Hemostatic textile
Abstract
A hemostatic tissue in the form of a wound bandage or suture, comprising: a textile material comprising a woven or knitted combination of glass fibers having a diameter of 5 nanometers to 15 micrometers and rayon fibers, said hemostatic tissue capable of activating hemostatic systems in the body when applied to a wound, in which glass fibers and hemostatic tissue are combined together.

Term
0.3 yearsto projected expiry
Projected expiry 10 January 2027, counted from filing; an application has no term until it is granted.
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12 claims: 9 independent, 3 dependent
- 1ES 2 610 397 T3 REIVINDICACIONES 1. Un tejido hemostático en la forma de una venda o sutura de heridas, que comprende:un material textil que comprende una combinación tejida o tricotada de fibras de vidrio que tienen un diámetro de 5 nanómetros a 15 micrómetros y fibras de rayón, dicho tejido hemostático capaz de activar los sistemas hemostáticos en el cuerpo cuando se aplica a una herida, en el que las fibras de vidrio y el tejido hemostático se combinan conjuntamente.
- 2El tejido hemostático según la reivindicación 1, en el que las fibras de rayón son fibras de rayón de bambú.
- 3El tejido hemostático según una cualquiera de las reivindicaciones precedentes, en el que las fibras de vidrio son filamentos continuos.
- 4El tejido hemostático según una cualquiera de las reivindicaciones precedentes, en el que las fibras de vidrio comprenden vidrios de aluminoborosilicato con bajo contenido de óxido de sodio.
- 5El tejido hemostático según una cualquiera de las reivindicaciones precedentes, en el que las cantidades relativas de las fibras de vidrio y las fibras de rayón varían de alrededor de 0,1% a alrededor de 99,9% en peso de fibras de vidrio y de alrededor de 99,9% a alrededor de 0,1% en peso de fibras de rayón, basado en el peso total de dicho tejido.
- 6El tejido hemostático según una cualquiera de las reivindicaciones precedentes, en el que las cantidades relativas de las fibras de vidrio y las fibras de rayón varían de alrededor de 50% a alrededor de 80% en peso de fibras de vidrio y de alrededor de 50% a alrededor de 20% en peso de fibras de rayón, basado en el peso total de dicho tejido.
- 7El tejido hemostático según una cualquiera de las reivindicaciones precedentes, que comprende una combinación de alrededor de 50% en peso de fibras de vidrio y alrededor de 50% en peso de fibras de rayón, basado en el peso total del tejido.
- 8El tejido hemostático según una cualquiera de las reivindicaciones precedentes, que comprende adicionalmente plaquetas sanguíneas liofilizadas.
- 9El tejido hemostático según una cualquiera de las reivindicaciones precedentes apropiado para la aplicación a una herida y el contacto con sangre.
- 10El tejido hemostático según cualquier reivindicación precedente, en el que el tejido hemostático está en la forma de un vendaje para heridas.
- 11Un tejido hemostático envasado que comprende un envase que contiene el tejido hemostático según una cualquiera de las reivindicaciones precedentes, en el que el envase está esterilizado.
- 12El tejido hemostático según cualquier reivindicación precedente para uso en un método de activación de sistemas hemostáticos en un cuerpo, comprendiendo el método aplicar el tejido hemostático a una herida tal que el tejido hemostático entra en contacto con la sangre.
Independent claims12
152 paragraphs in 6 sections, as filed
ES 2 610 397 T3
DESCRIPTION
Hemostatic tissue
Background of the invention
1. Field of the invention
The present disclosure relates to tissues, such as bandages, sutures, or fabrics, and more particularly to hemostatic tissues that include agents that can control bleeding rapidly and can be stored for long periods of time.
two. Description of Related Art
Despite considerable progress in understanding the pathophysiological processes involved in superficial (topical) hemostasis, there remains a considerable unmet need for materials that can be applied to bleeding sites to contain bleeding. Traumatic injury is the leading cause of death for individuals under 44 years of age (Bozeman, W. Shock, Hemorrhage (2001)). About half of the 100,000 deaths annually in the United States from traumatic injury, or 50,000 cases, are from exsanguination, (Peng, R., Chang, C., Gilmore, D. & Bongard, F. Am Surg Vol. 64 950 -4 (1998)) and approximately the same number of bleeding patients survive after massive red blood cell transfusion (Vaslef, S., Knudsen, N., Neligan, P., and Sebastian, MJ Trauma-Inj. Inf. Crit Care Vol. 53 291-296 (2002)). Thus, approximately 100,000 patients are in critical need of bleeding control in the US each year. The situation is equally critical in the care of combat casualties; in a recent review of military casualties (Burlingame, B. DOD's experiences in Afghanistan Advanced Technological Applications for Combat Casualty Care 2002 Conference in www.usaccc.org (2002)), the control of non-compressible bleeding was identified as the most important unmet need in military emergency medicine. Standard care is often the application of a tourniquet to control "compressible" bleeding and then gauze to control residual "non-compressible" bleeding. However, continued blood loss through the gauze is a major contributor to morbidity and mortality.
The prior art is replete with patents that refer to various forms of bandages. For example, US Patent No. 3,419,006 to King describes a sterile transparent wound dressing made of a hydrophilic polymer gel of an insoluble polymer, and US Patent No. No. 4,323,061 to Usukura describes a rigid bandage made of glass fibers and non-glass fibers. Furthermore JP5200104 A describes a bandage made of glass fibers with a reinforcing layer of cotton. In addition, various methods have been tried to quickly stop bleeding in an injured person. Several of these methods include items such as bandages supplemented with substances that chemically accelerate the body's natural clotting processes. Examples of such items include the following:
US Patent No. 3,328,259 to Anderson describes a wound dressing incorporating polymers such as sodium carboxymethylcellulose, hydroxyethylcellulose, polyoxyethylene, polyvinylpyrrolidone, and the like.
US Patent No. 4,192,299 to Sabatano describes a bandage that includes a package containing an antiseptic substance.
US Patent No. 4,390,519 to Sawyer describes a dressing in the form of a sponge and containing collagen or a collagen-like substance.
US Patent No. 4,453,939 to Zimmerman et al. describes a composition useful as a wound dressing and manufactured from a combination of collagen, fibrinogen, and thrombin.
US Patent No. 4,606,337 to Zimmerman et al. describes a resorption sheet for wound closure and treatment, and is composed of a glycoprotein matrix containing fibrinogen and thrombin.
US Patent No. 4,616,644 to Saferstein et al. describes an adhesive bandage that includes high molecular weight polyethylene oxide as a hemostatic agent.
US Patent No. 5,800,372 to Bell et al. describes a bandage made of an absorbent polymer and includes microfibrillar collagen.
US Patent No. 5,902,608 to Read et al. describes surgical aids such as bandages, gauze, sutures and the like, which contain fixed dry blood cells expressing platelet-derived growth factors.
