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HAEMORRHAGE, a general term for an escape of blood from a blood-vessel (see BLooD). It commonly results from in jury, as the tearing or cutting of a blood-vessel, but certain forms result from disease, as in haemophilia, scurvy, and purpura. The chief varieties of haemorrhage are arterial, venous, and capillary. Bleeding from an artery is of a bright red colour, and escapes from the end of the vessel nearest the heart in jets synchronous with the heart's beat. Bleeding from a vein is of a darker colour; the flow is steady, and the bleeding is from the distal end of the vessel. Capillary bleeding is a general oozing from a raw surface. By extravasation of blood is meant the pouring out of blood into the areolar tissues, which become boggy. This is termed a bruise or ecchymosis. Epistaxis is a term given to bleeding from the nose. Haematemesis is vomiting of blood, the colour of which may be altered by digestion, as is also the case in melaena, or pas sage of blood with the faeces, in which the blood becomes dark and tarry-looking from the action of the intestinal fluids. Haem optysis denotes an escape of blood from the air-passages. Haema turia means passage of blood with the urine.

Cessation of bleeding may take place from natural or from artificial causes. Natural arrest of haemorrhage arises from (1) the coagulation of the blood itself, (2) the diminution of the heart's action as in fainting, (3) changes taking place in the cut vessel causing its retraction and contraction. In the surgical treatment of haemorrhage minor means of arresting bleeding are: cold, which is most valuable in general oozing and local extravasa tions ; very hot water, 13o ° to 160 ° F, a powerful haemostatic ; position, such as elevation of the limb, valuable in bleeding from the extremities; styptics or astringents applied locally, as per chloride of iron, tannic acid, and others, the most valuable being suprarenal extract. In arresting haemorrhage temporarily the chief thing is to press directly on the bleeding part. The pres sure to be effectual need not be severe, but must be accurately applied. If the bleeding point cannot be reached, the pressure should be applied to the main artery between the bleeding point and the heart. In small blood-vessels pressure will be sufficient to arrest haemorrhage permanently. In large vessels it is usual to pass a ligature round the vessel and tie it with a reef-knot. Apply the ligature, if possible, at the bleeding point, tying both ends of the cut vessel. If this cannot be done, the main artery of the limb must be exposed by dissection at the most accessible point be tween the wound and the heart, and there ligatured.

Haemorrhage has been classified as—(1) primary, occurring at the time of the injury; (2) reactionary, or within 24 hours of the accident, during the stage of reaction; (3) secondary, occurring at a later period and caused by faulty application of a ligature or septic condition of the wound. In severe haemorrhage, as from the division of a large artery, the patient may collapse and death ensue from syncope. In syncope stimulants and strychnine may be given, but they should be avoided until it is certain the bleed ing has been properly controlled, as they tend to increase it. Transfusion of blood directly from the vein of a healthy person to the blood-vessels of the patient, and infusion of gum, glucose or saline solution into a vein, may be practised (see SHOCK). In the congenital condition known as haemophilia (q.v.) it is diffi cult to stop the flow of blood.

The effects of haemorrhage within the body are widespread, and immediate as well as delayed. As an immediate effect of loss of blood the volume of fluid within the blood-vessels and therefore the amount entering and leaving the heart is diminished. This change of volume is rectified within a few seconds or minutes by (1) contraction of the arterioles and (2) passage of fluid from the tissues into the capillaries and venules. Hence the original volume is rapidly re-established, but the blood, for a time, is more dilute than formerly. Of the delayed changes the most noticeable concern the blood corpuscles. Young and it may be nucleated red corpuscles are found in the circulating blood and the number of leucocytes, particularly the polynuclear variety, is raised above the normal. In the bone marrow there are signs of great activity, the tissue being bright red and highly cellular. The blood pres sure in the great arteries remains approximately at its normal level until about one-third of the original amount of blood has been lost, and then it falls abruptly.

blood, bleeding, vessel, heart, artery, colour and blood-vessels