24th July 2024

Blood products

Types of blood product

The components of blood are separated out and can be used individually to correct isolated parameters or used in conjunction for conditions which affect multiple factors of the haemostatic/bleeding pathways.  Whole blood is rarely used.

Common blood products include:

Major haemorrhage

The Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee defines major haemorrhage as:

• Loss of more than one blood volume within 24 hours (around 70 mL/kg, i.e. > 5L in a 70 kg adult)
• Half of total blood volume lost in less than 3 hours
• Bleeding in excess of 150 mL/minute.

This is difficult to calculate in an acute setting.  A more pragmatic approach is bleeding which leads to a systolic blood pressure of below 90 mmHg or heart rate above 110 beats per minute.

Management of major haemorrhage

All hospitals in the UK have a major haemorrhage protocol that will include the involvement of the blood products laboratory, haematologists, medical emergency team and porters. Major haemorrhages should be approached in an ABCDE manner with identification of bleeding source and stabilisation of the patient taking priority.

It is important not to forget the other blood products that are required in major bleeding. As well as red cells being lost in bleeding, plasma is also lost, which contains key components of the clotting cascade. If large quantities of only blood and IV fluids are transfused, this will lead to a dilutional coagulopathy. FFP, cryoprecipitate and platelets are therefore also required in major haemorrhage situations.

Anticoagulant therapy is common and it is important to reverse these agents during bleeding.

Certain conditions which cause major haemorrhage also require specific treatments. Terlipressin, a somatostatin analogue, is indicated in variceal bleeding as it acts as a splanchnic vasoconstrictor. In major trauma, immediate tranexamic acid is recommended, however in upper GI bleeds the recent HALT-IT trial has not endorsed its use. The management of bleeding in thrombophilic conditions such as haemophilia are covered elsewhere.

Complications of blood products

It is important to remember that blood transfusions, whilst increasingly safe, can have side effects. Patients must be informed of the risks prior to starting a transfusion. Note also that if a patient receives a blood transfusion, they cannot donate blood in the future.

Common complications include:

• ABO incompatibility: occurs when the blood group of transfused blood is incompatible with the recipient blood group, for example group AB blood being given to a patient who is O group. A serious haemolytic reaction will occur, potentially causing cardiovascular instability.
• Transfusion-associated circulatory overload (TACO): often associated with patients with heart failure who receive a transfusion. The patient presents with dyspnea, oxygen requirement and bilateral infiltrates on chest X-ray. Usually, this occurs within 6 hours of transfusion. As with pulmonary oedema, treat with diuretics.
• Transfusion-related acute lung injury (TRALI): presents with hypoxia (due to non-cardiogenic pulmonary oedema), fever and often hypotension. It is thought to be immune mediated. Typically, symptoms appear around 6 hours post transfusion. Treatment is supportive and discussion with intensive care may be needed. TRALI is rare, with an incidence of 1 in 150,000  units transferred.
• Bacterial contamination can occur, especially with platelet transfusions which are stored at 22-24°C (a temperature compatible with bacterial growth). Symptoms are similar to an acute sepsis response, with hypotension, tachycardia and fever. The transfusion should be stopped and the ‘sepsis 6’ protocol initiated.
• Febrile non-haemolytic transfusion reactions (common): typically, the patient develops a temperature whilst having a transfusion but is otherwise well. Paracetamol, slowing the transfusions and close observation is usually sufficient. However, fever may be the first symptom of a more serious reaction and thus close observation is advised.

References

• NICE Guidelines. Blood Transfusion (NG24). 2015 [cited December 17 2021] Available from: https://www.nice.org.uk/guidance/ng24
• Norfolk D. Handbook of transfusion medicine. 5th ed. London: H.M.S.O.; 2013