Acute Lung Injury Following Blood Transfusion: Expanding the Definition

The classic transfusion-related acute lung injury (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 antileukocyte 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 (OR of 2.13; 95% CI, 1.75-2.52) of the development of the acute respiratory distress syndrome, 6-72 hrs 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%. Although the delayed transfusion-related acute lung injury 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 transfusion-related acute lung injury syndromes is essentially supportive.