Abstract:
A hemostatic dressing for applying a hemostatic material such as lyophilized thrombin to a wound. The wound dressing includes an impermeable backing material and a sealing member to provide a seal against the skin. The wound dressing enables the application of pressure in order to seal the sealing member against the patient&#39;s skin to the wound without the need for attendance by a health care professional. The seal may be applied by a compressive band or by application of a pressure sensitive adhesive. The wound dressing creates a sealed localized procoagulation environment to facilitate the formation of a clot initiated by the presence of substantial quantities of externally supplied lyophilized thrombin or another dry coagulant.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a hemostatic wound dressing.  
         BACKGROUND OF THE INVENTION  
         [0002]    Many medical procedures in use today involve the insertion of a medical device into a living body in order to pierce the wall of a blood vessel or other similar structures within the body. Instruments such as biopsy needles, laparascopes, trochars, introducers and various other probes may be inserted into the body. The surgical insertion of such instruments creates a wound which, of course, tends to bleed. For example, patients undergoing periodic kidney dialysis may incur arteriopunctures several times weekly.  
           [0003]    In order to stop the bleeding of such puncture wounds, it is common for medical personal to apply pressure to the wound for a substantial period of time to facilitate hemostasis. Direct pressure is often applied digitally, that is, with the fingers. The need to apply such pressure for extended periods of time leads to a less than efficient utilization of highly skilled medical personnel. Of particular concern are situations that require that digital pressure be applied for longer than five minutes to achieve a 95% success rate of stopping bleeding. Such needs arise particularly acutely in the case of arteriopunctures of major arteries.  
           [0004]    A variety of pressure dressings have been utilized in an effort to provide appropriate pressure to create hemostasis. Pressure dressings stop blood flow mechanically and are generally a thick gauze, cotton or other absorbent breathable material in pad form applied to the wound.  
           [0005]    Another approach to creating hemostasis is to apply an agent that accelerates blood clotting in the wound. The clot stops hemorrhaging by physically blocking the outflow of blood and provides a supporting structure for the formation of scar tissue and thus begins the healing process. One such clotting agent is, thrombin, a naturally produced protein agent, is available in either a liquid solution or a lyophilized (freeze-dried) form. During coagulation thrombin cleaves fibrinogen in the blood to form fibrin, leading to the ultimate step in coagulation and the formation of a fibrin clot.  
           [0006]    In U.S. Pat. No. 6,447,799, B1 issued to Ullman, a hemostatic kit is disclosed that includes an absorbent pad, a thrombin retainer and a non-stick backing. The thrombin retainer holds a measured quantity of thrombin in liquid solution. The thrombin retainer can be broken to release the thrombin solution which then soaks the absorbent pad. The thrombin soaked gelatin foam pad of this invention can then be applied to a wound with pressure in order to stem bleeding.  
           [0007]    Other approaches to applying medications to body sites include those disclosed in U.S. Pat. No. 4,899,739 issued to Konishi, and U.S. Pat. No. 3,580,254 issued to Stewart. These patents both disclose devices for releasing medication from a sealed storage receptacle into a bandage-like dressing utilizing permeable backing.  
           [0008]    While these approaches represent a possible solution to the problems of dressings for wounds such as surgical insertions that require more than five minutes of digital pressure to stop bleeding, each of these approaches allow blood from the wound to seep from the wound area without being coagulated. As a result, these devices are not entirely effective in stemming bleeding from these kinds of significant wounds.  
           [0009]    It would be beneficial to have a device for applying a hemostatic agent to a wound, with pressure, without the need for constant attention from a health professional during the time of application that could overcome the limitations of existing techniques.  
         SUMMARY OF THE INVENTION  
         [0010]    The present invention is a hemostatic wound dressing that prevents leakage of blood from the region occupied by the hemostatic material and the area immediately adjacent to the wound. The present invention facilitates hemostasis following percutaneous and transcutaneous procedures. The invention further allows the application of pressure to the wound without the need for constant attendance from a health care professional.  
           [0011]    The invention generally includes a hemostatic dressing for providing a hemostatic material, such as lyophilized thrombin, in a ready-to-use form. The invention further includes an impermeable backing material and a sealing member to create a seal with the skin. One embodiment of the present invention provides for the application of pressure in order to seal the sealing member against the patient&#39;s skin surrounding the wound without the need for attendance by a health care professional. The pressure may be applied by a compressive band or by an adhesive bandage-like application. The pressure application utilized with the invention is not intended to, or sufficient to stop bleeding by mechanical or hydraulic pressure or force. Rather, the application of pressure by this arrangement creates a sealed localized procoagulation environment in order to facilitate the formation of a clot initiated by the presence of substantial quantities of externally supplied lyophilized thrombin or similar preformed coagulant. Preferably, the localized procoagulation environment facilitates and the exclusion of ambient air.  
