An advanced hemorrhage control bandage and methods of its application would substantially augment available hemostatic methods. To date, the application of continuous pressure with gauze bandage remains the preferred primary intervention technique used to stem blood flow, especially that from severely bleeding wounds. However, this procedure neither effectively nor safely stanches severe blood flow. This has been, and continues to be, a major survival problem in the case of severe life-threatening bleeding from a wound.
Furthermore, it is widely accepted that severe bleeding is the leading cause of death from wounds on the battlefield, accounting for approximately 50 percent of such deaths. It is estimated that one-third of these deaths may be preventable with enhanced hemorrhage control methods and devices. Such enhanced hemorrhage control would also prove most useful in the civilian population where hemorrhage is the second leading cause of death following trauma.
Currently available hemostatic bandages, restricted to use in surgical applications, such as collagen wound dressings or dry fibrin thrombin wound dressings are not sufficiently resistant to dissolution in high blood flow nor do they have strong enough adhesive properties to serve any practical purpose in the stanching of severe blood flow. These currently available surgical hemostatic bandages are also delicate and thus prone to failure should they be damaged by bending or loading with pressure.
There is prior art relating to chitosan and chitosan dressings. For example, U.S. Pat. No. 4,394,373 employs chitosan in liquid or powder form to agglutinate blood in microgram/ml quantities. Also, U.S. Pat. No. 4,452,785 is directed to a method of occluding blood vessels therapeutically by injecting chitosan directly into the vessels. U.S. Pat. No. 4,532,134 further relates to hemostatis, inhibiting fibroplasias, and promoting tissue regeneration by placing in contact with the tissue wound a chitosan solution or water-soluble chitosan. The chitosan forms a coagulum which prevents bleeding.
Moreover, U.S. Pat. No. 5,858,350 relates to a process to make diatom derived biomedical grade, high purity chitin and chitin derivatives (so called protein-free even though this is not demonstrated by analysis in the patent). The proposed advantage of so called protein-free chitin/chitosan materials are that they should be significantly less antigenic than current shrimp and crab derived chitin materials.
Mi, F L, et al, Fabrication and Characterization of a Sponge-Like Assymetric Chitosan Membrane as a Wound Dressing, Biomaterials, 22(2):165-173 (2001) describes the fabrication and wound healing function of an asymmetric chitosan membrane produced by a phase inversion method.
Chan, M W, et al, Comparison of Poly-N-acetyl Glucosamine (P-GlcNAc) with Absorbable Collagen (Actifoam), and Fibrin Sealant (Bolheal) for Achieving Hemostasis in a Swine Model of Splenic Hemorrhage, J. Trauma, Injury, Infection, and Critical Care, 48(3):454-458 (2000) describes the testing of chitin/chitosan hemostatic patches under the moderate blood flow and oozing typical of the swine spleen capsular stripping test.
Cole, D. J., et al, A Pilot Study Evaluating the Efficacy of a Fully Acetylated poly-N-acetyl glucosamine Membrane Formulation as a Topical Hemostatic Agent, Surgery 126(3):510:517 (1999) describes hemostatic agent testing in the swine spleen capsular stripping test.
Sandford, Steinnes A., “Biomedical Applications of High Purity Chitosan” in Water Soluble Polymers, Synthesis, Solution Properties and Applications, ACS Series 467, Shalaby W S. McCormick C L. Butler G B. Eds. ACS, Washington, D.C. 1991, Ch 28, 431-445. This is a general review paper describing chitosan use with reference to a chitosan sponge.
Mallette, W. G., et al, Chitosan: A New Hemostat, The Annals of Thoracic Surgery, 36(1), 55-58, (1983) See comments concerning the Malette patents above.
Olsen, R., et al, In Chitin and Chitosan, Sources, Chemistry, Biochemistry, Physical Properties and Applications, Elsevier Applied Science, London and New York, 1989, 813-828. This paper concerns the agglutinating efficiency of chitosan.
Japanese Patent 60142927 covers a chitosan medical band with improved tack Japanese patent 63090507 A2 describes a water insoluble and 2% acetic acid insoluble chitosan sponge for external hemostatic application or for protection of a wound.
U.S. Pat. No. 5,700,476 describes collagen based structurally inhomogeneous sponges for wound dressings and/or implant applications formed by freeze drying techniques employing at least one pharmacological agent and at least one substructure.
U.S. Pat. No. 2,610,625 relates to freeze dried sponge structures that are highly effective in stopping the flow of blood or other fluids and which will be absorbed after a time in the body. This patent describes collagen sponge preparation.
U.S. Pat. No. 5,836,970 comprises a wound dressing formed of a blend or mixture of chitosan and alginate.
USPTO Backgrounds
USPTO Backgrounds