wound while permitting pressurized air and/or other fluids to pass out of the chest cavity, and which can be made fully occlusive and able to fully exclude airborne contaminants such as sand, and there is also a need for such a dressing , as well as other medical appliances, that can be used efficiently in low-light conditions. 
     SUMMARY OF THE INVENTION 
     A chest seal dressing as disclosed herein provides answers to the afore-mentioned needs. 
     In accordance with a first aspect of the invention, there is provided a medical dressing in the form of a chest seal bandage, the dressing including a one-way valve assembly that can be mounted over a wound in a patient, the valve assembly having a valve body defining a passage through the body, the valve assembly further comprising a valve member configured to permit air and/or other fluids to flow through the passage in an outward direction of the valve so that, in use, air and/or other fluids are able to exit the wound through the passage but are prevented from entering the wound through the passage; and the dressing also comprises a closure member for selectively covering the one way valve assembly, occluding it and preventing entry of sand or other airborne contaminants into the valve and thus preventing such contaminants from reaching the wound. 
     In one embodiment the dressing includes a flexible outer panel or sheet of material having an inner surface and an outer surface and defining an opening therethrough, the panel having an adhesive on the inner surface for attaching the panel to the skin of the patient, and the one-way valve is carried on the flexible panel, aligned with the opening through the panel. 
     When the closure member mentioned above is in a functioning position, the passage through the valve body is sealed, and the dressing acts as an occlusive dressing which prevents air from entering or leaving the patient&#39;s chest cavity through the wound. The closure member protects both the valve assembly and the wound against airborne contaminants such as sand and dust. 
     In a medical dressing or chest seal bandage in accordance with the first aspect of the invention, the closure member can be removed to allow operation of the one-way valve assembly. The passage can thus be opened up to enable pressurized air and/or other fluids to exit from the wound through the passage. 
     As another aspect of the invention the chest seal medical wound dressing disclosed herein may include a handling tab at each of a pair of opposite ends of the flexible panel or sheet of material, to improve the convenience of holding the dressing while placing it into a required position on a patient. 
     As another aspect of the invention such a medical wound dressing may include an easily identifiable marking on one of the handling tabs to improve visibility of the dressing in conditions of low levels of ambient light. 
     As another aspect of the invention a pattern of markings may be provided over a large area of a flexible panel of a medical wound dressing such as a chest seal bandage to facilitate seeing the dressing while applying it to a patient in conditions of low levels of ambient light. 
     As another aspect of the invention an area of a material highly reflective of infrared light may be provided on a medical wound dressing such as the chest seal bandage to enable the dressing to be seen using night vision equipment and a source of infrared illumination. 
     As another aspect of the invention a marking visible with night vision equipment may be provided on the one-way valve assembly. 
     As yet another aspect of the invention an area of material highly reflective of light may be provided on a medical wound dressing such as a chest seal bandage, covered by a layer of material blocking transmission of visible light yet allowing passage of infrared light, so that the highly reflective material is clearly visible using night vision goggles and infrared illumination, but is invisible without such infrared illumination. 
     As yet a further aspect of the invention an area of material that is luminescent in a selected range of light wavelengths in response to being exposed to light energy of a required wavelength may be provided on a medical wound dressing to facilitate visibility of the dressing at night. 
     As another aspect of the invention such markings that are visible using night vision equipment and a light source in a related frequency range may be provided on other medical appliances and equipment to facilitate their safe use in combat situations during darkness. For example such night vision markings can be provided on splints, tourniquets, slings, gloves, gauze, tape, IV equipment, and cricothyrotomy utensils. 
     The foregoing and other features of the invention will be more readily understood upon consideration of the following detailed description of the invention taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL DRAWINGS 
         FIG. 1  is an isometric view of a chest seal bandage that is one embodiment of the invention disclosed herein. 
         FIG. 2  is an exploded isometric view of the chest seal bandage shown in  FIG. 1 . 
         FIG. 3A  is a sectional view of a valve incorporated in the bandage shown in  FIGS. 1 and 2 . 
         FIG. 3B  is a view at an enlarged scale of a detail of  FIG. 3A . 
         FIGS. 4A ,  4 B,  4 C, and  4 D are isometric views of the valve base portion of the chest seal bandage shown in  FIGS. 1 and 2 . 
         FIGS. 5A ,  5 B,  5 C,  5 D, and  5 E are views of the valve top member portion of the chest seal bandage shown in  FIGS. 1 and 2 . 
         FIG. 6  is an isometric view of the flexible valve closure member or diaphragm of the chest seal bandage shown in  FIGS. 1 and 2 . 
         FIGS. 7A ,  7 B,  7 C,  7 D, and  7 E are views of a dome-shaped cover portion of the chest seal bandage shown in  FIGS. 1 and 2 . 
         FIGS. 8A ,  8 B,  8 C,  8 D,  8 E, and  8 F are views of a chest seal bandage that is an alternative embodiment of the chest seal bandage shown in  FIGS. 1 and 2 , and that includes a dome-shaped cover that can be twisted to open or occlude a valve. 
         FIG. 9A  is a top plan view of a chest seal bandage similar to a portion of the chest seal bandage shown in  FIG. 1  and  FIG. 2 , but without a one-way valve assembly. 
         FIG. 9B  is an exploded view of the chest seal bandage shown in  FIG. 9A . 
         FIG. 10A  is an isometric view in humanly visible light of a bandage similar to that shown in  FIG. 9A , showing indicia thereon to provide enhanced visibility at night. 
         FIG. 10B  is a view similar to  FIG. 10A  showing the bandage as it would appear illuminated by near infrared light and viewed using appropriate night vision equipment. 
         FIG. 10C  is a sectional view at an enlarged scale taken along line  10 C- 10 C of  FIG. 10A . 
         FIG. 10D  is an isometric view of a bandage similar to that shown in  FIG. 10A , but with a different arrangement of night vision indicia. 
         FIG. 11A  is an isometric view of a one-way valve assembly and a dome-like cover attached to the valve assembly by a flexible member. 
