Abstract:
Hemostatic wound dressings for substantially arresting the flow of severe, life threatening bleeding from a wound by rapidly adhering to the wound site, absorbing and concentrating and thickening the blood at the dressing blood interface and accelerating the natural clot formation beneath the dressing and finally, forming a strong seal that will substantially prohibits further flow of blood out of the wound site. These hemostatic wound dressings are formed of unique combinations of hemostatic dressing aspects which achieve wound seal strengths that are significantly higher than the sum of seal strengths expected from the individual aspects alone. Some embodiments also achieve these synergistic seal strengths by combining one hemostatic dressing with a non-hemostatic device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable 
       INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
       [0003]    Not applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    This invention relates generally to wound care and hemostatic dressings and more particularly to a novel topically applied dressing composition that dramatically arrests traumatic and severe bleeding in wounds and provides wound-healing properties. 
         [0006]    2. Description of Related Art 
         [0007]    Hemostatic agents are well known in the prior art. Patterson et al., U.S. Pat. No. 6,187,347, discloses a free flowing powder to arrest bleeding from a wound comprising the steps of providing a substantially anhydrous compound of a salt ferrate which will hydrate in the presence of blood to clot blood and produce oxygen and applying said compound to the wound for a time sufficient to arrest blood flow and substantially reduce the microbial population by the presence of oxygen and forming a protective coating over the wound. In one embodiment, a cation exchange material is mixed with the salt ferrate to provide a protective coating over the wound for protection and enhanced healing. The salt ferrate provides the oxygen required to substantially reduce the level of bacteria, virus and fungus at the wound site. 
         [0008]    In military and civilian trauma units, the use of cotton gauze pads capable of absorbing 250 ml of blood are known as passive dressings for controlling bleeding at active bleeding wound sites such as an external hemorrhage. Cotton gauze pads are considered passive since they do not initiate or accelerate blood clotting. Cellulose hemostatic compositions have been disclosed in U.S. Pat. Nos. 2,914,444 and 3,122,479. U.S. Pat. No. 4,626,253 teaches the preparation of surgical hemostats made from a knitted fabric of oxidized cellulose having superior handling and hemostatic properties. 
         [0009]    Faster hemostasis is provided by the use of calcium-modified oxidized cellulose as taught by Stilwell et al. U.S. Pat. No. 5,484,913. Cochrum et al. in U.S. Pat. No. 7,101,862 describe an article that promotes hemostasis that contains cellulose and a polysaccharide covalently linked to the cellulose. U.S. Pat. No. 6,652,840 by Prevendar discusses a bleeding control composition consisting of regenerated oxidized cellulose, ferric sulfate, aluminum chloride, aluminum ammonium sulfate, absorbable gelatin and a solvent. U.S. Pat. No. 7,279,177 by Looney et al. describes a hemostatic wound dressing that utilizes a fibrous, fabric substrate made from carboxylic-oxidized cellulose with a biocompatible, water soluble or water swellable cellulose polymer distributed within the fabric. Zhang et al. in U.S. Pat. No. 7,262,181 teach that hemostatic materials can be made of water-soluble cellulose ether derivatives, such as methylcellulose, ethylcellulose and hydroxyethylcellulose. Improved hemostatic wound dressings can be made from distributing hydroxyethyl cellulose uniformly into a piece of absorbable hemostat based on oxidized regenerated cellulose as discussed in U.S. Pat. No. 7,019,191 by Looney et al. 
         [0010]    Alginates and chitosan have long been known as effective hemostatic wound dressings. A synergistic combination of alginate and chitosan with high absorption capacity provide better hemostatic properties as discussed by Pandit in U.S. Pat. No. 5,836,970. 
