How has the United States implemented measures to reduce the risk of Transfusion-Related Acute Lung Injury (TRALI) in blood banks?

Measures Implemented in US Blood Banks to Reduce TRALI Risk

The United States has significantly reduced TRALI risk through implementation of male-predominant plasma strategies, donor screening for leukocyte antibodies, and improved component processing techniques, making TRALI prevention one of the most successful blood safety initiatives in recent decades. 1

Understanding TRALI and Its Significance

• TRALI presents as acute lung injury within 6 hours of transfusion with key clinical features including hypoxemia, respiratory distress, and bilateral pulmonary infiltrates without evidence of circulatory overload 2
• TRALI has been identified as a leading cause of transfusion-related morbidity and mortality in the United States, requiring prompt recognition and reporting to blood banks 2
• The syndrome results primarily from immune reactivity of leukocyte antibodies, with signs and symptoms typically appearing 1-2 hours after transfusion 3

Key Risk Mitigation Strategies Implemented in US Blood Banks

Male-Predominant Plasma Strategy

• The AABB requires that all plasma-containing components and whole blood for transfusion must be collected from men, women who have not been pregnant, or women who have tested negative for human leukocyte antigen antibodies 1
• This strategy was implemented after recognizing that plasma components from female donors with leukocyte antibodies were responsible for most TRALI cases 4
• The American Red Cross demonstrated effective reduction of TRALI risk with this approach, increasing male donor plasma from 55% in 2006 to 95% in 2008, resulting in significantly reduced TRALI cases (32 vs. 7 cases; OR = 0.21) 5

Expanded Mitigation Requirements for Platelet Products

• AABB Standards expanded TRALI risk mitigation requirements to include apheresis platelets by October 2016 6
• Fresh frozen plasma (FFP) and platelet concentrates were identified as the blood components most frequently implicated in TRALI 7
• This expansion was expected to further decrease TRALI risk beyond what was achieved with plasma mitigation alone 6

Donor Screening and Testing

• Implementation of screening for donors with leukocyte antibodies, particularly focusing on female donors with previous pregnancies 4
• Female blood donors with previous pregnancies frequently have HLA antibodies with an overall prevalence of 24%, increasing with the number of pregnancies 4
• Testing of female apheresis platelet donors for HLA antibodies has been implemented as an additional risk reduction strategy 4

Effectiveness of TRALI Risk Mitigation

• The incidence of TRALI has decreased significantly following implementation of these mitigation strategies, though it remains an important cause of transfusion-associated mortality 1
• The American Red Cross demonstrated that TRALI involving only plasma transfusion was reduced to a level no longer different from the rate observed for RBC transfusion (4.0 vs. 2.3 per million distributed components) 5
• These measures have been particularly effective at reducing antibody-mediated TRALI in plasma components 6

Additional Risk Mitigation Options

• Plasma replacement with platelet additive solution for apheresis platelets 6
• Component washing and volume reduction techniques 6
• Careful assessment of transfusion need, especially in high-risk patients 2
• Using appropriate ratios of blood products during massive transfusion protocols 2

Ongoing Challenges

• Despite significant progress, TRALI remains an important cause of transfusion-related mortality 1
• The "two-hit" mechanism of TRALI, where neutrophil priming factors in transfused components can cause TRALI in patients with pulmonary endothelial activation, presents ongoing challenges 4
• Further research is needed to understand blood component and patient risk factors to develop additional risk reduction strategies 4