         FIG. 11B  is an isometric view of the valve assembly shown in  FIG. 11A  with the dome-like cover in place and occluding the valve assembly. 
         FIG. 12  is a partially cutaway side elevational view of a valve assembly equipped with a cover mounted on a center post arrangement. 
         FIG. 12A  is an exploded sectional detail view of a latching arrangement for the center post shown in  FIG. 12 . 
         FIG. 13A  is an exploded isometric view of a valve assembly in which a valve top part can be attached to the valve base portion by the use of threads, and in which the valve top portion includes a hinged cover. 
         FIG. 13B  is an isometric view of the valve shown in  FIG. 13A  with the cover shown in an open position. 
         FIG. 13C  is an isometric view of a valve similar to that shown in  FIGS. 13A and 13B , with an adhesively attached removable cover shown in place. 
         FIG. 13D  is a view similar to  FIG. 13C , but with the cover partially peeled back. 
         FIG. 14  is an isometric view of a top member including a pair of hinged covers, for use in a valve assembly such as the one shown in  FIG. 13A . 
         FIG. 14A  is an exploded, partially cutaway view of a valve assembly including the top member shown in  FIG. 14 . 
         FIG. 15  is an isometric view of an emergency orthopedic splint including night vision indicia. 
         FIG. 16  is an isometric view of a tourniquet including night vision indicia. 
         FIG. 17  is an isometric view of a device for emergency support of an injured pelvis, including night vision indicia. 
         FIG. 18  is a view of a surgical glove including night vision indicia. 
         FIG. 19  is an isometric view of a spool of tape including night vision indicia. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to  FIGS. 1 through 7E , a first embodiment of a medical dressing in the form of a chest seal bandage  10  includes a flexible base sheet, or panel,  12  and a one-way valve assembly  14  mounted on the panel. The panel  12  has an opening  12   a,  which is preferably located centrally of the panel, and the valve assembly  14  is mounted to the panel  12  in alignment with and covering the opening  12   a.    
     The flexible panel  12  may be a thin sheet of flexible material of an appropriate shape. As illustrated in the present embodiment the panel  12  in the chest seal bandage  10  is generally ellipsoid in shape, with a pair of opposite ends  13  of rounded triangular shape. It will be appreciated that the actual shape of the panel is not essential to the invention. The panel  12  can be of any suitable shape for a dressing intended for a particular type of use, and could be rectangular or circular, for example. 
     The panel  12  can be made of any medically suitable flexible sheet material which can occlude the wound. For example, the panel  12  can be made from a film of polyurethane or polyethylene. The panel  12  is preferably made of a transparent or at least translucent material for use in a chest seal bandage, but this is not essential. As an example, the panel  12  may be of a transparent polyurethane film having a thickness of about 0.002 in (0.05 mm) 
     The panel  12  has an inner surface  16  intended to face toward a patient, and an outer surface  18 . The inner surface  16  is covered with a layer of an adhesive  17  to enable the panel  12  to be adhered to the skin of a patient about an open chest wound. When the dressing  10  is applied, it is likely that the patient&#39;s skin in the region of the wound will be covered in blood, sweat and other contaminants such as oil and the like and may also be covered in hair. The skin surrounding the wound should ideally be cleaned prior to applying the dressing  10  but cleaning may not be totally effective, particularly if the dressing  10  is being applied in battlefield conditions. It is important, therefore, that the adhesive  17  used enables the panel to be firmly attached all the way around the wound, even where the skin is not thoroughly cleaned. 
     Any suitable adhesive can be used but the adhesive  17  will typically be a pressure sensitive adhesive that is transparent or translucent, such as an acrylic adhesive, in a thin layer. A relatively thick layer  17   a  of an additional adhesive, such as an aggressive hydrogel or a hydrocolloid gel, both of which have a good wet tack capability and so are able to adhere to damp skin and retain their tackiness over time, may also be provided, covering the layer of adhesive  17  covering the inner surface  16  of the panel  12  to a uniform thickness. Alternatively, the layer  17   a  of hydro gel or hydrocolloid might not extend to the outer perimeter of the panel  12 , so as to leave the adhesive  17  exposed along a peripheral border portion  16   a  of the surface  16 . This results in a panel  12  which when adhered to the skin presents a lower profile at the edges and therefore would be less likely to roll up and be detached from the skin. The border portion  16   a  may extend inwardly for about 5 to 10 mm, for example, along the outer perimeter of the panel  12 . 
     The dressing  10  will usually be supplied with a non-stick, peelable, protective backing sheet  19  which covers the adhesive  17  and which can be peeled away easily when the dressing is to be applied to a person. A slender strip  19   a  of protective sheet material such as a thin plastic film may cover the margin of the adhesive  17  at each end of the dressing  10  and be overlapped by the ends of the peelable sheet  19 , to allow a margin at each end of the peelable sheet  19  to be grasped easily for removal when the dressing is to be used. 
     Handling tabs  20  of a plastic or other flexible material somewhat stiffer than the panel  12  may be positioned on and attached to the inner surface  16  by the adhesive  17  at the opposite ends  13  of the panel  12  so that the dressing  10  can be grasped at the ends of the panel  12  to remove the protective backing sheet  19  and to position the dressing over the wound. The handling tabs  20  may be of a convenient shape, such as being generally triangular with a rounded outermost corner, congruent with the ends  13  of the panel  12  so as not to catch on an object and cause the dressing  10  to be dislodged, and while they need not be as flexible as the panel  12 , they may advantageously be somewhat flexible, so as not to be subject to being easily snagged. The backing sheet  19  may overlap the handling tabs  20  slightly as an area to be grasped to remove the backing sheet  19  from the adhesive  17 . 
