Purpose of review: This review summarizes the current evidence base for commonly transfused blood components with a particular focus on the nonacutely bleeding patient.
Recent findings: There remains little definitive evidence to guide transfusion practices in the critically ill. The most rigorous evidence to guide red blood cell (RBC) transfusion practice is derived from the Transfusion in Critical Care Trial (TRICC Trial) that was published in 1999. Specific subgroups of patients may be at particular risk of the adverse effects of anemia, and require further study. There are no randomized controlled trials addressing clinically important outcomes evaluating frozen plasma, platelet thresholds, or impaired platelet activity in the critically ill.
Summary: As all blood components have some level of risk, the general approach to transfusion should be one of minimization. For the nonacutely bleeding critically ill patient, a RBC transfusion trigger of 70 g/l is clinically acceptable. For patients at potentially higher risk of adverse effects related to anemia such as those with septic shock, severe and/or acute ischemic heart disease, or brain injury, a higher threshold (80–90 g/l) may be considered. There is insufficient evidence to recommend specific thresholds for transfusion of frozen plasma or platelets in the critically ill.