What is a Diffuse Alveolar Haemorrhage?

Key Facts About Diffuse Alveolar Haemorrhage

Diffuse alveolar haemorrhage (DAH) is not an individual disease but a serious, potentially life-threatening clinical syndrome with alveolar bleeding caused by extensive damage to the small pulmonary vessels. Pulmonary capillaritis, a small-vessel vasculitis, is the most significant cause of DAH. However, it can also occur due to immune complex deposition, coagulopathies, drug reactions, infections, or idiopathic reasons.

The illness usually occurs in the form of haemoptysis, anaemia, diffuse pulmonary infiltrates, and hypoxemic respiratory failure, while these findings are usually not specific. Now, DAH may be acute or subacute, but its consequences can be adverse if not recognised early and treated.

Let us explore this condition in more detail!

What are the Symptoms of Diffuse Alveolar Haemorrhage?

The following are the major symptoms and clinical manifestations of diffuse alveolar haemorrhage (DAH), both representative of alveolar bleeding and indications of possible underlying systemic conditions:

• Shortness of breath or dyspnoea, is one of the most frequent and initial symptoms, typically presenting as subacute or acute in nature.
• Coughs are the initial symptoms that can progress based on the underlying aetiology.
• Fever, typically of the underlying autoimmune or infectious aetiology.
• Haemoptysis (coughing up blood) is a classic symptom, but is absent in as many as one-third of cases because blood accumulates within the alveoli.
• Acute respiratory failure can present in severe cases and needs mechanical ventilation.
• Anaemia, which is usually progressive, is caused by persistent intra-alveolar bleeding and decreased haematocrit.
• There are no characteristic physical findings, and thus, clinical suspicion is essential for diagnosis.
• Other systemic manifestations may includehaematuria in vasculitis, arthritis in lupus, or cardiac murmurs in mitral stenosis.

What are the Causes of Diffuse Alveolar Haemorrhage?

There are different conditions that can lead to alveolar haemorrhage, including:

• Autoimmune disorders (for example, Goodpasture syndrome, systemic vasculitis, systemic rheumatic disorders, antiphospholipid syndrome)
• Haematopoietic stem cell or solid organ transplantation
• Cardiac disorders (such as mitral stenosis)
• Isolated pauci-immune pulmonary capillaritis
• Coagulation disorders resulting from diseases or anticoagulant therapies
• Idiopathic pulmonary haemosiderosis
• Pulmonary infections (like hantavirus infection)
• Adverse reactions to medications (including amiodarone, propylthiouracil, nitrofurantoin, methotrexate, infliximab montelukast)
• Toxic exposures (such as isocyanates, crack cocaine, trimellitic anhydride, certain pesticides, vaping)

How to Diagnose Diffuse Alveolar Haemorrhage?

Diffuse alveolar haemorrhage diagnosis involves a systematic process combining imaging, laboratory testing, and bronchoscopy to diagnose alveolar haemorrhage and determine its aetiology. The following are the main diagnostic methods:

• Clinical Test: Diagnosis is first analysed by presentation with symptoms like dyspnoea, cough, haemoptysis, and new bilateral alveolar infiltrates on chest imaging. Suspicion is high, especially when haemoptysis is not present, which happens in up to one-third of patients.
• Imaging Tests: A chest X-ray is usually characterised by patchy or diffuse alveolar opacities, whereas high-resolution CT scans can show ground-glass opacities, consolidation areas, and reticular patterns in long-standing cases.
• Bronchoscopy with Bronchoalveolar Lavage (BAL): This is the gold standard for diagnosis. BAL fluid with ongoing or rising blood throughout sequential aliquots indicates alveolar bleeding. Microscopic examination reveals many erythrocytes and siderophages (haemosiderin-containing macrophages). It is especially helpful in subacute or recurrent presentations.
• Laboratory Examinations: Important baseline investigationsare complete blood count (CBC) with anaemia and leukocytosis, platelet count, coagulation studies, and inflammatory markers (raised ESR, CRP).
• Serologic Test: Done to screen for autoimmune or vasculitic aetiology. Key markers are ANCA (particularly p-ANCA), anti-GBM antibodies, ANA, anti-dsDNA, antiphospholipid antibodies, and complements (C3, C4). These are useful in diagnosing systemic illnesses like Goodpasture syndrome, lupus, or microscopic polyangiitis.
• Renal Assessment: Urinalysis, BUN, and serum creatinine are useful in detecting pulmonary-renal syndromes. Haematuria, proteinuria, and red cell casts suggest underlying glomerulonephritis.
• Pulmonary Function Tests (PFTs): Patients who are stable may show elevated DLCO (diffusing capacity for carbon monoxide) due to intra-alveolar haemoglobin (acute-phase only). The test is not practical when there is active bleeding. Chronic patients can have restrictive and occasionally obstructive patterns based on underlying lung damage.

How to Treat Alveolar Haemorrhage?

Treatment of DAH entails both management of the alveolar haemorrhage and the underlying disease process. The major treatment approaches are as follows:

• Corticosteroids: Intravenous high-dose methylprednisolone (for example, 500 mg every 6 hours for 4–5 days) is the backbone of treatment for DAH, particularly in DAH associated with autoimmune illness or vasculitis.
• Immunosuppressive Agents: In severe to moderate or corticosteroid-refractory disease, agents like rituximab, azathioprine, cyclophosphamide, mycophenolate mofetil, or methotrexate may be given.
• Plasma Exchange (Plasmapheresis): This is utilised in Goodpasture syndrome or severe ANCA-associated vasculitis with elevated circulating levels of pathogenic autoantibodies or immune complexes. It helps remove these antibodies rapidly to minimise endothelial damage.
• Recombinant Activated Human Factor VII: This pro-coagulant has proved promising in case reports for the treatment of life-threatening steroid-resistant alveolar haemorrhage. However, its clinical uses have the potential risk of thromboembolic complications.
• Supportive Interventions: These comprise supplementary oxygen, bronchodilators for symptomatic improvement, correction of coagulopathies, and intubation with lung-protective ventilation strategies in patients with respiratory failure or acute respiratory distress syndrome (ARDS).
   

Diffuse alveolar haemorrhage is a critical medical emergency that needs to be recognised and treated expeditiously. Although it may start with nonspecific respiratory symptoms, its pathophysiology, diagnosis, and treatment are multifaceted and very specialised. Proper diagnosis and treatment are critical to help patients manage the condition effectively.

Furthermore, having a health insurance plan, under such circumstances, can help avail of quality treatment without delays, which may lead to favourable outcomes.  

Contact Star Health today for further details!

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