These cells circulate in the body with the red and white cells and play an important role in the clotting process of the blood. Transfusion of platelets separated from several units of blood is now an important part of the treatment of platelet deficiency.
White cell transfusion
It is now established that successful transfusion of white cells can assist patients to combat infections when, as it sometimes happens in certain blood diseases, the patients' body is unable to produce its own white cells, These transfusions involve the use of specialised techniques and cell separation equipment. It is not possible to collect sufficient white cells through conventional blood donation.
plasma and albumin
Plasma Protein Fraction (PPF) is a clear fluid containing approximately 5% albumin. This is an end-product of plasma fractionation, it is widely used for the treatment of surgical shock and burns or, in remote areas, to maintain the volume of fluid in the circulation until a patient can be removed to a hospital with full transfusion facilities, or until compatible blood can be provided. Thus, it is extremely valuable in small hospitals and to ships, which traditionally carried dried plasma (which has now been largely succeeded by PPF). A more concentrated solution of lbumin, about 20 per cent, is also available.
Fresh Frozen Plasma
Fresh Frozen Plasma (FFP) is prepared from freshly collected blood by spinning it in a centrifuge. On separation, the plasma is immediately deep frozen and stored at minus 40°C. FFP contains all the proteins required for normal clotting of blood, and is commonly used in clotting factor deficiency usually caused by liver diseases.
This is prepared from Fresh Frozen Plasma by allowing it to thaw under conditions so adjusted that the Factor VIll settles out as a solid substance or precipitate. This can be separated by removal of the greater part of the thawed plasma after spinning in a centrifuge, and then deep frozen in packs. Cryoprecipitate also contains fibrinogen, another protein essential for normal clotting of blood. In some conditions, this disappears temporarily from blood and bleeding ensues. Transfusion of cryoprecipitate rapidly corrects the deficiency of fibrinogen and stops the bleeding. It can stored for one year at minus 40°C.
factor VIII Concentrate
This preparation has certain advantages over cryoprecipitate for the treatment of haemophiliacs. In particular, it enables them to be treated at It is also convenient for the control of bleeding when they undergo major surgery. This concentrate is prepared by fractionation of fresh plasma
These are substances carrying the antibodies which the body forms to protect itself against infectious diseases and foreign materials Immunoglobulins separated from the blood of healthy adults are valuable in preventing or attenuating certain infectious diseases such as measles and hepatitis. The blood of certain persons may contain particularly large amounts of one antibody for example, antibody against chicken pox or antibody against Rhesus factor D. The immunoglobulin prepared from such blood will contain high level of the antibody and is called, for example, anti-chicken pox immunoglobulin, or anti D immunoglobulin. Such specific immunoglobulins are of great value, particularly in case of Rhesus incompatibility between father and mother, which may lead to the birth of a child affected with haemolytic disease, the mother at risk can be sensitised with anti D immunoglobulins.
Autologous Blood Transfusion
In autologous blood transfusion, the patient serves as one's own blood donor. The underlying principle is that one's own blood will certainly be compatible and will not contain extraneous transmissible infections. The assumption is that 'one's own blood is the safest blood. ' This is true, but it should not be assumed that autologous blood can be used indiscriminately. Even autologous blood should be transfused only when absolutely needed. There are three basic forms of autologous blood use:
Autologous Blood Collection Prior to Planned Surgery
Persons who require surgery, but are otherwise in good health and able to donate blood safely, may reasonably donate blood for themselves prior to surgery. It is generally possible for a patient to donate 2 to 6 units of blood in this way, within a period of 2 to 4 weeks. A slight fall in haemoglobin level (not below llg-l00ml) is acceptable. Prescription of iron supplement, is usual which generally prevents the development of significant anaemia Some centres treat such patients with erythropoietin (EPO), a powerful hormone drug which stimulates the production of red blood cells in the bone marrow. The use of EPO in autologous donor/patients is stil controversial because of the cost and the possibility of side-effects such a: thrombosis.
Autologous donation has become well established in preparation for certain orthopaedic procedures which are likely to require blood transfusion (e. g- spinal fusion) and has been widely used in plastic surgery. More controversial, but also widely practised, is the collection of autologous blood prior to cardiac surgery or caesarean section. Some industrial and advanced countries have active autologous transfusion programmes for paediatric patients; others accept patients of any age (including above 90 years), regardless of cardiac status. There are concerns about the potential risk of such aggressive programmes.
Indications for Autologous DonationGenerally accepted
'Apheresis' refers to a type of donation in which the desired component is selectively withdrawn from the donor while residual parts of the blood are transfused back to the donor during the blood collection process itself. Apheresis techniques are most commonly used to obtain plasma and platelets. The principal factor limiting the amount of blood that can be collected from a donor is the slow replacement of red cells after donation. By returning the red cells to the donor, it becomes possible to collect much larger amounts of plasma, platelets, leukocytes. Apheresis may be applied therapeutically (therapeutic apheresis) as well as to obtain Products for transfusion.
PlasmapheresisPlasmapheresis is useful in three distinct situations:
Establishment of a volunteer donor plasmapheresis programme is a major decision. It is possible to develop large-scale programmes of this type, as has been demonstrated dramatically in Belgium. Many other countries have smaller but growing programme of his kind, for example Canada, France and England. The decision to initiate such a programme cannot be taken lightly because it requires a huge expansion in facilities, investment in cell separators, training of staff and complete reorganisation of the way the donors are recruited and organised.
Cytapheresis. or selective removal of specific cells like platelets, white cells etc. from the donor, while returning red cells and plasma with the help of machine known as cell separator. In case of platelet pheresis. sufficient platelets can be removed from a single donor in less than two hours to provide all the platelet needed for one patient. Naturally the donor has to stay in blood bank for longer hours. This also needs motivation. The donor recruiters have to be prepared to meet such requirement.