27th May 2023

Indications

Red cell transfusion is an essential tool in clinical medicine. In an actively bleeding patient, transfusion can prevent circulatory collapse and maintain tissue perfusion. In a patient with acute ischaemia, it can improve tissue oxygen delivery, relieve symptoms, and prevent complications. In a patient with chronic anaemia, it can relieve symptoms and improve quality of life. Blood product transfusion is, however, associated with significant potential risk and high cost. Judicious stewardship and selection of blood products is critical.

The decision to transfuse red cells is based on clinical assessment of the patient, as well as a full blood count (FBC) value. As a result, there is no universal trigger for transfusion and instead a patient-centred decision must be made. However general principles apply:

• In the haemodynamically stable, non-bleeding patient, transfusion should be considered if the haemoglobin (Hb) is 80g/L or less.
• If the Hb is below 70g/L, transfusion is usually indicated.
• Higher thresholds may be appropriate in individual cases, for example an anaemic patient with ischaemic heart disease and chest pain.
• In patients with gastrointestinal bleeding, once haemodynamically stable, over-transfusion may increase the risk of recurrent bleeding by increasing portal venous pressure.  Therefore, individual targets taking into account the case complexities should be used.
• Local protocols should be followed post-cardiac surgery and in cases of acute cerebral ischaemia/traumatic brain injury.

A red cell transfusion of 4ml/kg will produce an average rise in haemoglobin of ~10g/L, so a unit of packed red cells (250-300ml) should produce a 10g/L rise for a patient weighing 70-80kg. Patients who are not bleeding should be transfused a single unit and then reassessed before further blood is given. Haematology, oncology, gastrointestinal medicine (including liver disease) and renal medicine are the largest users of blood products.