     The valve assembly  14  can be seen best in  FIGS. 2 through 6  and includes a valve base  22  and a valve top member  24  which together form a valve body  26 . The base  22  as shown is a generally disc shaped member having a relatively thin annular flange portion  28  surrounding a raised, thicker, central portion  30 . Arcuate valve openings  32  shaped as segments of an annulus extend through the central portion  30  between an inner ring  34  and a radially outer ring  36 . The inner ring  34  has an annular planar outer surface  35 , facing outwardly away from a wound site when the dressing  10  is in use. The arcuate valve openings  32  are arranged as a circle in the central portion  30  and are separated by radial spokes  40  which connect the inner and outer rings  34 ,  36 , and the outer ring  36  and spokes  40  all have outer surfaces that are coplanar with the surface  35 . The inner ring  34  may define a central opening  42  through the base  22 , as shown in  FIGS. 4A ,  4 C, and  4 D, but the inner ring  34  could also be smaller than shown, and the central opening  42  need not be provided. A stepped annular lip  44  projects outwardly, that is to say away from the wound site in use, from a radially inner edge of the annular outer surface  35  of the inner ring  34 , for reasons that will be discussed below. 
     Four resilient catches  45  extend outwardly from the flange  28  of the base  22  at locations spaced apart around the outer ring  36 . 
     The valve top member  24  is circular in plan view, as may be seen in  FIGS. 5A and 5D , having a centrally located, or inner, domed housing portion  46  and an outer annular flange portion  48  that extends radially outwardly from the base of the domed portion  46  to cover the annular flange portion  28  of the valve base  22 . The domed portion  46  as shown has a low cylindrical or conical annular wall region  50  at its base, a flattened upper surface  52  and a generally curved wall portion  54  between the annular wall region  50  and the upper surface. Openings  56  are spaced circumferentially about the curved wall portion  54 . The openings  56  form a fluid outlet of the valve assembly  14  as will be described in more detail later. 
     The valve top member  24  and base  22  are mated together. The inner diameter of the annular wall region  50  is about equal to the outer diameter of the raised central portion  30  of the valve base  22 , so that the central portion  30  of the base  22  is received snugly and sealingly within the domed portion  46  of the valve top member  24  when the cover and base are assembled and held together by the catches  45 . A hollow spigot  58 , seen best in  FIG. 5B , projects inwardly from the center of the flattened upper surface  52 . An annular recess  60  may be defined by the inner surface of the free end of the spigot  58  to surround and engage with the lip  44  extending from the inner ring  34  of the valve base, and an outer end portion of the annular lip  44  can be inserted into the recess  60 , optionally with an interference or snap fit to help to hold the top member  24  and the valve base  22  together. When the base  22  and the top member  24  are assembled, the flange portion  48  of the top member  24  overlies the flange portion  28  of the base  22 , and the catches  45  engage seats  62  which are located in the openings  56 , along the wall  50 , as shown, although the seats could instead be separately located. 
     The valve base  22  and the valve top member  24  may both be made from a generally rigid material, such as a rigid but resilient and not brittle polymeric plastics material. Preferably, the valve base  22  and the valve top member  24  are made from a transparent or translucent polymeric material, such as polypropylene, acetyl or other suitable synthetic plastics material with a hardness defined as for polypropylene, for example, by a tensile modulus that may be in the range of 140-210 Kpsi, or 965-1448 Mpa, and the base  22  and top member  24  may be manufactured by means of injection molding, for example. 
     A flat, annular, flexible valve member  64  shown in  FIG. 6  is fitted to the central portion  30  of the valve base  22  about the annular lip  44 . The flexible valve member  64  has an outer diameter Do which may be slightly less than the outer diameter of the raised central portion  30  of the valve base  22  and has an inner diameter Di which may be slightly larger than the outer diameter of the lip  44 , so that the valve member covers all of the valve openings  32  as well as at least a portion of each of the top surface  35  of the inner ring and of the upper, or outer, surface of the outer ring  36 . In the present embodiment, when the top member  24  is assembled to the base  22 , the annular free end of the central spigot  58  in the valve top member  24  overlies a radially inner portion of the valve member  64  to hold it in position against the annular top surface  35  of the inner ring  34  of the base. In an alternative arrangement, however, the inner diameter Di of the valve member  64  may be slightly larger than the outer diameter of the spigot  58  so that the valve member  64  is able to slide along the outer surface of the spigot  58  above the flat surface  35 . The valve member  64  is made of a flexible material, such as a flexible polymer (e.g., silicone rubber) which preferably is transparent or at least translucent and which is soft enough to seat sealingly on the spokes  40  and the inner and outer rings  34 ,  36 . 
     To mount the valve assembly  14  to the panel  12 , a layer  65  of an adhesive material as shown in  FIG. 3A , or a film  68  carrying a layer  65 ′ of an adhesive on each of its faces, as shown in broken line in  FIG. 3B , may be used to adhere the annular flange portion  28  of the base  22  to the outer surface  18  of the panel  12 , to ensure that an air-tight seal is formed between the panel  12  and the flange  28 . The valve top member  24  and the valve base  22  may be held together solely by the engagement of the catches  45  with the seats  62 , or they may also or instead be adhered together using a suitable adhesive material (not shown), or they may be welded together, for example by means of ultrasonic welding. 
     Where the base  22  and cover  24  are bonded together using adhesive or ultrasonic welding, the recess  60  and the annular lip  44  could be omitted and the inner end of the spigot  58  may have a flat surface that abuts the flat top surface  35  on the inner ring  34 . 
     With the dressing  10  assembled as described above, the arcuate openings  32  in the base  22 , the space between the base  22  and the inner surface of the valve top member  24  and surrounding the central spigot  58 , and the openings  56  in the curved wall portion of the valve top member  24  together form a passage extending through the valve body  26  as indicated by the arrows  66  in  FIGS. 3A ,  4 A,  5 A, and  5 C. Air and other fluids can flow outward through the passage by displacing the flexible valve member  64  temporarily, but are prevented from flowing inward by the valve member  64  when it is seated on the rings  34  and  36  and the spokes  41 . 