         [0011]    Current hemostatic agents absorb blood to different degrees but have limited ability to stop bleeding. A hemostatic dressing has yet to be developed that controls traumatic and uncontrolled bleeding while cutting down the time to hemostasis substantially. 
         [0012]    The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those skilled in the art upon a reading of the specification and a study of the drawings. 
       BRIEF SUMMARY OF THE DISCLOSURE 
       [0013]    This disclosure is directed to improved hemorrhage control wound dressings and the methods of applying such dressings. The wound dressing is capable of substantially stopping the flow of severe, life-threatening bleeding from the wound by rapidly adhering to the wound site, absorbing, concentrating and thickening the blood at the dressing/blood interface, accelerating the natural clot formation beneath the dressing and forming a strong seal that substantially prohibit the flow of blood out of the wound site. The novel dressing includes a combination of hemostatic dressings which achieve seal strengths (defined by mm pressure to failure) that are significantly higher than the sum of seal strengths expected from the individual components. In some cases, the increase in seal strengths is achieved by combining one hemostatic dressing with a non-hemostatic device such as a polyurethane foam. 
         [0014]    It is therefore an object of this invention to provide a wound dressing which is capable of substantially stopping the life threatening flow of blood from a wound. 
         [0015]    Still another object of this invention is to provide a wound dressing which accelerates the natural blood clot formation from a severely bleeding wound. 
         [0016]    Yet another object of this invention is to provide a wound dressing capable of forming a strong seal over the wound to substantially inhibit blood flowing from the wound site. 
         [0017]    The following embodiments and aspects thereof are described and illustrated in conjunction with systems, tools and methods which are meant to be exemplary and illustrative and not limiting in scope. In various embodiments one or more of the above-described problems have been reduced or eliminated while other embodiments are directed to other improvements. In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following descriptions. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
         [0018]      FIG. 1  is a perspective view of one embodiment of the invention. 
           [0019]      FIG. 2  is a section view in the direction of arrows  2 - 2  in  FIG. 1 . 
           [0020]      FIG. 3  is a perspective view of a second embodiment of the invention. 
           [0021]      FIG. 4  is a section view in the direction of arrows  4 - 4  in  FIG. 3 . 
           [0022]      FIG. 5  is a perspective view of a third embodiment of the invention. 
           [0023]      FIG. 6  is a section view in the direction of arrows  6 - 6  in  FIG. 5 . 
           [0024]      FIG. 7  is a perspective view of a fourth embodiment of the invention. 
           [0025]      FIG. 8  is a section view in the direction of arrows  8 - 8  in  FIG. 7 . 
           [0026]      FIG. 9  is a perspective view of a fifth embodiment of the invention. 
           [0027]      FIG. 10  is a section view in the direction of arrows  10 - 10  in  FIG. 9 . 
           [0028]      FIG. 11  is a perspective view of a sixth embodiment of the invention. 
           [0029]      FIG. 12  is a section view in the direction of arrows  12 - 12  in  FIG. 11 . 
           [0030]      FIG. 13  is a top plan view of a seventh embodiment of the invention. 
           [0031]      FIG. 13A  is a section view in the direction of arrows  13 A- 13 A in  FIG. 13 . 
           [0032]      FIG. 14  is a simplified section view of a test fixture used in in vitro hemostasis test apparatus. 
           [0033]      FIG. 15  is a simplified schematic view of the in vitro hemostasis testing system incorporating the test fixture of  FIG. 14 . 
           [0034]      FIG. 16  shows the hemostasis test fixture of  FIG. 14  incorporating a weight applied over the hemostasis agent being tested. 
       
