Haematology - Understanding blood transfusions

GPs need to be aware of the risks and benefits of receiving blood, explains Dr Megan Rowley.

Some innovative schemes allow certain patients to receive blood in their own homes (Photograph: SPL)
Some innovative schemes allow certain patients to receive blood in their own homes (Photograph: SPL)

Most GPs are not involved in the administration of a blood transfusion. However, they need to be aware of the benefits and risks of receiving blood so that they can participate in the preparation of patients who might need blood during major surgery or, alternatively, support patients who have already had blood and are concerned.

Although most transfusions take place in hospital, patients can elect to be transfused in community hospitals and some innovative schemes allow some groups of patients to receive blood in their own homes.

The blood supply
In the UK blood is donated by volunteer donors aged 17 years and over. Modern testing strategies used by the UK blood services mean that transmission of infection by blood, such as HIV and hepatitis B or C, is extremely rare. The current estimated risk of an infectious donation in the UK for HIV is one in 5.13 million.1

The benefits and the risks
In patients who are bleeding catastrophically, for example as a result of trauma, childbirth or in people with liver disease, blood can be lifesaving. Hospitals caring for these patients must be able to provide compatible blood quickly and safely.

A recent Rapid response report from the National Patient Safety Agency (NPSA) recommended that hospitals have clear, effective and unambiguous policies in place for the transfusion support.

Outside the emergency setting, the benefit of blood transfusion is debated and audits of 'appropriate' transfusion in medical and surgical patients have shown unjustifiable variation in transfusion rates for any given clinical situation. The general trend is to use donated blood as little as possible.

Surgical setting
In the surgical setting a multifaceted blood conservation strategy can successfully reduce transfusion rates with the same or improved patient outcomes.

  • This starts with identifying and treating anaemia before major elective surgery and preferably in primary care, where consideration can be given to cause of iron deficiency.
  • Where surgical blood loss is inevitable, intraoperative salvage using specialised 'cell savers'; red cell collection and washing equipment which enables the patient to have their own blood back.
  • Postoperatively, the Hb threshold that triggers transfusion is now below 8g/decilitre for most, with a slightly higher threshold of 9g/decilitre in older patients and those with severe cardiovascular, cerebrovascular or respiratory problems. The volume of blood transfused is calculated to raise the Hb above the threshold, not to normalise it.

Medical setting
In the medical setting transfusion therapy in the treatment of anaemia should be limited to those where the cause of the anaemia has been investigated and there is no alternative treatment. In chronic iron deficiency, oral or even the new IV iron preparations should be considered as an alternative.

Those with inherited anaemia, such as bone marrow failure, as a result of haematological disease or as a result of treatment will need individualised transfusion plans.

Blood transfusions are not always given in patients with anaemia. It should be remembered that transfusion is invasive, can be uncomfortable and is time consuming, taking two to three hours every few weeks.

Anaemic symptoms can take 24 to 48 hours to improve and may be short lived as the Hb level falls within a few days. Studies of regularly transfused patients demonstrate that quality of life is influenced by peaks and troughs in Hb levels.

The blood supply is not limitless and should be conserved, where possible, for emergencies. In addition, blood is expensive - currently £124 per unit. It is also important to remember the potential complications of transfusion and every individual should have these balanced against the benefits.

Complications
Over the years, studies have suggested that transfusion increases mortality, infection rates and spread of cancer through immunomodulation but it is difficult to separate the reason the transfusion was given from the effects of the transfusion itself and there are no clear conclusions to say that transfusion is directly harmful.

However, there are some direct and serious complications associated with blood transfusion. While the risk of transmission of hepatitis and HIV by transfusion is extremely low, the most effective way of protecting patients against both known and unrecognised blood-borne infections is to avoid the use of blood products or tissues unless there is a well-founded reason.

The Serious Hazards of Transfusion (SHOT) scheme was established in 1996. It is a confidential system that encourages detailed evaluation of the root cause of adverse transfusion events. SHOT has enabled those involved in clinical transfusion practice, as well as blood services and policy-makers, to continually improve.

Since the beginning of SHOT, the number of deaths and serious adverse events caused by transfusion has reduced. In 2009, there was only one reported death directly due to transfusion.

Blood types
One of the most serious and preventable hazards of transfusion is giving the wrong blood to the wrong patient. ABO incompatibility can cause immediate collapse due to massive destruction of red cells by complement- fixing naturally occurring antibodies.

An NPSA report in 2006, Right patient, right blood, highlighted this as an area for improvement.

This initiative identifies a multi-step process involving phlebotomists, nurses, doctors, transfusion laboratory staff, porters and the patient themselves. All have to understand their role, and follow the correct procedure.

Competencies are now assessed for taking the blood sample to determine the patient's blood group and crossmatch against the donor blood; for collecting blood labelled by the transfusion laboratory; for bedside checking using a patient identification wristband prior to administration of the blood and for caring for the patient being transfused.

Patient information
Patients who need transfusion, or who have received a transfusion, may have questions and it is important that they are given a balanced view about the risks and the benefits.

Healthcare professionals and patients can access information leaflets on blood transfusion produced for adults and children of all ages by NHS Blood and Transplant.

  • Dr Rowley is a consultant haematologist, NHS Blood and Transplant and St Mary's Hospital, London

Reflect on this article and add notes to your CPD Organiser on MIMS Learning

CPD IMPACT: EARN MORE CREDITS

These further action points may allow you to earn more credits by increasing the time spent and the impact achieved.

  • Hold a practice meeting to discuss patients who may need a blood transfusion, with an emphasis on the support you can provide, including patient information leaflets.
  • Research the risks and benefits of identifying anaemia prior to major elective surgery so that patients can be investigated and treated.
  • Find out if blood transfusion is available in the community setting and ensure that staff involved have been trained and competency assessed.

Reference
1. Blood Transfusion Services and Health Protection Agency Professional Advisory Committee. Position Statement: Estimates of the frequency (or risk) of HBV, HCV, HIV and HTLV l infectious donations entering the blood supply per million donations (and 1 per million donations) tested. September 2010.

Further reading: McClelland DBL (editor). Handbook of transfusion medicine (fourth edition) Norwich, The Stationery Office. 2007.

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