     An excluder cover  70 , which may be made of a stiff but somewhat resilient plastic material similar to that of the valve base  22  and valve top member  24 , fits over the valve top member  24  and may be latched to the valve body  26 , as shown in  FIGS. 1 and 3A , to occlude the valve assembly  14  and prevent airborne matter such as dust or sand from entering into the valve assembly  14  either through the openings  56  in the valve top member  24  or between the flange  28  of the valve base  22  and the flange  48  of the valve top member  24 . The cover  70  may have a radially extending generally planar annular outer portion  72  and a dome-like central portion  74  of a shape and size to conform to and fit over the valve top member  24 . A handle  76  may be provided, extending radially outward from the central portion  74  and optionally having a non-slip surface configuration that may include a group of small grooves as may be seen in  FIGS. 7A and 7E . An annular generally cylindrical skirt portion  78  depends from the periphery of the outer portion  72  and may include inwardly projecting catches  80  as shown in  FIGS. 7B and 7E , located so as to extend radially inward into a small groove  84  beneath a narrow rim  82  extending around the upper (as seen in  FIGS. 4A and 4B ) edge of the valve base  22 , to latch the excluder cover  70  to the valve body. The skirt portion  78  may also extend a small distance downward, or inward, beyond the depth or thickness  81  of the flange portion  28  of the valve base  22 , thus pressing against the outer surface of the flexible panel  12 , creating a seal against intrusion of air and airborne particles. The handle  76  may be used to aid in removing the cover  70  from the valve body when the risk of contamination by airborne materials is acceptable and it is desired to take advantage of the function of the valve assembly  14 . 
     In another embodiment of the chest seal  10 , the excluder cover  70  might be made of a softer, more flexible and elastic material such as a silicone rubber, and the catches  80  might be replaced by an inwardly projecting narrow, annular, securing rim  86 , as partially shown in broken line in  FIG. 7B , extending entirely around the lower edge of the skirt  78  to engage the groove  84  and elastically grip the valve body beneath the rim  82  so as to provide an airtight engagement of the excluder cover  70  with the valve base  22 . 
     In use, the chest seal bandage or 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 backing layer or panel  12  adhering to the patient&#39;s skin around the wound by virtue of the adhesive material  17  or  17   a,  to form an air-tight seal. With the dressing  10  in position but without the excluder cover  70  in place, air and other fluids are able to pass only out of the wound, through the passage  66 , but are kept out of the wound by the valve member  64 . 
     That is, when the pressure of the ambient air acting on an outer surface of the valve member  64  is greater than the pressure of the air and other fluids, such as blood, in the chest cavity acting on an inner surface of the valve member  64 , the valve member is pressed against the outer face of the raised central portion  30  of the valve base  22  closing the arcuate openings  32  and preventing air from being drawn into the chest cavity through the valve assembly  14  and the wound. However, should the pressure of the air and/or other fluids in the chest cavity exceed the ambient air pressure, the flexible valve member  64  is at least partially lifted away from the outer surface of the central raised portion  30  of the valve base  22 . This permits any pressurized air or other fluids in the chest cavity to flow outwardly through the arcuate openings  32  in the valve base, through the space between the valve base and the inner surface of the valve cover  24  surrounding the central spigot  58  and out through the openings  56  in the curved wall portion of the valve cover. The ability of pressurized air and other fluids to escape from the chest cavity through the passage  66  in the valve assembly  14  helps in treating, and in certain circumstances preventing the occurrence of, a tension pneumothorax and/or a hemothorax. When it is not desired to use the valve assembly  14  the occluding and excluding cover  70  may be placed over the valve body, protecting against contamination of the valve body  26  and the wound by airborne matter and preventing passage of fluids in either direction through the dressing  10 . 
     In another embodiment of the chest seal dressing, shown in  FIGS. 8A-8F , an excluder cover  88  may generally be similar in shape to the excluder cover  70 , but defines several openings  90  spaced about the dome-like portion  92 . The openings  90  may be located so as to be aligned directly in registration with respective ones of the holes  56  in the central part  46  of the valve top member  24 . The excluder cover  88  is fitted over the valve body  26  and is arranged to rotate about the valve body, such as by having a ridge  93  at its base that protrudes inwardly and fits into the groove  84  beneath the ridge  82  in the valve base  22  similar to the excluder cover  70 , or by being attached via a central pin (not shown) to the top member  24  of the valve body, for example. The cover  88  could either remain on the valve body  26  or be removed as with the cover  70 . Sufficient solid material  94  is provided between the openings  90  so that when the cover  88  is rotated to one position with respect to the valve top member  24  all of the holes  56  in the curved part  54  of the valve top member  24  are covered. The valve top member  24  and the excluder cover  88  must be of closely related shape and size, with the holes  56  in the valve top member  24  being small enough and spaced apart from each other far enough for all of the holes  56  to be covered by material  94  of the closed parts of the excluder cover  88 , and the shape and exterior size of the valve top member  24  must fit closely against the inner surface of the excluder cover  88 , so as to exclude effectively all of the airborne dust or sand that may be present and to effectively occlude the valve assembly  14  and prevent opening of the one-way valve when the excluder cover  88  is in its closed position. Detents may be provided to hold the excluder cover  88  in a selected fully open or fully occluded position of rotation about the valve body  26 . 