           [0012]    A first embodiment of the invention includes a gasket supported by two arms of unequal length. The ends of the unequal arms are operably, slidably connected with a circumferential band adapted to encircle a body part in order to hold the hemostatic dressing in place. The circumferential band is not a pressure applying band in the conventional medical sense. It does not serve to stop bleeding by application of direct pressure to a wound. Rather, this embodiment of the invention provides a localized procoagulant environment that is maintained with a gasket and an impermeable backing. Blood vessels in the area of the wound are not occluded by operation of the circumferential band due to the arms extended from the gasket. In other words, a tourniquet like situation is undesirable and avoided.  
           [0013]    A second embodiment of the invention includes an impermeable pressure sensitive adhesive backing which also seals around the perimeter of the procoagulant material to create a localized environment for retaining blood to effectively interacts with the procoagulant material. This embodiment of the invention also provides a localized, procoagulant environment that is preferably anaerobic. In this embodiment, the seal minimizes air ingress and prevents fluid egress to the environment occupied by the procoagulant material through an adhesive bond between the impermeable backing and the skin of the patient rather than a pressure operated gasket.  
           [0014]    A third embodiment includes a rigid gasket disk to seal around the preformed coagulant and a flexible pressure sensitive adhesive support for securing the disk-coagulant assembly to the skin.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 is a partially exploded, perspective view of a first embodiment in accordance with the present invention;  
         [0016]    [0016]FIG. 2 is a front plan view of the embodiment of FIG. 1;  
         [0017]    [0017]FIG. 3 is a perspective view of the embodiment of FIG. 1 from another angle;  
         [0018]    [0018]FIG. 4 is a top plan view of the embodiment of FIG. 1;  
         [0019]    [0019]FIG. 5 is a perspective view of a backplate in accordance with the present invention;  
         [0020]    [0020]FIG. 6 is a top plan view of a second embodiment of the present invention;  
         [0021]    [0021]FIG. 7 is a top plan view of the second embodiment of the invention including a partially opened removable backing;  
         [0022]    [0022]FIG. 8 is an exploded elevational view of the second embodiment of the present invention;  
         [0023]    [0023]FIG. 9 is a perspective view of a third embodiment in accordance with the present invention;  
         [0024]    [0024]FIG. 10 is a perspective view of the embodiment of FIG. 8 from a reverse angle; and  
         [0025]    [0025]FIG. 11 is a perspective view of a support block in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0026]    Referring to FIGS. 1, 2 and  3 , a first embodiment of the hemostatic dressing  10  generally includes preformed procoagulant  12 , impermeable backing  14 , sealing member  16 , and securement  18 . Referring particularly to FIG. 1, procoagulant  12  preferably includes lyophilized thrombin. Procoagulant  12  is preferably in the form of a disk or pad having a thickness of between 1.0 and 10.0 millimeters. The disk may have a diameter of one to two centimeters. Desirably, procoagulant  12  contains at least ten units of thrombin or an amount of another procoagulant having similar level of procoagulant activity.  
         [0027]    The shape of procoagulant  12  may be circular or polygonal, and preferably conforms to a shape of a perimeter  20  of the sealing member  16 . Procoagulant  12  is supported by and/or adhered to impermeable backing  14  and surrounded at perimeter  20  by sealing member  16 .  
         [0028]    Still referring to FIGS. 1, 2 and  3 , in this embodiment of the invention impermeable backing  14  generally includes back plate  22 , annulus  24 , short arm  26 , and long arm  28 . Referring to FIG. 3, back plate  22  preferably is a flat disc shaped structure having a depression  29  therein formed from a material that is impermeable to ambient air and to the components of procoagulant  12 .  
         [0029]    Referring to FIGS. 3 and 4, back plate  22  is joined to annulus  24  and supported thereby. Back plate  22  and annulus  24  cooperate in concert with the skin of the patient in the vicinity of the wound, to create an enclosed procoagulant microenvironment. Backplate  22  and annulus  24  are depicted in FIG. 5 as generally circular but can be any shape desired. Short arm  26  and long arm  28  may be formed as an interconnected unit joined by ring  29 , as depicted in FIG. 3. Back plate  22  and annulus  24  may be formed as an integral unit and joined to ring  29  in a press fit fashion.  