US Patent No. 6,638,296 to Levinson describes a bandage that includes a pad containing glucosamine or a glucosamine derivative.
ES 2 610 397 T3
US Patent No. 6,762,336 and International Patent Application Publication No. WO / 99/59647 to MacPhee et al. describes a multilayer bandage that includes a layer of thrombin sandwiched between two layers of fibrinogen.
US Patent No. 6,897,348 to Malik describes an adhesive bandage that contains an antimicrobial agent and a hemostatic agent (e.g. chitosan, niacinamide, or ascorbic acid) or a single healing agent that contains both antimicrobial and hemostatic activities ( eg, chitosan niacinamide ascorbate salt).
US Patent No. 6,891,077 to Rothwell et al. describes fibrinogen dressings that include a procoagulant such as propyl gallate, gallic acid, or a derivative thereof. Optional ingredients such as thrombin or an antimicrobial agent can also be included.
New Generation Medical Corporation International Patent Application Publication No. WO 97/28823 describes a hemostatic dressing containing powdered fibrinogen and thrombin bonded to a fibrous matrix with a non-aqueous viscous adhesive such as a viscous polysaccharide, glycol or petrolatum.
Despite considerable progress in understanding the pathophysiological processes involved in hemostasis, tissue remodeling, and resolution at wound sites, there remains a critical unmet need for a material that can be applied to wound sites to accelerate these processes. The present invention is believed to be an answer to that need.
Summary of the invention
The present invention relates to a hemostatic tissue, comprising: a material comprising a combination of glass fibers and rayon fibers, as defined by claim 1, wherein the hemostatic tissue is capable of activating hemostatic systems in the body when applied to a wound.
In another aspect, the present invention relates to a hemostatic fabric, comprising a material comprising a combination of about 65% by weight of glass fibers and about 35% by weight of regenerated bamboo fibers; hemostatic tissue capable of activating hemostatic systems in the body when applied to a wound.
In yet another aspect, the present invention relates to a hemostatic fabric, comprising: a material comprising a combination of about 65% by weight of glass fibers and about 35% by weight of regenerated bamboo fibers; and from about 0.1 to about 5% by weight of thrombin or a fraction comprising thrombin based on the total weight of the tissue; hemostatic tissue capable of activating hemostatic systems in the body when applied to a wound.
In yet another aspect, the present invention relates to a hemostatic fabric, comprising: a material comprising a combination of about 65% by weight of glass fibers and about 35% by weight of regenerated bamboo fibers; and one or more hemostatic agents selected from the group consisting of RL platelets, RL blood cells, fibrin, and fibrinogen, wherein RL platelets and RL blood cells comprise from about 0.1 to about 20% and fibrin and fibrinogen comprise from about 0.1 to about 5% by weight, based on the total weight of the tissue; hemostatic tissue capable of activating hemostatic systems in the body when applied to a wound.
In yet another aspect, the present invention relates to a hemostatic tissue, comprising: a material comprising a combination of about 65% by weight of glass fibers and about 35% by weight of regenerated bamboo fibers; from about 0.1 to about 5% by weight of thrombin or a fraction comprising thrombin based on the total weight of tissue; and one or more hemostatic agents selected from the group consisting of RL platelets, Rl blood cells, fibrin, and fibrinogen, wherein RL platelets and RL blood cells comprise from about 0.1 to about 20% and fibrin and fibrinogen comprise from about 0.1 to about 5% by weight, based on the total weight of the tissue; hemostatic tissue capable of activating hemostatic systems in the body when applied to a wound.
These and other aspects will become apparent upon reading the following detailed description of the invention.
Brief description of the figures
The invention will be better understood when taken in conjunction with the following figures in which:
Figure 1 shows representative thrombin generation curves using one embodiment of the present invention;
Figure 2 shows times for thrombin generation using embodiments of the present invention;
Figure 3 shows the thromboelastographic analysis of materials according to the present invention;
ES 2 610 397 T3
Figure 4 shows a comparison of blood cells on double fiber and gauze;
Figure 5 shows the interaction of red blood cells (RBCs) with materials according to the present invention;
Figure 6 shows platelet activation on glass filaments used in the present invention; Y
Figure 7 shows total blood loss using the materials of the present invention.
Detailed description of the invention
The inventors of the present invention have unexpectedly found that a hemostatic tissue can be prepared from a glass fiber composite and one or more secondary fibers. The hemostatic tissue made from the fiber composite exhibits excellent hemostatic properties and fluid absorption. To further improve the hemostatic properties of the hemostatic tissue made from the composite, additional blood factors such as thrombin, lyophilized blood cells, lyophilized platelets, fibrin, fibrinogen, or combinations thereof can be added. These additional factors help activate the body's natural hemostasis cascade and result in a material that can quickly stop bleeding. The inventors have discovered that the combination of glass fibers, secondary fibers, and additional blood factors produces a new hemostatic tissue that rapidly stops bleeding and is useful in situations where there are large bleeds or when a patient cannot be immediately admitted to a hospital. hospital or trauma treatment center.
The hemostatic tissue of the present invention provides significant advantages over current products that activate hemostasis. The present invention is capable of rapidly activating the body's natural hemostatic systems, such as the blood coagulation cascade, providing locally high concentrations of substances that activate that cascade. Furthermore, using lyophilized blood proteins, the hemostatic tissue of the present invention can be stored in a dry state ready for immediate use for long periods of time. This aspect is particularly advantageous because previous products and systems required hydrated proteins for activation.
As indicated above, the present invention is a hemostatic fabric, as defined by claim 1, comprising a material comprising a combination of glass fibers and rayon fibers. Each of these components is discussed in more detail below.
The fiberglass component is preferably a fiberglass prepared by extrusion or electrospun processes, and has fiber diameters of 5 nanometers to 15 microns. Types of glass contemplated for use in the present invention include, but are not limited to, low sodium oxide aluminoborosilicate glasses, borosilicate glass, lead glass, aluminosilicate, barium alkali silicate, vitreous silica, glass chalcogenide, phosphate glass and bioactive glass sold under the trade name BIOGLASS. The dimensions of the fiberglass component can be described by conventional nomenclature, which includes the following designations: B (3.5 microns in diameter); C (4.5 microns in diameter); D (5 microns in diameter); OD (6 microns in diameter); E (7 microns in diameter); G (9 micron diameter); H (10 microns in diameter); or K (13 microns in diameter). Also, the fiberglass component strand count can range from 900 to 37. The grade of the fiberglass can be any electrical grade (E), chemical grade (C), or high strength ("S"), and the filaments can be in any arrangement, eg, continuous, chopped, or textured. The fiberglass fibers can also be used individually or in a folded state using from 2 to 20 or more fibers. Fiberglass material is commercially available from various vendors such as Owens Corning, and is commercially available as Grades G75, Grade E fiberglass, and the like, using the designations described above.