     Referring next to  FIGS. 9A and 9B , a bandage  100  similar in some respects to the chest seal bandage  10 , but not having a valve assembly  14 , is shown in some detail. A flexible main sheet or top panel  102  of sheet material, similar to the flexible panel  12  of the chest seal dressing  10 , may be of flexible transparent or translucent polymeric material such as a film of polyurethane, carrying a layer  104  of an adhesive such as the gel adhesive of the layer  17  in the chest seal assembly  10 . The flexible main sheet  102  might instead be of a woven textile fabric for an application other than a chest seal bandage, if an airtight seal is unnecessary. The margin of the adhesive layer  104  may be spaced inwardly apart from the periphery of the panel  102  by a small distance, and the resultant overhanging portion of the top panel  102  may have a thin layer  105  of a suitable medical adhesive such as an acrylic adhesive. At each end of the top panel  102  a handling tab  106  which may be similar to the handling tabs  20  described above, may be adhered to the material of the top panel  102 , as by the layer  105  of acrylic adhesive just mentioned. As shown in  FIG. 9A , the gel adhesive layer  104  may overlap an inner margin  107  of the handling tab  106 . A peelable cover or backing layer  108  of PET or coated paper may be provided to protect the gel adhesive layer  104  and the acrylic adhesive layer  105  around the margin of the flexible upper panel  102  prior to use of the chest seal bandage  100 . A slender strip  109  of protective sheet material such as a thin plastic film may overlie the adhesive gel  104  at each end, where the gel  104  overlaps the margin  107 , leaving an area of the peelable layer  108  available to be grasped to remove the peelable layer  108  from the adhesive material of the layers  104  and  105  to facilitate removing the cover layer  108  from the adhesive gel layer  104 . 
     Medical Treatment During Combat in Darkness 
     When military personnel are operating at night it is important not to disclose their positions by use of humanly visible illumination (light in the wavelength range of about 390-750 mm, hereinafter referred to at times simply as “visible light”), and yet it is necessary to attend medically to injured personnel. While night vision equipment capable of amplifying starlight or infrared light is available, previously available chest seal bandages are usually transparent, or at least translucent, for light in the humanly visible spectrum and thus are not easily seen, even with night vision equipment, using available light such as starlight or moonlight. 
     Night vision goggles (NVG) such as the PVS-14 monocular in use by US military forces can do two things. One is the conversion of near infrared (nIR) light (˜750-950 nm) into visible light. Second is amplification of visible and nIR light to provide a visible image for a user. 
     There are two viewing modes for the NVGs. Used in a “passive” mode, the viewer at night observes amplification of only the naturally available light (starlight, moonlight, etc.). Since there is typically more visible light than nIR light under those conditions, the visible light typically overwhelms the nIR as seen by the viewer through NVGs. In an “active” mode, a source of illumination such as an LED or laser providing predominantly nIR is activated. Under dark conditions, the nIR light then overwhelms the available visible light, so most of the light available to the viewer through NVGs is in the nIR range. 
     Features can be included in a medical dressing such as a chest seal device to increase its visibility using NVG and thus improve usability. As mentioned previously, a chest seal dressing  10  may be transparent and thus not show up well through the NVGs. Adding a feature that is highly visible using NVG allows the medical personnel to see, for example the handling tabs  20  and edges of the dressing to increase the likelihood of successful use. 
     Referring next to  FIGS. 10A ,  10 B, and  10 C, in a medical dressing such as a chest seal bandage  110  that is another embodiment of the device disclosed herein a flexible backing sheet or top panel  112  is imprinted over its upper, or outer, surface  114  with night vision indicia  115  that are visible but not highly reflective in ordinary light. The NVG-visible indicia  115  may be distributed over substantially the entire area of the outer surface  114 , in the form of numerous small areas of actual imprint, spread apart far enough to preserve the ability to see a patient&#39;s wound through a transparent sheet of material of the dressing  110  when sufficient light is available. Handling tabs  116  located at each of the opposite ends of the bandage  110  may also include stripes  118  visible under ordinary illumination or starlight. The stripes  118  may have a well defined size to make the handling tabs  116  easily identifiable. Making the handling tabs  116  very visible and identifiable when using NVGs is desirable to increase ease and speed of use of such a dressing. Narrower stripes  120  of reflective material also present on the handling tabs  116  are obscured by the stripes  118  in normal light, but become visible when viewed through the appropriate night vision equipment, when the bandage  110  is exposed to infrared light. 
     The stripes  120  may be of a reflective material or retroreflective material (such as 3M Solas 3255 or 3150, 3M Photoelectric tape 7800, 7610 or 3000x, 3M Diamond Grade tape such as 983-10). A retroreflective material typically includes tiny glass beads that direct the reflected light back in the direction of the source rather than scattering the light. This accomplishes a much higher visibility than non-retroreflective materials, and prevents bystanders or enemy combatants from seeing the reflection except within a small angle. The stripe  120  of reflective material can be laminated to the outside surface of the dressing or laminated under the dressing&#39;s top panel or backing layer  112  (between the handling tab  116  and backing layer  112 ). Due to the high cost of material, a narrow strip of reflective material, having, for example, a  0 . 5  inch width, is desired and may be used as a reflective stripe  120  on a handling tab  116 . 
     Reflective or retroreflective material is not desired to be left uncovered since it reflects light at all frequencies, and at night sources of stray visible light (headlights, spotlights, flashlights, etc.) could cause a reflection back toward the light source and thus reveal the location of medical personnel using the chest seal dressing  10 . To solve this problem, a layer of a material called “IR black,” that appears opaque and black in visible light but is tranmissive to nIR light, is put over the reflective material. This can be accomplished to provide the stripes  118  on handling tabs  116  in several ways, including by printing with an ink including the IR black material over the stripes  120 , by printing the IR black in an ink over a lamination on top of the reflective material (such as the polyurethane backing layer  112  of the dressing, as shown in  FIG. 10C ), or by laminating an IR black tape or film onto or above the reflective or retroreflective material  120  in the chest seal dressing  110 . This allows the reflection from the stripe  120  to be seen when using NVGs in the active mode but not in the passive mode. IR black inks may be specialized security inks such as Flint Group Xsys IR black, BASFs Lumogen FK 4280 or FK 4281, Paliogen Black S 084 or Perylene. Alternatively, a CMYK ink formulation consisting of C=100, M=100, Y=100, K=0 makes ink that appears black to the unaided eye but transmits nIR light. A tape or plastic film could likewise be formulated incorporating similar pigments to create the same effect. An off-the-shelf material is also available in the form of Wratten 87C photographic filter material. 