    
    
       [0035]    Exemplary embodiments are illustrated in reference figures of the drawings. It is intended that the embodiments and figures disclosed herein are to be considered to be illustrative rather than limiting. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    The following provides a general description of each of the aspects or elements of the present invention utilized to formulate the various embodiments of the invention described below and with respect to the drawings. 
       Material A 
       [0037]    The water soluble or water-swellable, adhesive hemostatic dressing, material or pouch A can be a knitted, non-woven or woven fabric made from oxidized cellulose, poly-vinylpyrrolidone or its copolymers, alginate, crosslinked polyvinyl alcohol or copolymers of polyvinylalcohol. Desired physical properties of A include: high water absorption, high swellability, strong wet-strength and instant strong adherence to the wound site. 
         [0038]    The oxidized celluloses include but are not limited to: regenerated etherized and oxidized natural fiber cellulose, carboxylic-oxidized cellulose, carboxy methyl cellulose, hydroxyl ethyl cellulose, methyl cellulose, ethyl cellulose, hydroxyl propyl cellulose, methyl hydroxyl propyl cellulose and methyl, hydroxyl ethyl cellulose. An embodiment includes blends of oxidized cellulose such as mixtures of hydroxyl propyl cellulose, methyl hydroxyl propyl cellulose, and methyl hydroxyl ethyl cellulose. The oxidized celluloses can be post treated with a water sensitive coating of polyvinylpyrrolidone or polyacrylic acid or sodium alginate to improve its adhesive properties to increase adhesion to skin or human tissue. 
       Material B 
       [0039]    Hemostatic Powder (B) includes any powder material that exerts a passive or active mode of action in hemostasis. An example of a passive hemostatic powder is a blend of potassium ferrate and the acid form of a cross-linked ion exchange resin (copolymer of polystyrene and divinylbenzene) known as PRO QR Powder as described in U.S. Pat. No. 6,187,347. Other passive hemostatic powder can include microporous, controlled porosity polysaccharide (such as HEMADERM or TRAUMADEX), ethyl cellulose beads and beads of other oxidized celluloses, powder with blend of maltodextrin and other hemostatic agents (an example is deRoyal Multidex Hydrophilic Powder Wound Dressing which is a blend of maltodextrin, sodium alginate and chitosan), powder composed of calcium and sodium alginates with or without chitosan, granular zeolite with strong absorption and exothermic hydration properties such as QUIKCLOT, clays such as bentonite (also known as smectites or montmorillonite). 
       Material C 
       [0040]    Water absorbing material (C) in powder form may include any highly hydrophilic materials whether natural or synthetic. Examples include super absorbing polymers (SAP) (salt of crosslinked polyacrylic acid and its copolymers; vitrified starch such as Safe and Natural Absorbent Polymers), synthetic ion exchange resins (weak acid and strong acid cation organic exchange resin, anion organic exchange resin), inorganic ion exchange resins including zeolites, and absorbents such as clays. 
       Material D 
       [0041]    Water insoluble pouch (D) includes polymer mesh prepared from hydrophobic polymers such as polypropylene and other polyolefins, polyamides, polyesters, polyurethanes and mixtures thereof. 
       Material E 
       [0042]    Moisture absorbing backing (E) include any foam or solid sheet material that can absorb moisture or blood easily and provide back pressure to reinforce A. For example, if A was a regenerated and oxidized cellulose non-woven fabric, the oxidized cellulose would wet quickly in the presence of blood and strongly adhere to the wound site and surrounding tissues. The backing foam (E) wicks the blood away and provides strength to oxidized cellulose which normally would quickly turn into a gel without E resulting in rebleeding or continued blood loss. 
         [0043]    The following types of wound dressings are preferred combinations of the above aspects of this invention:
       1. A water soluble or water-swellable, adhesive hemostatic pouch (A) containing a hemostatic powder (B) ( FIGS. 1 and 2 ); or the powder B on top of a gauze of material A ( FIGS. 3 and 4 ).       
 
         [0045]    2. Pouch A containing water absorbing material (C) ( FIGS. 1 and 2 ); the dressing can simply be material C on top of a gauze of same material as pouch A.
       3. Hemostatic powder B in water-insoluble pouch (D) wherein D is placed inside the pouch A ( FIGS. 5 and 6 ).   4. Material A in the form of a gauze backed by a moisture absorbing backing (E) such as a hydrophilic polyurethane foam ( FIGS. 7 and 8 ); or, Pouch A containing material E ( FIGS. 9 and 10 ).   5. A three-layer dressing including ( FIGS. 11 and 12 ):
           a. top layer of water soluble/swellable adhesive material A   b. intermediate layer of hemostatic powder B or water absorbing material C   c. bottom layer of moisture absorbing backing E   
           6. An impermeable outer pouch (Material D) containing super absorbing polymer (SAP) with a hemostatic powder B separated from the SAP by an inner moisture impermeable pouch (also formed of Material D) having a lower surface formed of Material A to deploy Material B to the wound site as the bulk of the blood is absorbed through a wicking lower surface of pouch by the SAP ( FIGS. 13 and 13A ).       
 