         [0030]    Short arm  26  is operably joined to back plate  22  and annulus  24 . Short arm  26  is angled or curved away from procoagulant  12 . Short arm  26  is pierced by slot  30 . Slot  30  is sized and proportioned to accommodate securement  18 .  
         [0031]    Long arm  28  is operably connected to back plate  22  and annulus  24 . Long arm  28  is longer in length than short arm  26  and is pierced by slot  32 . Slot  32  is sized and proportioned to allow passage of securement  18  therethrough.  
         [0032]    In this embodiment, sealing member  16  may be integrally formed as part of annulus  24  or may be a separate operably connected structure. Sealing member  16  is preferably raised relative to procoagulant  12  and is preferably formed from a biocompatible and hypoallergenic material. Sealing member  16  is structured to provide a leak resistant seal between sealing member  16  and the skin of a patient.  
         [0033]    Referring to FIGS. 1 and 3 in this first embodiment of the invention, securement  18  includes circumferential band  34  and clasp  35 . Circumferential band  34  is sized and proportioned in order to pass through slot  30  and slot  32 . Circumferential band  34  is further sized and proportioned to encompass a desired body part. For example, if used to encourage hemostatis in a puncture wound used to access the femoral artery, circumferential band  34  should be proportioned to encompass the circumference of the upper thigh region of a human being.  
         [0034]    Circumferential band  34  may also support a comfort pad (not shown). Comfort pad may be a gauze pad or another material to cushion the skin under circumferential band  34 . For example, a foam or fabric pad would also be appropriate.  
         [0035]    Clasp  35  may include a ratchet mechanism  36 . Circumferential band  34  may include a plurality of closely spaced ratchet positions  37 , as best seen in FIG. 3, so that when circumferential band  34  interacts with clasp  35  the circumference encircled by circumferential band  34  may be adjusted essentially infinitely. Circumferential band  34  and clasp  35  may interact in any way known in the art in order that the circumference encompassed by circumferential band  34  when secured by clasp  35  is variable within a range required to encompass a desired body part. Clasp  35  may be releasable in order to facilitate adjustment and/or removal of the circumferential band  34  relative to a body part. Any other length adjusting mechanism and/or bond retention mechanism known may also be utilized to make circumferential band  34  length adjustable.  
         [0036]    Procoagulant  12  is preferably secured by an adhesive or mechanical means to impermeable backing  14  at back plate  22 . Procoagulant  12  may be placed into depression  31 . Procoagulant  12  may also, be infused, absorbed or otherwise integrated into impermeable backing  14 .  
         [0037]    [0037]FIGS. 6-8 depict a second embodiment of the invention. The second embodiment of hemostatic dressing  10  also includes procoagulant  12 , impermeable backing  14 , and securement  18 . In this embodiment, impermeable backing  14  includes flexible impermeable membrane  38  that also acts as the securement  18 . Flexible impermeable membrane  38  supports absorbent pad  40 , nonstick pad  42 , quadrilateral procoagulant  44 , first peelable layer  46 , and second peelable layer  48 .  
         [0038]    Flexible impermeable membrane  38  is substantially impermeable to air. Flexible impermeable membrane  38  is coated on a first side thereof with pressure sensitive adhesive  50 . Preferably, pressure sensitive adhesive  50  secures adsorbent pad  40  to flexible impermeable membrane  38 . Pressure sensitive adhesive  50  also removably secures flexible impermeable membrane  38  to first peelable layer  46  and second peelable layer  48 . First peelable layer  46  and second peelable layer  48  are formed of a material that will adhere to pressure sensitive adhesive  50  in a releasable fashion so that first peelable layer  46  and second peelable layer  48  can be removed from flexible impermeable membrane  38  readily to prepare hemostatic dressing  10  for use. Pressure sensitive adhesive  50  is preferably substantially impermeable to ambient air and forms an adhesive seal that minimizes any exchange of ambient air from the anaerobic hemostatic region and prevents egress of bodily fluids.  
         [0039]    Absorbent pad  40  is covered by nonstick pad  42 . Nonstick pad  42  preferably has the quality of being non-adherent to wounds and surrounding skin but allows wound exudates such as serum, blood or liquid to pass therethrough so as to be absorbed by absorbent pad  40 . Quadrilateral procoagulant  44  covers nonstick pad  42  and is further covered by first peelable layer  46  and second peelable layer  48 . Procoagulant  12  can be infused, or otherwise integrated into absorbent pad  40  or nonstick pad  42  as well.  
         [0040]    [0040]FIGS. 9-11 depict a third embodiment of the invention. This embodiment generally includes preformed procoagulant  12 , impermeable backing  14 , sealing member  16 , and securement  18 .  
