Which blood products have a higher incidence of Transfusion-Related Acute Lung Injury (TRALI)?

Fresh Frozen Plasma Has the Highest Incidence of TRALI Among Blood Products

Fresh frozen plasma (FFP) has been identified as the blood component with the highest risk for causing Transfusion-Related Acute Lung Injury (TRALI), followed by platelet concentrates. 1

Understanding TRALI

• TRALI is now recognized as one of the leading causes of transfusion-associated fatalities 2
• It presents as non-cardiogenic pulmonary edema resulting from immune reactivity, with symptoms typically appearing 1-2 hours after transfusion 1
• Key clinical features include hypoxemia, fever, dyspnea, and fluid in the endotracheal tube 1
• TRALI must be distinguished from Transfusion-Associated Circulatory Overload (TACO), which presents with similar respiratory distress but is characterized by fluid overload and cardiovascular changes 1

Blood Product Risk Hierarchy for TRALI

1. Fresh Frozen Plasma (FFP)

   • Highest risk due to its high plasma volume and potential for containing leukocyte antibodies 1
   • Most frequently implicated in TRALI cases 1, 3
   • The implementation of male-only plasma donation policies has significantly reduced TRALI incidence, confirming plasma's high-risk status 1

2. Platelet Concentrates

   • Second highest risk for TRALI 1
   • Platelets are stored at 20°–24°C, which facilitates bacterial growth (a separate transfusion risk) 2

3. Red Blood Cells

   • Lower risk compared to plasma-containing components, but still can cause TRALI 2, 3
   • Contains less plasma volume than FFP or platelet concentrates

Pathophysiology of TRALI

• TRALI is primarily caused by donor antibodies in plasma-containing blood components interacting with antigens on the patient's granulocytes 2

• Two main mechanisms have been proposed 3, 4:

  1. Antibody hypothesis: Passive transfusion of leukocyte antibodies (HLA class I, HLA class II, or neutrophil-specific antibodies) from donors
  2. Two-event hypothesis: Predisposing patient factors plus transfused biological response modifiers

• Leukocyte antibodies are identified in 60-85% of TRALI cases 3

• Multiparous female donors are the most frequent source of these antibody-containing components 3, 5

Risk Mitigation Strategies

• Blood banks have implemented measures to reduce TRALI risk, including 1, 5:

  • Screening donors for leukocyte antibodies
  • Using male-only plasma donors
  • For female donors, using only those without a history of pregnancy or with negative testing for antibodies against HLA I, II or HNA

• These strategies have been highly effective - in Germany, no TRALI-related deaths have been registered since implementing male-only plasma donation in 2009 5

Management of Suspected TRALI

• Immediately stop the transfusion 2, 1
• Provide critical care supportive measures and oxygen therapy 1
• Avoid diuretics, which are ineffective for TRALI (unlike TACO) 1
• Treatment is primarily supportive, focusing on respiratory support 2

Common Pitfalls and Caveats

• TRALI is often underdiagnosed and misidentified as TACO 3
• The incidence is likely higher than reported (commonly cited as 1:5,000 plasma-containing components) 3
• Certain patient groups may be at significantly higher risk 3
• In rare cases, recipient antibodies against donor leukocytes can cause "reverse TRALI" 6
• Always consider TRALI in the differential diagnosis when respiratory distress occurs within 6 hours of transfusion 2, 1