Transfusion reactions

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What is Transfusion reactions?

Blood transfusion is associated with a number of potential side effects. These include:

Fever

Allergic reaction

Acute haemolysis (immediate breakdown of red blood cells)

Delayed haemolysis (delayed breakdown of red blood cells)

Anaphylaxis (severe allergic reaction)

Transmission of infection - Hepatitis B virus, Hepatitis C, and HIV are the most important

Electrolyte toxicity (for example low calcium, high potassium)

Iron overload

Who gets Transfusion reactions?

All transfusion reactions are uncommon: most are very rare. Approximate risk rates are given below:

Fever: 2:100
Allergic reaction (mild): 2:100
Acute haemolytic reaction: 1:12 000
Delayed haemolytic reaction: 1:1000
Anaphylaxis: 1:150 000
Hepatitis B transmission: 1:66 000
Hepatitis C transmission: 1:100 000
HIV transmission: 1:700 000

Predisposing Factors
Rigorous checks and screening of blood for compatability and blood-borne infections are carried out in Australia and throughout the Western world. Failure to perform these procedures would predipose to acute haemolysis and transmission of infection.

Patients with previous mild allergic reactions to blood transfusion are more likely to suffer this side effect. Deficiency of IgA antibodies in the bloodstream (rare) can predispose to anaphylaxis reactions.

Transfusion of large amounts of blood predisposes to electrolyte disturbance and iron overload.

Progression
Fever: antibodies are present in the recipient which are directed against donor white blood cells
Mild allergic reaction: an immune response is directed against various plasma proteins present in donor blood
Delayed haemolytic reaction: previous transfusion primes the recipient's immune system to reject donor cells during the next transfusion (alloimmunisation).
Acute haemolytic reaction: antibodies to donor red blood cells are already present in the recipient. For example, a recipient with 'B' blood group has antibodies to 'A' group blood; if group A blood is given the recipient's immune system will destroy the cells. Recipients with blood group 'O' can only recieve group 'O' blood, as they have antibodies to both group A and group B red blood cells.
Anaphylaxis - patients with Ig A antibody deficiency may be sensitive to this type of antibody. Donor blood with IgA sets off a severe allergic response in the recipient.
Hepatitis A, B, HIV are all blood-borne viruses which can survive in stored blood and will infect the recipient if present in transfused blood
Electrolyte toxicity - low calcium may occur due to the presence of citrate in transfused blood. Citrate is added to prevent blood from clotting while it is stored, however it may (rarely) cause low calcium in blood recipients. Potassium levels increase the longer blood is stored, as it leaks out of blood cells. This is only a problem if very large amounts of blood are transfused.

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