     Providing visible indicia in locations spread over the area of a transparent or translucent dressing allows medical personnel to visualize the shape of the dressing for accurate placement in low-light situations. A polyurethane top panel may be reflective enough to provide visible contrast with black markings on a dressing, but better visibility would be preferred. A reflective ink may be printed on the dressing, or on top of a black ink layer, to provide additional contrast. The reflective ink may be a retroreflective ink such as 3M 8000 or reflective inks such as a metallic ink (Flint Group Metalglow) or Opaque Titanium White that is highly reflective to nIR light. An ink may also be used that is formulated with pigments that absorb visible light but reflect nIR light, such as materials from Shepherd Color or Plasticolors. If an ink is used that is reflective to all frequencies, for the same reasons as above it is desired to overcoat the reflective ink with an “IR black” ink. 
     To permit use of a light (such as mid-IR) that is outside of the detection range of the NVGs, photoluminescent inks or pigments may be used to create a glowing effect rather than a detectable nIR reflection. The photoluminescent material would absorb in an appropriate light source&#39;s frequency and be excited to emit at a frequency detectable by the NVGs. This kind of material is available commercially from Evident Technologies (quantum dot technology), Stardust Materials, or in the form of a number of organic pigments that have that characteristic. If a photoluminescent material is to be excited by light having a frequency that is detectable by the NVGs a filter should be used with the NVGs to block the part of the light source&#39;s radiation spectrum that could be detected by the NVGs, so that the light emitted by the photoluminescent material is not overwhelmed by light from the source of illumination. 
     In particular, referring to  FIG. 10A , the indicia  115  are visible as lettering and small black shapes  122  in daylight illumination and seen with the naked eye. In order to improve nighttime visibility of a chest seal bandage as disclosed herein, however, each of the shapes  122  may have beneath it a small imprint  124  in reflective ink, such as for example, the letters “SCS” as shown in  FIG. 10B , printed in one of the reflective or photoluminescent inks mentioned above. The imprints  124  are visible when the chest seal bandage  110  is viewed using night vision goggles and illuminated by infrared or near infrared light. If the reflective ink used for the imprint  124  of the initials “SCS” is also reflective of light in the normally visible spectrum as well as infrared light, “IR black” ink may be printed over the imprint  124 , covering it to provide a black shape as seen at  122  in  FIG. 10A . This black shape, covering the reflective imprint  124  as seen in visible light, reduces the likelihood that the bandage might be seen at night by enemy personnel as a result of reflection of stray visible light from the imprints  124  on the medical dressing  110 . Alternatively, particularly if the material of the outer layer or top panel  112  is somewhat reflective, a bottom layer of opaque black ink with open areas such as the letters “SCS” may be provided in the shape  122  as shown in  FIG. 10B . The bottom layer of ink may be covered with a layer of IR black to have the entire shape  122  appear black in daylight as seen in  FIG. 10A , but reflect the “SCS” under near IR illumination and seen using NVGs. 
     A medical dressing or bandage  110 ′, shown in  FIG. 10D  as being of the same overall shape as the dressing  110 , is provided with night vision indicia including a stripe  125  of reflective or photoluminescent material, visible with night vision equipment, extending along the outer margin of the dressing or bandage  110 ′. A masking stripe  126  of IR black material at least as wide and preferably wider than the reflective stripe  125  covers the stripe  125  and appears to be black under humanly visible light, as shown at  127 . Similar night vision indicia can be provided on bandages  110 ′ of other shapes and of various sizes. 
     It will be understood that the dressing  110 , although shown with no valve assembly, could also be equipped with a valve assembly such as the valve assembly  14  described previously and shown in broken line in  FIG. 10A , to make the dressing  110  particularly useful as a chest seal dressing for use during darkness. Night vision indicia  115  may also be imprinted on any of the valve assemblies disclosed herein, such as is shown in broken line on the valve assemblies  14  and  70  in  FIGS. 1 and 7A . 
     Alternative Valve Assemblies 
     Referring now to  FIGS. 11A and 11B , in a valve assembly  128 , generally similar to the valve assembly  14 , an excluder cover  130  may be attached to the base portion  22  of the valve assembly  128  by a so-called “living” hinge  132  formed as a relatively thin flexible part of the plastic of the valve assembly  128  during manufacture, and the excluder cover  130  may thus be of the same sort of material as which the valve base  22  is made. A catch  134  may be provided to engage the valve base  22  to keep the excluder cover  130  in a closed position as shown in  FIG. 11B , to fully occlude the valve and exclude sand or other airborne contamination from the valve assembly  128 . 
     As a further alternative construction, a valve assembly  138  shown in  FIG. 12  may include a cover  140  secured to the valve assembly by a movable central post  142  engaged in a tube  144  defined centrally within the valve top member  24 ′. A suitable resilient catch  143  (shown in  FIG. 12A ) may be provided to operate between the post  142  and the tube  144  as in drinking water bottle closures, engaging one of a pair of grooves  145  so as to retain the excluder cover  140  in a tightly closed condition against the flange portion  48  of the valve top member  24 ′ when it is desired to occlude the openings  56  in the valve assembly to exclude airborne materials. When it is desired to permit the valve assembly  138  to function as a one-way valve during use of a chest seal bandage including the valve, the excluder cover  140  may be raised to the position shown in broken line in  FIG. 12  to provide space around its periphery for exhaust of air, blood, etc., that has exited from a wound and passed through the valve assembly. 
     As an alternative to the use of the catches  45  and seats  62  to interconnect the base and the top member of the valve assembly  14  described above, a valve assembly  148  shown in  FIG. 13A  may include valve base  150 , provided with helical threads  152  on an exterior portion corresponding with the center part  30  of the valve base  22  shown in  FIG. 2 , and a valve top member  154  may be provided with mating internal threads  155  to attach the valve top member  154  to the valve base  150  securely and with little likelihood of intrusion of sand or dust between the flange portion  156  of the valve base  150  and the bottom edge  158  of the valve top member  154 . The threads  152  and  155  may be accompanied by a ratchet structure similar to those use in a child-proof medicine bottle, with teeth  157  beneath the threads  152  on the valve base  150  and one or more flexible plastic pawls  159 , inside the valve top member  154 , near its lower edge, so as to prevent medical personnel from disassembling the valve assembly  148 . The valve assembly  148  incorporating the valve base  150  and the valve top member  154  may also include a simple flat excluder cover  160  similar in function to the excluder cover  130  shown in  FIGS. 11A and 11B , attached by a living hinge  132  and including a catch  134  arranged to engage a projection  136  on the valve top member  154  or another excluder cover such as one similar to the cover  70  described above. 
