Disclosed herein are hemostatic devices and hemostatic agents that are applicable to bleeding wounds to promote hemostasis. The hemostatic agents generally include diatomaceous earth that, when brought into contact with a bleeding wound, can minimize or stop blood flow by absorbing at least portions of the liquid phases of the blood, thereby facilitating clotting. The hemostatic devices and agents disclosed herein are not limited to diatomaceous earth, however, as the use of other silica-based materials such as clays in conjunction with diatomaceous earth is within the scope of the present invention.
As used herein, the term “diatomaceous earth” refers to a mineral derived from the fossilized shell remains of fresh water algae and marine algae. These algae are unicellular or colonial algae from the class Bacillariaphyccae and are known as diatoms. Diatoms are characterized by very irregular shapes and generally spiny structures having pitted surface areas. Structurally, they may be barrel-shaped, cylindrical, disk-shaped, etc. and average about 5 to about 20 microns in diameter.
The diatomaceous earth mineral, which is composed of the diatoms and is typically found in deposits in sedimentary rock formed as the result of receding waterlines in lakes and oceans, is about 86% silicon, about 5% sodium, about 3% magnesium, and about 2% iron, such components typically being present in oxide form. Other elements such as copper, strontium, manganese, titanium, and sodium, as well as other elements, may also be found in diatomaceous earth. The porosity of diatomaceous earth is about 85%.
For the hemostatic devices and agents of the present invention, various materials may be mixed with, associated with, or incorporated into the diatomaceous earth to maintain an antiseptic environment at the wound site or to provide other beneficial functions. Exemplary materials that can be used include, but are not limited to, antibiotics, antifungal agents, antimicrobial agents, anti-inflammatory agents, analgesics, antihistamines (e.g., cimetidine, chloropheniramine maleate, diphenhydramine hydrochloride, and promethazine hydrochloride), compounds containing silver or copper ions, combinations of the foregoing, and the like. Other materials that can be incorporated to provide additional hemostatic functions include ascorbic acid, tranexamic acid, rutin, thrombin, and combinations of the foregoing materials. Botanical agents having desirable effects on the wound site may also be added. The diatomaceous earth of the present invention may also be mixed with or otherwise used in conjunction with other materials to provide additional clotting functions and/or improved efficacy. Such materials include, but are not limited to, magnesium sulfate, sodium metaphosphate, calcium chloride, dextrin, combinations of the foregoing materials, and hydrates of the foregoing materials.
For use in the present invention, the diatomaceous earth is preferably formed into particles. As used herein, “particles” include beads, pellets, granules, rods, or any other surface morphology or combination of surface morphologies. Irrespective of the surface morphology, the particles are about 0.2 mm (millimeters) to about 10 mm, preferably about 0.5 mm to about 5 mm, and more preferably about 1 mm to about 2 mm in effective diameter. As used herein, the term “effective diameter” means the average diameter of the particle.
The diatomaceous earth is formed into particles by any of several various methods. Such methods include mixing, extrusion, spheronizing, and the like. Equipment that can be utilized for the mixing, extruding, or spheronizing of the diatomaceous earth is available from Caleva Process Solutions Ltd. in Dorset, United Kingdom. Other methods include the use of a fluid bed or a pelletizing apparatus. Fluid beds for the production of diatomaceous earth particles are available from Glatt Air Technologies in Ramsey, N.J. Disk pelletizers for the production of diatomaceous earth particles are available from Feeco International, Inc., in Green Bay, Wis. Preferably, the diatomaceous earth is extruded through a suitable pelletizing device. The present invention is not limited in this regard, however, as other devices and methods for producing particlized diatomaceous earth are within the scope of the present invention.
It is believed that the cellular clotting mechanisms of diatomaceous earth, as well as other silica-based materials, activate certain contact factors when applied to blood. More specifically, it is believed that such materials initiate one or more adsorption-type mechanisms by which water is removed from the liquid phases of blood to facilitate clotting functions.
