Blood transfusion and the lung: first do no harm?

Marked variability in transfusion practice exists in cardiac surgical patients, with consumption of approximately 20% of the worldwide allogeneic blood supply. Observational studies have reported an association between red blood cell transfusion and adverse outcome, including pulmonary complications, in cardiac surgery. Tuinman and colleagues report that transfusions were associated with activation of pulmonary inflammation and coagulation by measurement of biomarkers in bronchoalveolar lavage fluid, and suggest that transfusion may be a mediator of acute lung injury. This study provides interesting preliminary data, but is limited by multiple confounding variables (plasma transfusion, use of anticoagulants and heparin antagonists) and the small sample size. A large multicenter, prospective, randomized clinical trial regarding the safety (inclusive of pulmonary complications) and efficacy of red blood cell transfusion in cardiac surgery is needed.