     A valve assembly  148 ′ shown in  FIGS. 13C and 13D  is similar to the valve assembly  148  shown in  FIGS. 13A and 13B , but its valve top member  154 ′ lacks the excluder cover  60  and the living hinge  132  shown in  FIG. 13B . Instead, an excluder cover  176  may be provided in the form of a thin, preferably flexible, membrane that may be of a material such as polyethylene, polyester, polyurethane, or another plastic capable of being produced in the form of a thin film. For example, the excluder cover  176  might have a thickness in the range of 0.002-0.005 inch (0.50-1.27 mm) The excluder cover  176  is generally of a size and shape to cover and conform to the shape of the valve top member  154 ′, and also includes a pull-tab  178  which may be of the same film material, projecting outward beyond the valve top member  154 ′ in a convenient location to be grasped. The excluder cover  176  is attached to the valve body top member  154  by a layer  180  of an adhesive. The layer  180  of adhesive may be re-adherable and may have an appropriate thickness determined by the nature of the adhesive material itself, which may be an acrylic adhesive, a rubber-based adhesive, or another adhesive that has satisfactory properties for the material of the excluder cover  176  and the valve body top member  154 ′. The valve assembly  148 ′ could be provided with the excluder cover  176  attached to and closing the openings in the top member  154 ′, as shown in  FIG. 13C . With the excluder cover  176  having an appropriate thickness it may be removed as necessary by grasping the pull-tab  178  and peeling it back as shown in  FIG. 13D . If desired, night vision indicia  115 , as shown in  FIG. 13C , may be included on the excluder cover  176  to make it more conveniently useful during nighttime military operations. 
     As a further alternative construction for an excluder cover in a valve assembly  161  for a chest seal dressing, as shown in  FIGS. 14 and 14A , a pair of flapper lids  162  and  164  may be attached by living hinges  166  and  168  to a valve top member  170 . The flapper lids  162  and  164  may be closed to bring a depending rim  172  of each lid into latching engagement with a radially protruding lip  174  on the valve top member  170  to occlude the valve assembly when desired. With the flapper lids  162 ,  164  open, openings  176  through the top member  170  provide a suitable passage for expulsion of air or blood that has passed through a one-way valve assembly  161  including the valve top member  170 . The valve assembly  161  may be similar, otherwise to the valve assembly  148  shown in  FIGS. 13A and 13B . 
     Additional Medical Applications of Night Vision Improvements for Use in Combat 
     Referring now to  FIG. 15 , an emergency orthopedic splint  190 , shown as it might be seen through night vision equipment when illuminated by near infrared light (nIR), may be of a type similar to, for example, the splints described in Scheinberg U.S. Pat. No. 4,676,233. Such splints have a soft sheet metal central member covered by a layer of closed-cell foam padding, so that the splint can be transported in a rolled or folded configuration and bent to a desired shape by a medical care provider at the time of use to immobilize a patient&#39;s injured limb. Such emergency splints may have a basically simple form including a pair of opposite faces  198  and  200  that may be flat before the splint is manipulated to place it into a desired form for a particular use. To improve the ease of use of such an emergency splint in nighttime combat conditions where night vision equipment such as NVGs capable of detecting near infrared light is available, the splint  190  is provided with night vision indicia such as a border stripe  192  extending along the lateral margins  194  and end margins  196  on at least one of the opposite major faces  198  and  200  of the splint. The border stripe  192  may be provided on the splint  190  in a manner similar to that described above with respect to application of the indicia  118 ,  120 ,  122  and  124  to the bandage  110 . 
     That is, a stripe  202  of reflective, retroreflective, or photoluminescent material is provided along the lateral and end margins  194  and  196 , spaced a small distance inwardly from the extreme edge of either face  198  or  200 . The stripe  202  is then covered with a masking stripe  204  of, for example, IR black at least as wide as, and preferably slightly wider than, the stripe  202 . The masking stripe  204  is shown outlined by broken line in  FIG. 15 , and is provided to prevent humanly visible light from impinging upon and being reflected from the reflective stripe  202 , which because of its high reflectivity might, if not masked, reflect stray visible light in a direction where it might attract attention of enemy combatants. Additionally, the masking stripe  204 , because of its appearance as being black in color in humanly visible light, as shown at  205  in  FIG. 15  can be seen with enough contrast to assist in shaping and placing the splint  190  under conditions of minimal ambient light, both without night vision equipment and when using night vision equipment without an nIR illumination. When using NVG or other night vision equipment in combination with illumination by a source of light of a frequency not visible to humans but detectable by the night vision equipment, the reflective stripe  202  will be even more clearly visible to a medical care provider, helping to facilitate and optimize use of the splint  190  in nighttime military operations. 
     Night vision indicia such as the stripes  202  and  204  may be provided on the splint  190  in ways similar to the provision of the stripes  118  and  120  on the handling tabs  116  of the bandage  100 . That is , the reflective stripe  202  may be provided as an imprint of an ink including reflective materials such as those described above with respect to the bandage  100 , and the stripe  204  may be an imprint of ink including IR black pigment combinations such as those described above with respect to the stripes  118  and the black shapes  122 . Alternatively, the stripes  202  and  204  may be flexible films of polymeric plastic material including the required reflective materials and pigments, attached to the faces  198  and  200  of the splint  190  by an appropriate adhesive material. 