The secondary fibers used in the fabric of the invention are rayon fibers.
Preferred secondary fibers include regenerated bamboo fibers (eg, chemically processed), which have high moisture absorbance and which are capable of activating the intrinsic coagulation cascade. Secondary fibers can be prepared using conventional methods, including ring spinning, open end (EO), rotor, or air jet, and can have counts ranging from 1/1 to 100/1 Ne.
As will be appreciated by one skilled in the art, the secondary fibers can be used individually, or in combinations of two, three, four or more in a mixed or stranded state. For example, in one embodiment, two or more secondary fibers can be produced individually and then mixed or twisted together to form a composite yarn. In another embodiment, the secondary fibers may be formed in the form of a conjugate comprising blocks of selected types of fibers, for example, alternating blocks of polyesters and polysaccharides. In yet another embodiment, the secondary fibers can be formed as a homogeneous combination of different yarns.
The relative amounts of glass fibers and secondary fibers can vary widely, for example, from about 0.1 to 99.9% by weight of glass fibers and from about 99.9% to 0.1% by weight of secondary fibers,
ES 2 610 397 T3 based on total dry fabric weight. Preferable amounts of these materials range from about 30 to 80% by weight of glass fibers and from about 70 to 20% by weight of secondary fibers and more preferably from about 50 to 80% by weight of glass fibers to from about 50 to 20% by weight of secondary fibers. Examples of useful proportions of glass and secondary fibers in the hemostatic fabric of the invention include about 50% by weight of glass fibers and about 50% by weight of secondary fibers; about 40% by weight of glass fibers and about 60% by weight of secondary fibers; about 30% by weight of glass fibers and about 70% by weight of secondary fibers; or about 20% by weight of glass fibers and about 80% by weight of secondary fibers. A particularly useful combination is about 65% by weight of glass fibers and 35% by weight of bamboo fibers. The glass fiber component and the secondary fiber component are combined using conventional methods such as spinning or knitting.
In use, the hemostatic tissue of the invention can take any configuration. In one embodiment, the hemostatic tissue consists of a hemostatic layer designed to accelerate hemostasis, and an outer layer designed for surface texture, moisture transfer, fluid adsorption, and microbial protection. In another embodiment, the hemostatic tissue consists of three layers: a hemostatic layer designed to accelerate hemostasis, a middle layer for bandage strength and elasticity, and an outer layer designed for surface texture, moisture transfer, adsorption. fluid and microbial protection. Additional configurations are conceivable by those skilled in the art.
The hemostatic tissue of the invention can also be treated with various agents that enhance its effectiveness. Examples of additional agents include organic or inorganic compounds that are microstatic or microcidal; organic or inorganic compounds that react covalently with blood clotting proteins; organic or inorganic compounds that react covalently with injured tissue to form covalent bonds for improved adhesion to tissues; organic or inorganic compounds that polymerize to form a three-dimensional polymeric network in or on the wound; imaging agents such as ultrasound contrast agents (eg, gas-filled microbubbles, metallic nanoparticles, and the like), radiopaque agents (eg, iodinated small molecules such as iopromide, high molecular weight iodinated polymers, and the like) ), magnetic resonance probes (e.g. iron oxide nanoparticles, superparamagnetic metal nanoparticles, gadolinium chelated with diethylenetriaminepentaacetate (DTPA), and DTPA-chelated gadolinium-containing polymers, and the like).
Additional agents that can be included in the hemostatic tissue of the invention include skin conditioners such as aloe vera, vitamin E, coenzyme Q, collagen, and the like; anti-inflammatory agents such as aspirin, ibuprofen, acetaminophen, vitamin C, COX-2 inhibitors, steroids, and the like; analgesics such as lidocaine, tetrocaine, opiates, cocaine, antihistamines, and the like; antimicrobial or antifungal agents such as bacitracin, silver salts, iodide, and the like; vasoconstrictors such as epineferin, norepinephrine, vasopressin, hemoglobin, endothelin, thromboxanes, NO scavengers, and the like; growth factors such as inhibitors of MMP, PDGF, and the like; anti-scar agents such as IL-11, anti-keloid compounds, and the like; cauterizing agents that undergo an exothermic reaction upon rehydration such as zeolites; dehydrating agents that are hydroscopic such as dextran; prothrombotic agents, such as zeolite, dextran sulfate, polyphosphate, mineral interfaces, phosphatidylserine, calcium, and the like.
The textile matrix of the invention may also include additional factors that act to activate the body's natural hemostatic systems and thus help to rapidly stop bleeding. Such additional factors include thrombin or a plasma fraction including thrombin, lyophilized rehydrated platelets (RL), RL blood cells, fibrin, fibrinogen, and combinations thereof. In a preferred embodiment, thrombin is incorporated into tissue to impart additional hemostatic action. Thrombin can be from any source (naturally isolated, recombinant, etc.) or it can be in the form of a plasma or serum fraction containing thrombin and additional clotting factors such as factor XII, factor XIIa, factor XI, factor XIa, factor XIII, factor XIIIa, factor IX, factor IXa, factor VIII, factor VIlla, factor vWF, factor V, factor Va, factor X, factor Xa, and combinations thereof, or other coagulation cofactors such as components of animal venom, such as reptilase, or vasoactive agents such as endothelin, thromboxanes, nitrous oxide (NO) scavengers, or combinations thereof. These factors, or any of the factors listed above, can be in dry or liquid form when incorporated into the fabric of the invention.
Thrombin contemplated for use in the tissue of the invention can take any form including highly purified thrombin IIa from human or animal sources, genetically modified plants, or other natural or recombinant protein expression systems. Furthermore, partially purified thrombin from human or animal sources, genetically modified plants or other natural or recombinant protein expression systems can be used in the present invention. The thrombin contemplated for use in the present invention may also be contained in purified or partially purified serum or plasma. In one embodiment, the thrombin used in the tissue of the present invention is a partially purified serum fraction containing thrombin IIa.
The preferred amount of thrombin in the fabric of the invention ranges from about 0.01% by weight to about 10% by weight, based on the total weight of the dry fabric. The most preferred amounts of thrombin included in the
ES 2 610 397 T3 fabric of the invention range from about 0.05% by weight to about 7% by weight and most preferably from about 0.1% by weight to about 5% by weight, all based on the total weight of the dry fabric.
As explained in more detail in the examples below, to produce a hemostatic tissue that includes thrombin, the textile matrix is soaked in a solution containing thrombin and frozen and lyophilized. Preservatives such as glycerol, propanediol, polyoxyethylene glycol (PEG) trehalose, and the like, can be included in the soak solution to prevent the fabric from becoming brittle or chalky during lyophilization. In general, the preservative concentrations in the thrombin solution vary up to a maximum of about 20% (v / v). In preferred embodiments, about 12% (v / v) glycerol is used.
