1. Chitosan
Chitosan is a natural biopolymer produced by deacetylation of chitin. It is an alkaline polysaccharide polymerized from glucosamine. It has abundant reserves and a wide range of sources. It is non-toxic itself and its decomposition products. Chitosan and its derivatives can enhance the adhesion and aggregation of platelets, and cause blood clots to form through interaction with negatively charged platelets and red blood cells; in addition, platelets are activated and release effective substances, thereby accelerating coagulation. Chitosan also has antibacterial activity and can be used with other materials to make hemostatic dressings. Chitosan is a candidate for an ideal hemostatic agent with biological activity. In order to improve the hemostatic performance, chitosan is mixed with other functional ingredients to prepare a chitosan-based composite material, which can achieve rapid and effective hemostasis.
2. Cellulose
In 1945, oxidized cellulose hemostatic materials were introduced into surgical operations. They are easy to use and have good biocompatibility and bactericidal properties. Regenerated oxidized cellulose is a cellulose acid gauze-like or cotton-like absorbable hemostatic material made by oxidizing cellulose. As a cellulose derivative, it is non-toxic and has good biocompatibility and biodegradability. Its degradation products contain glucose and cellobiose, which can be absorbed in the body within 2-7 days and completely degraded within 4-8 weeks. It is easy to use, very easy to adhere to irregular bleeding surfaces, and has no adhesion on the surface of medical devices such as instruments and gloves, but cellulose products have strong water absorption, so the instruments should be kept dry before use.
3. Starch
Starch is a high polymer of glucose, which can be degraded into glucose by α-amylase in the body. The principle of starch hemostatic materials is that the surface micropores of microporous polysaccharide particles act as molecular sieves, which can instantly absorb water from the blood and gather the formed elements in the blood (such as coagulation factors, platelets, fibrin, red blood cells, etc.) on the surface of the particles to produce "instant gel", which plays a role in mechanically blocking vascular ruptures; at the same time, the local concentrations of platelets, coagulation factors and fibrin are significantly increased, and the endogenous coagulation mechanism is activated and accelerated. Starch hemostatic products are suitable for cardiothoracic surgery, urology and otolaryngology surgery.
4. Collagen and gelatin
Collagen accounts for a large part of the extracellular matrix, plays a structural scaffold role in tissues, has good cell compatibility, and affects cell functions such as differentiation, migration and protein synthesis. Collagen has a large water-absorbing surface. When the material is applied to the surface of the wound, it can absorb blood flow several times larger than its own mass, and the water absorption can reach more than 30 times its own volume. The most commonly used collagen dressing is type I or denatured type I collagen, and most collagen dressings contain bovine, sheep or processed porcine collagen.
Gelatin is a hydrolyzed colloid made by enzymatic (acid or alkali) hydrolysis of collagen. Gelatin hemostatic materials act in the final stage of the blood coagulation cascade to promote the formation of fibrin. They are available in the form of sponges, powders and granules. Gelatin materials can adapt to irregular wounds and surgical cavities. Gelatin can absorb up to 40 times its mass of blood and expand to 200% of its initial size. Dried gelatin sponges can be cut into any size and shape, and can be dry-applied or applied directly to the bleeding surface. Once pressure is applied, bleeding can be stopped.
Unlike oxidized cellulose, collagen and gelatin hemostatic materials have a neutral pH value, so they can be used alone or with local biological agents such as thrombin, which helps to stop bleeding. They are usually absorbed by the body in 4-6 weeks, so they can be left in the body cavity or wound cavity.
5. Fibrinogen
Fibrinogen hemostatic materials are mainly composed of fibrinogen prepared from human plasma (containing coagulation factor ⅩⅢ, fibronectin and aprotinin) and thrombin concentrate. When these two components are mixed, they simulate the last step of the thrombin chain reaction. Fibrinogen is activated by thrombin, and fibrinogen gradually aggregates and finally forms a fibrin solid, which plays a role in preoperative and postoperative hemostasis and tissue adhesion.
Fibrin glue products are not suitable for use in clinical surgery in cases of arterial and large venous bleeding. When using fibrin glue products, care must be taken not to allow the product to enter the blood vessels to avoid thrombosis. Liquid fibrin glue containing tranexamic acid is neurotoxic and therefore cannot be used in surgeries with cerebrospinal fluid leakage or dura mater tears. Liquid fibrin glue is ineffective in preventing pancreatic, bile duct, urinary system, intestinal and air leakage, so routine use is not recommended.