     Another medical device whose nighttime use can be facilitated by improved visibility is the tourniquet  210 , drawn in  FIG. 16  to represent its appearance when illuminated by nIR and viewed using night vision equipment such as NVG. The tourniquet  210  includes a main strap portion  212  and an associated buckle  214  or another arrangement that may be used for adjusting the initial circumferential length of the strap  212  to provide an initial loop size as needed for a particular patient&#39;s limb to which the tourniquet  210  is to be applied. A winding rod  216  of suitable material may be used to twist the strap  212  as indicated by the arrows  218 , in order to reduce the circumference of a loop  217  of the strap  212  while it is in place around a patient&#39;s limb. 
     To make the tourniquet  210  more easily usable during nighttime conditions where it is desired for the patient and medical aid personnel to remain unseen, night vision indicia may be provided on the main strap  212 , as for example, a reflective stripe  219  covered by an IR black masking stripe  220 , outlined in broken line, since it would not be seen if illuminated only by nIR light. The stripes  218  and  220  may be imprinted in a medial position, for example, along the length of at least one side of the strap  212 , and the stripe  220  would be visible in humanly visible illumination, as shown at  221 . 
     Similarly, bands  222  of reflective material masked by wider bands  224  of IR masking material may be provided on the rod  216  in one or more convenient locations, such as near one or each end of the rod  216 , as may also be seen in  FIG. 16 . Indicia including a reflective marking  226 , masked by an IR blacking marking  228 , may also be provided on the buckle  214 . The reflective stripe  219 , bands  222 , and indicia  226  may be affixed to the tourniquet  210  in one of the ways mentioned above with respect to the bandage  100  and the splint  190 . The IR black masking stripe  220 , band  224 , and masking marking  228  may also be provided in one of the same ways described with respect to the bandage  100  and splint  190 . Alternatively, the strap  212  may include one or more threads or strips of reflective, retroreflective, or photoluminescent material covered by a masking of IR black material and sewn or woven into the material of the strap  212  as shown at  230 . 
     Referring next to  FIG. 17 , stabilizing support devices  240  known for use in immobilizing a fractured pelvis are described, for example, in U.S. Pat. Nos. 6,554,784 and 7,008,389, and in pending Polliack et al. U.S. patent application Ser. No. 12/462,754, filed Aug. 7, 2009, now U.S. Patent Application Publication No. 2011/______ A1. Such devices, often called “pelvic slings,” typically include a wide belt-like main body  242  from whose opposite ends strap members  244  and  246  extend, to be interconnected adjustably with each other by a special buckle  248 . At least one of the straps  244  and  246  may be held by statistical hook-and-loop fastener material  250  to maintain a required amount of tension in the pelvic sling  240  to support a patient&#39;s injured pelvis. To facilitate proper application of such a pelvic sling  240  to a patient under nighttime conditions where personnel wish to remain unseen by enemy combatants night vision indicia may be provided on the pelvic sling  240  in a form generally similar to those previously discussed incorporating masked reflective, photoluminescent or retroreflective indicia such as a stripe  254 , covered by a masking stripe  256 , on each of the straps  244  and  246 , a reflective, retroreflective, or photoluminescent marking  258  covered by a masking shape  260  on the buckle  248 , and reflective, retroreflective, or photoluminescent indicia  262  and  264  covered by masking material  266  and  268 , located on the main body  242  to disclose the shape and location of the main body  242  and the locations of the fastener material  250 . As shown at  269 , in humanly visible light the stripe  266  of masking material is visible as a dark stripe, hiding the reflective stripe  262 . 
     As shown in  FIG. 18 , a surgical glove  270  may include night vision indicia such as reflective, retroreflective, or photoluminescent markings  272  located where they can be seen during use of the glove  270  during a medical procedure. For example the reflective indicia  272  may be provided as shown on the back of each fingertip  273 , or on the back of the hand. The reflective indicia  272  are masked by masking indicia  274  visible as black shapes by an unaided human eye in daylight, as shown on the thumb at  275 , or with use of night vision equipment without infrared illumination in conditions of low ambient light. The masking indicia  274  are transmissive of light in a selected spectrum such as near infrared and infrared that can be used to illuminate the gloves and enable the reflective indicia  272  to be viewed using the appropriate night vision equipment, as discussed above. 
     Other medically useful materials such as gauze or adhesive tape  280 , which may be in the form of folded sheets or a spool or coil  282 , as shown in  FIG. 19 , may also be provided with night vision indicia on the tape  280  in selected patterns or locations or simply as a medial stripe  284 , to make it easier for the gauze or adhesive tape to be seen during use in low-light situations where it is important for involved medical or injured personnel not to be visible to personnel without special night vision equipment. The indicia  284  may be provided in the same or similar manner as those described previously, that is, by imprinting with ink including reflective, retroreflective, or photoluminescent materials, covered by a masking layer  286  of IR black material or ink containing other masking materials appropriate for a type of light not visible to an unaided human eye yet detectable using appropriate night vision equipment intended for use with the material. Thus the indicia would appear in daylight as shown at  288 . Alternatively, specially prepared threads may be woven into the gauze or tape, as discussed above with respect to the tourniquet  210 . 
     Other medically useful equipment and materials could also be provided with night vision indicia to improve their capabilities for use in nighttime combat situations. For example, indicia visible with the use of night vision equipment but not visible in darkness to the unaided human eye might be applied in the ways described above to items of intravenous injection equipment and materials, or to a cricothyrotomy tube and associated cricothyrotomy tube insertion devices, to improve their usefulness in nighttime combat situations. 
     While the devices mentioned hereinabove have been described specifically in connection with use of near infrared illumination and detection by night vision equipment capable of detecting near infrared and converting it to an image visible to the user of such night vision equipment, the same advantages may also be available using illumination by light in other frequency bands that are not visible to an unaided human eye, but which can be detected by appropriate equipment capable of converting a detected reflection of light in such other frequency bands to a visible image. 
     The terms and expressions which have been employed in the foregoing specification are used therein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims which follow.