escape of blood from blood vessels that have been injured as a result of trauma or vascular disease.
Hemorrhages may be arterial (scarlet blood spurts like a fountain), venous (a flow of dark blood), capillary, or mixed. The intensity of bleeding depends on the size of the injured vessel and the condition of its wall. Blood may flow to the outside, into the lumen or body of an organ (stomach, intestine, brain), or into a cavity (abdominal, pleural). Bleeding is accompanied by pallor of the skin and mucosa, dizziness, weakness, dyspnea, thirst, a drop in arterial pressure, and a weak and rapid pulse. A large and rapid blood loss (25 percent of the blood volume or 4—4.5 percent of the body weight) produces loss of consciousness and may result in death. Persons weakened by a disease can be severely affected by even a small blood loss. In persons with atherosclerosis of the blood vessels, bleeding continues longer and is more difficult to stop. Bleeding in hemophilia patients, which arises when there is the slightest trauma, is extremely persistent.
Measures for stopping bleeding depend on its cause and source. Arrest of bleeding may be temporary or permanent. For temporarily stopping bleeding, a tourniquet, or pressure bandage, is applied to the extremities; vasoconstrictors, ice, or hemo-static sponges (on wounds) are also used. These measures often lead to complete cessation of bleeding; if bleeding does not stop it becomes necessary to resort to surgical methods (ligation of the vessel, suturing, removal of the injured or affected organ or of part of it) to achieve permanent cessation of bleeding. Blood transfusion or transfusion of blood substitutes that increase blood coagulation is a necessary part of treatment to control hemorrhage.
A. B. GALITSKII