Idiopathic Pulmonary Fibrosis

Question 1

def

Answer 1

inflammatory condition of the lung resulting in fibrosis of alveoli & interstitium

Question 2

aetiology

Answer 2

a genetically predisposed individual (telomerase/surfactant protein mutations) has recurrent injury to alveolar epithelial cells which causes cytokine & GF secretion (TNF-a, IL-1) which causes fibroblast activation, recruitment, proliferationm differentiation into myofibroblasts & increased collagen synthesis & deposition
profibrogenic molecules (PDGF, TGF-B) are secreted from inflammatory, epithelial, endothelial cells

Question 3

what drugs can cause a similar illness to idiopathic pulmonary fibrosis

Answer 3

methotrexate

amiodarone

Question 4

what are the histological patterns in idiopathic pulmonary fibrosis

Answer 4

1 usual interstitial pneumonia
-patchy interstitial fibrosis
2 desquamative interstitial pneumonia
-diffuse intra-alveolar accumulation of macrophages
3 non-specific interstitial pneumonia

Question 5

risk factors

Answer 5

1 smoking
2 occupational exposure to metal or wood
3 microaspiration

Question 6

what is aspiration

Answer 6

entry of material (pharyngeal secretions, food/drink, stomach contents) into the lungs

Question 7

epi

Answer 7

rare
6/100,000PA
more common in males than females (with increasing age)

Question 8

history

Answer 8

gradual onset of progressive dyspnoea on exertion
dry irritating cough
no wheeze
symptoms may be preceded by a viral-type illness

Question 9

examination

Answer 9

clubbing (50%)
bibasal fine late inspiratory crepitations
signs of RHF (RV heave, raised JVP, peripheral oedema)

Question 10

investigations

Answer 10

1 bloods
-ABG (normal in early disease however PO2 decreases with exercise, there is normal PCO2 in early disease however this increases with late disease)
-1/3 have rheumatoid factor or antinuclear antibodies
2 CXR
-often normal at presentation
-early disease may have small lung fields & ‘ground glass’ shadowing
-late disease may show reticulonodular shadowing, especially at bases
-severe disease may show honeycombing
3 high resolution CT
-more sensitive in early disease than CXR
4 pulmonary function tests
-restrictive ventilatory defect (decreased FEV1, decreased FVC, normal or increased ration)
-decreased lung voumes
-decreased lung compliance
5 bronchoalveolar lavage
-to exclude infection/malignancy
6 lung biopsy
-gold standard for diagnosis however may not be appropriate
7 echo
-to look for pulmonary HTN