Freezing plasma for transportation, Army Blood Supply Depot, Southmead Hospital, Southmead Road, Bristol
Samples of plasma or serum extracted from blood donations being placed in a bowl of CO2 snow (solid carbon dioxide and alcohol). This process freezes the liquid plasma and thus reduces the time taken to extract the moisture to dry it. Plugs of cotton wool keep the ampouls free from exterior bacteria. Once dried the plasma is much easier and lighter to transport. It can then be rehydrated ready for use when required, whereas a 'whole' blood does not keep well and is difficult to transport. The Army Blood Supply Depot, based at Southmead Hospital, was established in 1938 and began collecting blood from local donors in summer 1939. During the campaign in France in 1940, the Army Blood Supply Depot provided nearly all the blood and plasma required. Donated blood could be exchanged between the civilian and military blood depots, but the two services drew blood from separate pools of donors. Britain’s blood depot, established during World War One, and its fully functioning transfusion service pre-war meant that the transfusion service of the British army was well-organised compared to other armed forces.