Transfusion-Related Acute Lung Injury: An Update

Abstract

Transfusion-associated acute lung injury (TRALI) has emerged as a leading cause of transfusion-related morbidity and mortality. TRALI is characterized by acute non-cardiogenic pulmonary edema and respiratory compromise in the setting of transfusion. The study of TRALI has been hampered by inadequate case definitions and an incomplete understanding of the pathologic mechanisms. Recent consensus conferences took an important first step by providing a framework for case definition. Recent advances in the understanding of the pathogenesis of TRALI have also occurred. TRALI has been primarily attributed to donor leukocyte antibodies that are thought to interact with recipient neutrophils, resulting in activation and aggregation in pulmonary capillaries, release of local biologic response modifiers causing capillary leak, and lung injury. An alternate mechanism termed the "two hit" or "neutrophil priming" hypothesis postulates that a pathway to neutrophil activation and aggregation can occur without leukocyte antibodies. A first event such as sepsis or trauma can induce pulmonary endothelial activation, release of cytokines, and priming of neutrophils. A subsequent second event such as exposure to lipids, cytokines or antibodies in a blood component would then cause activation of adherent neutrophils and a release of bioreactive molecules leading to lung injury. There are limited clinical and animal studies to support the "two hit" model. These proposed mechanisms are not mutually exclusive in that donor leukocyte antibody can be pathogenic in both models and have implications for new strategies to prevent TRALI.Advances in blood safety have greatly reduced the risk of transfusion-associated infectious disease transmission. As a result, noninfectious serious hazards of transfusion have come to the forefront as increasingly important blood safety issues. Transfusion-associated acute lung injury (TRALI) has emerged as a leading cause of transfusion related morbidity and mortality.1 This report will summarize recent consensus conferences that have provided practical clinical definitions of TRALI to aid the clinician in diagnosis and to facilitate its study. Recent advances in understanding of the pathogenesis of TRALI will be presented with a potential unifying hypothesis. DefinitionA lack of a standardized definition of TRALI has hindered accurate clinical diagnosis, epidemiology, and research investigation. A recent NHLBI working group convened to identify research needs addressed this critical issue by providing the following definition: "new acute lung injury (ALI) occurring during or within 6 hours after a transfusion, with a clear temporal relationship to transfusion, in patients without or with risk factors for ALI other than transfusion."2 Limitations to the proposed NHLBI working group definition are the exclusion of patients with preexisting ALI, excluding cases with onset more than 6 hours after transfusion, lack of laboratory diagnostic criteria, and a required severity of hypoxia that would miss cases of mil...

Transfusion-related acute lung injury: A dangerous and underdiagnosed noncardiogenic pulmonary edema

“…Although the clinical picture of TRALI is indistinguishable from ALI or ARDS due to other than transfusion causes, the mortality rate for ARDS is 29-70% while for TRALI it is between 5% and 10% [30,35]. In 80% of cases the patient's condition improves within 48-96 h while in others the infi ltrates in the X-ray persist and the patients require prolonged ventilatory support.…”

“…The main symptom is dyspnea, which often co-occurs with tachypnea, tachycardia, cyanosis and frothy pulmonary secretions. Fever, hypotension or hypertension are also reported [6,25,30]. Decreased breath sound and diffuse crackles over the lung fi elds are revealed in physical examination [25].…”

“…Hemodynamic monitoring helps to differentiate TRALI and cardiogenic pulmonary edema. Normal or low pulmonary capillary wedge pressure and central venous pressure values are characteristic for TRALI [4,30].…”

Transfusion-related acute lung injury: a rare and life-threatening complication of a common procedure

“…[2][3][4] The clinical picture is similar to acute respiratory distress syndrome (ARDS) with sudden onset respiratory distress due to noncardiogenic pulmonary oedema, hypovolaemia/ hypotension (less commonly hypertension), fever (typically 1-2°C increase) and copious frothy pink pulmonary secretions. 3,[5][6][7] The CXR exhibits bilateral fluffy infiltrates with type 2 respiratory failure on ABG analysis. 3,5,7 There is no evidence of fluid overload and the CVP and pulmonary wedge pressure are normal.…”

“…3,[5][6][7] The CXR exhibits bilateral fluffy infiltrates with type 2 respiratory failure on ABG analysis. 3,5,7 There is no evidence of fluid overload and the CVP and pulmonary wedge pressure are normal. 7 Laboratory findings may include haemoconcentration, leukopenia, neutropenia or neutrophilia, hypoalbuminemia and hypocomplementemia.…”