Transfusion-related acute lung injury (TRALI)

Learning objectives

Transfusion-related acute lung injury (TRALI) is a transfusion reaction characterized by an acute, noncardiogenic pulmonary edema associated with hypoxia
The leading cause of death from transfusion
Caused by damage to pulmonary vasculature due to the immune response to antibodies or proinflammatory factors from the transfusion product that bind to antigens of the recipient
Symptoms include acute dyspnea, fever, hypotension, and tachycardia

Two-hit hypothesis:
- First hit: Priming of neutrophils due to shock, sepsis, organ damage, previous surgery, stress, trauma
- Second hit: Antibodies or proinflammatory factors in the transfusion product activate neutrophils, resulting in capillary leakage and subsequent pulmonary edema
Threshold hypothesis
- No first hit, a threshold must be overcome to induce TRALI
- Threshold depends on the susceptibility of the patient and the quantity of antibodies/proinflammatory factors in the transfusion product

Diagnostic criteria:
- Symptoms develop during or within 6 hours of transfusion without any risk factors for developing acute lung injuries (sepsis from pneumonia, aspiration, shock)
Clinical findings:
- Exudative bilateral infiltrates on chest radiograph
- No evidence of pulmonary vascular overload
- Hypoxemia: SpO2 <90% on room air, ratio of partial oxygen pressure to fractional inspired oxygen concentration <300 mmHg
- Possible TRALI: Other risk factors for acute lung injury
- Delayed TRALI: 6 – 72 hours after transfusion

Septic transfusion reaction: Signs of sepsis
Anaphylactic transfusion reaction: Laryngeal and bronchial edema
Transfusion-related circulatory overload: Increased pulmonary artery occlusion pressure (>18 mmHg)