Appendix B - Transfusion risks in the context of patient blood management
Traditionally, it has been assumed that blood transfusion benefits patients; however, a benefit has not been demonstrable in many clinical scenarios. In addition, evidence is accumulating that transfusion- related acute lung injury is more common than previously thought, and that more recently identified conditions – including transfusion-related immunomodulation – may cause patients harm.
The risk of transmission of infectious diseases has reduced significantly in recent years through improved manufacturing and laboratory processes. Nevertheless, there is still a small potential for transfusion of an unrecognised infectious agent.
Despite improvements in systems management, there remains a risk of transfusion-related harm due to administrative error. Such an error has the potential to result in acute haemolytic reaction from ABO incompatibility, which may be fatal.
Of the recognised adverse events associated with transfusion, the most common is transfusion- associated circulatory overload, which is reported in up to 1% of patients receiving transfusions.
The clinical decision to undertake transfusion therapy should only be made after full consideration of the risks and benefits. Table B.1 summarises the risks and benefits; Table B.2 puts the risks into perspective; and Table B.3 presents the Calman chart, which may be useful to clinicians for explaining risks to patients.296
Table B.1 Transfusion risks and benefits
|Blood transfusion, including RBCs, platelets, FFP and cryoprecipitate||
FFP, fresh frozen plasma; RBC, red blood cell
Table B.2 Transfusion risks in perspective
|TRANSFUSION RISK||ESTIMATED RATE a (HIGHEST TO LOWEST RISK)||CALMAN RATING b|
|Transfusion-associated circulatory overload (iatrogenic)||Up to 1 in 100 transfusions||High|
|Haemolytic reactions||Delayed: 1 in 4,000–9,000
Acute: 1 in 12,000–77,000
|Anaphylaxis (IgA deficiency)||1 in 20,000–50,000||Very low|
|Bacterial sepsis: platelets||1 in 75,000||Very low|
|Bacterial sepsis: RBCs||1 in 500,000||Minimal|
|Transfusion-related acute lung injury||1 in 5,000–190,000||Low to minimal|
|Hepatitis B||1 in 739,000||Minimal|
|HIV||1 in 5.4 million||Negligible|
|Hepatitis C||1 in 2.7 million||Negligible|
|Malaria||1 in 4.9 million – 10.2 million||Negligible|
|Variant CJD (not tested)||Never reported in Australia||Negligible|
|Transfusion-associated graft-versus-host disease||Rare||Negligible|
|Transfusion-related immunomodulation||Not quantified||Unknown|
CJD, Creutzfeldt-Jakob disease; IgA, immunoglobulin A; RBC, red blood cell
a Risk per unit transfused unless otherwise specified
Source: Australian Red Cross Blood Service website (www.transfusion.com.au), accessed 9 December, 2009
Note: The above estimates may change over time. Refer to the Australian Red Cross Blood Service website (www.transfusion.com.au) for the most recent risk estimates.
Table B.3 Calman chart (United Kingdom risk per one year)
|Negligible||<1 in 1,000,000||Death from lightning strike|
|Minimal||1 in 100,000–1,000,000||Death from train accident|
|Very low||1 in 10,000–100,000||Death from an accident at work|
|Low||1 in 1,000–10,000||Death from a road accident|
|High||>1 in 1,000||Transmission of chicken pox to susceptible household contacts|
Patient blood management involves a precautionary approach to the administration of blood components, particularly red cells. Discussion of alternative strategies is relevant for all patients, not just those who choose not to accept a transfusion.
Patient blood management aims to improve clinical outcomes by avoiding unnecessary exposure to blood components. It includes the three pillars of:
- optimisation of blood volume and red cell mass
- minimisation of blood loss
- optimisation of the patient’s tolerance of anaemia.
In the process of obtaining consent, a clinician should allow the patient sufficient time to ask questions, and should answer those questions. If the patient is unable to speak or understand English, the clinician may need to involve an interpreter. In certain contexts, a trained medical interpreter may be required (rather than a family member or a friend). Written information and diagrams may be appropriate in certain circumstances to aid understanding.