interstitial lung disease Flashcards
occupational lung disease, IPF, general ILD
what is cumulative asbestos exposure expressed as?
fibre years -inhaled fibres/ml times years of exposure
what is the delay between asbestos exposure and asbestosis?
10-20 years but can be >40 years
what occupations have a risk of being exposed to asbestos?
mining or milling asbestos
construction
insulation
fireproofing
brake linings
ship building
pipe fitting
boiler fitting
carpentry
electric repair
regularly washing work clothes with asbestos in them
demolishing buildings with asbestos in them
highest risk in UK -carpenters, plumbers, and electricians
how does asbestos exposure lead to lung disease?
asbestos directly toxic to lung parenchymal cells
it also induces cytokine, protease, and reactive oxygen release which leads to inflammation.
what sort of pulmonary fibrosis does asbestos cause?
slow progressive and diffuse
what are the histological findings for asbestosis?
asbestos bodies can be seen -transparent asbestos fibres encased in iron and protein
what criteria diagnose asbestosis?
helsinki criteria
what are the diagnostic features of asbestosis?
1) evidence of structural pathology inkeeping with asbestos on either radiology or histology
2) evidence of causation by asbestos from occupational/environmental history, markers of exposure, or asbestos bodies. duration of 10-20years exposure is sufficient along with correct lag period.
3) exclusion of alternative causes of findings
when is histology used for cases of asbestosis?
not required or recommended in most cases
only used when diagnostic uncertainty for an ILD and mainly used to exclude treatable disease
what is the management of asbestosis?
-avoid further exposure
-smoking cessation
-annual flu and one off pneumococcal vaccine
-pulmonary rehab
-screening for other asbestos related diseases
-long term oxygen therapy
-no evidence for use of antifibrotics
which has a better prognosis IPF or asbestosis?
asbestosis
where in the lungs do asbestos fibres tend to move?
to the pleura -forming pleural plaques
what are the effects of asbestos fibres in the lungs?
pleural plaques, effusions, fibrosis, and in some cases cancer in the form of mesothelioma
what actually are pleural plaques and where are they found?
smooth areas of hyaline fibrosis
usually occur bilaterally on parietal pleura of chest wall, diaphragm, or mediastinum
what are some signs of pleural plaques?
pleural rub may be audible
cam modestly reduce lung volumes on spirometry if extensive
what is the significance of pleural plaques?
just show asbestos exposure
don’t require treatment, biopsy, or specific followup -don’t turn into cancer and are not markers of increased mesothelioma risk
what is benign asbestos pleural effusion (BAPE)?
unilateral pleural effusion caused by asbestos exposure. early sign -usually within 10 years.
what are the features of BAPE?
exudate
may be blood stained
how do you diagnose BAPE?
diagnosis of exclusion -need to rule out malignancy and other causes of unilateral pleural effusion
how do you manage BAPE?
will often resolve spontaneously after a few months but repeated aspirations or pleurodesis may be needed if patient is symptomatic.
what is pleurodesis?
putting a mildly irritant mineral powder into pleural cavity to ‘stick’ lungs to pleura to try and prevent pleural effusion build up as it seals the cavity.
what can happen to the lungs after a BAPE?
diffuse pleural thickening (DPT)
fibrosis of pleura -involves visceral and parietal pleura
investigations for diffuse pleural thickening (DPT)?
CXR -smooth, conglomerate opacity along pleura
CT -pleura >3mm thick
biopsy -sometimes needed to differentiate DPT from mesothelioma
PFTs-reduced vital capacity, TLCO low, KCO normal/high
what are the symptoms of diffuse pleural thickening?
pain and breathlessness from lung restriction.
