Restoration of blood vessels
Typically, the surgeon can restore one or more arteries that have dense walls, which allows blood to flow to the tissues. However, the veins have thin walls, which are very difficult to work with. As a rule, the surgeon is able to provide blood to the sewn part of the body, but is often unable to provide adequate venous outflow. As a consequence, the re-implanted part of the body due to venous congestion becomes cold and cyanotic - and there is a serious risk of its eventual loss. Leeches help to ensure the outflow of blood due to the fact that it prevents its coagulation. Leeches are used to eliminate venous congestion for one or two days following a skin graft or replanting a part of the body. The benefits of using them are invaluable because the place of bite of a medical leech bleeds on average for 10 hours. No medical product is able to provide such a prolonged bleeding from a pinpoint wound. Leeches do the job with ease.
Application of leeches
Surgeons give one or two leeches to suck in the area of the flap with impaired blood circulation and leave them until they are saturated (about 30 minutes). After the leeches disappear, the slow bleeding at the bite site continues for many hours. It provides artificial circulation, which immediately facilitates the patient's condition. Fresh blood enters the flap through the arteries, but now it has a path of outflow from the affected area. This allows you to keep the flap or the resplanted part of the body alive until the body naturally restores its own venous connections. Usually it takes 3-5 days. If necessary, leeches are re-planted approximately every 8 hours or when bleeding from previous bites ceases. The result of using leeches is amazing. A flap of cold and blue becomes warm and pink in just a few minutes. Confirmed success rate is more than 90%. However, it should be borne in mind that for this, first of all, adequate blood supply should be provided. With arterial insufficiency, leeches do not help. In these cases, the flap is susceptible to infection (including the leeches themselves). Leeches are also used to relieve painful or discomforting symptoms in edema associated with certain cancers. For example, in cases where the patient does not open his eyes due to edema or the scrotum is painfully enlarged. The leech has suckers on both ends of the body. The posterior sucker serves only for attachment, while the anterior one surrounds the mouth. While there are about 650 species of leeches in the world, only a few of them are adapted to parasitize mammals. In modern surgery, the European medical leech Hirudo medicinalx is used.
How Leeches Feed
Medical leech is well adapted to feeding blood of mammals. It has three protruding jaws, the edge of each of which carries about 100 sharp teeth. When feeding the jaws cut into the skin of the victim while between the teeth stands out. In other words, the jaws act simultaneously as a saw, causing a wound consisting of three converging slits at one point. Saliva of leeches contains a whole set of pharmacologically active substances, some of which have been isolated and well studied by now. The best of them is the powerful anticoagulant hirudin, inhibitor of thrombin (an enzyme involved in the process of blood coagulation). Hirudin is currently being produced with the help of genetic engineering and is successfully used in the treatment of deep vein thrombosis.
Bleeding time
Experiments, however, have shown that non-hirudin is responsible for the unique duration of bleeding that occurs as a result of a bite of a leech. This substance is washed out of the wound in about 15 minutes, after which the blood should be folded. Despite this, bleeding continues for 10 hours. Obviously, during the natural selection of leeches developed more effective ways. He joins collagen, which is one of the most powerful stimulants of blood clotting, and inhibits its ability to trigger the process of thrombosis. The bleeding blood in all other respects is normal and capable of coagulation. By joining to the collagen at the edges of the wound, the caleline does not wash out from it, thus prolonging the effect for many hours. The world need for leeches for microsurgery is so great that they are specially bred for this purpose on special farms, where they feed pig blood through the membrane. Saturated adult individuals are placed for reproduction in cells lined with wet moss. By the time of laying eggs, the leech gives off a frothy secret in the form of a cocoon in the middle part of the body. This cocoon slides over the head, each cocoon is divided into approximately 15 cells, each of which contains a tiny leech. At each feeding, the developing leech grows about 5 times in body size. After about 5 feedings the leech reaches a length of about 7 centimeters and is ready for use for clinical purposes.