In another preferred embodiment, one or more of the lyophilized rehydrated platelets (RL), RL blood cells, fibrin, or fibrinogen are incorporated into the tissue to impart additional hemostatic action. Rehydrated lyophilized blood cells and rehydrated platelets and methods for their manufacture are known in the art. See, for example, US Patent Nos. 4,287,087; 5,651,966; 5,891,393; 5,902,608; 5,993,804.
Briefly, RL platelets are prepared by isolating the platelets, exposing them to a fixative such as formaldehyde, and drying. RL platelets are also commercially available from Entegrion, Inc. (Research Triangle Park, NC) under the trade name STASIX. Methods of isolation and purification of fibrin and fibrinogen are also known in the art.
Briefly, to produce RL blood cells, blood can be obtained from healthy volunteers, after signed informed consent, in citrate-phosphate-dextrose with adenine (CPDA-I) and subjected to centrifugation at 1000xg for 20 min to obtain RBCs. Erythrocytes are diluted to hematocrit = 5% in phosphate buffered saline (PBS) and centrifuged at 2,000xg for 10 min. This step can be repeated two additional times to separate RBCs from plasma proteins. The RBCs can then be cross-linked with glutaraldehyde (for glut-RL RBCs) or a mixture of paraformaldehyde and glutaraldehyde (for para-RL RBCs). The unreacted aldehyde can be removed from the RBCs by centrifugation (as for the removal of cells from plasma proteins), and finally the cells are frozen and lyophilized at -30 ° C.
Fibrin and fibrinogen are also commercially available from various sources. For example, clinical grade material is sold under the trade name HAEMOCOMPLETTAN P from ZLB Behring (Marburg, Germany) and TISSEEL from Baxter (Deerfield, IL USA). Research grade material is available from Enzyme Research Laboratories (South Bend, IN USA). Fibrin and fibrinogen can also be isolated according to procedures known in the art (eg, van Ruijven-Vermeer IA, et al., Hoppe Seylers Z Physiol Chem. 360: 633-7 (1979)). Fibrin and fibrinogen can also be isolated using precipitations in glycine, ammonium sulfate, or ethanol which are known in the art.
RL platelets, RL blood cells, fibrin, or fibrinogen can be added as a powder by spreading or blowing the dry material onto the matrix and lyophilizing. Alternatively, these materials can be added to the matrix in solution form, and frozen and dried as described above. Preservatives such as glycerol, propanediol, polyoxyethylene glycol (PEG) trehalose, and the like, can be included in the soak solution to prevent the tissue from becoming brittle or chalky during lyophilization. In general, preservative concentrations in the thrombin solution vary up to a maximum of about 20% (v / v). In preferred embodiments, 12% (v / v) glycerol is used.
Any combination of RL blood cells, RL platelets, fibrin, and / or fibrinogen can be incorporated into the tissue of the present invention. Preferably, the total amount of RL blood cells, RL platelets, fibrin, and / or fibrinogen ranges from about 0.1% to about 50% based on the total weight of the dry tissue. In exemplary embodiments, the hemostatic tissue of the invention may include the following combinations (all percentages by weight are based on the total weight of the dry tissue):
<td>Interval</td><td>RL platelets or RL blood cells (% by weight)</td><td>Fibrin or fibrinogen (% by weight)</td>
<td>Preferred range</td><td>0.1 to 20</td><td>0.1 to 5</td>
<td>Most preferred range</td><td>from 1.0 to 10</td><td>0.5 to 2</td>
<td>Most preferred interval</td><td>from 3 to 7</td><td>from 0.75 to 1.5</td>
In yet another embodiment, the textile matrix of the invention includes both thrombin or a thrombin-containing fraction and one or more lyophilized rehydrated platelets (RL), RL blood cells, fibrin, or fibrinogen. For example, a preferred combination of dry platelets, fibrinogen, and thrombin is about 3 to 7% by weight of RL platelets, 0.75 to 1.5% by weight of fibrinogen, and 0.1 to 5% by weight. thrombin, all based on total dry tissue weight. In a particularly preferred embodiment, a combination of about 5% is used
ES 2 610 397 T3 by weight of RL platelets, about 1% by weight of fibrinogen and about 0.1% by weight of thrombin.
A hemostatic tissue is preferably prepared containing both thrombin and one or more of the lyophilized rehydrated platelets (RL), Rl blood cells, fibrin, or fibrinogen by first incorporating thrombin into the matrix followed by incorporation of one or more of the lyophilized rehydrated platelets ( Rl), RL blood cells, fibrin or fibrinogen using techniques generally described above. In one embodiment, the hemostatic tissue of the invention can be infused with a combination of fibrinogen and thrombin as described in U.S. Patent No. 6,113,948, incorporated herein by reference, and available from ProFibrix BV (Leiderdorp, Netherlands) under the trade name FIBROCAPS (a combination of fibrinogen microspheres and thrombin microspheres). Preservatives such as glycerol, propanediol, polyoxyethylene glycol (PEG) trehalose, and the like, can be included in the soak solution to prevent the tissue from becoming brittle or chalky during lyophilization. In general, the preservative concentrations in the thrombin solution vary up to a maximum of about 20% (v / v). In preferred embodiments, 12% (v / v) glycerol is used.
Generally, the hemostatic tissue of the invention is manufactured by the following steps:
1. RL platelets or RL blood cells are prepared and lyophilized according to published procedures;
two. The hemostatic tissue is manufactured from the textile components. During this stage, the tissue can be chemically treated by adding a defined amount of agents such as glycerol, propanediol, polyoxyethylene glycol (PEG) to preserve the tissue and aid the adhesion of hemostatic proteins. Additionally, at this stage, serum or plasma containing thrombin is lyophilized on the textile matrix.
3. Haemostatic proteins such as RL platelets, RL blood cells, fibrin, or fibrinogen are applied directly to a selected surface of hemostatic tissue (e.g., a surface that will contact injured tissue) with a preselected particle density (protein per square area of textile surface) or percentage by weight based on the total weight of the fabric. The hemostatic proteins can be applied in any order, and they can be applied to tissue in solution form in a dry form. In one embodiment, RL platelets can be aldehyde stabilized, applied to tissue in a liquid state, and then lyophilized onto tissue.
Four. The infused hemostatic tissue is packaged and optionally subjected to sterilization (eg, gamma or UV irradiation).
Detailed examples of hemostatic tissues and their manufacturing method are described below.
The textile matrix of the invention is capable of activating hemostatic systems in the body when applied to a wound, including blood coagulation systems and vasoconstriction systems. Various materials have long been known to activate platelets and other blood clotting factors when they come into contact with an injured site. Platelets, as the main cellular component of the blood that provide hemostasis in response to vascular damage, are activated on contact when exposed to foreign materials such as metallic glasses and plastics. See, for example, Barr, H. The stickiness of platelets. Lancet ii, 775 (1941)). Furthermore, it is well known that thrombin converts fibrinogen to fibrin in the blood coagulation cascade. The combination of components in the hemostatic tissue of the present invention work together locally and synergistically to activate the blood coagulation cascade in a highly concentrated and localized manner when applied to a wound.
