Making the most of donors’ blood

Press, 24 February 1984, Page 15

Making the most of donors’ blood

Last year, 11,607 blood donors in Canterbury contributed about 18,853 units of blood, a remarkable effort for a voluntary service.

Most of these donors would be surprised to learn that each of their donations helped several patients. During the year 12,398 units of blood was issued to Canterbury hospitals, and a further 5962 units of plasma was made available for separating into components for specialised treatments. Mr Kevin McLoughlin, the charge technologist in the Blood Bank at Christchurch Hospital, explains that since the introduction of plastic packs in 1965 there has been a quiet but continuous revolution in the use of blood. Plastic bags connected by tubing as double bags, triple bags, and even quadruple bags, provide the possibility of dividing a donation aseptically in a closed system into different blood components.

Blood is made of straw-coloured fluid called plasma in which are suspended many tiny living cells. These are mostly red blood cells with some white cells and platelets. Altogether, the cellular components make up 45 per cent of the blood volume. Many cellular and protein components of blood can be separated from each other. Each blood component can then be used to replace a specific blood deficiency. Whole blood is required for about half of all transfusion therapy. In the other cases, component therapy provides accurate and scientific treatment.

With this blood component therapy, one donor’s 500 ml blood donation can be used to help several patients, each of whom will be receiving the particular portion they most require without any excess volume.

As an example, cryo-precipitate. which is a by-product of snap frozen fresh plasma rich in clotting

factor VIII, can be prepared as a 10ml concentrated component which is the only part of a blood unit that a haemophiliac needs to help stop episodes of bleeding. The average dose for bleeding problems is about 6 units of cryo-precipitate but this represents a total volume of around 60ml rather than 6 by 500 ml of blood (3 litres — a volume impossible to be assimilated in one dose by a human being). Other blood components produced by the Blood Bank are platelet concentrates and fresh frozen plasma. Even time-expired donations are used, for the plasma is removed for processing at the fractionation plant in Australia into a stable protein plasma solution (a very useful plasma substitute which can be used in emergency transfusions before blood is available), albumin solution (used in the treatment of severe illnesses with low plasma protein levels due to liver deficiency), immunoglobulins, which are used in cases where there is no active immunity against disease, and into other products. All are returned for local use. To permit the removal and processing of plasma, many of the red cell transfusions are resuspended in a sugar/salt solution. About onethird is still given as whole blood. Another special product is Rh(D) immunoglobulin which is used to prevent Rh disease in newborn babies. Donor appointment times have been introduced to provide a steady flow of donations for processing and to give each donor and donation the time needed for a quality service. Lifegiving blood is a free neighbourly gift in New Zealand, and the Blood Transfusion Service Centre and the Blood Bank take their responsibility seriously for looking after donors and making the most of their donations.

By

DENIS DWYER,

, information officer,

Canterbury Hospital Board.