Red blood cell transfusion: what is the evidence when to transfuse?

Purpose of reviewThis review provides a summary of the clinical trials evaluating transfusion thresholds and recommendations for red blood cell transfusion. We highlight the trial results in patients in the critical care setting, undergoing surgery, and patients with gastrointestinal bleed, acute coronary syndrome, and acute brain injury.Recent findingsClinical trials in hip fracture patients with underlying cardiovascular disease or risk factors, and in cardiac surgery, support the findings from prior studies in intensive care unit patients that restrictive transfusion (7-8g/dl) is well tolerated even in elderly high-risk patients. Restrictive transfusion strategy (7g/dl) was further supported by the statistically lower mortality in patients with gastrointestinal bleeding compared with liberal transfusion (10g/dl) strategy. Pilot trials in acute coronary syndrome raise the possibility that liberal transfusion improves outcome, but large trials are needed.SummaryA restrictive transfusion strategy of administering red blood cell transfusion in patients with hemoglobin concentration of 7-8g/dl in most patients is supported by randomized clinical trials. Further randomized clinical trials are needed to establish the optimal transfusion threshold in patients with acute coronary syndrome and brain injury, and to elucidate physiological triggers.