The hemostatic tissue of the invention is useful as a wound dressing, eg, a bandage, gauze, and the like, or it can be shaped into sutures for use in surgery. Additional uses include forming the hemostatic fabric of the invention into fabrics for use in the manufacture of protective clothing or clothing liners, or for use in tourniquets. Additionally, in another embodiment, the hemostatic tissue of the present invention is in the form of a kit for use in surgery or emergency or trauma situations. The kit includes the hemostatic tissue of the invention in rolls, sheets, or other appropriate form, and can be used with or without the additional blood factors.
Examples
All parts and percentages are by weight and all temperatures are in degrees Celsius unless explicitly stated otherwise.
Materials
The following solutions were used in the Examples described below
Dextrose citrate (ACD) anticoagulant: 0.042 M Na3 Citrate, 0.035 M citric acid, 20% w / v anhydrous dextrose, pH 4.5.
Citrated saline solution: 6.2 mM Na3Citrate, 150 mM NaCl, pH 6.5.
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Imidazole buffered saline: 84 mM imidazole, 150 mM NaCl, pH 6.8.
4% Paraformaldehyde: 20 grams of paraformaldehyde and 9.4 grams of NaH2PO4 are suspended in 400 ml of deionized H2O and heated to about 60 ° C in a water bath until dissolved. The pH is set to 7.2 and water is added up to 500 ml.
Fixing solution (prepared immediately before use): combine 1 ml of ACD, 10 ml of 0.135 molar NaH2PO4, pH = 6.5, and 9 ml of 4% (w / v) paraformaldehyde.
Imidazole buffer: 84 mM imidazole, pH = 6.8.
Citrate standard solution: 3.2% sodium citrate, pH = 7.4.
Examples 1-7: Preparation of hemostatic tissues
The following specific textile combinations were made and used in the experiments below:
Weave I: weave style; G75 fiberglass in the warp; 30/1 100% OE bamboo rayon in the weft.
The above combination was a fiberglass / bamboo co-woven with the glass fibers (G75, E-grade extruded glass E225 electronic grade spun yarn) in the long (warp) orientation and the bamboo fibers going to through the fabric (padding).
Fabric 2: Fabric Style; ECBC150 1/0 1.0 Z fiberglass in the warp; 18/1 100% MJS bamboo rayon in the weft.
Weave 3: Weave Style; ECE225 2/0 4.0 Z fiberglass in the warp; 18/3 100% RS bamboo rayon in the weft.
Fabric 4: Knit Style; 1 end - ECG75 1/2 Fiberglass; 1 end - 18/1 100% OE bamboo rayon in weft.
Fabric 5: Knit Style; 2 layers - ECGl 50 1/0 fiberglass twisted with 20/1 100% bamboo rayon.
Weave 6: Weave Style; ECE225 2/0 4.0 Z fiberglass in the warp; 16/2 100% linen in the weft.
Weave 7: Weave Style; ECH 18 1/0 0.7 Z fiberglass in the warp; 18/2 100% Lyocel MJS in the weft.
Example 8: Preparation of a hemostatic textile matrix including thrombin
120 mg of angel hair grade fiberglass was combined with 8 ml of plasma (Innovative Research, Inc., Southfield, MI) and 80 µl of 1M CaCl2 and placed on a rocker. The mixture was gently mixed on the rocker for about 90 minutes, and the glass fiber was separated from the mixture by centrifugation (300xg for 5 minutes). The supernatant was collected and glycerol was added to a final concentration of 9% by weight. The final product is a serum containing thrombin IIa.
cm<sup>2</sup> of Tissue 1 above were soaked for about 1 minute in approximately 5 ml of the above serum. Excess serum was allowed to drain off and the soaked textile matrix was frozen at -20 ° C and lyophilized.
Example 9: Preparation of a hemostatic textile matrix including thrombin and an additional hemostatic agent
A. Textile matrix including thrombin and rehydrated lyophilized platelets (RL).
Two methods for preparing tissue-based hemostatic matrices with lyophilized rehydrated platelets and thrombin (RL) are detailed here. The quality of the preparations can be evaluated using the Thrombin Generation Assay described below.
1. Method 1
In this method, the RL platelets are manufactured separately, and then added to the textile matrix.
(to). RL platelet preparation
RL platelets are prepared as described in US Patent Nos. 5,651,966 and 6,139,878. Alternatively, the following procedure can be used:
Platelet Rich Plasma (PRP) is prepared by first drawing fresh venous blood in ACD (for example, 42.5 ml of blood in 7.5 ml of aCd in a 50 cm syringe<sup>3</sup>). The blood is subjected to centrifugation (10 minutes, 1,200 rpm at 25-27 ° C) to deposit the red blood cells. The PRP is in the supernatant. Alternatively, the PRP can be isolated from stored and / or expired platelets by removing the cells from the storage bag and
ES 2 610 397 T3 centrifuging for 10 minutes at around 1200 rpm to remove contaminating red blood cells and aggregated platelets.
Plasma proteins are removed from PRP using centrifugation (10 minutes at about 2,400 rpm) and resuspending isolated platelets in citrated saline buffer. Platelets are washed twice in citrated saline buffer and resuspended in citrated saline buffer to a final concentration of about 8x10<sup>9 </sup>platelets / ml. Alternatively, plasma proteins can be removed from PRP using size chromatography (Sepharose 4B equilibrated with citrated saline buffer). Turbidity fractions can be collected, pooled, and platelets isolated by centrifugation. The platelets are then resuspended in citrated saline buffer to a final concentration of about 8 x 10<sup>9</sup> platelets / ml.
Isolated platelets are cross-linked by adding 3.5 ml of fixative solution dropwise to 1.25 ml of isolated platelets at a concentration of about 8 x 10<sup>9</sup> platelets / ml with gentle shaking. The fixative solution is added to a final volume of about 10 ml and the mixture is incubated for 1 hour at room temperature without mixing or shaking. Cross-linked platelets are isolated by centrifugation (10 min at 2400 rpm) and resuspended in imidazole buffered saline, washed, and finally resuspended in imidazole buffered saline to a final concentration of approximately 1 x 10<sup>9</sup> platelets / ml.
Cross-linked platelets are frozen and lyophilized by first suspending them in imidazole buffered saline with 5% bovine serum albumin at pH 6.8 to a final platelet concentration of approximately 0.8 x 10<sup>9</sup> platelets / ml. The mixture is distributed into 1 ml aliquots, frozen at -80 ° C, and lyophilized overnight or longer. The lyophilized product can be stored at -20 ° C. The lyophilized cross-linked platelets can be rehydrated by resuspending them in imidazole buffer.
(b). Adding RL platelets to a matrix.
