Gelatin is collagen that has been processed and denatured. The properties of gelatin allow it to be applied on irregular wound surfaces. When gelatin is applied at the bleeding site, it conforms to the wound and swells. The swollen gelatin particles restrict blood flow and provide a stable matrix around which a clot can form. Gelatin-based products are generally derived from bovine or porcine sources and are available in granular or sponge forms.
Collagen is a structural protein found in abundance in the human body. It is derived from bovine tendon or ligament. Collagen-based products are passive hemostats that stop bleeding by promoting the aggregation of platelets (at the surgical site), which is initiated by contact between blood and the collagen. These products are available in the forms of powder, paste or sponges. As they are derived from animal tissues, they carry the risk of causing allergic or immune reactions in some patients. In addition to activating hemostasis, collagen also helps in the wound healing process and can reduce the degree of adhesion or scarring in internal organs and fascia.
These hemostats are typically thrombin in combination with passive hemostatic agents such as collagen, gelatin or ORC. More recently, however, synthetic hemostatic patches containing polyethylene glycol (PEG) in combination with either ORC or collagen have also been launched under this category. These are active hemostatic agents, meaning they directly participate in the coagulation cascade to induce a clot at the bleeding site. These products are highly effective compared to passive hemostats, as they arrest the bleeding at a much more rapid rate and are easier to use. The thrombin can either be bovine-sourced or from a human donor (homologous) or they can be from the patient themselves (autologous).
Plant-derived and purified starch is processed to create polysaccharide hemostats. These hemostats are biocompatible and absorbed within 24 to 48 hours. When they come in contact with blood, each particle absorbs fluid and concentrates platelets and coagulation proteins. This quickly activates the clotting cascade and provides a substrate for structural elements to form.
First Responder Hemostats
Traditionally used on the battlefield, first responder hemostats (FRH) quickly stop blood flow from external wounds and are used by paramedics, law enforcement officers and nurses who must quickly stop life threatening blood loss. FRH can be derived from clay or the shells of crustaceans (chitosan).