Transfusion triggers: How low can we go?

The goal of transfusion therapy should be to provide enough blood to meet the oxygen carrying needs of a patient to minimize mortality and morbidity, and to maximize functional outcomes. Pursuing the goal of 'how low can you go?' should be abandoned since the risks of blood transfusion are low and inconsistent with the goal of optimizing outcome. One well designed clinical trial in intensive care unit patients suggests that a 7-g/dl threshold is as safe, and perhaps safer, than a 10-g/dl threshold. Observational studies have confirmed this result. In patients with cardiovascular disease the evidence on the ideal transfusion trigger is less clear. A subgroup analysis of patients with cardiovascular disease from the TRICC trial found a non-significant trend towards lower mortality in patients receiving enough blood transfusion to keep the haemoglobin level above 10 g/dl. Several observational studies also suggest that higher red cell concentrations may be advantageous in patients with underlying cardiovascular disease. However, firm conclusion awaits further clinical trials in patients with cardiovascular disease like the one that is starting soon [14].