Hypersensitivity Pneumonitis Flashcards
(26 cards)
Hypersensitivity Pneumonitis
Inhalation of allergens provoke hypersensitivity reaction => IgG & immune complexes deposited in walls of alveoli & bronchioles causing inflammation.
Type of Hypersensitivity reaction
Type III or Type IV
How long does it take for symptoms to appear in acute hypersensitivity Pneumonitis?
4-6 hours after acute exposure
Chronic inflammatory disease
Repeated low dose antigen exposure over time (years) resulting in granuloma formation & obstructive bronchitis in small airways & interstitium.
Cause of farmers lung
Spores from hay
Cause of pigeon fanciers lung
Avian proteins in bird poo
Cause of malt workers lung
Aspergillus from malt
Causes
Spores, proteins, aspergillus, drugs & 30% idiopathic.
Symptoms of acute HP
Dry cough, dyspnoea, fever, myalgia, fever, rigors
Signs of acute HP
Pyrexia, crackles, hypoxia
Symptoms of chronic HP
Progressive, increasing or exertional Dyspnoea, progressive cough, weight loss.
Signs of chronic HP
Crackles, clubbing
Investigations for acute HP
Bloods, CXR, spirometry
Investigations for chronic HP
Blood, CXR, spirometry, DCLA,
Investigations for chronic HP
Blood, CXR, spirometry, DCLO.
Bloods for acute HP
Neutrophilia & increased ESR
CXR for acute HP
Upper zone consolidation, widespread pulmonary infiltrates.
Spirometry for acute HP
Reversible restrictive pattern
Blood for chronic HP
Positive serum precipitants
CXR for chronic HP
Upper lobe fibrosis, honeycomb lung
Spirometry for chronic HP
Restrictive defect: Low FEV1 & FVC, high or normal ratio, low gas transfer.
DCLO for chronic HP
Reduced.
Treatment for Acute HP
Avoid allergen, oxygen, steroid (oral prednisolone), anti-fibrotic therapy in cases of progressive fibrosis (pirfenidone or nintedanib)
Treatment for Chronic HP
Avoid allergen & long term steroids