To prepare a matrix containing RL platelets, RL platelets are first ground in a dry state to a fine powder. The fine powder is spread evenly on a flat sterile surface such as a Petri dish and one side of the lyophilized thrombin loaded matrix prepared in Example 8 above is pressed onto the Rl powder and removed. Powdered RL platelets can also be blown into tissue using known blowing techniques. As an alternative method, RL platelets can be prepared without lyophilization and in the absence of serum albumin, and resuspended in the thrombin serum prepared in Example 8 above. Soaking the desired matrix in this solution produces the final product. As a second alternative, the rehydrated RL platelets can be resuspended in the thrombin serum described in Example 8 above and used to soak the desired matrix to produce the final product.
two. Method 2
In this method, RL platelets are stabilized in aldehyde after binding to the textile matrix, as a component of the matrix. The principle here is to first allow the platelets to be activated by contact and adhere to the matrix via normal interactive procedures between the hemostatic cells and the textile fibers. The platelets and the textile matrix are then led to the aldehyde stabilization process together. This method includes the following stages:
(a) Platelet rich plasma (PRP) is prepared as described above or alternatively normally liquid stored platelet rich plasma is obtained.
(b) The platelet rich plasma is incubated with an amount of the textile matrix that has been predetermined to bind 90% of the platelets. To predetermine the extent of binding, a matrix sample is incubated with excess platelets (more than enough to saturate the matrix) and the amount of platelets remaining in the mixture is calculated after the matrix is removed.
(c) The PRP matrix is removed and the platelet concentration in the residual fluid is measured.
(d) Tissue is incubated in a 10x volume of citrated saline for 5 minutes on a rocker and excess fluid is drained. This stage is repeated three times. The soaked textile matrix is then placed in an appropriate volume of citrated saline for an 8 x 10 bound textile platelet count.<sup>9 </sup>platelets / ml for use in the crosslinking step described below.
(e) 3.5 ml of fixative solution are added dropwise to 1.25 ml of platelets-soaked matrix (with 8 x 10<sup>9 </sup>platelets / ml) with gentle vortex to mix. The mixture is further diluted to a final volume of 10 ml with a rapid addition of fixative solution for a final tissue-bound platelet count of 1 x 10<sup>9 </sup>platelets / ml. Incubation is carried out for 1 hr at room temperature without mixing or shaking. Finally, the platelet textile matrix is diluted in about ten volumes of midazole buffered saline and incubated for 5 min on a rocker, the excess fluid is drained off. This stage is repeated three times.
(f) To include thrombin, excess imidazole buffered saline is removed from the platelet textile matrix as thoroughly as possible and then soaked in excess serum as directed.
ES 2 610 397 T3 described above. The excess serum IIa is removed and the textile matrix is frozen and lyophilized as described above.
(g) Characterize the lyophilized hemostatic matrix using thrombin generation assay (described below).
It will be appreciated by those skilled in the art that although Examples 8 and 9 utilize Fabric 1 above to prepare an embodiment of the present invention, any textile combination described herein may alternatively be used (eg, fabrics 2-7 described above). .
Thrombin generation analysis
This procedure follows Fischer, TH et al. Synergistic platelet integrin signaling and factor XII activation in poly-Nacetyl glucosamine fiber-mediated hemostasis. Biomaterials 26, 5433-43 (2005). Briefly, thrombin generation kinetics can be used to reflect the ability of hemostatic matrices to function as a catalytic surface for components (eg, factor XII) of the coagulation cascade. In this assay, thrombin (IIa) cleaves the non-fluorescent synthetic substrate peptide-D-Phe-Pro-Arg-ANSNH to generate a fluorescent product. The time sequence for fluorescence generation is followed in a 96-well fluorescent platelet reader in kinetic mode.
96-well plates are filled with 150 µl of 5% BSA and citrated saline overnight at 37 ° C, then stored at 4 ° C until use. Pieces of 4mm (approximately) diameter hemostatic matrix are prepared with a 4mm Trephine Awl or sharp razor or scissors. Fluoromeric substrate IIa D-Phe-Pro-Arg-ANSNH (Cat # SN-17a- CeHn from Haematologic Technologies, Inc., Essex Junction, VT) is diluted 1/200 in plasma, followed by CaCl2 to a final concentration of 10 mM. The mixtures are placed in a fluorimeter and the fluorescence (490 nm) is measured for approximately two hours. The data is analyzed by plotting the time sequence of each well and measuring the initial and maximum slope of the relative fluorescence change curve and the time required to obtain the maximum slope. The initial and maximum slopes, along with the time to maximum slope, are the quality metrics. The higher the slopes and the shorter the time to maximum slope, the more pro-hemostatic the matrix will be.
Example 10: Preparation of a double fiber fabric
This Example illustrates the preparation of a fabric made of glass fibers in combination with another selected textile fiber. Two lines of evidence point to the continuous filament glass yarn as a potential component of a hemostatic tissue. First, platelets were found to become activated and adhere to glass (Barr, H. Lancet 238, 609-610 (1941)). As a consequence, glass vessels are generally avoided in in vitro handling of platelets, and binding to glass is a long-standing method of evaluating platelet activity (McPherson, J. & Zucker, MB Blood 47, 55-67 ( 1976); Tsukada, T. & Ogawa, T. Rinsho Ketsueki 14, 777-84 (1973); Cooper, RG, Cornell, CN, Muhrer, ME & Garb, S. Tex Rep Biol Med 27, 955-61 (1969 )). Second, plasma proteins (Stouffer, JE & Lipscomb, HS Endocrinology 72, 91-4 (1963); Lissitzky, S., Roques, M. & Benevent, MT CR Seances Soc Biol Fil 154, 396-9 (1960), HB Biochim Biophys Acta 19, 464-71. (1956)), FXII (Ratnoff, OD & Rosenblum, JM Am J Med 25, 160-8 (1958)) and fibrinogen (Sit, PS & Marchant, RE Thromb Haemost 82, 1053-60 (1999); Rapoza, RJ & Horbett, TA, J. Biomed Mater Res. 24, 1263-87 (1990), Perez-Luna,
VH, Horbett, TA & Ratner, BDJ Biomed Mater Res 28, 1111-26 (1994)) which are well-studied examples, undergo chemical and physical adsorption processes on foreign surfaces (Silberberg, AJ Physical Chem. 66, 1872-1883 ( 1962)). FXII (Hageman Factor) was found to be particularly important because it initiates humoral coagulation at the glass / blood interface (Ratnoff, supra; Ratnoff, OD & Margolius, A., Jr. Trans Assoc Am Physicians 68, 149-54 ( 1955)). Platelet activation and the production of intrinsic coagulation are highly interrelated mechanisms, in part due to the role of platelets as a catalytic surface for the assembly of the Va / Xa complex for the generation of thrombin. Platelet activation by biomaterials (e.g. via internal-external integrin signaling) can result in surface presentation of phosphatidylserine, an important component of catalytic complexes for thrombin generation (Fischer, TH, Connolly, R., Thatte, HS & Schwaitzberg, SS Microsc Res Tech 63, 168-74 (2004)). Factor XII has been found to be peripherally associated with the surface of platelets for the activation of the intrinsic coagulation pathway in the cell microenvironment (Iatridis, PG, Ferguson, JH & Iatridis, SG Thromb Diath Haemorrh 11, 355-71 (1964); Shibayama, Y., Reddigari, S. & Kaplan, AP Immunopharmacology Vol. 32 24-7 (1996)), although the series of proteolytic steps involving factor XII that occur on the surface of platelets are poorly understood. The net effect of the close relationship between Xlla-mediated coagulation and platelet activation is synergism for earlier initiation of fibrin polymerization.
