When to give blood

With increased public awareness of the risks of blood transfusion and the decreased availability of blood products, the decision to transfuse a patient should be considered carefully. Most patients require a blood transfusion when haemoglobin levels fall below 8 g=dl or when there is greater than 30% loss of blood volume. However, the main indication for transfusing a patient is to increase their oxygen-carrying capacity and through invasive monitoring provide evidence of inadequate tissue oxygenation. Blood transfusions should be based on the patient’s risks of developing complications of inadequate oxygenation rather than on a single haemoglobin ‘trigger’.