Acute lung injury following blood transfusion: expanding the definition

Acute lung injury (ALI) is a well known complication following the transfusion of blood products and is commonly referred to as transfusion-related acute lung injury (TRALI). The objectives of this review are to summarize current knowledge of TRALI with an emphasis on issues pertinent to the intensivist and to define the newly recognized "Delayed TRALI syndrome."

The classic TRALI syndrome is an uncommon condition characterized by the abrupt onset of respiratory failure within hours of the transfusion of a blood product. It is usually caused by anti-leukocyte antibodies, resolves rapidly, and has a low mortality. A single unit of packed cells or blood component product is usually implicated in initiating this syndrome. It has, however, recently been recognized that the transfusion of blood products in critically ill or injured patients increases the risk (odds ratio 2.13; 95% confidence interval 1.75-2.52) for the development of the ALI 6-72 hours after the transfusion. This "delayed TRALI syndrome" is common, occurring in up to 25% of critically ill patients receiving a blood transfusion, and is associated with a mortality of up to 40%. While the delayed TRALI syndrome can develop after the transfusion of a single unit, the risk increases as the number of transfused blood products increase. The management of both the classic and delayed TRALI syndromes is essentially supportive.

Both the classic and delayed TRALI syndromes are among the most important complications following the transfusion of blood products and are associated with significant morbidity and increased mortality. The risk and benefits of all blood products should be assessed before transfusion.