The interaction of fluids with glasses is largely controlled by surface tension phenomena related to hydrophobicity, zeta potential and wettability. There is minimal fluid interaction with the interior of the filaments. Thus, a second, more absorbent fiber type was sought to compensate for the low fluid transport and absorptivity of glass. A panel of natural and synthetic fibers was tested for the tendency to activate platelets and the intrinsic coagulation cascade. A dual fiber product consisting of continuous filament E-type glass and special rayon was prepared and tested to determine hemostatic effectiveness in porcine models for bleeding.
ES 2 610 397 T3
Materials. Type E continuous filament glass (ECDE 11.6 fiberglass) was provided by Carolina Narrow Fabrics, Inc. (Winston-Salem, NC). Special rayon made from bamboo (Bambusa textiles) and other natural and synthetic fibers were provided by Cheraw Yarn Mills, Inc. (Cheraw, SC). The special fiberglass / rayon dual weave fabric was prepared by Carolina Narrow Fabrics, Inc. (Winston-Salem, NC). The gauze was originally from Kendall (Mansfield, MA).
Platelet Rich Plasma Isolation. Peripheral blood from consenting normal volunteers was drawn on anticoagulant citrate, then platelet-rich plasma was isolated with differential centrifugation as detailed in Fischer, TH et al. Biomaterials 26, 5433-43 (2005). Platelet concentration in platelet-rich plasma was measured with a Hiska hematology analyzer, and platelet concentration was adjusted to 150,000 platelets / ul by diluting the sample with platelet-free plasma.
Thrombin generation kinetics. The effect of fibers on the kinetics of thrombin generation in platelet rich plasma (at 150,000 platelets / ul) was investigated by following hydrolysis of the thrombin substrate D-Phe-ProArg-ANSNH to give a fluorescent reaction product. 300 µg of each fiber was tested in 100 µl of platelet-rich plasma in triplicate with the fluorogenic substrate D-Phe-Pro-Arg-ANSNH. The time sequence for thrombin generation was initiated by adding 10 mM CaCl2 to each sample. The lag time for thrombin generation was defined as the moment in which the fluorescence increased by 10% over the initial base value.
Thromboelastography. Thromboelastographic (TEG) measurements were performed with a Thrombelastograph TEG-5000 Hemostasis Analyzer (Haemoscope Corporation, Niles, IL). The assays were started by adding 10 mM CaCl2 to platelet-rich plasma (at 150,000 platelets / μl) and then immediately transferring 327 μl of the calcified platelet-rich plasma to the thromboelastography chamber containing the materials in 33 μl of citrated saline. The final fiber concentration was 3.0 mg / ml. Measurements were carried out for one hour in triplicate at 37 ° C, and then relevant parameters were extracted from the stiffness curve.
Scanning electron microscopy. SEM analysis of glucosamine-based materials was performed as follows. Whole peripheral blood from normal human volunteers was allowed to flow directly from the venipuncture butterfly onto the tissue or double fiber gauze so that 1 cm x 1 cm of each material was covered by 2 ml of whole blood. The materials were allowed to incubate for one minute, then diluted to 50 ml with citrated saline + 1 mM EGTA to cool the hemostatic processes. The materials were allowed to settle for 5 minutes by gravity, then re-diluted with citrated saline. This procedure was repeated two more times to obtain each material free of unbound RBCs. After one minute of contact with blood and multiple cycles of dilution and sedimentation of the material / RBC complex, glutaraldehyde was added for 0.1% (wt / v) and the samples were allowed to incubate at room temperature for one hour. . Samples were diluted 1/1 (v / v) with 4% paraformaldehyde for a final concentration of 2%, and then additional glutaraldehyde was added for a final concentration of 0.5%. The initial stabilization step with 0.1% glutaraldehyde has been shown to minimize osmotic alterations in red blood cell (RBC) morphology due to paraformaldehyde exposure (Fischer, TH et al., Microsc Res Tech 65, 62 -71 (2004)). Samples were stored at 4 ° C overnight and then examined with a Cambridge S200 scanning electron microscope at 20 kV.
Measurement of bound RBCs - 10 mg double fiber or gauze samples were exposed directly to 1.0 ml of whole peripheral blood and washed as detailed for scanning electron microscopy. The pGlcNAc were then placed in 10 ml of distilled water with 1% TX-100 to release hemoglobin from bound RBCs. The samples were centrifuged at 10,000xg for five minutes, then the absorbance at 414 nm was measured to quantify the total amount of hemoglobin (and thus the number of red blood cells) associated with each material.
Measure of the extent of RBC lysis due to contact with the material. 10 mg double fiber or gauze samples were exposed to 1.0 ml of whole peripheral blood as in the last two sections. After one minute of exposure, the samples were centrifuged at 10,000xg for five minutes to form pellets of blood cells and other materials. Optical density at 414 nm was measured to quantify the amount of hemoglobin released in the supernatants, and thus the amount of blood spilled.
Porcine femoral artery and brachial plexus transection hemorrhage model. Mixed breed pigs weighing 40 to 50 kg are anesthetized with isofluorane and then various sensors are placed to monitor hemodynamic and vasoactive processes: a pulmonary artery thermodilution catheter is inserted via the external jugular vein into a pulmonary artery; micromanometric tip catheters are placed through the left femoral vessels in the right atrium and thoracic aorta; a 22-gauge catheter is inserted into the left femoral artery and connected to a retrieval pump; Catheters are placed via the left femoral vessels.
The bleeding challenge phase of the experiment was conducted in two phases. First, the transactional laceration of the contralateral brachial arteries was performed. The brachial arteries and two associated veins ~ 3 mm in diameter were surgically exposed. One on each side of the artery and two veins were completely transected with a single blow of the scalpel. The wounds were established almost simultaneously, and then each side was immediately packed with the double fiber fabric or gauze. Penetrating cut sites
ES 2 610 397 T3 were completely plugged with each material and then the pressure was maintained for six minutes. The plug was removed and the amount of spilled blood was checked as described below. Both wounds were then re-capped with the double fiber material to stabilize the animals. The second phase of the experiment was performed by the contralateral surgical exposure of the femoral arteries. The two contralateral femoral arteries were transected almost simultaneously and then the surgical sites were plugged with double fiber tissue or gauze. The pressure was maintained for six minutes, then the materials for the determination of the spilled blood were removed.