       Methods of Preparing Etherized Celluloses 
       [0053]    A number of examples of test results using this test apparatus and procedure are as follows: 
       Method 1 
       [0054]    One method of making etherized celluloses includes pre-washing the cellulose gauze or fabric in an ethanol or similar solution. Next the gauze is placed in an aqueous solution of sodium or potassium hydroxide at 20 C to 50 C for 1 to 4 hours to break down the celluloses and add OH bases to the molecules. The gauze is then treated with one or more halogenated alkyl compounds, such as methyl chloride, ethyl chloride, and propyl chloride, chloroacetic acid, chloropropanoic acid and chlorobutanoic acid, among others. Additional alkenyl oxides may also be used, such as ethylene oxide and propylene oxide, among others. The mixture is heated at a temperature from 50 C to 160 C. for about 2-6 hours. The product is then neutralized with C 1  to C 5  lower alkyl alcohols which include methanol, ethanol, propanol, butanol, pentanol, and isopropyl alcohol, together with acids such as acetic acid or phosphoric acid, to a pH of about 5-8. 
       Method 2 
       [0055]    Another method of preparing etherized celluloses is to treat a medical grade absorbent gauze first in an alcoholic solution followed by treating the gauze in an aqueous or ethanolic, strongly alkaline solution at 20 to 50 C for a specified time. Next the gauze is treated in a solution of acetic chloride (acetic acid, acetic acid salt or any acid or acid salt with a carboxylic acid group in the molecule can be used in place of acetic chloride) at a concentration of 20-80% in an ethanol solution for 2-6 ours at 20 C to 80 C. This step produces carboxy methyl cellulose converting the gauze to a soluble hemostatic wound dressing. The resulting alkaline gauze is washed with several ethanol washes to remove the alkalinity and the gauze is dried in the oven, packaged and sterilized. 
       Method 3 
       [0056]    Yet another method of preparing a water-soluble, hemostatic gauze matrix includes the steps of mixing one or more of the etherized cellulose compounds, (typically produced as described hereinabove), and a hemostatic compound in a non-aqueous solvent such as ethanol to form a fibrous pulp, said hemostatic compound typically comprising chitosan, one or more water-soluble polysaccharide gums, and one or more surfactants. 
         [0057]    After ensuring a substantially even dispersion of the mixture, the fibrous pulp is collected on forming fabric such as used in paper manufacturing to allow drainage of the pulp solution while retaining the fibers. The fibrous pulp is collected onto the forming fabric under vacuum conditions. The collected wet pulp undergoes compression and freeze drying to produce a sponge. 
         [0058]    Referring now to the drawings, and firstly to  FIGS. 1 and 2 , a first embodiment of the invention is there shown generally at numeral  10  and includes a water soluble or water-swellable hemostatic pouch  12  containing a hemostatic powder  16  sealed therewithin along sealed margins  14  of the pouch  12 . The pouch  12 , as previously discussed, is preferably formed of Material A, while the hemostatic powder is preferably formed of Material B. The pouch  12  is preferably formed to be symmetric so that it may be applied on either side thereof against the surface of skin S. This embodiment  10  may also be formed having the water absorbing Material C in place of Material B. 
         [0059]    Referring now to  FIGS. 3 and 4 , a second embodiment of the invention is there shown generally at numeral  20  and includes a quantity of gauze  22  formed of Material A atop which a quantity  24  of powder B is applied and enmeshed into the fibers of the gauze  22 . The unpowdered surface of the gauze  22  is applied against the skin S covering the wound. 
         [0060]    Referring now to  FIGS. 5 and 6 , a third embodiment of the invention is there shown generally at numeral  30  and includes a water insoluble inner pouch  36  preferably formed of Material D and filled with a hemostatic powder  40  formed of Material B and placed within a water soluble or water-swellable hemostatic outer pouch  32  formed of Material A. The inner pouch  36  is seamed and sealed closed at margins  38 , while the outer pouch  32  is sealed around its margins  34 . Again, this embodiment  30  may be placed with either side of the outer pouch  32  against the wound in the skin S. 
         [0061]    Referring now to  FIGS. 7 and 8 , a fourth embodiment of the invention is there shown generally at numeral  50  and includes a panel of gauze material  54  formed of Material A backed by a moisture absorbing backing  52  formed of Material E in the form of a hydrophilic polyurethane foam. In use, this embodiment  50  would be applied against the skin S with the panel of gauze  54  thereagainst covering the wound. 
         [0062]    In  FIGS. 9 and 10 , a fifth embodiment of the invention is shown generally at  60  and includes the same foam backing material  62  adhered against one surface of a pouch  64  formed of Material A and containing a quantity of particles  68  formed of Material B. 
         [0063]    Referring now to  FIGS. 11 and 12 , a sixth embodiment of the invention is there shown generally at numeral  70  and includes a bottom layer of the water soluble, water-swellable material  74  formed of Material A, an intermediate layer  76  of hemostatic powder formed of Material B or a water absorbing material formed of Material C, and a top layer of moisture absorbing material  72  formed of Material E. 
