Makindo Medical Notes

🩸 Diffuse Alveolar Haemorrhage (DAH) is a rare but life-threatening condition where blood acutely fills the alveoli. A retrospective review of 34 cases revealed that ~30% were due to granulomatosis with polyangiitis (GPA, formerly Wegener’s). 🚨 Rapid recognition is essential because untreated DAH carries a high risk of respiratory failure and death.

ℹ️ About

• DAH: Acute bleeding into multiple alveolar spaces caused by capillary disruption. 🫁
• Unlike haemoptysis from airway disease, DAH originates from the pulmonary microvasculature (arterioles, venules, capillaries).
• Represents a pulmonary emergency often associated with systemic disease.

🧬 Aetiology & Pathophysiology

• Disruption of the alveolar–capillary basement membrane → leakage of blood into alveoli.
• Triggered by inflammation (e.g. vasculitis), immune injury, toxins, or hypertension.
• Bleeding arises from pulmonary (not bronchial) circulation, explaining diffuse involvement.
• Key mechanisms: • Capillaritis (vasculitis, SLE, ANCA) • Bland haemorrhage (anticoagulation, mitral stenosis, toxins) • Diffuse alveolar damage (ARDS, infection, transplantation).

🤝 Associations

• ANCA-associated vasculitides: • Microscopic polyangiitis • Granulomatosis with polyangiitis (GPA) • Eosinophilic granulomatosis with polyangiitis (EGPA, Churg-Strauss)
• Autoimmune: Goodpasture (anti-GBM), SLE, mixed connective tissue disease, antiphospholipid syndrome.
• Other: HSP, cryoglobulinaemia, coagulopathy, HIV, Kaposi sarcoma, inhaled toxins, drugs (e.g. amiodarone, nitrofurantoin), mitral valve disease, pulmonary veno-occlusive disease, malignancy.
• Post allo-HSCT: DAH can complicate engraftment or GVHD.

🔺 Classical Triad

• Symptoms: Dyspnoea, haemoptysis (may be absent in 30%), anaemia.
• Imaging: CXR/CT → bilateral ground-glass opacities ± “bat-wing” alveolar infiltrates, usually no effusion, heart size normal.
• Bronchoscopy with BAL: Progressively bloodier aliquots on lavage = diagnostic. 🧪

👩‍⚕️ Clinical Features

• Rapid onset hypoxaemia, cough, haemoptysis (may be subtle or occult).
• Constitutional features if vasculitis/SLE present (fever, arthralgia, rash, renal disease).
• Severe cases: shock, acute respiratory failure, acute renal failure (pulmonary–renal syndrome).

🧪 Investigations

• Bloods: Falling Hb/Hct, ↑LDH.
• Serology: ANCA, anti-GBM, ANA, dsDNA, antiphospholipid antibodies.
• Clotting screen: Rule out coagulopathy.
• CXR: Diffuse bilateral alveolar infiltrates.
• CT Chest: Patchy or diffuse ground-glass opacities; sometimes “crazy-paving.”
• ABG: Hypoxaemia, possible Type I respiratory failure.
• Echo: Exclude cardiac cause (mitral stenosis, LV dysfunction).
• Bronchoscopy: Bloody BAL fluid diagnostic.

⚠️ Complications

• Acute respiratory failure requiring mechanical ventilation.
• Disseminated intravascular coagulation (DIC).
• Progression to organising pneumonia and pulmonary fibrosis.

💊 Management

• Stabilisation: ABC protocol, high-flow O₂, ventilatory support if required. Treat superadded infection with broad-spectrum antibiotics if suspected.
• Stop offending agents: Withdraw anticoagulants, offending drugs, correct coagulopathy.
• Immunosuppression: High-dose IV corticosteroids (methylprednisolone). Add cyclophosphamide or rituximab for vasculitis.
• Plasma exchange: Indicated in anti-GBM (Goodpasture) and severe vasculitis with pulmonary–renal syndrome.
• Targeted therapy: • ANCA vasculitis → Cyclophosphamide/Rituximab • Anti-GBM → PLEX + Cyclophosphamide • SLE/APL → Steroids ± Rituximab, anticoagulation balancing bleeding risk

📚 References

• Diffuse Alveolar Haemorrhage – Pulmonology Advisor
• Diffuse Alveolar Haemorrhage: Pathogenesis, Diagnosis and Management – PubMed Review