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The mesh 12 is defined by interconnected strands, filaments, or strips of material. The strands, filaments, or strips can be interconnected in any one or a combination of manners including, but not limited to, being woven into a gauze, intertwined, integrally-formed, and the like. Preferably, the interconnection is such that the mesh can flex while substantially maintaining the dimensions of the openings defined thereby. The material from which the strands, filaments or strips are fabricated may be a polymer (e.g., nylon, polyethylene, polypropylene, polyester, or the like), metal, fiberglass, or an organic substance (e.g., cotton, wool, silk, or the like).
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To apply the pouch 10 to a bleeding wound, the pouch is removed from the packaging and placed on the bleeding wound. The particlized diatomaceous earth 14 in the mesh 12 contacts the tissue of the wound and/or the blood emanating from the wound, and at least a portion of the liquid phase of the blood is adsorbed by the clay material, thereby promoting clotting. The flexibility of the mesh 12 allows the mesh to conform to the shape of the bleeding wound and to retain that shape upon application.
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The diatomaceous earth-laden mesh 112 is defined by interconnected strands, filaments, or strips of material that are interconnected by being woven, intertwined, or integrally formed as in the above-disclosed embodiments. The mesh 112 includes particles 15 of diatomaceous earth. Although the particles 15 of diatomaceous earth are shown as being concentrated along portions of the edges of the mesh 112, it should be understood that the diatomaceous earth is dispersed throughout the material from which the mesh is fabricated. Preferably, the interconnection of the strands, filaments, or strips to form the mesh 112 is such that the device 110 can flex while substantially maintaining the dimensions of the openings, thereby allowing the diatomaceous earth (or other) particles 14 to be retained.
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The gauze 20 of the present invention is not limited solely to diatomaceous earth, however, as clays such as attapulgite, bentonite, and combinations thereof may be used in addition to the diatomaceous earth. Furthermore, other silica-based materials such as bioactive glasses and the like may also be utilized in addition to diatomaceous earth.
In any embodiment, once the diatomaceous earth is dried onto the gauze substrate to form the gauze 20, the gauze is sufficiently flexible to allow the gauze to be folded, rolled, or otherwise manipulated for packaging. The flexibility of the substrate of the gauze 20 allows the gauze to form to a shape of the bleeding wound and to retain the shape of the bleeding wound upon application.
One manner of causing the diatomaceous earth coating to be retained on the gauze substrate includes combining the diatomaceous earth with a binder such as chitosan. The present invention is not limited to the use of chitosan as a binder however, as other materials (e.g., polysaccharides, polyvinyl alcohol, guar gum, glycerol, gelatinized starches, cellulose (e.g., carboxymethyl cellulose), calcium alginate, and the like) are suitable for use as binders and therefore within the scope of the present invention. In any embodiment, the material of the binder is biocompatible.
Other manners of causing the diatomaceous earth to be retained on the gauze include the use of heat. More specifically, it has been found that by heating a diatomaceous earth/water slurry to or near boiling temperatures, the adhesion of the diatomaceous earth to the gauze material is facilitated. Preferably, the slurry is heated to boiling because higher temperatures tend to promote the adhesion of the diatomaceous earth to the gauze while also providing an effective form of agitation that uniformly disperses the diatomaceous earth in the liquid phase. The gauze (or other substrate material) is then immersed in the boiling slurry for an amount of time sufficient to cause the diatomaceous earth to deposit onto the gauze material. Given the rheology of wetted diatomaceous earth and the material from which the gauze or substrate is fabricated, the diatomaceous earth may adhere as a film directly to the surfaces of the substrate, or it may agglomerate in the interstices of the strands as well as along the strands themselves, thereby being trapped in the fiber matrix.
Another manner of depositing the kaolin coating on the substrate includes applying the diatomaceous earth in slurry form on one side of the gauze substrate using a spraying technique, a slot die technique, or a combination thereof. In using any technique, the amount of slurry applied to the gauze substrate is limited to avoid or at least minimize the saturation of the substrate. Preferably, the diatomaceous earth provides a stable suspension of the material with suitable viscosity for application using the slot die technique.
Once sprayed or applied using the slot die technique, the coated gauze substrate is then rolled or scraped to further embed the diatomaceous earth into the material of the substrate. The gauze substrate is then dried.
