Which carries the biggest risk: Anaemia or blood transfusion?

It is well recognized that anaemia, a frequent complication of critical illness, is associated with poor outcomes, perhaps particularly in patients with ischaemic heart disease. But studies have also reported increased morbidity and mortality in patients who receive blood transfusions. So which carries the biggest risk, when should we transfuse and when should we hold off? Should we have fixed transfusion triggers and if so in all patients, or different triggers for different groups of patients? Indeed, these are more complex decisions than initially apparent. ICU patients are very heterogeneous and will react differently to the same intervention. As such, decisions to transfuse or not must be individualized, taking into account specific patient factors, such as age and comorbidities, physiologic variables, as well as the haemoglobin value. This approach will ensure that anaemia is treated when necessary while avoiding unnecessary exposure to red blood cells.