The amount of blood spilled on the original packing materials was measured by placing the double fiber or gauze in one liter of distilled water to lyse the RBCs. After two hours of stirring at room temperature and storage at 2 ° C, the optical density at 414 nm was measured to determine the amount of hemoglobin released and, thus, the number of spilled RBCs and the loss of blood in volume.
Results
The experiments were carried out in three stages. First, candidate materials to formulate hemostatic tissue were identified by measuring the ability of selected fibers to activate hemostatic processes in platelet-rich plasma. Second, a double fiber blend was subjected to TEG and SEM analysis to obtain information on the mechanism of the activity. Finally, the ability of double fiber tissue to provide hemostasis with porcine bleeding models was evaluated. Details of these experiments below.
Activation of the hemostatic system by the candidate fibers. A panel of common textile fibers was tested for their ability to activate platelets and accelerate the production of the intrinsic (contact) pathway of coagulation. The behavior of representative fibers in the fluorogenic thrombin generation assay is represented in Figure 1. In Figure 1, duplicate samples of glass fibers, special rayon or gauze were placed in platelet rich plasma containing a fluorogenic thrombin substrate and then the thrombin generation time sequence was initiated by adding calcium. Arrows indicate times for thrombin generation. As shown in Figure 1, exposure of platelet rich plasma to E-type continuous filament glass resulted in the generation of thrombin in approximately eight minutes. The specialty rayon was less prothrombogenic with thrombin generation occurring within 12 minutes, while the gauze fiber was considerably slower.
The behavior of a more expansive fiber panel is presented in Figure 2. In Figure 2, the indicated fibers were tested as detailed in Figure 1 to measure thrombin generation times. The error bars represent the standard deviation of the duplicate analysis. As shown in Figure 2, glass and specialty rayon were the first and second most thrombogenic material tested, respectively. Chitin and gauze, which are components of products for superficial hemostasis, did not strongly accelerate thrombin generation. A prototype bandage was thus constructed of glass and special rayon.
In vitro properties of special glass / rayon double textile fiber. The double fiber matrix and the gauze were compared in the thromboelastographic analysis with the platelet rich plasma represented in Figure 3. In Figure 3, double fiber or gauze was placed in the thromboelastographic tray with normal saline solution and then plasma was added. rich in platelets and calcium to initiate the time sequence of clot formation. Normal saline without material was used as a negative control. As shown in Figure 3, the specialty glass / rayon fabric was found to significantly accelerate fibrin clot formation compared to gauze or saline control. Analysis of the double fiber matrix and gauze after contact with excess peripheral blood was performed using scanning electron microscopy as shown in Figure 4. In Figure 4, the double fiber or gauze was saturated with excess peripheral blood and then examined with scanning electron microscopy as detailed above. The white arrows on the two double grained panels on the left indicate specialty rayon fibers. As shown in Figure 4, the special glass / rayon matrix tightly bound a significant number of RBCs, whereas these cells only sparsely covered the gauze matrix.
The quantification of the number of RBCs in each array is shown in Figure 5. In Figure 5, double fiber or gauze was saturated with excess peripheral blood and then the number of bound RBCs was measured as described above. The error bars represent the standard deviation of the duplicate measurements. As shown in Figure 5, the double fiber fabric bound approximately ten times more RBCs than the gauze. No significant lysis of RBCs occurred (data not shown). SEM examination of the double fiber matrix also showed a large number of highly activated platelets on the continuous glass filament component, as shown in Figure 6, which shows the saturated double fiber washed with peripheral blood and examined with scanning electron microscopy. These results indicate that the special glass / rayon matrix is more effective in providing superficial hemostasis than gauze.
Dual fiber dressing ability to provide hemostasis in porcine models. The double fiber matrix was compared with gauze in severe transection lesions of porcine large vessels. Two types of lesions were established in each of four pigs. First, the brachial artery and two associated great veins in the 12
ES 2 610 397 T3 areas of the contralateral plexus were completely transected almost simultaneously. This results in exsanguinating bleeding that is both arterial and venous in nature. The contralateral cut / wound sites were immediately plugged with as much double fiber tissue or gauze as required to fill the injury site. The pressure was maintained for six minutes and then the sites were uncovered and the degree of hemostasis was considered to be complete (no visible bleeding), partial (with less than 3 ml of blood loss per minute), or uncontrolled (with more than three ml of blood loss per minute). Blood loss in the packing materials and any blood spilled from each wound site were measured. The contralateral brachial plexus injury sites were then reattached with double fiber tissue to stabilize the animal for the second set of femoral injuries. The contralateral femoral arteries were exposed, and then completely transected almost simultaneously to initiate a bleeding hemorrhage. As with brachial plexus injuries, injury sites were immediately plugged with double-fiber tissue or gauze. After holding pressure for six minutes the sites were uncapped and the degree of hemostasis was judged as described for brachial injuries. An important feature of this model of large vessel transection is that the animals were not in hemorrhagic shock. Because the lesions were immediately plugged with pressure, the mean arterial pressure remained in the range of 45 to 55 mm Hg and the total blood loss was no more than ~ 5% of the total blood volume. The total amount of blood loss with the dual fiber material was about half that with gauze from both brachial and femoral plexus injuries as shown in Figure 7. In Figure 7, the total amount of blood shed and absorbed by the material was measured from the six-minute pressure period of the brachialis (left panel A) and femoral (right panel B). The error bars represent the standard deviation of blood loss from similar lesions in five animals. As shown in Figure 7, there was a marked tendency for the gauze to tear off the hemostatic plug (to the extent that there was one), while the double fiber tissue was not strongly incorporated into the hemostatic site.
The above results show that the fundamental principles of hemostasis can be used to design inexpensive materials for superficial hemostasis. Special glass / rayon fabric outperformed gauze in porcine models of both capillary and large vessel injury; bleeding times and blood loss were roughly halved when the textile fiber component was optimized for thrombogenicity
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Numbers
- Publication
- 2610397
- Application
- 7717956
Titles2
- Spanish
- Tejido hemostático
- English
- Hemostatic tissue
Classification
- CPC, 22
- A61L15/18
- A61L15/00
- A61F13/01042
- A61L15/42
- A61L2400/04
- Y10T442/40
- Y10T442/30
- A61P7/04
- A61L15/28
- A61K9/70
- A61L15/20
- D02G3/18
- A61K36/899
- A61L15/16
- A61F2013/00089
- A61F2013/00463
- C08K7/14
- A61F13/01012
- A61F13/01017
- A61F13/00072
- A61F13/00991
- A61F13/00063
- IPC, 2
- A61L15 18
- A61L15 42