THE process of giving a blood transfusion to a patient, or treating him or her with a blood product, begins with the recruitment of donors.
Donors should be between 18 and 65, weigh at least 8st, be in normal health and have no history of infectious hepatitis (jaundice). However, as hepatitis B can be asymptomatic, the donor does not necessarily know if he or she has had it.
When the blood (about three-quarters of a pint) is given, a sample is taken to screen for the presence of hepatitis B and C antibodies, for HIV or syphilis. If any of these conditions is detected the patient is notified.
The sample is also used to determine the donor's ABO and rhesus groups. The majority will be in the O group (in Ireland about 55 per cent of the population are in this group); 31 per cent in group A; 11 per cent in group B; and 3 per cent in group AB. Some 85 per cent will be rhesus positive, with IS per cent rhesus negative.
A conflict between the rhesus factor in the blood of a rhesus negative mother and her rhesus positive foetus is the condition which required the use of the anti-D blood product among the women who contracted hepatitis C.
The blood is then divided into three components, red cells, plasma and platelets. The platelets make up about 10 per cent of the blood, and the remainder is fairly evenly divided between plasma and red cells.
Red cells are used to treat conditions such as anaemia and haemorrhage. Different preparations are also made which incorporate red cells, like CPDA-1, used in exchange transfusion in very young babies.
Plasma, the fluid in which blood cells are suspended, is obtained through donation of whole blood, and through apheresis.
This involves taking a blood component from a donor using a cell separator. For example, only platelets and plasma are taken at the time of donation, and other fractions, such as red cells, are returned.
Plasma is important for the manufacture of a range of blood products. Once acquired, it is pooled and processed into components like Factor 8 concentrate (used in the treatment of haemophilia).
Plasma can also be given to patients through plasma exchange.
Platelets are small particles in the blood which clump together and seal off holes in blood vessels following injury. When they are reduced, individuals bruise and bleed easily, which in certain circumstances can be life-threatening. Platelets can be given by transfusion.
The blood components are either held in a pool at the temperatures appropriate to the different ones or made into the various blood products. Once they reach the hospitals, they are checked for compatibility with the patient due to receive them, and administered.
Records of every stage of all these processes should be kept. However, some of those relating to donations given and products made before 1985 have gone missing in the BTSB.