TRALI

OVERVIEW

Transfusion-related acute lung injury (TRALI) is defined as hypoxia and bilateral pulmonary edema occurring during or within 6h of a transfusion in the absence of other causes such as cardiac failure or intravascular volume overload

• incidence is 1 in 5,000 U of plasma-containing products (FFP, platelets or whole blood)

CAUSE

Theories

1. donor anti-granulocytic antibodies called leukoagglutinins in plasma target recipient leucocyte antigens on neutrophils sequestered in the lungs, resulting in an immune reaction
2. “biological response modifiers” (BRMs) such as cytokines and biologically active lipids (e.g. in aged cellular components) cause a lung-mediated response

Pathophysiology

“2 hit” model: lung capillaries are primed by an underlying illness and then triggered by exposure to irritants in blood transfusion

• Step 1: underlying illness -> complement activation -> pulmonary sequestration of neutrophils
• Step 2: transfusion -> neutrophil activation -> endothelial cell damage and capillary leak syndrome

CLINICAL FEATURES

• dyspnoea
• hypoxia
• fever
• hypotension or hypertension

DIAGNOSIS

• acute onset ALI(within 6 hours of a transfusion
• hypoxia (PaO2/FiO2 <= 300mmHg regardless of PEEP or SpO2)
• bilateral pulmonary infiltrates
• not cardiogenic in origin (PAWP < 18mmHg)

DIFFERENTIAL DIAGNOSIS

• acute pulmonary oedema e.g. TACO (transfusion-associated circulatory overload), LVF, negative pressure pulmonary edema, neurogenic
• aspiration pneumonitis
• inhalational injury
• ALI/ ARDS due to sepsis or other causes
• fat embolism
• diffuse alveolar haemorrhage (expect hemoptysis)

INVESTIGATIONS

• haemoconcentration
• hypoalbuminaemia
• neutropenia or neutrophilia
• pulmonary fluid analysis (hydrostatic versus capillary leak)

MANAGEMENT

• stop transfusion
• respiratory support (may require NIV or intubation)
• lung protective ventilation if intubated
• haemodynamic support if needed e.g. noradrenaline
• supportive care and monitoring
• no evidence for steroids
• inform blood bank and haematology

PROGNOSIS

• most recover within 48-96 hours
• radiological changes often last 7 days
• mortality 5%

PREVENTION

• limit transfusion of blood products
  • preoperative optimization of blood volume (dietary supplements, Fe2+, EPO), prevent hypothermia, use antifibrinolytics, cell salvage
• avoid donations (especially FFP) from multiparous women

References and Links

References

• Gajic O, Gropper MA, Hubmayr RD. Pulmonary edema after transfusion: how to differentiate transfusion-associated circulatory overload from transfusion-related acute lung injury. Crit Care Med. 2006 May;34(5 Suppl):S109-13. PMID: 16617253.
• Sayah DM, Looney MR, Toy P. Transfusion reactions: newer concepts on the pathophysiology, incidence, treatment, and prevention of transfusion-related acute lung injury. Crit Care Clin. 2012 Jul;28(3):363-72 PMC3380279.
• Shaz BH, Stowell SR, Hillyer CD. Transfusion-related acute lung injury: from bedside to bench and back. Blood. 2011 Feb 3;117(5):1463-71. PMID: 20944069.
• Triulzi DJ. Transfusion-related acute lung injury: current concepts for the clinician. Anesth Analg. 2009 Mar;108(3):770-6. PMID: 19224781.

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