Blood can be thought of as a biological fluid that
is essential to human life, since without it the human body would be unable
to function. Blood is made up of several important components, and each
of these plays a key role in the everyday processes that take place in
the body.
For example, the body's white blood cells work hard to help us fight disease,
whilst small fragments of cells, known as platelets, allow the blood to
clot and stop us from bleeding to death when we cut ourselves.
Perhaps the most important role of the blood is to transport the two respiratory
gases:
1. Oxygen - into the body, from the respiratory surfaces of the lungs to our organs, e.g. heart and brain.
2. Carbon dioxide - out of the body, from the organs to the lungs and back out into the environment.
Red blood cells, (RBCs) are responsible for carrying these gases around our bodies, and it is for this reason that they make up such a large percentage the blood's composition.
One of the principle uses of blood in medicine, and the reason for the
development of blood transfusions, is to maintain the carriage of oxygen
to the organs during invasive surgery. This is required since surgery
is often associated with considerable blood loss.
What is blood transfusion?
 |
Blood transfusion is a remarkably safe, routine clinical procedure, which has been practised for decades. The procedure is necessary when a patient loses over 40% of their total blood volume, and subsequently, is unable to adequately transport the oxygen their vital organs require. A transfusion is then administered to replace
the lost blood volume, but also to replace RBCs, which are required
to transport the respiratory gases around the body and keep our
vital organs alive. |
Transfusions save countless lives and have allowed for the development of successful, complex, invasive surgery over the last 20 years. However, in the past few years the safety of blood transfusion has been questioned since the procedure has a number of associated problems. Such problems include:
- Problem of compatibility (need for crossmatching blood types)
- Problem of effective storage
- Problem of donor recruitment (blood shortages)
- Issues surrounding Human error
- Issues surrounding unnecessary transfusions
- Need for sophisticated blood processing
- Risk of disease transmission
- Issues of cultural and religious objection
Of these problems, it is the issues surrounding the risks of disease transmission, which have featured largely in the media over recent years. This has contributed to a loss in public faith in transfusion and subsequently to problems with recruiting blood donors. Only about 6% of the eligible UK population are considered active donors.
Despite rigorous screening to reduce the likelihood of viral disease transmission, as with all clinical procedures, a very small risk still remains:
| Risk factor | Estimated frequency per blood unit transfused | Deaths per million units of blood |
| Hepatitis B | 1 in 250,000 - 1 in 1,000,000 |
<0.5 |
| Hepatitis C | 1 in 3,000,000 | <0.5 |
| HIV | 1 in 4,000,000 | <0.5 |
| Bacterial contamination | 1 in 500,000 | <0.25 |