         [0041]    Impermeable backing  14  generally includes back plate  22  and annulus  24  which are similar in structure to those in the first embodiment disclosed above and depicted in FIG. 5. Sealing member  16  may be integrally formed as part of annulus  24  or may be a separate operably connected structure. Sealing member  16  is preferably raised relative to procoagulant  12  and is preferably formed from a biocompatible and hypoallergenic material. Sealing member  16  is structured to provide a leak resistant seal between sealing member  16  and the skin of a patient. Annulus  24  is desirably rigid enough to resist blood pressure in a large artery but flexible enough to seal with the skin prevent leakage of blood from the localized procoagulant environment.  
         [0042]    In this embodiment, securement  18  includes a flexible self adhesive membrane  56 . Flexible self adhesive membrane  56  is temporarily join to first peelable layer  58  and second peelable layer  60  by pressure sensitive adhesive  62 . Pressure sensitive adhesive  62  is also adapted to provide a secure adhesion to the skin of the treated patient.  
         [0043]    Securement  18  also preferably includes a support block  64 . Support block  64  is preferably generally rectangular in shape and is pierced by back plate aperture  66 . Backplate aperture  66  is sized and shaped to accept back plate  52 , desirably, in a press fit fashion. Backplate aperture  66  and backplate  52  may be of any shape desired.  
         [0044]    Support block  64  also defines beveled edge  68 . Support block  64  is joined to flexible adhesive membrane  56 . The joining may be accomplished by pressure sensitive adhesive  62  or by any other means known to the art.  
         [0045]    In operation, the invention is utilized following a medical procedure that creates a skin wound. For example, after completion of kidney dialysis and removal of a dialysis needle, hemostatic dressing  10  is placed in contact with the patient&#39;s skin so that procoagulant  12  is in proximate contact with the wound and the nearby surrounding area. Thus, procoagulant  12  is enclosed and contained between impermeable backing  14  and the patient&#39;s skin. Sealing member  16  encircles procoagulant  12  and prevents procoagulant  12  leakage from the localized area.  
         [0046]    The health care provider then grasps circumferential band  34  and manipulates it to encompass the limb or body part to which the hemostatic dressing  10  is to be secured. Once circumferential band  34  encompasses the body part, clasp  35  is utilized to secure circumferential band  34  about that body part. Clasp  35  and circumferential band  34  are adjusted so that procoagulant  12  is positioned over the wound and so that sealing member  16  is sealed against the patient&#39;s skin. Circumferential band  34  is tightened only enough to provide a tight seal between sealing member  16  and the patient&#39;s skin. It is noted that the interaction of circumferential band  34  with short arm  26  and long arm  28  allows sufficient pressure to be applied to sealing member  16  to form a tight seal without applying enough pressure to occlude arteries or veins beneath the skin. The structure of this embodiment prevents a tourniquet effect from occurring.  
         [0047]    Once hemostatic dressing  10  is in place and secured, procoagulant  12  interacts with blood and wound exudate to be released directly into the wound and surrounding vicinity in order to facilitate coagulation and ultimate healing of the wound. Wound exudates dissolve and rehydrate thrombin from procoagulant  12  and the thrombin then interacts with the wound exudates within the localized procoagulant environment to initiate or speed the clotting process.  
         [0048]    Referring to FIGS. 6, 7, and  8 , when utilizing another embodiment of the invention, the physician removes first peelable layer  46  and second peelable layer  48  from flexible impermeable membrane  38 . Doing so exposes pressure sensitive adhesive  50 . The physician applies hemostatic dressing  10  so that quadrilateral procoagulant  44  is positioned over the wound in the skin. The physician then applies pressure to the non-adhesive side of flexible impermeable membrane  38  so that pressure sensitive adhesive  50  adheres to the skin of the patient on either side of the wound as well as around the perimeter of quadrilateral procoagulant  44 . This produces a locally contained anaerobic procoagulant environment in the vicinity of the wound to facilitate the clotting and healing process.  
         [0049]    Referring to FIG. 5, this embodiment of the invention is used in a fashion generally similar to the embodiment that is depicted in FIGS. 6, 7 and  8 . Care should be taken to apply flexible self adhesive membrane  56  so that pressure sensitive adhesive  62  holds annulus  54  firmly against the skin of the patient thus creating a tight seal.  
         [0050]    The present invention may be embodied in other specific forms without departing from the central attributes thereof, therefore, the illustrated embodiments should be considered in all respects as illustrative and not restrictive, reference being made to the appended claims rather than the foregoing description to indicate the scope of the invention.