In some embodiments, the diatomaceous earth may be combined with the binder and sprayed onto the gauze substrate. As indicated above, preferred binders include chitosan or other polysaccharides as well as polyvinyl alcohol, all of which have adhesive qualities, are compatible with biological tissue, and also exhibit hemostatic properties.
One exemplary method for the production of this device may comprise the steps of unwinding cotton gauze from a roll, immersing the gauze in a slurry of diatomaceous earth and water, applying pressure to the gauze by rolling the wet gauze under high pressure to incorporate the hemostatic material into the material of the gauze, drying the rolled, wet gauze, and removing dust from the gauze (e.g., via blasting with air knives or air nozzles, through the use of electrostatic energy, vacuuming, or brushing with direct contact brushes). Following the removal of dust from the gauze, the gauze may be wound back onto a roll, or it may be cut into sheets for individual packaging.
One or more variables may be manipulated to optimize the amount and integrity of the diatomaceous earth retained on the gauze. These variables include, but are not limited to, slurry temperature, immersion time, the slurry agitation method, and the type of liquid (of the slurry). The elevation of the slurry temperature, as indicated above, aids in the retention of the diatomaceous earth on the gauze. The agitation may be effected by forcing air or other gas through nozzles, stirring, bubbling, boiling, or ultrasonic vibration.
The liquid used for the slurry may also be something other than water. For example, the liquid may be an aqueous ammonia solution. Aqueous ammonia has been found to induce swelling in certain fibrous materials, such as the materials typically utilized to fabricate gauze.
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In either gauze or cloth embodiments, the gauze or cloth material may be cross-linked with a polysaccharide or similar material.
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The substrate 52 is a plastic or a cloth member that is conducive to being retained on the skin of an injured person or animal on or proximate a bleeding wound. An adhesive 54 is disposed on a surface of the substrate 52 that engages the skin of the injured person or animal. Particularly if the substrate 52 is a non-breathable plastic material, the substrate may include holes 56 to allow for the dissipation of moisture evaporating from the skin surface.
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The substrate 62 is an absorbent gauze material that defines a matrix. The gauze may be defined as a rayon/polyester cellulose blend or the like. Other materials from which the substrate 62 may be fabricated include woven fabric, non-woven fabric, silk, paper (e.g., kraft paper and the like), and cellulose material (e.g., cotton in the forms of balls, swabs, and the like). Any material from which the substrate 62 may be fabricated may have an elastic quality. When elastic materials are used as the substrate 62, the sponge 60 becomes both a hemostatic device and a pressure bandage, particularly in embodiments in which a surface cohesive agent or mechanical fastener is added to secure the sponge in place over a wound.
The hemostatic agent used in the sponge 60 is not limited to particlized diatomaceous earth 14. Clay materials such as attapulgite, bentonite, or combinations of the foregoing may be used with diatomaceous earth. Furthermore, other materials such as bioactive glass, biological hemostats, and combinations thereof with diatomaceous earth are also within the scope of the present invention.
The particlized diatomaceous earth 14 may be bound to the substrate 62 via coulombic forces, by impregnating or otherwise incorporating the diatomaceous earth directly into the material of the substrate, by using a binder, by trapping the hemostatic material within the matrix, or the like.
When using a binder to bind the particlized diatomaceous earth 14 to the substrate 62, the binder material may provide additional functionality to the sponge 60. Materials from which the binder may be fabricated include, but are not limited to, chitosan, polyvinyl alcohol, guar gum, gelatinized starches, polysaccharides, glycerol, cellulose (e.g., carboxymethyl cellulose), calcium alginate, and the like, as well as combinations of the foregoing.
In embodiments in which the particlized diatomaceous earth 14 is incorporated into the substrate 62 directly, the particlized diatomaceous earth may be added during the substrate fabrication. If the substrate is a non-woven gauze material containing rayon and polyester, then the particlized diatomaceous earth 14 may be incorporated into or onto the fibers of rayon and polyester. For example, the particlized diatomaceous earth 14 may be in powder form and applied to molten polyester, and polyester fibers may be drawn from the polyester/diatomaceous earth melt. If the substrate is a woven gauze (e.g., cotton), the diatomaceous earth 14 in powder form may be incorporated into the cotton threads during formation of the threads.
