Blood Transfusion Practice

Our completed work has described current use of blood transfusions in intensive care units.

Background

Understanding the risk to benefit balance of giving blood transfusions is important because many patients receive them in intensive care. Many patients become anaemic during critical illness. This results from many factors including bleeding, blood sampling, and blood “dilution” as a result if the intravenous fluids usually required during treatment of critical illness. We also know that many patients do not produce red blood cells effectively when they are critically ill. When a patient becomes anaemic doctors often correct this with blood transfusions, but much uncertainty remains about exactly when blood transfusions should be given. This decision is easier when patients are bleeding and transfusions are used to replace lost blood, but most blood transfusions are given to treat anaemia alone. In this situation most doctors use a trigger value for the haemoglobin concentration and have a safe target range in their mind when deciding whether to given a transfusion. Understanding the risk to benefit balance of giving blood transfusions is important because many patients receive them in intensive care.

Completed work

Our completed work has described current use of blood transfusions in intensive care units, and the factors that influence the decision to prescribe a transfusion. We have shown that the presence of heart disease makes clinicians think anaemia is less safe, although the evidence to support this is weak. We have also shown that anaemia is very common, and often severe, following critical illness. It persists for many months in some patients and may be associated with persisting inflammation in the body. Together with colleagues in Canada, we are interested in whether the time that blood is stored prior to transfusion is important. We conducted the first randomised trial of older versus fresher blood transfusions in critically ill patients finding no difference in “physiological” outcomes.

International ABLE trial

We are currently completing a randomised trial of two different blood transfusion strategies for older sicker patients requiring intensive care. We are also leading recruitment in the UK to the international ABLE trial, which is a large trial comparing the use of transfusions with blood stored for a week or less in the blood bank with the current standard blood transfusions, which typically have been stored for 3 weeks.

Our other studies in this area relate to the use of plasma and platelets in intensive care. We have completed large studies describing how common coagulation abnormalities are, how plasma is currently used, and the factors that may influence clinicians when using plasma.