Blood transfusion

Why this is important

The literature suggests that there may be some evidence of harm with the use of restrictive red blood cell thresholds in populations with coronary ischaemia at baseline. In this guideline a level of 80–100 g/litre was used for patients with acute coronary syndrome, but further studies are needed to determine the optimal transfusion threshold for patients with chronic cardiovascular disease.

Why this is important

The clinical evidence evaluating electronic decision support systems is of low quality. There is also no evidence on their cost effectiveness within the NHS, and this is particularly important because of the potentially high setup and running costs of these systems. An evaluation of the clinical and cost effectiveness of electronic decision support systems for blood transfusion is needed. Important outcomes are rates of inappropriate transfusion, overall rates of transfusion, and patient safety outcomes including mortality and transfusion errors. Secondary outcomes should include length of hospital stay and quality of life; and pre‑transfusion haemoglobin levels, platelet count and coagulation results.

Why this is important

There was some evidence for benefit from post‑operative cell salvage, but the quality was low. Reducing blood loss during cardiac surgery may reduce the risk of complications. However, post‑operative cell salvage carries additional cost. Studies are needed to determine whether post‑operative cell salvage is more clinically and cost effective than existing practice for patients having cardiac surgery with a significant risk of post‑operative blood loss. Important outcomes should include the use of red blood cells and other blood components, clinical outcomes and quality of life.

Why this is important

Audits have shown that fresh frozen plasma is widely used for non‑bleeding patients in the intensive care unit (ICU) and many other clinical settings. There is a large variation in dose and no real evidence base to guide practice. Fresh frozen plasma transfusions may cause adverse outcomes in people who are critically ill, including transfusion‑related acute lung injury, transfusion‑related circulatory overload, multi‑organ failure and an increased risk of infections.

A multicentre study (2011) of ICUs in the UK showed that 12.7% of patients admitted to the ICU received fresh frozen plasma. The median dose was 10.8 ml/kg, but doses varied widely (range 2.4–41.1 ml/kg). This study showed that a high proportion of fresh frozen plasma transfusions had unproven clinical benefit.

Better evidence from clinical trials could significantly alter how fresh frozen plasma is used, and in particular ensure that clinically effective doses are given to patients.