With the outbreak of war appearing imminent in 1938, the War Office created the Army Blood Supply Depot (ABSD) in Bristol, headed by Lionel Whitby and in control of four large blood-depots around the country. British policy through the war was to supply military personnel with blood from centralized depots, in contrast to the approach taken by the Americans and Germans where troops at the front were bled to provide required blood. The British method proved more successful in adequately meeting all requirements, and over 700,000 donors were bled over the course of the war. This system evolved into the National Blood Transfusion Service established in 1946, the first national service to be implemented. Stories tell of Nazis in Eastern Europe during World War II using captive children as repeated involuntary blood-donors. Medical advances
A blood-collection program was initiated in the US in 1940 and Edwin Cohn pioneered the process of blood fractionation. He worked out the techniques for isolating the serum albumin fraction of blood plasma, which is essential for maintaining the osmotic pressure in the blood vessels, preventing their collapse. Gordon R. Ward, writing in the correspondence columns of the British Medical Journal, proposed the use of blood plasma as a substitute for whole blood and for transfusion purposes as early as 1918. At the onset of World War II, liquid plasma was used in Britain. A large project, known as "Blood for Britain", began in August 1940 to collect blood in New York City hospitals for the export of plasma to Britain.
Transfusions with large amounts of red blood cells, whether due to severe hemorrhaging and/or transfusion inefficacy (see above), can lead to an inclination for bleeding. The mechanism is thought to be due to disseminated intravascular coagulation, along with dilution of recipient platelets and coagulation factors. Close monitoring and transfusions with platelets and plasma is indicated when necessary. Metabolic alkalosis can occur with massive blood transfusions because of the breakdown of citrate stored in blood into bicarbonate. Hypocalcemia can also occur with massive blood transfusions because of the complex of citrate with serum calcium. Calcium levels below 0.9 mmol/L should be treated. Blood doping is often used by athletes, drug addicts or military personnel for reasons such as to increase physical stamina, to fake a drug detection test or simply to remain active and alert during the duty-times respectively. However a lack of knowledge and insufficient experience can turn a blood transfusion into a sudden death. For example, when individuals run the frozen blood sample directly in their veins this cold blood rapidly reaches the heart, where it disturbs the hearts original pace leading to cardiac arrest and sudden death. Frequency of use
Globally around 85 million units of red blood cells are transfused in a given year.In the United States, blood transfusions were performed nearly 3 million times during hospitalizations in 2011, making it the most common procedure performed. The rate of hospitalizations with a blood transfusion nearly doubled from 1997, from a rate of 40 stays to 95 stays per 10,000 population.