         [0064]    Referring now to  FIGS. 13 and 13A , a seventh embodiment of the invention is there shown generally at numeral  80  including a two-stage approach to blood absorption and blood flow arrest from a wound. The first stage of blood absorption is performed by a quantity of a super-absorbing polymer formed of Material C (SAP) within an outer pouch  82  formed of Material D having a porous wicking bottom surface  84  which is positioned against the skin surrounding the wound. This SAP absorbs a large amount of blood which has exited the wound site and is laying atop the skin surface therearound. 
         [0065]    A second stage of this device  80  includes a quantity of hemostatic powder  92  formed of Material B and separated from the SAP by an inner pouch  90  formed of Material D. The bottom surface  94  beneath the hemostatic agent particles  92  is formed of a water-soluble material made of Material A. This bottom panel  94  is seamed at  98  to the outer bottom panel  84 , the water-soluble layer  94  being protectively covered with a removable aluminum foil panel  96  which remains in place until the device  80  is ready for use. 
         [0066]    Referring additionally to  FIG. 14 , the test system includes an analytical balance (not shown), a timer, a test block  100 , and a hemostasis apparatus shown generally at numeral  110 . The hemostasis apparatus  110  includes a peristaltic pump which forces blood upwardly into a column  114  to provide a constant head pressure at the test block  100 . The height of the column of blood  114  in relation to the test block  100  is proportional to the pressure at the outlet  108  of the test block  100  in passageway  104 . The apparatus  110  must flow blood by the peristaltic pump at a sufficiently high flow rate of approximately 50-100 ml/min to demonstrate failure, but the velocity of the blood must be kept low to avoid lysing cells. A manometer P 1  is used to maintain that consistent level of blood pressure. 
         [0067]    The test block  100  is preferably formed of vinyl or PVC having an entry passageway  102  with a diameter of 7/16″. That passageway  102  is interconnected with a smaller passageway  104  having a diameter of 3/32″ leading to the open upper end  108 . The sample  116  to be tested is applied over the open end  108  of this smaller passageway  104  atop the blood pool  106 . 
         [0068]    The manometer P 1  is manufactured by Control Company under Model No. 06-664-19 having a pressure arrange capability of −15 to +15 psi. The peristaltic pump, made by Cole Parmer Easy Load II Head K-77200-60 is a constant on type pump to maintain the desired pressure level in the system, returning additional or overflow blood back into the one liter container of blood supply. Return and vacuum break tubing used in this apparatus  110  is ½″ diameter while the remainder of the tubing is ¼″, ⅛″ tubing being used between the valve and the test block  100  to minimize excess blood flow when test sample failure occurs. 
         [0069]    The material used for the blood sample was Na EDTA treated blood or another form of stabilized whole bovine blood, 1.5 g Na EDTA/liter whole blood. 
       Test Procedure 
       [0070]    The preferred procedure for testing each test sample  106  for blood pressure to failure, i.e., when the test sample  116  fails to maintain the blood under pressure within the test block  100 , includes the following steps:
       1. With the valve closed and the pump running, record the blood pressure at the manometer P 1  and record the height of the blood column.   2. With the valve closed, position a test block  100  at a height of the valve which is the same height  112  as the T connecting the manometer P 1  to the blood flow line. Connect the opening of conduit  102  to the downstream side of the valve.   3. Open the valve slightly to allow a small quantity of blood  106  to flow to the surface of the valve  100  through the open end  108  of passageway  104 , then close the valve.   4. Spread the blood  106  around the open end  108  of the passageway  104  to cover the area of at least ¼″ radius around the passageway  104  opening.   5. Cover this area around the opening of passageway  104  with approximately one gram of the hemostasis agent  116  to be tested, being sure to cover the outlet hole  108  and the immediate area therearound with the hemostasis agent  116  to a depth of at least 2 mm. A 1″×1″ dressing made with Material A may be used by itself or with one gram of hemostatic agent or absorbing agent on top of the dressing for testing.   6. Place a vial or bottle  128  over the test sample  126  as seen in  FIG. 16 , the vial or bottle  128  weighing 42 g and having a base diameter of approximately 1.25″.   7. With the valve remaining closed, keep the bottle or vial  128  in place for approximately 30 seconds, 60 seconds or 180 seconds, based upon the test being performed.   8. Open the valve to allow blood pressure into the test block  100 , but do not remove the bottle or vial  118 .   9. After 30 seconds, remove the bottle or vial  118  and wait for an additional 30 seconds.   10. If after 30 seconds, there is no sign of bleeding through the test sample  116 , the test sample  116  has passed this test.   11. If the test fails, record the time to failure in seconds from the opening of the valve.       
 