The release agent 64 is a material that is disposed on the wound-contacting side of the substrate 62 to facilitate the easy removal of the sponge 60 from the wound tissue after the formation of blood clots. The release agent 64 may be a continuous film, or it may be discontinuous on the surface of the substrate. One material that may be used as a release agent is polyvinyl alcohol, which is a biocompatible material that may be formed as a thin film and that does not significantly affect the absorbency and liquid permeability of the sponge 60. The release agent 64 may be applied directly to the wound-contacting surface of the substrate 62.
In the alternative, the release agent 64 may be applied to the non-wound contacting surface of the substrate 62 as a slurry of diatomaceous earth and release agent. In such an embodiment, the concentration of the polyvinyl alcohol is such that at least some of the alcohol seeps to the wound-contacting surface of the substrate 62, while the diatomaceous earth remains on or near the non-wound contacting surface. In any embodiment, the polyvinyl alcohol serves not only as a release agent, but as an agent that suppresses the dust of the particlized diatomaceous earth 14.
Other materials that may be used as release agents that are within the scope of the present invention include, but are not limited to, silicone, glycerol, and gelatinized starches. As with polyvinyl alcohol, either may be applied in film form.
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The sponge 60 (as well as the sponges shown at 160, 260, and 360) may be folded and used in various manners. The sponge 60 may be folded such that the surfaces on which the particlized diatomaceous earth 14 is disposed are on the inside surfaces of the folded sponge, so as to minimize problems of dusting and detachment of the hemostatic material from the substrate 62. The sponge 60 (and the sponges 160, 260, and 360) can also be folded into a pleated form or into a configuration to produce a number of distinct plies attached along the edges. By configuring the sponge 60 in such a manner, the compliancy and absorbency requirements of different applications can be addressed. The sponge 60 can also be cut or formed into elongated strips for wrapping over the wounds of an injured person or animal or for incorporation into cylinders or swabs. The sponge 60 can also be cut, ripped, ground, or otherwise formed into small pieces for applications such as stuffing into mesh containers.
Also, the sponge 60 (as well as the sponges shown at 160, 260, and 360) may further include a component that imparts a radiopaque characteristic to the sponge. In such an embodiment, barium sulfate may be incorporated into a slurry that includes the particlized diatomaceous earth 14 and applied to the substrate 62, or the barium sulfate may be incorporated directly into the substrate material. Furthermore, the sponge 60 may further include water or alcohol incorporated into one or more of the substrate, the diatomaceous earth, and the release agent, thereby allowing the sponge to be used as a wipe.
Although this invention has been shown and described with respect to the detailed embodiments thereof, it will be understood by those of skill in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed in the above detailed description, but that the invention will include all embodiments falling within the scope of the appended claims.
This application is related to U.S. Provisional Patent Application Ser. No. 60/808,618, filed May 26, 2006, entitled “Blood Clotting Compound”; U.S. Provisional Patent Application Ser. No. 60/810,447, filed Jun. 1, 2006, entitled “Hemostatic Device with Oxidized Cellulose Pad”; U.S. patent application Attorney Docket No. 6989-0067, filed Oct. 6, 2006, entitled “Hemostatic Compositions and Method of Manufacture”; U.S. patent application Attorney Docket No. 6989-0069, filed Oct. 20, 2006, entitled “Devices and Methods for the Delivery of Hemostatic Agents to Bleeding Wounds”; U.S. patent application Ser. No. 11/590,427, filed Oct. 30, 2006, entitled “Clay-Based Hemostatic Agents and Devices for the Delivery Thereof”; and U.S. patent application Attorney Docket No. 6989-0073, filed Nov. 29, 2006, entitled “Heat Mitigating Hemostatic Agent”; the contents of all of the above-referenced applications being incorporated herein by reference in their entireties.
Number | Date | Country | |
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60808618 | May 2006 | US | |
60810447 | Jun 2006 | US |