Severinov S.I., Bobkov O.V., Kushnir K.G.

State Insitution “Crimea State Medical University named after S. I. Georgievsky "

Modern approaches to contact hemostasis

It is well known that hemorrhage is one of the factors that cause death in case of many different types of wounds and traumas. Gunshot wounds, polytraumas, incised and stabbed wounds, open fractures, animal bites and mine-blast traumas often cause bleeding and the person may lose a lot of blood for a short time. Loss of more than 70% of circulating blood volume (more than 3,5 liters for a person with body weight about 80 kg) is mortal, massive blood loss (2,0-3,5 liters) is as much dangerous as mortal blood loss. Also it should be mentioned that the process of hemostasis in such cases is very difficult because of the velocity of bleeding, which is usually more than 1 liter per 1 hour, and in some cases bleeding may be even faster (direct injuries of femoral artery, splenic rupture etc.). Tn this cases bleeding should be stopped as soon as possible.

In the human body blood loss is stopped by coagulation processes. Coagulation (thrombogenesis) is the process by which blood forms clots. It is an important part of hemostasis, the cessation of blood loss from a damaged vessel, wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel. But in cases of massive blood loss coagulation processes cannot stop hemorrhage because of its intensity and clots cannot form in time, what may lead to hemorrhagic shock and death. Massive blood loss can be stopped fast by only 3 ways - application of tourniquet, ligation of bleeding vessel and mechanical obturation <j£ wound and vessels. But tourniquet applying may be used only in cases of limbs and neck wounds, ligation of vessel requires is elusive because of surgical manipulations. That’s why mechanical obturation of wound is one of the best ways foi hemorrhage stop and preparation of wound for further surgical debridement, angioplasty and sewing. But such a method of hemostasis became possible only few years ago.

In 1978 the American engineer Frank Hursey created the company manufacturing oxygen machines the military uses to separate oxygen and nitrogen from air. The machines remove moisture from the air using a clay-based product, called zeolite, that works like a water magnet.

That led Hursey to start thinking about blood, which is about 90 percent water. From those musings, Hursey got the patent on the hemostasis by zeolite direct impact. In the year 2002 zeolite-based haemostatic agent was officially adopted by U.S. Armed Forces. In this time British company «MedTrade Products Limited« invented haemo-

static agent based on chitosan ( linear polysaccharide composed of randomly distributed |3-(i-4)-linked D-glucosamihe and N-acetyl-D-glucosamine). This haemostatic stops bleeding by the chitosan granules bonding with red blood cells and blood plasma. It does not set off the normal clotting cascade, it only clots the blood it comes directly into contact with. These hemostatics are widely used by U.S. Armed Forces, British Armed Forces, IDF. They are also used by many lifeguard services all over the world.

Such type of haemostatic agents work on the principle of contact hemostasis.

Contact hemostasis is based on the principle of blood clotting in contact with certain substances and forming of «artificial clot» - the clot, composed of coagulated blood and bulged, polymerized clotting agent which keeps blood inside and obturates wound and bleeding vessels. This process is similar to normal blood coagulation but it is instantaneous. As the biochemical processes do not take part in this type of hemostasis such clotting agents may be used for heparinized blood and in case of hypothermia. Also clotting factor XII is activated mechanically what promotes better blood coagulation.

Today there are 3 basic substances for such type of hemostasis. It is clay-based hemostatics based on zeolite and kaolin and chitosan-based hemostatics. But zeolite creates exothermic reaction in contact with blood what causes thermal bums of wound tissues, kaolin is too hygroscopic and has certain problems with transporting. Chitosan is one of the best haemostatic agents for contact hemostasis process, but modern chitosan-based hemostatics have certain lacks. Among this lacks we should say that chitosan has no antibacterial action, and because blood is good substratum for pathogenic microorganisms multiplication clotting of wounds with chitosan may cause to local microbial contamination, infectious diseases (among them tetanus and gas gangrene, because these diseases often accompany dirty wounds and combat traumas) and even sepsis. As such hemostatics are created for first aid in battlefield and extreme conditions, the final wound treatment occurs through the few hours after contact hemostatics application, that’s why modern haemostatic agents based on artificial clot effect should be improved.

After some researches the methods of improvement were created. The core of improvement is based on adding of antibiotics and antiseptics to the structure of contact hemostatics in order to prevent growth of gram-positive and gram-negative microflora, fungi and protozoa, for example C.perfrmgens and C.tetani which are the main contagiums in case of combat traumas and dirty wounds. We suggest adding of antibiotics for both gram-positive and gram-negative microorganisms inactivation and adding of lyophiiized antiseptics for primary prevention of wound infection. We call this new method «pharmacologic contact hemostasis». This method of hemostasis eliminates lacks of modern haemostatic agents and helps to create more effective haemostatic agents then medicines, existing nowadays.