interstitial lung diseases Flashcards Preview

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Flashcards in interstitial lung diseases Deck (30)
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1
Q

what is the interstitium?

A

supporting structures of the lungs: alveolar endothelium, capillary endothelium, basement membrane, connective tissue

2
Q

what thickens the interstitium?

A

fluid, cells and fibrosis

3
Q

what are the functions of the extracellular matrix?

A
  • tensile strength/elasticity
  • low resistance for effective gas exchange
  • tissue repair/modelling
4
Q

what happens to the extracellular matrix during fibrosis?

A

aberrant wound healing leads to excessive deposition in the interstitium

5
Q

what are the simple classifications of interstitial lung diseases?

A
  • idiopathic
  • sarcoidosis
  • connective tissue disease
  • hypersensitivity pneumonitis
  • drugs
6
Q

what are the symptoms and clinical signs of IPF?

A
  • slow progressive exertional dyspnoea
  • non-productive cough
  • dry, inspiratory bibasal velcro crackles
  • +/- clubbing of fingers
  • abnormal pulmonary function test results: restriction impaired gas exchange
7
Q

what is the summary of IPF?

A
  • unknown cause
  • causes progressive, irreversible fibrosis and is fatal
  • is limited to the lungs
  • affects lower and peripheral lung
  • minimal inflammation: no role for steroids
  • is a disease of older (median age 66 years)
  • is more common in men
  • is more common in smokers
  • HRCT is mainstay of dx but lung biopsy may be needed
8
Q

how do you manage IPF?

A

assess suitability for anti-fibrotic drugs

  • pirfenidone and nintedanib
  • can only be prescribed by specialist centres
  • aim is to slow rate of disease progression

criteria

  • diagnosis of IPF
  • forced vital capacity (FVC) 50-80%

assess suitability for lung transplant

  • age <65
  • no significant comorbidities
9
Q

how do you get hypersensitivity pneumonitis?

A
  • bird droppings
  • farmers lungs
  • aspergillus
  • antigen is unknown 50%
10
Q

what is hypersensitivity pneumonitis?

A
  • diffuse inflammation of parenchyma in response to inhaled antigen
  • tends to involve upper lobes
11
Q

how does acute hypersensitivity pneumonitis present?

A
  • dyspnoea, cough, fever, malaise, crackles within 4-6 hours of heavy exposure
  • often misdiagnosed as an infection
12
Q

how does subacute hypersensitivity pneumonitis present?

A

gradual onset of symptoms, weight loss is common

13
Q

how does chronic hypersensitivity pneumonitis present?

A
  • insidious onset, history of acute episodes may be absent
  • incomplete resolution with removal of antigen
  • may lead to irreversible fibrosis
14
Q

how do you diagnose hypersensitivity pneumonitis?

A

serum precipitins to specific antigen may be helpful

  • infinite number of possible antigens
  • may be positive in asymptomatic individuals
  • negative results do not exclude HP
15
Q

how do you manage hypersensitivity pneumonitis?

A
  • avoidance of inciting antigen
  • usually steroid-responsive in early disease
  • may be progress to irreversible fibrosis
16
Q

what are the characteristics of drug induced ILD?

A
  • medication history is very important
  • many drugs but most common: nitrofurantoin, amiodarone, methotrexate
  • always consider if medication may be implicated
  • association between initiation of drug and disease onset is important
  • ILD may develop months to years after starting the drug
17
Q

what are the characteristics of connective tissue disease related ILD?

A
  • rheumatoid arthritits
  • scleroderma
  • sjogrens
  • polymyositis
  • younger patients
  • female preponderance
  • detailed and: dry eyes/mouth, Raynauds, joint pain/swelling, rashes
  • bloods: antinuclear antibodies, rheumatoid factor
  • management: lipase with rheumatology, treat underlying disease
18
Q

what is the summary diagnosis of ILD?

A
  • clinical assessment: CTD symptoms, drugs, exposures
  • bloods: antinuclear antibodies, rheumatoid factor, angiotensin-converting enzyme (ACE)
  • spirometry/lung function: FVC, FEV/FVC ratio, gas transfer
  • CXR: reticular shadowing
  • HRCT pattern of disease: the cornerstone of diagnosis
  • lung biopsy: enhances diagnosis but rik often outweighs benefit, may differentiate IPF from other potentially reversible causes
19
Q

what is the summary treatment for ILD?

A
  • remove cause
  • immunosupression
  • anti-fibrotics for IPF
20
Q

what is sarcoid?

A
  • multisystem granulomatous disorder
  • non-necrotising granulomas
  • cause unknown: 3 x more common in afro-carribeans, more severe disease, some familial clusters
  • disease of the young: 75% of causes aged 30-60
  • unpredictable clinical course
21
Q

what is the histology of sarcoidosis?

A
  • characterised by granulomatous inflammation
  • unknown foreign antigen stimulates immune response including: CD4+ T cells, alveolar macrophages, multi nucleate giant cells
  • organise into granulomas
  • granulomas occur in TB and fungal infections, but in sarcoidosis they are non-necrotising
  • a biopsy demonstrating granulomas along with clinical picture is needed to confidently diagnose sarcoidosis
22
Q

what are the most common areas that sarcoidosis affects?

A
  • chest
  • skin
  • eyes
  • lymph node biopsy
  • hypercalcaemia
  • peripheral nerves
23
Q

what are the characteristics of lofgen’s syndrome?

A
  • erythema nodosum
  • bilateral hilar lymphadenopathy
  • arthralgia
  • excellent prognosis
  • usually self limiting
24
Q

what are the symptoms of pulmonary sarcoidosis?

A
  • may be asymptomatic
  • cough
  • dyspnoea with exertion
  • chest tightness
  • systemic symptoms: fatigue, sweats, weight loss, fevers, arthralgia
25
Q

how do you diagnose pulmonary sarcoidosis?

A
  • no single diagnostic test
  • combination of clinical picture, exclusion of alternative diagnoses and ideally biopsy of affected tissue
  • baseline tests: renal function, liver function, calcium, serum ACE, CXR, ECG
  • serum angiotensin-converting enzyme (ACE)
  • biopsy everything: skin, lymph nodes, blind endobronchial biopsies
26
Q

what are the characteristics of serum angiotensin converting enzyme (ACE)?

A
  • secreted by activated alveolar macrophages in granulomas
  • low sensitivity, poor specificity
  • polymorphisms in ACE gene —> variation in peripheral blood ACE levels
  • no correlation with CXR stage of disease
27
Q

how do you treat pulmonary sarcoidosis?

A

major organ involvement

  • ocular disease not responding to topical treatment
  • cardiac
  • neurological

less clear cut for pulmonary disease

  • often less severe than extra thoracic disease with spontaneous remission common
  • short-term symptomatic benefit
  • long term effect on natural history of disease not known

corticosteroids for 6-24 months are mainstay

  • inhaled corticosteroids may provide symptomatic benefit
  • additional immunosuppressants
28
Q

what is obstructive spirometry?

A
  • indicated the problem in the airways
  • useful diagnostic
  • reversible airflow obstruction
  • fixed airflow obstruction in a smoker
  • only a few other diseases of the airways
29
Q

what is restrictive spirometry?

A
  • indicated there is a problem
  • not useful diagnostically
  • useful for monitoring change
  • severity indicator for ILD
  • treatment criteria for IPF
30
Q

when do you use restrictive spirometry of ILD?

A
  • restriction of lung expansion of loss of lung volume
  • directly measured by TLC: required lung function lab
  • FVC reflects the TLC
  • can be done in clinic
  • useful for disease monitoring