Transfusion-Related Acute Lung Injury

As early as 1957, the entity that would become known as transfusion-related acute lung injury (TRALI) was recognized as a potential adverse reaction from blood transfusion. However, poor understanding of the mechanism behind this entity led to its underrecognition for decades. TRALI is defined as acute lung injury (ALI) occurring within 6 h of cessation of transfusion and the presence of hypoxemia. Hypoxemia is defined by any of the following methods: the ratio of arterial oxygen partial pressure to fractional inspired oxygen (PaO₂/FiO₂) less than or equal to 300 mm Hg, oxygen saturation less than 90% on room air, or other clinical evidence. Additionally, radiographic evidence of bilateral pulmonary infiltrates needs to be identified with no previous evidence of ALI before the transfusion and no evidence for left atrial hypertension leading to circulatory overload.