Hypothermia

Hypothermia, condition in which body temperature falls drastically as a result of exposure to cold. It may occur, for example, in hikers caught in a sudden cold front without sufficient clothing. The elderly can die from hypothermia at temperatures that would not harm younger persons. The condition involves a paradoxical response to sudden cold: the shutting off of blood flow to the body's surface. First aid may involve wrapping the victim in blankets (along with the rescuer, if necessary). Despite customary belief, alcohol causes loss of heat and should not be given. Treatment at a hospital involves slowly raising the body temperature by various means.

Hypothermia may also be induced for medical purposes. Reduction in body temperature causes a slowing of the metabolism. This is useful in certain types of surgery and to reduce bleeding in a particular part of the body.

Hodgkin’s Disease

Hodgkin’s Disease or Hodgkin's Lymphoma, less severe form of two types of cancer that arise in the lymphatic system (network of small vessels that carry lymph, a fluid containing white blood cells of the immune system). The other form is non-Hodgkin's lymphoma. Hodgkin's disease is characterized by usually painless but progressive enlargement of lymph nodes (or glands) and other lymphoid tissue.

Diagnosis of Hodgkin's disease is made with a biopsy (removal of a small tissue sample for examination under a microscope). Hodgkin's disease is primarily distinguished from non-Hodgkin's lymphoma by the presence of Reed-Sternberg cells, large cells that contain several nuclei. If the disease is diagnosed at an early stage and has not metastasized (spread to other areas of the body), radiation therapy is commonly used. With advanced cases, the doctor will usually prescribe chemotherapy (anti-cancer drugs) for approximately six months, often in combination with radiation therapy. For patients with disease resistant to conventional treatments, or for patients who have relapses (reappearance of symptoms after an apparent cure), doctors may try high-dose chemotherapy and bone-marrow transplants. The chemotherapy destroys all of the patient's unhealthy bone marrow in preparation for the transplantation of healthy bone marrow, so the body can once again produce healthy white blood cells. The healthy bone marrow is injected into the bloodstream and, if successful, the cells find their way to the bones and begin to grow

Heparin

Heparin, substance produced by cells of the liver, lungs, and intestines that keeps blood from clotting. It normally inhibits the clotting of blood by interfering with the production of thrombin, an enzyme necessary for clot formation. Heparin obtained from animals is administered after surgery to reduce the risk of thrombosis, the formation of a blood clot in a blood vessel. It is also used after pulmonary embolism to ensure that no further clots form, as well as during kidney dialysis.

Ulcer

Ulcer, shallow sore produced by the destruction of skin or mucous membrane. Skin ulcers may occur in association with a number of chronic illnesses, such as diabetes, kidney and heart ailments, varicose veins, syphilis, leprosy, tuberculosis, and cancer. Gastrointestinal ulcers occur with chronic gastritis, ulcerative colitis, and typhoid fever.

Peptic ulcers are ulcers of the stomach (gastric) or small intestine (duodenal). In addition to the pain caused by the ulcer itself, peptic ulcers give rise to such complications as hemorrhage from the erosion of a major blood vessel; perforation of the wall of the stomach or intestine, with resultant peritonitis; or obstruction of the gastrointestinal tract because of spasm or swelling in the area of the ulcer.

The direct cause of peptic ulcers is the destruction of the gastric or intestinal mucosal lining by hydrochloric acid, an acid normally present in the digestive juices of the stomach. Infection with the bacterium Helicobacter pylori is thought to play an important role in causing both gastric and duodenal ulcers. Injury of the gastric mucosal lining, and weakening of the mucous defenses such as by nonsteroidal anti-inflammatory drugs, are also responsible for gastric ulcer formation. Excess secretion of hydrochloric acid, genetic predisposition, cigarette smoking, and psychological stress are important contributing factors in duodenal ulcer formation and exacerbation.

Several different types of prescription drugs are used in the treatment of ulcers. Antacids may be ingested to neutralize the hydrochloric acid secretions. Drugs such as cimetidine and ranitidine block the action of histamine, the body chemical that triggers acid secretion, and have been shown to induce healing of ulcers in many patients. Omeprazole inhibits acid secretion by disabling the cellular pumps that pump acid into the stomach. Bismuth-containing compounds and antibiotics may be used to eradicate Helicobacter pylori infection, accelerating healing and reducing the rate of ulcer recurrence. Sucralfate forms a protective layer that enhances the mucosal lining of the stomach and intestines. Misoprostol is effective against gastric ulcers caused by nonsteroidal anti-inflammatory drugs. Quitting smoking can also accelerate the healing process. Alcohol and caffeine should be avoided, although in general a bland diet is of no benefit. In extreme cases surgery may be required.

Hemorrhage

Hemorrhage, excessive discharge of blood from blood vessels, caused by pathological condition of the vessels or by traumatic rupture of one or more vessels. Hemorrhage is a complication of many diseases. Peptic ulcer, for example, may cause hemorrhage by eroding a blood vessel. Stroke is sometimes due to hemorrhage in the brain. Hemophilia, a hereditary blood disease, is characterized by failure of the blood to coagulate. Sudden loss of more than about 1 liter (1 qt) of blood may lead to shock; unless the blood is replaced by transfusion, this shock can be fatal.

Bleeding normally stops through the process of coagulation, or clotting of the blood, and methods used to stop hemorrhage depend on stanching the flow of blood sufficiently for a clot to form. The hemorrhage is most effectively stopped by the application of pressure directly over the wound. Bleeding is also lessened by placing the body so that the wound is uppermost. A tourniquet should never be applied if there is another way to stop the bleeding, as application of a tourniquet increases the likelihood that amputation will be required.

Fibrin film and fibrin foam, plastics made from the blood protein fibrinogen, are extensively used in surgery. Fibrin foam is used in the form of a surgical sponge that rapidly stops bleeding by forming clots. Fibrin film is used to wrap nerves or tendons or as a membrane to cover the brain or other organs. Fibrin may be left without harm in the body, where it slowly dissolves.