       Test Examples 
       [0082]    An In Vitro Hemostasis Test Apparatus shown schematically in  FIG. 15  was used to evaluate the efficiency to control bleeding of various dressings. The test provides a measure of seal strength as defined by the blood pressure at which a dressing fails. 
       Example 1 
       [0083]    A 1″×1″ dressing of a regenerated etherized and oxidized natural fiber cellulose (cellulose gauze) was evaluated and found to sustain 30 mm blood pressure for 30 seconds, but failed at higher pressure. While not constructed as a pouch, the cellulose gauze represents Material A described hereinabove. 
       Example 2 
       [0084]    PRO QR Powder, a mixture of potassium ferrate and hydrogen formed of sulfonated, 2% crosslinked polystyrene resin in accordance with U.S. Pat. No. 6,187,347 was evaluated, and found to sustain 100 mm blood pressure for 30 seconds but failed at higher pressure. 
       Example 3 
       [0085]    Cabloc 3050F powder was evaluated and found to sustain 30 mm blood pressure for 30 seconds, but failed at higher pressure. Cabloc 3050F is a super absorbing polymer (SAP) derived from partially neutralized crosslinked polyacrylic acid from Stewart Superabsorbents. 
       Example 4 
       [0086]    A reticulated (open-pore) polyurethane foam (urethane foam) from Crest Foam Industries with a porosity of 75 pores per inch and a thickness of ¼″ was tested in the test apparatus and found to not sustain any blood pressure. Blood was observed to leak thru the open cell foam. 
       Example 5 
       [0087]    The Hemostasis test was applied to a composite material consisting of cellulose gauze (same gauze used in Example 1) in direct contact with blood and urethane foam on top of the cellulose gauze. Blood pressure of 100 mm was sustained for 30 seconds compared of an expectation of 30 mm only from the sum of the pressures for each component. 
       Example 6 
       [0088]    The hemostasis test was applied to a composite material consisting of cellulose gauze (same gauze used in Example 1) in direct contact with blood and Cabloc 3050F SAP on top of the cellulose gauze. A pressure of 100 mm was sustained for 15 seconds compared to an expectation of 60 mm from the sum of pressures from the individual components. 
       Example 7 
       [0089]    The hemostasis test was applied to a composite material consisting of cellulose gauze (same gauze used in Example 1) in direct contact with blood and PRO QR Powder on top of the cellulose gauze. A pressure of 150 mm was sustained for 60 seconds compared to an expectation of 130 mm from the sum of pressures from the individual components. 
         [0090]    Table 1 below summarizes the test results from Examples 1 to 7. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Seal Strength of Dressings 
               
             
          
           
               
                   
                   
                   
                 Seal Strength 
               
               
                 Ex- 
                   
                   
                 (blood 
               
               
                 ample 
                 Dressing 
                 Material 
                 pressure mm) 
               
               
                   
               
             
          
           
               
                 1 
                 Cellulose gauze 
                 A 
                 30 
               
               
                 2 
                 PRO QR Powder 
                 B 
                 100 
               
               
                 3 
                 Cabloc 3050F super absorbing 
                 C 
                 30 
               
               
                   
                 polymer 
               
               
                 4 
                 Urethane Foam 
                 E 
                 0 
               
               
                 5 
                 Cellulose gauze + urethane foam 
                 A&amp;E 
                 100 
               
               
                 6 
                 Cellulose gauze + Cabloc 3050F 
                 A&amp;C 
                 100 
               
               
                 7 
                 Cellulose gauze + PRO QR Powder 
                 A&amp;B 
                 150 
               
               
                   
               
             
          
         
       
     
         [0091]    While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permeations and additions and subcombinations thereof. It is therefore intended that the following appended claims and claims hereinafter introduced are interpreted to include all such modifications, permeations, additions and subcombinations that are within their true spirit and scope.