Transfusion of whole blood from one individual to another is indicated for two main reasons: firstly, when the volume of blood within the circulation system of the patient is less than that required to sustain life and, secondly, when the red blood cells are deficient either in quantity or quality. If we have insufficient red cells, or if our red cells are abnormal, there will not be enough haemoglobin to maintain the body efficiently and we are then said to be anaemic.

Blood loss through accident, surgery, or haemorrhage at childbirth, or from such a condition as the bleeding of a stomach ulcer, may reduce the amount of circulating fluid in our bodies below safe limits and we may die unless this loss is speedily replaced.

Indications of blood transfusion can be summed up as:

• Anaemia
• Major Surgical Operation
• Accidents resulting in considerable blood loss
• Cancer patients requiring therapy
• Women in childbirth and newborn babies in certain cases
• Patients of hereditary disorders like Haemophilia and Thalassaemia
• Severe burn victims.

Components

In addition to being used as whole blood, blood can be separated into its components: red cells, white cells, platelets, plasma, cryoprecipitate which are used to treat certain conditions. One of the components, plasma, can be further subdivided by chemical procedures into its constituent parts, the so called (plasma fractions] anti-hoemophilic factor concentrate, immunoglobulins, plasma protein fraction and albumin etc.

Transfusion of whole blood has long been a well-recognised life saver during and after major surgery and where there has been massive loss of blood in an accident or in childbirth. There are, however, various conditions which do not need whole blood replacement. For example, chronic anaemic condition requires transfusion of only the red cells of blood, Indeed, transfusion of unnecessary plasma may be harmful if the patient has a weak heart. Separation of red cells from plasma can be achieved either by allowing the container in which the blood is collected to stand for some hours during which the red cells will separate themselves from the plasma by gravity, or by spinning the container in a centrifuge, a machine which spins the container around a central axis. Adjustment of the number of revolutions per minute and the duration of spinning allow the different cells, e. g. red cells and blood platelets, to be separated from each other.