Transfusion-related acute lung injury: a change of perspective.

Two decades ago, transfusion-related acute lung injury (TRALI) was considered a rare complication of transfusion medicine. Nowadays, TRALI has emerged as the leading cause of transfusion-related mortality, presumably as a consequence of reaching international agreement on defining TRALI with subsequent increased recognition and reporting of TRALI cases. Specific patient populations such as critically ill patients have an increased risk of developing TRALI, which may be explained by the two-event hypothesis. The first event is the underlying condition of the patient resulting in priming of neutrophils. The second event is the transfusion of a blood product, after which either antibodies or bioactive lipids activate the primed neutrophils, resulting in pulmonary oedema. As opposed to the traditional view that TRALI has a good prognosis, TRALI may have a significant impact on morbidity and outcome, at least in specific patient groups. The association of transfusion with adverse outcome calls for blood product and donor management strategies aimed at decreasing the risk of acquiring TRALI. Excluding female donors from plasma donation seems to have reduced, but not prevented the occurrence of TRALI . Additional research is needed to determine whether the use of fresh blood products may be an additional measure to reduce TRALI. Studies are also needed to identify at-risk patients. In these studies, we advocate the use of the consensus definition to improve comparability of risk factors and outcome of TRALI across patient populations.